Posterior Paramedian Approach—A Simple Technique to Obtain a Lateral Viewing Angle for Spinal Lesions

Posterior Paramedian Approach—A Simple Technique to Obtain a Lateral Viewing Angle for Spinal Lesions | 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 Help Center Sign In Submit a Preprint Cite Share Download PDF Article Posterior Paramedian Approach—A Simple Technique to Obtain a Lateral Viewing Angle for Spinal Lesions Han Soo Chang, Fumiya Sano, Takatoshi Sorimachi, Mitsunori Matsumae This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-1563436/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract A wide lateral viewing angle is often necessary for spinal surgery. However, the skin and paraspinal muscles limit this angle in the traditional posterior midline approach. This article describes a simple, less-invasive approach that provides good lateral viewing angles to spinal lesions. The approach consisted of (1) a horizontal skin incision, (2) unilateral dissection and exposure of the laminae, (3) a horizontal fascial incision, and (4) application of retractors in the longitudinal direction with a minimal incision on the multifidus muscle. We successfully used this approach on 24 patients with various spinal diseases. The pathology of the lesions included nine schwannomas, five meningiomas, four ossification of ligamentum flavum (OLF), three malignant tumors, and three others. There were nine cervical, twelve thoracic, two lumbar, and one sacral lesions. We could achieve gross total removal in most cases without significant complications. The approach provided an excellent surgical field for removing ventrally located tumors with minimal cord retraction. This simple technique will be a valuable addition to the armamentarium of spine surgeons. case series ossification of ligamentum flavum spinal meningioma spinal schwannoma spinal tumor surgical technique Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Introduction Although the standard posterior midline approach can manage most spinal lesions, it is not free from disadvantages. Removing the midline structures such as spinous processes, supra-spinous ligament, and paraspinal muscle attachments weakens the posterior tension band and affects the spinal stability 1 . Also, laterally retracted skin and the paraspinal muscles block the surgeon’s lateral viewing angle 2 , 3 . This blockage is especially disadvantageous for a tumor located ventrally to the spinal cord, where an insufficient lateral viewing angle results in more spinal cord retraction. To compensate, the surgeon must make a longer skin incision and dissect longer spinal segments 2 . This blockage also prohibits the surgeon from approaching bilateral spinal lesions less invasively through a unilateral approach. We developed a simple technique to overcome these shortcomings that enabled a surgeon to gain a sufficient lateral viewing angle with minimal invasiveness. The technique consisted of a horizontal skin incision, subperiosteal dissection of the ipsilateral lamina, a horizontal fascial incision, and retraction of the paraspinal muscle longitudinally to the spinal column. So far, we have used this approach in 24 patients with various spinal pathologies and obtained excellent results. We will describe this technique and its application in detail. Materials And Methods Study Design This study is a retrospective observational study of a consecutive case series at a single teaching hospital. The Tokai University School of Medicine Review Board approved the study protocol (No. 21R179), and informed consent was obtained from all subjects and/or their legal guardians. All methods were performed in accordance with the relevant guidelines and regulations. The first author (a neurosurgeon with over 30 years of experience) operated on all cases from September 2015 to April 2021. Initially, we applied our approach to patients with spinal tumors located ventrally to the spinal cord. Later, as we recognized the usefulness of this approach, we gradually expanded its indication to other pathologies. The first author followed all the patients after surgery at the outpatient clinic. At the last clinical visit, he evaluated the