Comparison of the Inter-laminar Approach and Laminotomy Open Approach for Filum Terminale Lipoma: A Retrospective Analysis

Comparison of the Inter-laminar Approach and Laminotomy Open Approach for Filum Terminale Lipoma: A Retrospective Analysis | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Comparison of the Inter-laminar Approach and Laminotomy Open Approach for Filum Terminale Lipoma: A Retrospective Analysis Tomoki Nawashiro, Michihiro Kurimoto, Masamune Nagakura, Mihoko Kato, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3860133/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 11 You are reading this latest preprint version Abstract Purpose Filum terminale lipoma (FTL) causes spinal-cord tethering and is associated with tethered-cord syndrome, which is treated by dissection of the entrapment. The conventional treatment for FTL involves dissection of the spinal cord through a laminotomy open approach (LOA). However, in recent years, the interlaminar approach (ILA) has gained popularity as a minimally invasive surgery. This study compares the effectiveness of the minimally invasive ILA with the conventional LOA in treating FTL. Methods We retrospectively evaluated data on the ILA and LOA for FTL at our center. In total, 103 participants were enrolled, including 55 in the ILA group and 48 in the LOA group. Results The ILA required significantly less surgical time and resulted in less blood loss. The improvement rate of symptoms in symptomatic patients was 84%, and for urinary symptoms and abnormal urodynamic study findings, it was 77%. The postoperative maintenance rate for asymptomatic patients was 100%. Postoperative complications of ILA included delayed wound healing in two patients (3.6%). Conclusion Compared with LOA, ILA offers advantages in terms of shorter operative time and less blood loss, with no significant difference in long-term symptom-improvement rates between the groups. spina bifida filum terminale lipoma minimally invasive surgery tethered-cord syndrome Figures Figure 1 Figure 2 Introduction Filum terminale lipoma (FTL) is a type of spinal lipoma classified as closed spina bifida and type 4 lipoma as per the Morota classification [ 16 ]. The human spinal cord develops through primary and secondary neurulation; FTL originates from an abnormality occurring in the late stages of secondary neurulation [ 16 ]. As FTL causes tethered spinal cord, it is associated with tethered-cord syndrome. Furthermore, occult tethered-cord syndrome, which does not present with low spinal conus but has a symptomatic presentation, has been reported [ 15 ]. FTL detection rates on magnetic resonance imaging (MRI) and autopsy are 0.24–4% [ 3 ] and 4–6%, respectively [ 7 ]. The aim of surgical treatment for FTL is categorized according to symptomatic and asymptomatic cases to arrest/improve symptom progression and prophylaxis, respectively. In Japan, the universal health insurance system covers prophylactic surgery; historically, many prophylactic resections have been performed. Despite recommendations for prophylactic surgery, this intervention is controversial [ 13 , 33 ]. The standard surgical procedure for FTL is laminotomy-based dissection [ 9 ]; however, less-invasive techniques have been reported [ 8 , 10 , 22 ]. This study compared the effectiveness of the minimally invasive interlaminar approach (ILA) with the conventional laminotomy open approach (LOA) in FTL treatment. Moreover, although ILA has been reported to be safe, its long-term neurological prognosis has not yet been reported; thus, we investigated whether ILA can sufficiently improve prognosis. We believe that a less-invasive procedure should be selected only when its safety is established and its effects on neurological outcomes are comparable to that of surgery. Methods Study design This study retrospectively included 152 patients with terminally threaded lipoma who underwent surgery between April 2010 and November 2021 at a single center (Department of Neurosurgery, Aichi Children's Health and Medical Center), and their data were extracted from medical records (Online Resource 1). Symptomatic patients were excluded if there were no data of pre- or postoperative UDS or PT evaluation based on their symptoms, whereas asymptomatic patients were excluded if there was no UDS evaluation at the pre- or postoperative stage. Asymptomatic patients underwent motor-function evaluation during the physical examination by the physician-in-charge and a PT evaluation, if necessary. To ensure objectivity of the lower-extremity motor-function evaluation, the physician-in-charge uniformly evaluated deep-tendon reflexes, lower-extremity gross motor activity, and foot-deformity presence. The choice of ILA or LOA was determined by the operator. For the ILA technique, the height of the intervertebral approach and the skin incision (longitudinal or transverse) were examined. Around 2014, we began to use the ILA technique as a less-invasive method. The primary endpoints of the postoperative UDS and PT evaluations were statistically evaluated for worsening of neurological findings in asymptomatic patients and for improvement/maintenance/worsening of symptoms in symptomatic patients. The association between UDS and neuro-urological deterioration has been reported [ 30 ]; thus, UDS was used as an objective assessment of neurological findings. Diagnostic evaluation All cases were identified by spinal-cord MRI-based diagnosis. FTL diagnosis was defined as a fatty signal on MRI images and > 2-mm thickness on axial images. We defined a low conus as a spinal-cord conus height of L2/3 or less and recommended surgery for asymptomatic patients with a low conus. In the absence of a low conus, surgery was performed after obtaining informed consent while individually considering the presence or absence of complications in each case. Surgical procedures The LOA and ILA technique was performed (Online Resource 1). Neurological monitoring Neuromonitoring was performed using the NeuroMaster® (Nihon Kohden Co., Ltd. Tokyo, Japan). Surface electrodes were attached to the abductor pollicis brevis, quadriceps, tibialis anterior, and gastrocnemius muscles for the motor-evoked potential, and stimulating electrodes were attached to the median and tibial nerves for the somatosensory-evoked potential (SEP) (Online Resource 1). Postoperative protocol Postoperatively, all patients were managed in the general ward except those with higher risk, such as those with cardiac comorbidities. The patients were confined to bed rest for approximately 1 week after surgery, and their activity level was increased just after lumbar MRI on the seventh postoperative day to confirm the absence of any CSF leakage and dissection of the spinal cord (Online Resource 1). Patients were postoperatively followed up regularly in the outpatient clinic. Postoperative PT evaluation was continued during hospitalization, if necessary, after discharge. Postoperative UDS was performed at a median duration of 7.5 months. Statistical analysis Statistical analyses were performed using Welch's t-test, Fisher's test, and multivariate analysis of variance (MANOVA). Statistical significance was set at P < 0.05. Univariate analysis of variance was performed for the ILA and LOA groups. For parameters significant (P < 0.05) in the univariate analysis, a MANOVA was conducted using them as explanatory variables. Results Of the 103 participants, 55 and 48 patients were enrolled in the ILA and LOA groups, respectively (Table 1 ). The preoperative and postoperative UDS were performed at a median duration of 2.3 (range, 0.03–20.3) and 7.5 (range, 3.73–84.4) months before and after surgery, respectively. Table 1 Participant demographics stratified by the ILA and LOA subgroups Characteristics ILA group (n = 55) LOA group (n = 48) P -value All cases 55 (100%) 48 (100%) Asymptomatic cases 29 (52.7%) 30 (62.5%) 0.3277 Symptomatic cases 26 (47.3%) 18 (37.5%) Age, years (median) 1.4 1.7 Dimple pointed out 27 (49.1%) 23 (47.9%) 1 Low-set conus 18 (32.7%) 26 (54.2%) 0.0453 Concomitant malformation 12 (21.8%) 12 (2%) 0.8162 Syringomyelia 1 (1.8%) 5 (10.4%) 0.0947 Operating time, min 113.38 179.54 < 0.0001 Blood loss, mL 6.43 15.31 0.047 Complications 2 (3.6%) 2 (4.2%) 1 CSF leak 0 (0%) 1 (2.1%) Delayed wound healing 2 (3.6%) 1 (2.1%) Reoperation (suture repair) 1 (1.8%) 1 (2.1%) 1 Skin incision Vertical 19 (34.5%) Transverse 36 (65.5%) Approach L4/5 24 (45.5%) L5/S1 18 (32.7%) L3/4 8 (14.5%) L2/3 1 (1.8%) L1/2 1 (1.8%) S 3 (5.4%) CSF: cerebrospinal fluid, ILA: Inter-laminar approach, LOA: laminotomy open approach. For the ILA technique, the height of the intervertebral approach and the orientation of the skin incision (longitudinal or transverse) were examined. The primary endpoints were the postoperative UDS and PT evaluations (mean follow-up duration: 44.2 months). The median age at surgery in the ILA and LOA groups was 1 year and 4 months and 1 year and 7 months, respectively, without a significant intergroup difference. The most common cause of diagnosis was dimples (50 cases, 48.5%) in both groups. Other common reasons for diagnosis included lumbar spine ultrasonography, screening MRI associated with anorectal lesions, and urinary and lower-extremity symptoms. MRI images of the low set conus were observed in 18 (32.7%) patients in the ILA group and 26 (54.2%) patients in the LOA group, showing a significant difference ( P < 0.05). The most common approach for the vertebral segment in the ILA group was L4/5 (24 cases), followed by L5/S1 (18 cases). In the ILA group, 19 skin incisions were vertical, whereas 36 were horizontal. The mean operative time was significantly shorter in the ILA group ( P < 0.0001) (113 and 179 min for the ILA and LOA groups, respectively). The mean blood-loss volume was significantly lower in the ILA group than in the LOA group (6.4 mL vs. 15.3 mL, P < 0.05). Postoperative complications in the ILA group included delayed wound healing in 2 patients (3.6%), whereas in the LOA group, delayed wound healing occurred in 1 patient (2.1%), and CSF leak in 1 patient (2.1%), totaling 2 patients (4.2%). Reoperation involved wound re-stitching in 1 case (1.8%) in the ILA group and 1 case (2.1%) in the LOA group. Twenty-six and 29 patients in the ILA group and 18 and 30 patients in the LOA group were symptomatic and asymptomatic, respectively. Table 1 summarizes the multivariate analysis using ILA and LOA as explanatory variables; the low set conus (P = 0.047), operation time (P < 0.001) and blood loss (P = 0.028) significantly differed between the groups. The low set conus was significantly more common in the LOA group, whereas the operative time was significantly shorter and blood loss was significantly lower in the ILA group. In symptomatic cases, urinary symptoms and abnormal UDS findings were the most frequent presenting features in both groups, followed by lower limb symptoms. Symptoms of voiding included nocturia, urinary incontinence, and delayed toilet training. Abnormal UDS findings included vesicoureteral reflux (VUR), voiding overactivity (DO), dyscoordination of the voiding muscles and sphincter, and bladder wall irregularity. Lower extremity symptoms included muscle