patient’s outcome with the modified MacCormick grade4 (Table 1). Operative Technique Figure 1 shows the detail of this approach. With the patient in the prone position under general anesthesia, we determined the appropriate level on a lateral X-ray. We then made a 7 to 10-cm horizontal skin incision crossing the midline so that about one-third of the incision lay on the contralateral side (Figure 1A). A more prolonged longitudinal exposure required a longer skin incision. We then subperiosteally dissected the multifidus muscles off the ipsilateral spinous processes and laminae (Figure 1B). Next, we made a horizontal incision on the dorsal fascia covering the ipsilateral paraspinal muscles (Figure 1B). This fascial incision facilitated the lateral retraction of the muscles. We then made a horizontal incision on the most medial portion of the multifidus muscle as needed to obtain good exposure to the laminae. Finally, we placed a pair of self-retaining retractors to hold the surgical field (Figure 1C). We placed these retractors longitudinally to the spinal column so that there would be no obstacles to a lateral viewing angle (Figure 1D). We then approached the spinal canal through ipsilateral partial or complete hemilaminectomy. Estimation of postoperative pain From June 2016 to August 2017, we performed a short survey of postoperative pain. We asked patients who underwent spinal tumor surgery (intradural schwannomas or meningiomas) in this period to evaluate the maximal postoperative wound pain with the visual analog scale (VAS). We compared the scores between two groups: those who underwent the posterior paramedian approach and those who underwent the standard bilateral laminectomy. The first author determined the surgical approach (standard or paramedian) individually. We performed Student’s t-test using a statistical software package (R version 4.0.6, R Foundation for Statistical Computing, Vienna, Austria. https://www.R-project.org/ ) . A p-value less than 0.05 was considered statistically significant. Results Case Series Twenty-four patients underwent spinal surgery with the posterior paramedian approach during the study period. Table 2 shows the detailed information about the series. There were ten men and fourteen women with a mean age of 61.5 years and a standard deviation (SD) of 4.4. The mean follow-up period was 36.8 (SD 4.3) months. The series included nine schwannomas, five meningiomas, four OLF, three malignant tumors, and three others, of which nine were cervical, twelve thoracic, two lumbar, and one sacral lesion. The location of the tumors in the spinal canal was ventral or dumbbell/ventral in 10 cases, lateral or dumbbell/lateral in three cases, and dorsolateral in three cases. We previously reported Case 2 as a case report 5 . Representative Cases Case 24 This 50-year-old man complained of severe pain radiating to his bilateral flank areas, and he also had mild gait disturbance. Neurological exams showed hypesthesia below the level of T9, hyperreflexia in both lower extremities, and positive Babinski signs on both sides. Thoracic-spine MRI revealed a mass lesion on the ventral side of the spinal cord at T9/10 (Fig. 2A). This lesion was inhomogeneously enhanced after gadolinium administration (Fig. 2B, C). We chose the right posterior paramedian approach for this ventrally located tumor (Fig. 3A). After unilateral partial laminotomy of T9 and T10, the spinal cord still covered most of the tumor (Fig. 3B). We removed the tumor through a small space on the lateral side of the cord, repeating internal decompression and slight pulling out (Fig. 3C). The approach provided a wide and bright operative field with an excellent lateral viewing angle for the gross total removal of the tumor with minimal cord retraction (Fig. 3D). We removed only the medial portion of the facet joint, so fixation was unnecessary. Postoperatively, the patient immediately made a good neurological recovery. There was minimal wound-related pain either in the postoperative period or later. We could confirm gross total removal on a postoperative MRI (Fig. 4). The patient returned to his normal activities and was doing well six months after surgery. Case 19 This 75-year-old woman gradually worsened her gait with bilateral leg numbness. On exam, she had hyperreflexia in both lower extremities with positive Babinski signs. A thoracolumbar spine MRI showed spinal canal stenosis at T10/11 with thickening of the shadow of the yellow ligament (Fig. 5A, B). A thoracic-spine CT showed bilateral ossification of the yellow ligament at this level (Fig. 5C). We planned to remove the OYL through a unilateral laminotomy to avoid unnecessary spine fusion. For this purpose, we chose the posterior paramedian approach. With a horizontal skin incision, we dissected the multifidus muscle off the left side of the spinous processes of T10 and T11. We exposed the ossified yellow ligament with partial hemilaminectomy at T10 and 11. We carefully removed bilateral OLF with an ultrasonic aspirator (SONOPET, Stryker, Kalamazoo, MI, U.S.A.) under an operating microscope. The patient made an uneventful recovery after surgery. Her gait disturbance fully recovered after a month of rehabilitation. Some numbness in both lower extremities remained. Postoperative MRI and CT showed good cord decompression (Fig. 5D, E, F). After 19 months of follow-up, her condition was stable with well-kept alignment. She had no complaint of back pain. Case 4 This two-year-old boy had a right upper extremity weakness, which rapidly progressed to complete paralysis of his right arm. A cervical-spine MRI showed an ovoid-shaped mass on the ventral side of the spinal cord at the level of C5 and 6 (Fig. 6A, B), which extended into the right C5/6 foramen and exited along with the right longus colli muscle (Fig. 6C, D). We took the patient to the operating room on a semi-emergency basis. Because of the age and size of this boy, an anterior approach did not seem to be feasible. If we approached posteriorly, however, because of the tumor’s location on the ventral side, a lateral viewing angle seemed to be necessary. Thus, we chose the posterior paramedian approach, which could give us an excellent lateral viewing angle to the ventral side of the cord. Its unilateral approach seemed less invasive than the standard laminectomy, even if there was some inevitable muscle damage on the ipsilateral side. With C5, 6 hemilaminectomies, we could achieve a good exposure of the ventral tumor with a comfortably wide surgical field despite the unilateral approach on a two-year-old boy (Fig. 6E). The tumor was malignant and seemed to extend along the C7 motor root. Thanks to the good lateral viewing angle, we could carefully dissect the tumor from the ventral side of the spinal cord under direct microscopic vision. We could completely remove the tumor inside the spinal canal through unilateral laminectomy (Fig. 6F). We removed the tumor in the medial part of the foramen but left its lateral part. The patient made an uneventful recovery from surgery. Postoperative MRI showed good spinal cord decompression (Fig. 6G, H). His right upper-extremity weakness gradually improved, and he recovered full strength in about a month. The pathology was a desmoplastic small round cell tumor, and he was transferred to our pediatric oncology service and received chemotherapy. However, the patient died one year after surgery because of the spread of the malignant tumor. Case 2 This 79-year-old woman presented with weakness in her right hand and gait disturbance. Cervical-spine MRI showed a mass located on the ventral side of the cord at the level of C2 (Fig. 7 A, B). We selected the posterior paramedian approach because the surgery required a wide lateral viewing angle. The tumor was removed using the right-sided posterior paramedian approach through a C2 hemilaminectomy. The patient achieved full neurological recovery after surgery with no surgical complication. Postoperative MRI showed gross total removal of the tumor (Fig. 7 C, D). The patient complained of no neck pain or shoulder fatiguability postoperatively. There was no detectable muscle atrophy one year after surgery (Fig. 7 E). Outcomes and Complications We could achieve MacCormick grade I in 18 cases and grade II in four cases (Table 2 ). One patient (Case 22) with dissemination from a germ cell tumor had an outcome of grade IV. One patient (Case 3) died one year after surgery because of a malignant tumor. We could achieve gross total removal in all five meningiomas. We achieved gross total removal in three of the five dumbbell-shaped schwannomas and left a portion of the tumor outside the foramen in two. The unilateral laminotomy achieved good bilateral decompression for the four OLF cases. We could obtain MacCormick grade I results in 14 of the 17 tumor cases. One patient (Case 3) with cervical schwannoma originating from a motor root developed postoperative biceps weakness, which recovered to a nearly normal level in three months. There was no CSF leak or wound problem, and no patient complained of significant wound pain during the follow-up period. Table 1 Modified MacCormick Scale I Intact neurologically, normal ambulation, minimal dysesthesia II Mild motor or sensory deficit, functional independence III Moderate deficit, limitation of function, independent w/external aid IV Severe motor or sensory deficit, limited function, dependent V Paraplegia or quadriplegia, even w/flickering movement Table 2 Summary of the Series Case Age/Sex Pathology Location Type Resection Follow-up MacCormick Scale 1 38/m schwannoma thoracic dumbbell/lateral gross total 73 I 2 79/f meningioma cervical ventral gross total 70 I 3 69/f schwannoma cervical dumbbell/ventral subtotal 58 II 4 2/m DSRCT cervical dumbbell/ventral subtotal* 12 Dead 5 62/f meningioma cervical dorsolateral gross total 55 I 6 76/f schwannoma cervical ventral gross total 54 I 7 67/m schwannoma sacral dumbbell/dorsal Gross total 53 I 8 81/f schwannoma thoracic dorsolateral Gross total 51 I 9 73/f OLF thoracic dorsal Gross total 51 I 10 60/f meningioma cervical ventral Gross total 51 I 11 56/m schwannoma lumbar lateral Gross total 50 I 12 77/f meningioma thoracic dorsolateral Gross total 50 I 13 70/f meningioma thoracic lateral Gross total 46 I 14 37/f schwannoma lumbar lateral Gross total 38 I 15 74/f OLF thoracic dorsal Gross total 37 II 16 78m arachnoid cyst cervical ventral subtotal 30 II 17 31f germ cell tumor thoracic ventral subtotal 24 IV 18 60f schwannoma cervical dumbbell/ventral subtotal* 21 I 19 75f OLF thoracic dorsal Gross total 19 I 20 85m OLF thoracic dorsal Gross total 10 II 21 80m CSM cervical n/a n/a 10 I 22 18m germ cell tumor thoracic ventral subtotal 8 I 23 78m dural AVF thoracic lateral n/a 7 I 24 50m schwannoma thoracic ventral Gross total 6 I DSRCT: desmoplastic small round cell tumor CSM: cervical spondylotic myelopathy Postoperative Pain Six patients underwent the posterior paramedian approach (cervical 3, thoracic 1, lumbar 2), and seven patients underwent the standard bilateral laminectomy (cervical 3, thoracic 2, lumbar 1). The mean VAS score was significantly smaller (p = 0.04) in the paramedian approach group (mean 3.1, SD 2.0) compared to the standard approach group (mean 5.6, SD 2.0). Discussion We have described a simple surgical technique for spine surgery that provided a wide operative field and an excellent lateral viewing angle. We used this technique for 24 cases of various spinal pathologies, including spinal tumors and OLF, with excellent results. In spinal tumors located ventrally, the wide lateral viewing angle reduced the amount of spinal cord retraction. It also provided an excellent surgical field for removing bilateral OLF through a unilateral approach preserving the midline structures. When a tumor is located on the ventral side of the spinal cord, a posterior approach requires some spinal cord retraction. However, retracting an already compressed spinal cord poses some risk of postoperative neurological deficits 2 , 3 . To reduce this spinal cord retraction, one needs to have a lateral viewing angle. However, with the midline skin incision, the skin and the paraspinal muscles block the lateral viewing angle. We could solve this problem by incising the skin and the dorsal fascia horizontally. With a horizontal skin incision, the skin was no more an obstacle. Incising the dorsal fascia and the medial portion of the multifidus muscle, we could easily retract the paraspinal muscles, which presented no more obstacles. The skin incision could be elongated laterally during surgery, making this technique flexible. Also, our approach required shorter exposure segments because of its good lateral viewing angle. Recently, a few clinical series have shown that minimally invasive surgery (MIS) can provide a satisfactory outcome for patients with intradural extramedullary tumors. 