weakness, deformities (toe deformity, medial tuck, flat foot, concave foot, hammertoe, etc.), pain, and spasticity. Another defecation-related symptom was constipation. In the ILA group, 18 patients had urinary symptoms or abnormal UDS findings, compared with 13 in the LOA group. In the ILA group, 14 patients showed improvement and 4 maintained their urinary function (1 case of bladder-wall irregularity). In the LOA group, 10 improved, 2 maintained urinary function (1 case of VUR and 1 case of DO), and 1 deteriorated (1 case of VUR). Lower extremity symptoms were observed in 12 patients in the ILA group and 8 in the LOA group. In the ILA group, 11 patients showed improvement and 1 maintained improvement. In the LOA group, 4 patients improved and 4 maintained their improvement. Fisher's test revealed no significant intergroup difference in the rate of symptom improvement (Table 2 ). The symptomatic PT evaluation duration did not differ significantly between the groups (median: ILA, 12.4 months; LOA, 20 months, P = 0.49). The symptomatic UDS evaluation duration did not differ significantly between the groups preoperatively (median: ILA, 3.4 months; LOA, 1.7 months; P = 0.57) or postoperatively (median: ILA, 6.3 months; LOA, 8.2 months; P = 0.46). Table 2 Intergroup comparison of the ILA and LOA subgroups for symptomatic FTLs Characteristics ILA group (n = 26) LOA group (n = 17) P -value Abnormal UDS findings 14 (53.8%) 12 (70.6%) Improved 13 (50%) 9 (52.9%) 0.306 Stabilized 1 (3.8%) 2 (11.8%) Worsened 0 (0%) 1 (5.9%) Urinary symptoms 4 (15.4%) 1 (5.9%) Improved 1 (3.8%) 1 (5.9%) 0.4 Stabilized 3 (11.5%) 0 (0%) Worsened 0 (0%) 0 (0%) Defecation-related symptoms 4 (15.4%) 1 (5.9%) Improved 3 (11.5%) 1 (5.9%) 1 Stabilized 1 (3.8%) 0 (0%) Worsened 0 (0%) 0 (0%) Lower limb symptoms 12 (46.2%) 8 (47.1%) Improved 11 (42.3%) 4 (23.5%) 0.108 Stabilized 1 (3.8%) 4 (23.5%) Worsened 0 (0%) 0 (0%) FTL, filum terminale lipoma, ILA, interlaminar approach; LOA, laminotomy open approach; UDS, urodynamic study There were 29 asymptomatic patients in the ILA group, none of whom showed postoperative deterioration. In the LOA group of 30 patients, only one exhibited postoperative VUR, confirmed by UDS. The UDS evaluation duration did not differ significantly between asymptomatic patients in the ILA and LOA groups either preoperatively (median: asymptomatic ILA, 1.7 months; asymptomatic LOA, 2.0 months; P = 0.88) or postoperatively (median: asymptomatic ILA, 7.2 months; asymptomatic LOA, 7.6 months; P = 0.72). Fisher’s exact test showed no significant intergroup difference in the symptom-retention rates of asymptomatic patients in the ILA and LOA groups (Table 3 ). Table 3 Intergroup comparison of the ILA and LOA subgroups for asymptomatic FTLs Characteristics ILA group (n = 30) LOA group (n = 30) P -value Asymptomatic 29 (100%) 30 (100%) 1 Symptoms maintained 29 (100%) 29 (96.7%) Symptom appearance 0 (0%) 1 (3.3%) FTL: filum terminale lipoma, ILA: inter-laminar approach, LOA: laminotomy open approach Details on perioperative management are presented in Online Resource 1. Discussion Conventional surgical methods The standard surgical technique for FTL is a single vertebral laminotomy [ 9 , 34 ]. Yoshifuji et al. [ 34 ] reported that a single vertebral laminotomy is performed by cutting the supraspinous, interspinous, and yellow ligaments on the caudal side of the vertebral arch to be incised and that the width of the arch incision is made medially, slightly away from the intervertebral joint. Hayashi et al. [ 9 ] reported that postoperative back pain and wound pain can be minimized by performing the operation at the sacral level only, with vertebral arch resection at S1 or S2 and FTL resection. Accordingly, when performing the laminotomy, we chose the number of vertebrae to be incised and the unilateral or bilateral incision, depending on the case. We used a sagittal saw to make a unilateral incision, created a gutter on the contralateral side, and used it as a hinge to flip the vertebra to the contralateral side. A bilateral incision was made using a sagittal saw, and the interspinous ligament on the cephalic side was used as a hinge for flipping. Laminotomy has the advantage of allowing a wider surgical field; however, a disadvantage is the possibility of long-term postoperative pseudarthrosis of the vertebral arch [ 24 ]. Moreover, postoperative pain was relatively high, and the time until ambulation was prolonged [ 10 ]. The risk of CSF leakage is high because of the larger dural incision than in the ILA technique. Literature report on minimally invasive surgery and its comparison There have been several reports on minimally invasive surgeries. Potts et al. [ 22 ] reported a minimally invasive approach using a tubular retractor in adults. They found that the skin incision was 4–5 cm smaller than that used in conventional techniques, leading to paraspinal muscle dissection and less scar tissue. Okay et al. [ 19 ] reported a minimally invasive procedure using an endoscopic approach wherein a 2-cm skin incision was used. Greuter et al. [ 8 ] used an intervertebral approach through a longitudinal midline incision similar to our method. Although we performed a longitudinal skin incision in some cases, we often chose a transverse incision with a less conspicuous wound, and we chose a longitudinal incision in cases wherein repeat spinal surgery was expected in the longer term. Hayashi et al. [ 10 ] reported an approach from the intervertebral space on one side of the L4/5 or L5/S1, which supposedly has the advantage of no bone damage and less postoperative pain, blood loss, and duration of bedrest because the approach is based on the interspinous ligament. However, they mentioned that the approach may not be suitable for large FTLs because of the narrow surgical field. Compared with conventional laminotomy, minimally invasive surgery has the advantages of (1) a smaller skin incision, (2) less stress on the paraspinal muscles, and (3) less intraoperative blood loss. Similarly, in our study, the ILA technique showed the above advantages in addition to a shorter operative time. This ILA technique is similar to Hayashi et al.’s intervertebral approach but differs in that the approach is through the midline of the intervertebral space. Although the skin incision in this method was slightly larger (approximately 3 cm in the case of a transverse incision), we believe a sufficient operative field can be secured even with a relatively thick FTL. Comparison with literature reports on complications Previous reports exist on complications of the open laminotomy approach. Edström et al. [ 6 ] reported that non-operative complications occurred in 12% of cases after a single vertebral laminotomy. Solmaz et al. [ 25 ] reported that spinal fluid leakage occurred in 6.1% of cases after a single laminotomy. Bhimani et al. [ 2 ] reported a complication rate of 8.1% with a single laminotomy. Complication rates in other studies were 1.8–9.2% [ 5 , 10 , 14 , 20 , 21 , 31 ]. Hayashi et al. [ 10 ] reported no postoperative complications requiring additional surgery in 49 patients who underwent the ILA, no cases of postoperative symptomatic deterioration, such as retethering or neurological symptoms, and a significantly shorter hospitalization period than that for LOA. This was attributed to the fact that postoperative pain was less with the ILA technique. In our study, the rates of postoperative complications requiring reoperation were 1.8% and 2.0% in the ILA and LOA groups, respectively, which were lower than those in previous reports [ 2 , 5 , 6 , 10 , 14 , 20 , 21 , 25 , 31 ]. Hayashi et al. [ 10 ] prepared fibrinogen after dural suturing to prevent spinal fluid leakage by returning epidural fat to the dural suture surface. We did not use a fibrinogen product in cases wherein spinal fluid leakage was confirmed by the Valsalva maneuver after dural suturing and watertight closure were obtained. We believe the most important factor for preventing CSF leakage is firmly returning the epidural fat layer to the dural suture. Moreover, as described by Ogiwara et al. [ 17 ], close suturing of the fascia is important to prevent CSF leakage. Regarding postoperative supine rest, Hayashi et al. [ 10 ] reported that postoperative rest is basically unnecessary with the ILA technique. Kanematsu et al. [ 12 ] reported that the incidence of CSF leakage did not increase in patients who underwent FTL dissection via LOA, even without postoperative bed rest. In contrast, we started slowly ambulating patients in the supine position for approximately 1 week after surgery and weaned them off bed rest after confirming the presence or absence of CSF leakage by MRI. We believe that MRI examinations during hospitalization are useful; however, in view of past reports, we need to consider shortening the supine rest period. Improvement in neurological findings in symptomatic cases The efficacy of ILA for FTL is clear given their minimally invasive nature, as reported by Greuter et al. and Hayashi et al. [ 8 , 10 ]. However, the improvement rates of neurological findings in symptomatic patients with ILA have not yet been comprehensively reported. In contrast, several reports exist on the improvement rate of symptoms by the LOA method (Table 4 ) [4–6,11,13,15,20,23,25–28,31–33,], and the improvement rate ranges from 18.5–100%. The improvement rate of urinary symptoms and UDS findings were 20–100%, and that of lower limb symptoms were 14.2–100%. Table 4 Summary of literature review Author, publication year Research Patients Surgery Overall symptom improvement rate Rate of improvement of urinary symptoms and UDS Rate of improvement of lower limb symptoms Rate of improvement of other symptoms Xu, 2022 5 6literature systematic review OTCS, n = 293 Less invasive surgery with Xtube 88.74% Rezaee & Keykhosravi, 2022 24 10literature systematic review OTCS, n = 234 Unknown Urinary symptom: 59–100% Leg pain: 100% Muscle weakness: 25–100% Edström, 2022 14 Retrospective FTL, n = 62 LOA UDS: 48% Sensorimotor disorder: 42% Michael, 2021 2 17literature systematic review OTCS Unknown > 50% Ishisaka, 2020 25 Retrospective FTL + syringomyelia, n = 19 Unknown 47% Day, 2020 18 Retrospective FTL, TFT, n = 144 Unknown 81.00% UDS: 64.4% Back pain: 54.5%; Lower limb symptoms: 79.6% Scoliosis 18.2% Defecation-related disorder: 57.1% Tamura, 2017 26 Retrospective FTL, TFT Unknown Urinary symptom: 58.3% Strong, 2015 20 Retrospective FTL, n = 248 LOA,ILA 97.10% Ostling, 2012 21 Retrospective TCS, n = 99 LOA 88% (improved and stable) Cornips, 2012 27 Retrospective FTL, n = 25 ILA (partial laminectomy) 80% Urinary symptom: 76.4% Lower limb symptoms: 14.2% Solmaz, 2011 15 Retrospective TCS, n = 9 LOA 44.40% Urinary symptom: 20% Back pain: 100% Tredway, 2007 28 Retrospective TCS, n = 3 Less invasive surgery with Xtube 100% UDS: 100% Leg/back pain: 100% Wehby, 2004 29 Retrospective OTCS, n = 60 LOA Urinary symptom: 98% Leg pain/sensorimotor disorder: 100% Defecation-related disorder: 97% Wei, 1999 30 Retrospective TCS, n = 22 LOA Urinary symptom: 70% Lower limb symptoms: 100%;sensory disorder: 56% Defecation-related disorder: 2% La Marca, 1997 6 Retrospective FTL, n = 27 LOA 62.96% Incontinence: 37.5% Retension:33.3% Frequent UTI:100% foot deformity: 20% weakness:75%, spasticity:66.7% gait:100%, pain:500%, numbness:100% FTL: filum terminale lipoma; ILA: interlaminar approach; LOA: laminotomy open approach; OTCS: occult tethered cord syndrome; TCS: tethered cord syndrome; TFT: tight filum terminale ; UTI: urinary tract infection The improvement rate of all symptoms by ILA in this study was 82%, and the maintenance rate was 18%. The improvement rate of urinary symptoms and abnormal UDS findings was 77%, and that of lower-limb symptoms was 91%, with no worsening of postoperative symptoms. This rate did not significantly differ from that of symptom improvement using the LOA method in our study. These results are comparable to those reported in previous studies. Herein, blood loss was significantly lesser and operative time was significantly shorter in ILA. The primary endpoints of UDS and PT were similar between the two groups. The ILA group experienced less-invasive surgery and had non-inferior long-term neurological outcomes, compared with the LOA group. Retethering Herein, there was no case of postoperative re-adhesion during the follow-up period. Re-tethering was evaluated through a comprehensive evaluation of lower-extremity motor function by the physician-in-charge, periodic lumbar MRI imaging, and evaluation of the changes in UDS findings by a pediatric urologist. Ogiwara et al. [ 18 ] reported that retethering occurred in six (2.7%) of 225 cases of FTL and that, to prevent retethering, it is important to prevent bleeding into the subarachnoid space and adhesion between the soft membrane and surrounding tissues by avoiding damage to, and coagulation of, the soft membrane surface as much as possible. As Hayashi et al. [ 10 ] also reported, minimally invasive surgery, including the ILA, can minimize dural and arachnoid incisions, which is thought to reduce the incidence of retethering. As another method to prevent reattachment, Abdulrazeq et al. [ 1 ] reported that FTL resection through the spinal conus using a high intervertebral approach could minimize residual lesions and reduce the risk of retethering. The presence of retethering can be determined using postoperative MRI images. Tsuchida et al. [ 29 ] reported that MRI of the cauda equina in the supine and prone positions may be used to observe changes in the position of the cauda equina relative to gravity and to diagnose adhesions between the cauda equina and arachnoid/dura mater. Furthermore, due to its anti-inflammatory effects, dexamethasone was administered during the suturing of the dura mater to prevent retethering. Ogiwara et al. [ 18 ] reported a mean time from the initial surgery to retethering of 5.4 years. It is necessary to confirm whether retethering occurs in our study by following up the patients in the future. Conclusions The ILA and LOA approaches to FTL were examined retrospectively. ILA significantly shortened the operative time and reduced blood loss. The complication or reoperation rates did not significantly differ between the two approaches. Long-term symptomatic improvement rates were comparable or higher in the ILA approach. These results suggest that ILA is less invasive and more effective than LOA in the treatment of FTL. Declarations Acknowledgments: We would like to express our gratitude to Editage (www.editage.jp) for their assistance with English language editing. Competing Interests: None Funding: None Author Contributions: All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Tomoki Nawashiro, and Kousuke Aoki. The first draft of the manuscript was written by Tomoki Nawashiro and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript. Ethics Approval: This study was approved by the ethics committees of the Aichi Children’s Health and Medical Center in accordance with the ethical standards of the 1964 Declaration of Helsinki (approval number:2023084). 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Poonia S, Graber S, Corbett Wilkinson C, O’neill BR, Handler MH, Hankinson TC (2016) Outcome of hospital discharge on postoperative Day 1 following uncomplicated tethered spinal cord release. J Neurosurg Pediatr 17:651-656. https://doi.org/10.3171/2015.10.PEDS15318. Potts MB, Wu JC, Gupta N, Mummaneni PV (2010) Minimally invasive tethered cord release in adults: a comparison of open and mini-open approaches. Neurosurg Focus 29:E7. https://doi.org/10.3171/2010.3.FOCUS1077. Rezaee H, Keykhosravi E (2022) Effect of untethering on occult tethered cord syndrome: a systematic review. Br J Neurosurg 36:574-582. https://doi.org/10.1080/02688697.2021.1995589. Roberts SB, Tsirikos AI (2022) Paediatric spinal deformity surgery: complications and their management. Healthcare (Basel) 10:2519. https://doi.org/10.3390/healthcare10122519. Solmaz I, Izci Y, Albayrak B et al (2011) Tethered cord syndrome in childhood: special emphasis on the surgical technique and review of the literature with our experience. Turk Neurosurg 21:516-521. https://doi.org/10.5137/1019-5149.JTN.4394-11.1. Strong MJ, Thompson EM, Roundy N, Selden NR (2015) Use of lumbar laminoplasty vs. laminotomy for transection of the filum terminale does not affect early complication rates or postoperative course. Childs Nerv Syst 31:597-601. https://doi.org/10.1007/s00381-015-2615-8. Tamura G, Morota N, Ihara S (2017) Impact of magnetic resonance imaging and urodynamic studies on the management of sacrococcygeal dimples. J Neurosurg Pediatr 20:289-297. https://doi.org/10.3171/2017.5.PEDS16719. Tredway TL, Musleh W, Christie SD, Khavkin Y, Fessler RG, Curry DJ (2007) A novel minimally invasive technique for spinal cord untethering. Neurosurgery 60:ONS70-4; discussion ONS74. https://doi.org/10.1227/01.NEU.0000249254.63546.D7 Tsuchida R, Sumitani M, Azuma K et al (2020) A novel technique using magnetic resonance imaging in the supine and prone positions for diagnosing lumbar adhesive arachnoiditis: a preliminary study. Pain Pract 20:34-43. https://doi.org/10.1111/papr.12822. Valentini, L. G., M. Babini, R. Cordella, E. Beretta, F. Destro et al (2021) Early de-tethering: analysis of urological and clinical consequences in a series of 40 children. Childs Nerv Syst 37: 941-949. https://doi.org/10.1007/s00381-020-04838-6 Wehby MC, O’Hollaren PS, Abtin K, Hume JL, Richards BJ (2004) Occult tight filum terminale syndrome: results of surgical untethering. Pediatr Neurosurg 40:51-57; discussion 58. https://doi.org/10.1159/000078908. Wei W, Gao Y, Yang X, Lu P, E H (1999) Operative results of tethered cord syndrome. Zhonghua Wai Ke Za Zhi 37:488-489. Xu K, He J, Wang L (2022) A systematic review and meta-analysis of minimally invasive surgery in children with occult tethered cord syndrome. Transl Pediatr 11:403-410. https://doi.org/10.21037/tp-22-72. Yoshifuji K (2022) [Filum lipoma]. No Shinkei Geka 50:1203-11. https://doi.org/10.11477/mf.1436204687. Additional Declarations No competing interests reported. Supplementary Files OnlineResource.pdf Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 11 May, 2024 Reviews received at journal 10 May, 2024 Reviewers agreed at journal 07 May, 2024 Reviewers agreed at journal 05 Feb, 2024 Reviews received at journal 02 Feb, 2024 Reviewers agreed at journal 29 Jan, 2024 Reviewers agreed at journal 27 Jan, 2024 Reviewers invited by journal 24 Jan, 2024 Editor assigned by journal 15 Jan, 2024 Submission checks completed at journal 15 Jan, 2024 First submitted to journal 13 Jan, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-3860133","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":267204383,"identity":"d72d8162-895c-42dc-8ef5-ace708ea8653","order_by":0,"name":"Tomoki Nawashiro","email":"","orcid":"","institution":"Aichi Children's Health and Medical Center","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Tomoki","middleName":"","lastName":"Nawashiro","suffix":""},{"id":267204384,"identity":"1559d8de-dfb4-4b7c-b1e6-9331fab6d3ba","order_by":1,"name":"Michihiro Kurimoto","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAt0lEQVRIiWNgGAWjYHACNgYGAyDF3kC0DmawFgkGngMkaWEAapFIIFKD+Yz8Y49uFNTV8c98nfiAocYmmqAWmRvJ7MY5BoclJG7nbjZgOJaW20BIi4REMpt0jsEBCYbbudskGBsOE62lTkL+5tntP0jRwixhcIN3GwNxWngemwG1HJbceCZ3s0QCUX5hT3wmnfOnjl/u+NmNHz7U2BDWwiCQgMRJwKEIFfAfIErZKBgFo2AUjGQAAO+zOUXLEWdxAAAAAElFTkSuQmCC","orcid":"","institution":"Aichi Children's Health and Medical Center","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Michihiro","middleName":"","lastName":"Kurimoto","suffix":""},{"id":267204385,"identity":"81cf8951-8ac2-4126-9b24-2ad258b03b00","order_by":2,"name":"Masamune Nagakura","email":"","orcid":"","institution":"Aichi Children's Health and Medical Center","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Masamune","middleName":"","lastName":"Nagakura","suffix":""},{"id":267204386,"identity":"7a1a00d0-652f-4670-a39b-92beb3ccb926","order_by":3,"name":"Mihoko Kato","email":"","orcid":"","institution":"Aichi Children's Health and Medical Center","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Mihoko","middleName":"","lastName":"Kato","suffix":""},{"id":267204387,"identity":"c16c4f9c-7c96-412a-b88a-a9d4d81fbc69","order_by":4,"name":"Kousuke Aoki","email":"","orcid":"","institution":"Sylvester Comprehensive Cancer Center, University of Miami, Miller School of Medicine","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Kousuke","middleName":"","lastName":"Aoki","suffix":""},{"id":267204388,"identity":"4c90330b-2940-4b97-9ace-8c2af414b90c","order_by":5,"name":"Ryuta Saito","email":"","orcid":"","institution":"Nagoya University Graduate School of Medicine","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Ryuta","middleName":"","lastName":"Saito","suffix":""}],"badges":[],"createdAt":"2024-01-13 12:46:25","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3860133/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3860133/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":49762629,"identity":"82b87a2a-6b04-4bdc-98c6-5fd5876b226b","added_by":"auto","created_at":"2024-01-17 16:13:00","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":7847000,"visible":true,"origin":"","legend":"\u003cp\u003eIntraoperative findings of the inter-laminar approach. (A) Microscopic manipulation is performed after the application of a wound spreader. (B) The epidural space has been exposed, and (C) the dura is opened with a midline longitudinal incision in the cephalocaudal direction. (D) The cephalic side of the FTL has been coagulated and dissected, and (E) The caudal side of the FTL has been coagulated and partially dissected. (F) Hemostasis has been confirmed after resection of the FTL. (G) The dura is sutured with 6-0 proline. (H) The epidural fat is returned, and microscopic manipulation has been completed\u003c/p\u003e\n\u003cp\u003eAbbreviations: FTL- Filum terminale lipoma\u003c/p\u003e","description":"","filename":"Fig.1.png","url":"https://assets-eu.researchsquare.com/files/rs-3860133/v1/82f2efacf34d1588c9cb1c67.png"},{"id":49761787,"identity":"b7740a8d-2800-4d63-a128-6ede95901f4d","added_by":"auto","created_at":"2024-01-17 16:05:00","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":2249067,"visible":true,"origin":"","legend":"\u003cp\u003e(A) Feather® replacement blade scalpel No. 390. (B) Wound-opening device\u003c/p\u003e","description":"","filename":"Fig.2.png","url":"https://assets-eu.researchsquare.com/files/rs-3860133/v1/0c948e747c05c65a63552bbe.png"},{"id":49763673,"identity":"19d532e9-a843-4eab-b684-1e2488fa5003","added_by":"auto","created_at":"2024-01-17 16:21:05","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":5303768,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3860133/v1/e3e625fa-8ca8-471b-81b2-0109afcd2e46.pdf"},{"id":49761789,"identity":"9a96ff7f-14ec-4b6f-8a88-d707bff1c623","added_by":"auto","created_at":"2024-01-17 16:05:00","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":13734,"visible":true,"origin":"","legend":"","description":"","filename":"OnlineResource.