6 , 7 Our approach may be considered a modification of MIS. Both approaches use the less invasive unilateral laminectomy, and MIS makes a smaller paraspinal skin incision, incises the fascia, and retracts the muscle with a tubular retractor. Our technique uses unilateral subperiosteal dissection, fascial incision, minimal muscle incision, and longitudinal retraction. Although dissection is more expansive in our approach, actual damage to the muscle may be comparable to that of MIS. In MIS, however, a narrow tubular retractor makes microsurgical manipulation technically challenging 6 , while our approach provides a wide operative field for comfortable surgical maneuvers. Also, MIS may not be currently indicated for ventrally located intradural tumors6, while our approach is feasible. Some cases may require more complex approaches such as posterolateral approaches and their variations (costotransversectomy and extracavitary approaches 8 , 9 ), usually with facet removal 2 , 10 , and anterior or lateral approaches (anterior or lateral approaches to the cervical spine 11 , 12 , transthoracic approach 13 , retroperitoneal approach 14 ). However, these approaches are more invasive and often associated with complications. For example, unilateral facet removal tends to cause postoperative instability 10 , and corpectomy in anterior approaches requires fixation with cages and plates 14 , 15 . Also, their approach routes are often not familiar to ordinary spine surgeons. On the other hand, the unilateral midline dissection in our approach provides straightforward anatomy familiar to spine surgeons, and it also preserves the facet joint ensuring postoperative stability. There is a trade-off between the better exposure attainable by an approach and its invasiveness and complexity. The best strategy will be to adopt the most straightforward and least invasive technique that enables the surgeon to remove the lesion safely. As far as the arachnoid membrane is well-defined between the tumor and the cord, most intradural extramedullary tumors located ventrally can be removed safely from the posterolateral angle3. Thus, those cases that require complex and invasive approaches will be relatively rare. We believe that our approach provides a well-balanced solution with its good exposure combined with simple, familiar, and less-invasive techniques for most ventrally located tumors. One may be concerned that our approach damages the ipsilateral paraspinal muscles resulting in short-term or long-term complications. Our experience did not support this concern, and none of our patients had a stability problem or outstanding complaints related to paraspinal muscles. Our survey on postoperative pain suggested that our approach caused less postoperative pain than the standard technique. Thus, we believe that our technique has more advantages: less invasiveness of a short-segment unilateral approach, a wider lateral viewing angle, and familiar anatomy, compared to its minor disadvantage: the limited damage to the multifidus muscle. Our approach can be applied not only to spinal tumors but also to other pathologies. It was beneficial for bilateral removal of OLF through a unilateral laminotomy. Surgery on OLF is associated with a relatively high complication rate 16 , and the unilateral approach, albeit its better preservation of stability, poses a further technical challenge 17 . For this problem, our approach was quite valuable. There are some shortcomings of this study. It is a retrospective observational study at a single center without a comparative group, and the responsible pathology is inhomogeneous. The outcome measurement was surgeon-oriented. A detailed MRI analysis of the postoperative paraspinal muscle will be necessary for the future. Conclusions We described a simple, less-invasive unilateral approach to spinal lesions with a wide lateral viewing angle. This approach can be a valuable addition to the spine surgeon’s armamentarium. Declarations Data Availability All data generated or analysed during this study are included in this published article. References Iguchi T, Kurihara A, Nakayama J, Sato K, Kurosaka M, Yamasaki K. Minimum 10-year outcome of decompressive laminectomy for degenerative lumbar spinal stenosis. Spine (Phila Pa 1976). 