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3860133/v1/5455e2981c9e0c054051fa89.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Comparison of the Inter-laminar Approach and Laminotomy Open Approach for Filum Terminale Lipoma: A Retrospective Analysis","fulltext":[{"header":"Introduction","content":"\u003cp\u003eFilum terminale lipoma (FTL) is a type of spinal lipoma classified as closed spina bifida and type 4 lipoma as per the Morota classification [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. The human spinal cord develops through primary and secondary neurulation; FTL originates from an abnormality occurring in the late stages of secondary neurulation [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. As FTL causes tethered spinal cord, it is associated with tethered-cord syndrome. Furthermore, occult tethered-cord syndrome, which does not present with low spinal conus but has a symptomatic presentation, has been reported [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. FTL detection rates on magnetic resonance imaging (MRI) and autopsy are 0.24\u0026ndash;4% [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e] and 4\u0026ndash;6%, respectively [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe aim of surgical treatment for FTL is categorized according to symptomatic and asymptomatic cases to arrest/improve symptom progression and prophylaxis, respectively. In Japan, the universal health insurance system covers prophylactic surgery; historically, many prophylactic resections have been performed. Despite recommendations for prophylactic surgery, this intervention is controversial [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. The standard surgical procedure for FTL is laminotomy-based dissection [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]; however, less-invasive techniques have been reported [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThis study compared the effectiveness of the minimally invasive interlaminar approach (ILA) with the conventional laminotomy open approach (LOA) in FTL treatment. Moreover, although ILA has been reported to be safe, its long-term neurological prognosis has not yet been reported; thus, we investigated whether ILA can sufficiently improve prognosis. We believe that a less-invasive procedure should be selected only when its safety is established and its effects on neurological outcomes are comparable to that of surgery.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy design\u003c/h2\u003e \u003cp\u003eThis study retrospectively included 152 patients with terminally threaded lipoma who underwent surgery between April 2010 and November 2021 at a single center (Department of Neurosurgery, Aichi Children's Health and Medical Center), and their data were extracted from medical records (Online Resource 1).\u003c/p\u003e \u003cp\u003eSymptomatic patients were excluded if there were no data of pre- or postoperative UDS or PT evaluation based on their symptoms, whereas asymptomatic patients were excluded if there was no UDS evaluation at the pre- or postoperative stage. Asymptomatic patients underwent motor-function evaluation during the physical examination by the physician-in-charge and a PT evaluation, if necessary. To ensure objectivity of the lower-extremity motor-function evaluation, the physician-in-charge uniformly evaluated deep-tendon reflexes, lower-extremity gross motor activity, and foot-deformity presence.\u003c/p\u003e \u003cp\u003eThe choice of ILA or LOA was determined by the operator. For the ILA technique, the height of the intervertebral approach and the skin incision (longitudinal or transverse) were examined. Around 2014, we began to use the ILA technique as a less-invasive method. The primary endpoints of the postoperative UDS and PT evaluations were statistically evaluated for worsening of neurological findings in asymptomatic patients and for improvement/maintenance/worsening of symptoms in symptomatic patients. The association between UDS and neuro-urological deterioration has been reported [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]; thus, UDS was used as an objective assessment of neurological findings.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eDiagnostic evaluation\u003c/h2\u003e \u003cp\u003eAll cases were identified by spinal-cord MRI-based diagnosis. FTL diagnosis was defined as a fatty signal on MRI images and \u0026gt;\u0026thinsp;2-mm thickness on axial images. We defined a low conus as a spinal-cord conus height of L2/3 or less and recommended surgery for asymptomatic patients with a low conus. In the absence of a low conus, surgery was performed after obtaining informed consent while individually considering the presence or absence of complications in each case.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eSurgical procedures\u003c/h2\u003e \u003cp\u003eThe LOA and ILA technique was performed (Online Resource 1).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eNeurological monitoring\u003c/h2\u003e \u003cp\u003eNeuromonitoring was performed using the NeuroMaster\u0026reg; (Nihon Kohden Co., Ltd. Tokyo, Japan). Surface electrodes were attached to the abductor pollicis brevis, quadriceps, tibialis anterior, and gastrocnemius muscles for the motor-evoked potential, and stimulating electrodes were attached to the median and tibial nerves for the somatosensory-evoked potential (SEP) (Online Resource 1).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003ePostoperative protocol\u003c/h2\u003e \u003cp\u003ePostoperatively, all patients were managed in the general ward except those with higher risk, such as those with cardiac comorbidities. The patients were confined to bed rest for approximately 1 week after surgery, and their activity level was increased just after lumbar MRI on the seventh postoperative day to confirm the absence of any CSF leakage and dissection of the spinal cord (Online Resource 1).\u003c/p\u003e \u003cp\u003ePatients were postoperatively followed up regularly in the outpatient clinic. Postoperative PT evaluation was continued during hospitalization, if necessary, after discharge. Postoperative UDS was performed at a median duration of 7.5 months.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eStatistical analyses were performed using Welch's t-test, Fisher's test, and multivariate analysis of variance (MANOVA). Statistical significance was set at \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e \u003cp\u003eUnivariate analysis of variance was performed for the ILA and LOA groups. For parameters significant (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05) in the univariate analysis, a MANOVA was conducted using them as explanatory variables.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eOf the 103 participants, 55 and 48 patients were enrolled in the ILA and LOA groups, respectively (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The preoperative and postoperative UDS were performed at a median duration of 2.3 (range, 0.03\u0026ndash;20.3) and 7.5 (range, 3.73\u0026ndash;84.4) months before and after surgery, respectively.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eParticipant demographics stratified by the ILA and LOA subgroups\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCharacteristics\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eILA group\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;55)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLOA group\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;48)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e-value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAll cases\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e55 (100%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e48 (100%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAsymptomatic cases\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e29 (52.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e30 (62.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.3277\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSymptomatic cases\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e26 (47.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e18 (37.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge, years (median)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDimple pointed out\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e27 (49.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e23 (47.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLow-set conus\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e18 (32.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e26 (54.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.0453\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eConcomitant malformation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e12 (21.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e12 (2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.8162\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSyringomyelia\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1 (1.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5 (10.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.0947\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOperating time, min\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e113.38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e179.54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBlood loss, mL\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6.43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e15.31\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.047\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eComplications\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2 (3.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2 (4.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCSF leak\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0 (0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1 (2.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDelayed wound healing\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2 (3.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1 (2.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eReoperation (suture repair)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1 (1.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1 (2.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSkin incision\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVertical\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e19 (34.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTransverse\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e36 (65.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eApproach\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eL4/5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e24 (45.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eL5/S1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e18 (32.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eL3/4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8 (14.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eL2/3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1 (1.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eL1/2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1 (1.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3 (5.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003eCSF: cerebrospinal fluid, ILA: Inter-laminar approach, LOA: laminotomy open approach.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eFor the ILA technique, the height of the intervertebral approach and the orientation of the skin incision (longitudinal or transverse) were examined. The primary endpoints were the postoperative UDS and PT evaluations (mean follow-up duration: 44.2 months). The median age at surgery in the ILA and LOA groups was 1 year and 4 months and 1 year and 7 months, respectively, without a significant intergroup difference. The most common cause of diagnosis was dimples (50 cases, 48.5%) in both groups. Other common reasons for diagnosis included lumbar spine ultrasonography, screening MRI associated with anorectal lesions, and urinary and lower-extremity symptoms. MRI images of the low set conus were observed in 18 (32.7%) patients in the ILA group and 26 (54.2%) patients in the LOA group, showing a significant difference (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05). The most common approach for the vertebral segment in the ILA group was L4/5 (24 cases), followed by L5/S1 (18 cases). In the ILA group, 19 skin incisions were vertical, whereas 36 were horizontal.\u003c/p\u003e \u003cp\u003eThe mean operative time was significantly shorter in the ILA group (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.0001) (113 and 179 min for the ILA and LOA groups, respectively). The mean blood-loss volume was significantly lower in the ILA group than in the LOA group (6.4 mL vs. 15.3 mL, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003ePostoperative complications in the ILA group included delayed wound healing in 2 patients (3.6%), whereas in the LOA group, delayed wound healing occurred in 1 patient (2.1%), and CSF leak in 1 patient (2.1%), totaling 2 patients (4.2%).\u003c/p\u003e \u003cp\u003eReoperation involved wound re-stitching in 1 case (1.8%) in the ILA group and 1 case (2.1%) in the LOA group. Twenty-six and 29 patients in the ILA group and 18 and 30 patients in the LOA group were symptomatic and asymptomatic, respectively.\u003c/p\u003e \u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e summarizes the multivariate analysis using ILA and LOA as explanatory variables; the low set conus (P\u0026thinsp;=\u0026thinsp;0.047), operation time (P\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and blood loss (P\u0026thinsp;=\u0026thinsp;0.028) significantly differed between the groups. The low set conus was significantly more common in the LOA group, whereas the operative time was significantly shorter and blood loss was significantly lower in the ILA group.\u003c/p\u003e \u003cp\u003eIn symptomatic cases, urinary symptoms and abnormal UDS findings were the most frequent presenting features in both groups, followed by lower limb symptoms. Symptoms of voiding included nocturia, urinary incontinence, and delayed toilet training. Abnormal UDS findings included vesicoureteral reflux (VUR), voiding overactivity (DO), dyscoordination of the voiding muscles and sphincter, and bladder wall irregularity. Lower extremity symptoms included muscle weakness, deformities (toe deformity, medial tuck, flat foot, concave foot, hammertoe, etc.), pain, and spasticity. Another defecation-related symptom was constipation.\u003c/p\u003e \u003cp\u003eIn the ILA group, 18 patients had urinary symptoms or abnormal UDS findings, compared with 13 in the LOA group. In the ILA group, 14 patients showed improvement and 4 maintained their urinary function (1 case of bladder-wall irregularity). In the LOA group, 10 improved, 2 maintained urinary function (1 case of VUR and 1 case of DO), and 1 deteriorated (1 case of VUR). Lower extremity symptoms were observed in 12 patients in the ILA group and 8 in the LOA group. In the ILA group, 11 patients showed improvement and 1 maintained improvement. In the LOA group, 4 patients improved and 4 maintained their improvement. Fisher's test revealed no significant intergroup difference in the rate of symptom improvement (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The symptomatic PT evaluation duration did not differ significantly between the groups (median: ILA, 12.4 months; LOA, 20 months, P\u0026thinsp;=\u0026thinsp;0.49). The symptomatic UDS evaluation duration did not differ significantly between the groups preoperatively (median: ILA, 3.4 months; LOA, 1.7 months; P\u0026thinsp;=\u0026thinsp;0.57) or postoperatively (median: ILA, 6.3 months; LOA, 8.2 months; P\u0026thinsp;=\u0026thinsp;0.46).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eIntergroup comparison of the ILA and LOA subgroups for symptomatic FTLs\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCharacteristics\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eILA group\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;26)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLOA group\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;17)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e-value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAbnormal UDS findings\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e14 (53.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e12 (70.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eImproved\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e13 (50%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9 (52.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.306\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStabilized\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1 (3.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2 (11.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWorsened\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0 (0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1 (5.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUrinary symptoms\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4 (15.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1 (5.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eImproved\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1 (3.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1 (5.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStabilized\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3 (11.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0 (0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWorsened\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0 (0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0 (0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDefecation-related symptoms\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4 (15.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1 (5.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eImproved\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3 (11.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1 (5.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStabilized\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1 (3.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0 (0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWorsened\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0 (0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0 (0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLower limb symptoms\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e12 (46.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8 (47.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eImproved\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e11 (42.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4 (23.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.108\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStabilized\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1 (3.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4 (23.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWorsened\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0 (0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0 (0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003eFTL, filum terminale lipoma, ILA, interlaminar approach; LOA, laminotomy open approach; UDS, urodynamic study\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThere were 29 asymptomatic patients in the ILA group, none of whom showed postoperative deterioration. In the LOA group of 30 patients, only one exhibited postoperative VUR, confirmed by UDS. The UDS evaluation duration did not differ significantly between asymptomatic patients in the ILA and LOA groups either preoperatively (median: asymptomatic ILA, 1.7 months; asymptomatic LOA, 2.0 months; P\u0026thinsp;=\u0026thinsp;0.88) or postoperatively (median: asymptomatic ILA, 7.2 months; asymptomatic LOA, 7.6 months; P\u0026thinsp;=\u0026thinsp;0.72). Fisher\u0026rsquo;s exact test showed no significant intergroup difference in the symptom-retention rates of asymptomatic patients in the ILA and LOA groups (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eIntergroup comparison of the ILA and LOA subgroups for asymptomatic FTLs\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCharacteristics\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eILA group\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;30)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLOA group\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;30)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e-value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAsymptomatic\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e29 (100%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e30 (100%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSymptoms maintained\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e29 (100%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e29 (96.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSymptom appearance\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0 (0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1 (3.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003eFTL: filum terminale lipoma, ILA: inter-laminar approach, LOA: laminotomy open approach\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eDetails on perioperative management are presented in Online Resource 1.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eConventional surgical methods\u003c/h2\u003e \u003cp\u003eThe standard surgical technique for FTL is a single vertebral laminotomy [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. Yoshifuji et al. [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e] reported that a single vertebral laminotomy is performed by cutting the supraspinous, interspinous, and yellow ligaments on the caudal side of the vertebral arch to be incised and that the width of the arch incision is made medially, slightly away from the intervertebral joint. Hayashi et al. [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e] reported that postoperative back pain and wound pain can be minimized by performing the operation at the sacral level only, with vertebral arch resection at S1 or S2 and FTL resection. Accordingly, when performing the laminotomy, we chose the number of vertebrae to be incised and the unilateral or bilateral incision, depending on the case. We used a sagittal saw to make a unilateral incision, created a gutter on the contralateral side, and used it as a hinge to flip the vertebra to the contralateral side. A bilateral incision was made using a sagittal saw, and the interspinous ligament on the cephalic side was used as a hinge for flipping.\u003c/p\u003e \u003cp\u003eLaminotomy has the advantage of allowing a wider surgical field; however, a disadvantage is the possibility of long-term postoperative pseudarthrosis of the vertebral arch [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. Moreover, postoperative pain was relatively high, and the time until ambulation was prolonged [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. The risk of CSF leakage is high because of the larger dural incision than in the ILA technique.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eLiterature report on minimally invasive surgery and its comparison\u003c/h2\u003e \u003cp\u003eThere have been several reports on minimally invasive surgeries. Potts et al. [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e] reported a minimally invasive approach using a tubular retractor in adults. They found that the skin incision was 4\u0026ndash;5 cm smaller than that used in conventional techniques, leading to paraspinal muscle dissection and less scar tissue. Okay et al. [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e] reported a minimally invasive procedure using an endoscopic approach wherein a 2-cm skin incision was used. Greuter et al. [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e] used an intervertebral approach through a longitudinal midline incision similar to our method. Although we performed a longitudinal skin incision in some cases, we often chose a transverse incision with a less conspicuous wound, and we chose a longitudinal incision in cases wherein repeat spinal surgery was expected in the longer term. Hayashi et al. [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] reported an approach from the intervertebral space on one side of the L4/5 or L5/S1, which supposedly has the advantage of no bone damage and less postoperative pain, blood loss, and duration of bedrest because the approach is based on the interspinous ligament. However, they mentioned that the approach may not be suitable for large FTLs because of the narrow surgical field.\u003c/p\u003e \u003cp\u003eCompared with conventional laminotomy, minimally invasive surgery has the advantages of (1) a smaller skin incision, (2) less stress on the paraspinal muscles, and (3) less intraoperative blood loss. Similarly, in our study, the ILA technique showed the above advantages in addition to a shorter operative time.\u003c/p\u003e \u003cp\u003eThis ILA technique is similar to Hayashi et al.\u0026rsquo;s intervertebral approach but differs in that the approach is through the midline of the intervertebral space. Although the skin incision in this method was slightly larger (approximately 3 cm in the case of a transverse incision), we believe a sufficient operative field can be secured even with a relatively thick FTL.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eComparison with literature reports on complications\u003c/h2\u003e \u003cp\u003ePrevious reports exist on complications of the open laminotomy approach. Edstr\u0026ouml;m et al. [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e] reported that non-operative complications occurred in 12% of cases after a single vertebral laminotomy. Solmaz et al. [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e] reported that spinal fluid leakage occurred in 6.1% of cases after a single laminotomy. Bhimani et al. [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e] reported a complication rate of 8.1% with a single laminotomy. Complication rates in other studies were 1.8\u0026ndash;9.2% [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eHayashi et al. [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] reported no postoperative complications requiring additional surgery in 49 patients who underwent the ILA, no cases of postoperative symptomatic deterioration, such as retethering or neurological symptoms, and a significantly shorter hospitalization period than that for LOA. This was attributed to the fact that postoperative pain was less with the ILA technique. In our study, the rates of postoperative complications requiring reoperation were 1.8% and 2.0% in the ILA and LOA groups, respectively, which were lower than those in previous reports [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eHayashi et al. [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] prepared fibrinogen after dural suturing to prevent spinal fluid leakage by returning epidural fat to the dural suture surface. We did not use a fibrinogen product in cases wherein spinal fluid leakage was confirmed by the Valsalva maneuver after dural suturing and watertight closure were obtained. We believe the most important factor for preventing CSF leakage is firmly returning the epidural fat layer to the dural suture. Moreover, as described by Ogiwara et al. [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e], close suturing of the fascia is important to prevent CSF leakage. Regarding postoperative supine rest, Hayashi et al. [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] reported that postoperative rest is basically unnecessary with the ILA technique. Kanematsu et al. [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e] reported that the incidence of CSF leakage did not increase in patients who underwent FTL dissection via LOA, even without postoperative bed rest. In contrast, we started slowly ambulating patients in the supine position for approximately 1 week after surgery and weaned them off bed rest after confirming the presence or absence of CSF leakage by MRI. We believe that MRI examinations during hospitalization are useful; however, in view of past reports, we need to consider shortening the supine rest period.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eImprovement in neurological findings in symptomatic cases\u003c/h2\u003e \u003cp\u003eThe efficacy of ILA for FTL is clear given their minimally invasive nature, as reported by Greuter et al. and Hayashi et al. [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. However, the improvement rates of neurological findings in symptomatic patients with ILA have not yet been comprehensively reported. In contrast, several reports exist on the improvement rate of symptoms by the LOA method (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e) [4\u0026ndash;6,11,13,15,20,23,25\u0026ndash;28,31\u0026ndash;33,], and the improvement rate ranges from 18.5\u0026ndash;100%. The improvement rate of urinary symptoms and UDS findings were 20\u0026ndash;100%, and that of lower limb symptoms were 14.2\u0026ndash;100%.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eSummary of literature review\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"8\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAuthor, publication year\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eResearch\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePatients\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSurgery\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eOverall symptom improvement rate\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eRate of improvement of urinary symptoms and UDS\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eRate of improvement of lower limb symptoms\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eRate of improvement of other symptoms\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eXu, 2022\u003csup\u003e5\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6literature\u003c/p\u003e \u003cp\u003esystematic review\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eOTCS, n\u0026thinsp;=\u0026thinsp;293\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eLess invasive surgery with Xtube\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e88.74%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRezaee \u0026amp; Keykhosravi, 2022\u003csup\u003e24\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10literature\u003c/p\u003e \u003cp\u003esystematic review\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eOTCS, n\u0026thinsp;=\u0026thinsp;234\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eUnknown\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eUrinary symptom: 59\u0026ndash;100%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eLeg pain: 100%\u003c/p\u003e \u003cp\u003eMuscle weakness: 25\u0026ndash;100%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eEdstr\u0026ouml;m, 2022\u003csup\u003e14\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRetrospective\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFTL, n\u0026thinsp;=\u0026thinsp;62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eLOA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eUDS: 48%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eSensorimotor disorder: 42%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMichael, 2021\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e17literature\u003c/p\u003e \u003cp\u003esystematic review\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eOTCS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eUnknown\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;50%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIshisaka, 2020\u003csup\u003e25\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRetrospective\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFTL\u0026thinsp;+\u0026thinsp;syringomyelia, n\u0026thinsp;=\u0026thinsp;19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eUnknown\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e47%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDay, 2020\u003csup\u003e18\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRetrospective\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFTL, TFT, n\u0026thinsp;=\u0026thinsp;144\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eUnknown\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e81.00%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eUDS: 64.4%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eBack pain: 54.5%;\u003c/p\u003e \u003cp\u003eLower limb symptoms: 79.6%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eScoliosis 18.2%\u003c/p\u003e \u003cp\u003eDefecation-related disorder: 57.1%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTamura, 2017\u003csup\u003e26\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRetrospective\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFTL, TFT\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eUnknown\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eUrinary symptom: 58.3%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStrong, 2015\u003csup\u003e20\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRetrospective\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFTL, n\u0026thinsp;=\u0026thinsp;248\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eLOA,ILA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e97.10%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOstling, 2012\u003csup\u003e21\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRetrospective\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTCS, n\u0026thinsp;=\u0026thinsp;99\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eLOA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e88% (improved and stable)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCornips, 2012\u003csup\u003e27\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRetrospective\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFTL, n\u0026thinsp;=\u0026thinsp;25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eILA (partial laminectomy)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e80%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eUrinary symptom: 76.4%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eLower limb symptoms: 14.2%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSolmaz, 2011\u003csup\u003e15\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRetrospective\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTCS, n\u0026thinsp;=\u0026thinsp;9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eLOA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e44.40%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eUrinary symptom: 20%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eBack pain: 100%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTredway, 2007\u003csup\u003e28\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRetrospective\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTCS, n\u0026thinsp;=\u0026thinsp;3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eLess invasive surgery with Xtube\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e100%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eUDS: 100%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eLeg/back pain: 100%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWehby, 2004\u003csup\u003e29\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRetrospective\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eOTCS, n\u0026thinsp;=\u0026thinsp;60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eLOA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eUrinary symptom: 98%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eLeg pain/sensorimotor disorder: 100%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eDefecation-related disorder: 97%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWei, 1999\u003csup\u003e30\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRetrospective\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTCS, n\u0026thinsp;=\u0026thinsp;22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eLOA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eUrinary symptom: 70%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eLower limb symptoms: 100%;sensory disorder: 56%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eDefecation-related disorder: 2%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLa Marca, 1997\u003csup\u003e6\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRetrospective\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFTL, n\u0026thinsp;=\u0026thinsp;27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eLOA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e62.96%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eIncontinence: 37.5%\u003c/p\u003e \u003cp\u003eRetension:33.3%\u003c/p\u003e \u003cp\u003eFrequent UTI:100%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003efoot deformity: 20%\u003c/p\u003e \u003cp\u003eweakness:75%, spasticity:66.7%\u003c/p\u003e \u003cp\u003egait:100%, pain:500%, numbness:100%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"8\"\u003eFTL: filum terminale lipoma; ILA: interlaminar approach; LOA: laminotomy open approach; OTCS: occult tethered cord syndrome; TCS: tethered cord syndrome; TFT: tight filum terminale ; UTI: urinary tract infection\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe improvement rate of all symptoms by ILA in this study was 82%, and the maintenance rate was 18%. The improvement rate of urinary symptoms and abnormal UDS findings was 77%, and that of lower-limb symptoms was 91%, with no worsening of postoperative symptoms. This rate did not significantly differ from that of symptom improvement using the LOA method in our study. These results are comparable to those reported in previous studies. Herein, blood loss was significantly lesser and operative time was significantly shorter in ILA. The primary endpoints of UDS and PT were similar between the two groups. The ILA group experienced less-invasive surgery and had non-inferior long-term neurological outcomes, compared with the LOA group.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003eRetethering\u003c/h2\u003e \u003cp\u003eHerein, there was no case of postoperative re-adhesion during the follow-up period. Re-tethering was evaluated through a comprehensive evaluation of lower-extremity motor function by the physician-in-charge, periodic lumbar MRI imaging, and evaluation of the changes in UDS findings by a pediatric urologist. Ogiwara et al. [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e] reported that retethering occurred in six (2.7%) of 225 cases of FTL and that, to prevent retethering, it is important to prevent bleeding into the subarachnoid space and adhesion between the soft membrane and surrounding tissues by avoiding damage to, and coagulation of, the soft membrane surface as much as possible. As Hayashi et al. [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] also reported, minimally invasive surgery, including the ILA, can minimize dural and arachnoid incisions, which is thought to reduce the incidence of retethering. As another method to prevent reattachment, Abdulrazeq et al. [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e] reported that FTL resection through the spinal conus using a high intervertebral approach could minimize residual lesions and reduce the risk of retethering. The presence of retethering can be determined using postoperative MRI images. Tsuchida et al. [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e] reported that MRI of the cauda equina in the supine and prone positions may be used to observe changes in the position of the cauda equina relative to gravity and to diagnose adhesions between the cauda equina and arachnoid/dura mater. Furthermore, due to its anti-inflammatory effects, dexamethasone was administered during the suturing of the dura mater to prevent retethering. Ogiwara et al. [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e] reported a mean time from the initial surgery to retethering of 5.4 years. It is necessary to confirm whether retethering occurs in our study by following up the patients in the future.\u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusions","content":"\u003cp\u003eThe ILA and LOA approaches to FTL were examined retrospectively. ILA significantly shortened the operative time and reduced blood loss. The complication or reoperation rates did not significantly differ between the two approaches. Long-term symptomatic improvement rates were comparable or higher in the ILA approach. These results suggest that ILA is less invasive and more effective than LOA in the treatment of FTL.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgments:\u0026nbsp;\u003c/strong\u003eWe would like to express our gratitude to Editage (www.editage.jp) for their assistance with English language editing.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interests:\u0026nbsp;\u003c/strong\u003eNone\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u0026nbsp;\u003c/strong\u003eNone\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions:\u003c/strong\u003e All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Tomoki Nawashiro, and Kousuke Aoki. The first draft of the manuscript was written by Tomoki Nawashiro and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics Approval:\u0026nbsp;\u003c/strong\u003eThis study was approved by the ethics committees of the Aichi Children\u0026rsquo;s\u0026nbsp;Health and Medical Center in accordance with the ethical\u0026nbsp;standards of the 1964 Declaration of Helsinki (approval number:2023084).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to Participate\u003c/strong\u003e\u003cstrong\u003e:\u003c/strong\u003e This study was approved by the ethics committees of the Aichi Children\u0026rsquo;s Health and Medical Center in accordance with the ethical standards of the 1964 Declaration of Helsinki (approval number: 2023084). All participants provided informed consent.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to Publish:\u0026nbsp;\u003c/strong\u003eAgreed\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAbdulrazeq H, Shao B, Sastry RA, Klinge PM (2023) Microsurgical approach for resection of the filum terminale internum in tethered cord syndrome-a case demonstration of technical nuances and vignettes. Acta Neurochir (Wien) 165:3505-3509. https://doi.org/10.1007/s00701-023-05568-9.\u003c/li\u003e\n\u003cli\u003eBhimani AD, Selner AN, Patel JB et al (2019) Pediatric tethered cord release: an epidemiological and postoperative complication analysis. J Spine Surg 5:337-350. https://doi.org/10.21037/jss.2019.09.02.\u003c/li\u003e\n\u003cli\u003eCools MJ, Al-Holou WN, Stetler WR et al (2014) Filum terminale lipomas: imaging prevalence, natural history, and conus position. J Neurosurg Pediatr 13:559-567. https://doi.org/10.3171/2014.2.PEDS13528.\u003c/li\u003e\n\u003cli\u003eCornips EM, Vereijken IM, Beuls EA et al (2012) Clinical characteristics and surgical outcome in 25 cases of childhood tight filum syndrome. Eur J Paediatr Neurol 16:103-117. https://doi.org/10.1016/j.ejpn.2011.07.002.\u003c/li\u003e\n\u003cli\u003eDay EL, Proctor MR, Scott RM (2020) Surgical volume of simple tethered spinal cord releases: review of a large pediatric neurosurgical service experience. J Neurosurg Pediatr 26:60-64. https://doi.org/10.3171/2020.2.PEDS19743.\u003c/li\u003e\n\u003cli\u003eEdstr\u0026ouml;m E, Wessl\u0026eacute;n C, Fletcher-Sandersj\u0026ouml;\u0026ouml; A, Elmi-Terander A, Sandvik U (2022) Filum terminale transection in pediatric tethered cord syndrome: a single center, population-based, cohort study of 95 cases. Acta Neurochir (Wien) 164:1473-1480. https://doi.org/10.1007/s00701-022-05218-6.\u003c/li\u003e\n\u003cli\u003eEmery JL, Lendon RG (1969) Lipomas of the cauda equina and other fatty tumours related to neurospinal dysraphism. Dev Med Child Neurol Suppl 20:62-70. https://doi.org/10.1111/j.1469-8749.1969.tb09247.x.\u003c/li\u003e\n\u003cli\u003eGreuter L, Licci M, Terrier A, Guzman R, Soleman J (2022) Minimal invasive interlaminar approach for untethering of fatty filum terminale in pediatric patients \u0026ndash; how I do it. Acta Neurochir (Wien) 164:1481-1484. https://doi.org/10.1007/s00701-022-05204-y.\u003c/li\u003e\n\u003cli\u003eHayashi T, Shirane R (2005) Spina bifida: case with spinal lipoma. Spine Spinal Cord 18:137-144.\u003c/li\u003e\n\u003cli\u003eHayashi T, Kimiwada T, Kohama M, Shirane R, Tominaga T (2018) Minimally invasive surgical approach to filum lipoma. Neurol Med Chir (Tokyo) 58:132-137. https://doi.org/10.2176/nmc.oa.2017-0200.\u003c/li\u003e\n\u003cli\u003eIshisaka E, Usami K, Ogiwara H (2020) Surgical outcomes by sectioning a filum terminale in patients with terminal syringomyelia. Childs Nerv Syst 36:3035-3039. https://doi.org/10.1007/s00381-020-04615-5.\u003c/li\u003e\n\u003cli\u003eKanematsu R, Hirokawa D, Usami K, Ogiwara H (2020) Is the postoperative horizontal decubitus position following transection of a tight filum terminale in pediatric patients necessary? \u0026ndash; a retrospective cohort study. Neurol Med Chir (Tokyo) 60:252-255. https://doi.org/10.2176/nmc.oa.2019-0257.\u003c/li\u003e\n\u003cli\u003eLa Marca F, Grant JA, Tomita T, McLone DG (1997) Spinal lipomas in children: outcome of 270 procedures. Pediatr Neurosurg 26:8-16. https://doi.org/10.1159/000121155.\u003c/li\u003e\n\u003cli\u003eLim JX, Fong E, Goh C et al (2023) Fibrofatty filum terminale: long-term outcomes from a Singapore Children\u0026rsquo;s Hospital. J Neurosurg Pediatr 31:197-205. https://doi.org/10.3171/2022.8.PEDS22103.\u003c/li\u003e\n\u003cli\u003eMichael MM, Garton ALA, Kuzan-Fischer CM, Uribe-Cardenas R, Greenfield JP (2021) A critical analysis of surgery for occult tethered cord syndrome. Childs Nerv Syst 37:3003-3011. https://doi.org/10.1007/s00381-021-05287-5.\u003c/li\u003e\n\u003cli\u003eMorota N, Ihara S, Ogiwara H (2017) New classification of spinal lipomas based on embryonic stage. J Neurosurg Pediatr 19:428-439. https://doi.org/10.3171/2016.10.PEDS16247.\u003c/li\u003e\n\u003cli\u003eOgiwara H, Joko M, Takado M et al (2015) Duration of the horizontal decubitus position for prevention of cerebrospinal fluid leakage following transection of a tight filum terminale. J Neurosurg Pediatr 15:461-464. https://doi.org/10.3171/2014.9.PEDS14289.\u003c/li\u003e\n\u003cli\u003eOgiwara H, Lyszczarz A, Alden TD, Bowman RM, McLone DG, Tomita T (2011) Retethering of transected fatty filum terminales. J Neurosurg Pediatr 7:42-46. https://doi.org/10.3171/2010.10.PEDS09550.\u003c/li\u003e\n\u003cli\u003eOkay O, Dalgic A, Yildirim AE et al (2021) Endoscopic untethering of tight filum terminale: an operative technique. Turk Neurosurg 31:73-75. https://doi.org/10.5137/1019-5149.JTN.29771-20.2.\u003c/li\u003e\n\u003cli\u003eOstling LR, Bierbrauer KS, Kuntz C (2012) Outcome, reoperation, and complications in 99 consecutive children operated for tight or fatty filum. World Neurosurg 77:187-191. https://doi.org/10.1016/j.wneu.2011.05.017.\u003c/li\u003e\n\u003cli\u003ePoonia S, Graber S, Corbett Wilkinson C, O\u0026rsquo;neill BR, Handler MH, Hankinson TC (2016) Outcome of hospital discharge on postoperative Day 1 following uncomplicated tethered spinal cord release. J Neurosurg Pediatr 17:651-656. https://doi.org/10.3171/2015.10.PEDS15318.\u003c/li\u003e\n\u003cli\u003ePotts MB, Wu JC, Gupta N, Mummaneni PV (2010) Minimally invasive tethered cord release in adults: a comparison of open and mini-open approaches. Neurosurg Focus 29:E7. https://doi.org/10.3171/2010.3.FOCUS1077.\u003c/li\u003e\n\u003cli\u003eRezaee H, Keykhosravi E (2022) Effect of untethering on occult tethered cord syndrome: a systematic review. Br J Neurosurg 36:574-582. https://doi.org/10.1080/02688697.2021.1995589.\u003c/li\u003e\n\u003cli\u003eRoberts SB, Tsirikos AI (2022) Paediatric spinal deformity surgery: complications and their management. Healthcare (Basel) 10:2519. https://doi.org/10.3390/healthcare10122519.\u003c/li\u003e\n\u003cli\u003eSolmaz I, Izci Y, Albayrak B et al (2011) Tethered cord syndrome in childhood: special emphasis on the surgical technique and review of the literature with our experience. Turk Neurosurg 21:516-521. https://doi.org/10.5137/1019-5149.JTN.4394-11.1.\u003c/li\u003e\n\u003cli\u003eStrong MJ, Thompson EM, Roundy N, Selden NR (2015) Use of lumbar laminoplasty vs. laminotomy for transection of the filum terminale does not affect early complication rates or postoperative course. Childs Nerv Syst 31:597-601. https://doi.org/10.1007/s00381-015-2615-8.\u003c/li\u003e\n\u003cli\u003eTamura G, Morota N, Ihara S (2017) Impact of magnetic resonance imaging and urodynamic studies on the management of sacrococcygeal dimples. J Neurosurg Pediatr 20:289-297. https://doi.org/10.3171/2017.5.PEDS16719.\u003c/li\u003e\n\u003cli\u003eTredway TL, Musleh W, Christie SD, Khavkin Y, Fessler RG, Curry DJ (2007) A novel minimally invasive technique for spinal cord untethering. Neurosurgery 60:ONS70-4; discussion ONS74. https://doi.org/10.1227/01.NEU.0000249254.63546.D7\u003c/li\u003e\n\u003cli\u003eTsuchida R, Sumitani M, Azuma K et al (2020) A novel technique using magnetic resonance imaging in the supine and prone positions for diagnosing lumbar adhesive arachnoiditis: a preliminary study. Pain Pract 20:34-43. https://doi.org/10.1111/papr.12822.\u003c/li\u003e\n\u003cli\u003eValentini, L. G., M. Babini, R. Cordella, E. Beretta, F. Destro et al (2021) Early de-tethering: analysis of urological and clinical consequences in a series of 40 children. Childs Nerv Syst 37: 941-949. https://doi.org/10.1007/s00381-020-04838-6\u003c/li\u003e\n\u003cli\u003eWehby MC, O\u0026rsquo;Hollaren PS, Abtin K, Hume JL, Richards BJ (2004) Occult tight filum terminale syndrome: results of surgical untethering. Pediatr Neurosurg 40:51-57; discussion 58. https://doi.org/10.1159/000078908.\u003c/li\u003e\n\u003cli\u003eWei W, Gao Y, Yang X, Lu P, E H (1999) Operative results of tethered cord syndrome. Zhonghua Wai Ke Za Zhi 37:488-489.\u003c/li\u003e\n\u003cli\u003eXu K, He J, Wang L (2022) A systematic review and meta-analysis of minimally invasive surgery in children with occult tethered cord syndrome. Transl Pediatr 11:403-410. https://doi.org/10.21037/tp-22-72.\u003c/li\u003e\n\u003cli\u003eYoshifuji K (2022) [Filum lipoma]. No Shinkei Geka 50:1203-11. https://doi.org/10.11477/mf.1436204687.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"childs-nervous-system","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"cnsy","sideBox":"Learn more about [Child's Nervous System](http://link.springer.com/journal/381)","snPcode":"381","submissionUrl":"https://submission.nature.com/new-submission/381/3","title":"Child's Nervous System","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"spina bifida, filum terminale lipoma, minimally invasive surgery, tethered-cord syndrome","lastPublishedDoi":"10.21203/rs.3.rs-3860133/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3860133/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003ePurpose\u003c/h2\u003e \u003cp\u003eFilum terminale lipoma (FTL) causes spinal-cord tethering and is associated with tethered-cord syndrome, which is treated by dissection of the entrapment. The conventional treatment for FTL involves dissection of the spinal cord through a laminotomy open approach (LOA). However, in recent years, the interlaminar approach (ILA) has gained popularity as a minimally invasive surgery. This study compares the effectiveness of the minimally invasive ILA with the conventional LOA in treating FTL.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eWe retrospectively evaluated data on the ILA and LOA for FTL at our center. In total, 103 participants were enrolled, including 55 in the ILA group and 48 in the LOA group.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eThe ILA required significantly less surgical time and resulted in less blood loss. The improvement rate of symptoms in symptomatic patients was 84%, and for urinary symptoms and abnormal urodynamic study findings, it was 77%. The postoperative maintenance rate for asymptomatic patients was 100%. Postoperative complications of ILA included delayed wound healing in two patients (3.6%).\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eCompared with LOA, ILA offers advantages in terms of shorter operative time and less blood loss, with no significant difference in long-term symptom-improvement rates between the groups.\u003c/p\u003e","manuscriptTitle":"Comparison of the Inter-laminar Approach and Laminotomy Open Approach for Filum Terminale Lipoma: A Retrospective Analysis","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-01-17 16:04:55","doi":"10.21203/rs.3.rs-3860133/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-05-11T09:43:21+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-05-10T12:23:24+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"192261045825332804741745422827037475678","date":"2024-05-08T00:58:02+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"4200387c-1179-48de-98c5-ee8d0c8a16a5","date":"2024-02-06T00:04:35+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-02-02T09:19:39+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"38b89566-d668-4c69-a1e5-58c3d191518d","date":"2024-01-29T08:00:02+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"88f9c978-6fe3-4af0-bdef-7b3357091177","date":"2024-01-27T10:38:41+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-01-24T17:20:50+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-01-15T14:51:37+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-01-15T14:51:36+00:00","index":"","fulltext":""},{"type":"submitted","content":"Child's Nervous System","date":"2024-01-13T12:38:17+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"childs-nervous-system","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"cnsy","sideBox":"Learn more about [Child's Nervous System](http://link.springer.com/journal/381)","snPcode":"381","submissionUrl":"https://submission.nature.com/new-submission/381/3","title":"Child's Nervous System","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"8fb87ab1-acf7-495b-abc1-82688f008562","owner":[],"postedDate":"January 17th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2024-06-16T10:48:55+00:00","versionOfRecord":[],"versionCreatedAt":"2024-01-17 16:04:55","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-3860133","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3860133","identity":"rs-3860133","version":["v1"]},"buildId":"FbvkV6FR0MCFSLy54lSbu","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}