2000;25(14):1754–1759. doi: 10.1097/00007632-200007150-00003 Slin’ko EI, Al-Qashqish II. Intradural ventral and ventrolateral tumors of the spinal cord: surgical treatment and results. Neurosurg Focus. 2004;17(1):ECP2. doi: 10.3171/foc.2004.17.1.9 Angevine PD, Kellner C, Haque RM, McCormick PC. Surgical management of ventral intradural spinal lesions. J Neurosurg Spine. 2011;15(1):28–37. doi: 10.3171/2011.3.SPINE1095 Manzano G, Green BA, Vanni S, Levi AD. Contemporary management of adult intramedullary spinal tumors—pathology and neurological outcomes related to surgical resection. Spinal Cord. 2008;46(8):540–546. doi: 10.1038/sc.2008.51 Chang HS. Posterior Paramedian Approach to a Ventrally Located Spinal Meningioma. World Neurosurg. 2017;105:755–759. doi: 10.1016/j.wneu.2017.06.085 Mannion RJ, Nowitzke AM, Efendy J, Wood MJ. Safety and efficacy of intradural extramedullary spinal tumor removal using a minimally invasive approach. Operative Neurosurgery. 2011;68(suppl_1):ons208-ons216. Wong AP, Lall RR, Dahdaleh NS, et al. Comparison of open and minimally invasive surgery for intradural-extramedullary spine tumors. Neurosurgical focus. 2015;39(2):E11. Simpson JM, Silveri CP, Simeone FA, Balderston RA, An HS. Thoracic disc herniation. Re-evaluation of the posterior approach using a modified costotransversectomy. Spine (Phila Pa 1976). 1993;18(13):1872–1877. Larson SJ, Holst RA, Hemmy DC, Sances A. Lateral extracavitary approach to traumatic lesions of the thoracic and lumbar spine. J Neurosurg. 1976;45(6):628–637. doi: 10.3171/jns.1976.45.6.0628 Ito K, Aoyama T, Miyaoka Y, Seguchi T, Horiuchi T, Hongo K. Surgery for ventral intradural thoracic spinal tumors with a posterolateral transpedicular approach. Acta Neurochir (Wien). 2016;158(8):1563–1569. doi: 10.1007/s00701-016-2864-7 Arnautović KI, Al-Mefty O, Husain M. Ventral foramen magnum meninigiomas. J Neurosurg. 2000;92(1 Suppl):71–80. doi: 10.3171/spi.2000.92.1.0071 Abdullah KG, Schlenk RS, Krishnaney A, Steinmetz MP, Benzel EC, Mroz TE. Direct lateral approach to pathology at the craniocervical junction: a technical note. Neurosurgery. 2012;70(2 Suppl Operative):202–208. doi: 10.1227/NEU.0b013e31824042e6 Gokaslan ZL, York JE, Walsh GL, et al. Transthoracic vertebrectomy for metastatic spinal tumors. Journal of Neurosurgery. 1998;89(4):599–609. doi: 10.3171/jns.1998.89.4.0599 Steinmetz MP, Mekhail A, Benzel EC. Management of metastatic tumors of the spine: strategies and operative indications. Neurosurgical Focus. 2001;11(6):1–6. doi: 10.3171/foc.2001.11.6.3 Byvaltsev VA, Kalinin AA, Aliyev MA, Azhibekov NO, Shepelev VV, Riew KD. Poor Fusion Rates Following Cervical Corpectomy Reconstructed With an Expandable Cage: Minimum 2-Year Radiographic and Clinical Outcomes. Neurosurgery. 2021;89(4):617–625. doi: 10.1093/neuros/nyab240 Osman NS, Cheung ZB, Hussain AK, et al. Outcomes and Complications Following Laminectomy Alone for Thoracic Myelopathy due to Ossified Ligamentum Flavum: A Systematic Review and Meta-Analysis. Spine. 2018;43(14):E842-E848. doi: 10.1097/BRS.0000000000002563 Baba S, Oshima Y, Iwahori T, Takano Y, Inanami H, Koga H. Microendoscopic posterior decompression for the treatment of thoracic myelopathy caused by ossification of the ligamentum flavum: a technical report. Eur Spine J . 2016;25(6):1912–1919. doi: 10.1007/s00586-015-4158 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted 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. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies 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-1563436","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":101223317,"identity":"16360529-4fad-4ac0-adc9-c288695399b7","order_by":0,"name":"Han Soo Chang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAw0lEQVRIiWNgGAWjYDACCRBRAeeyEavlDJjJ2EC8FsY2uBYiAP/s5mcPv86rk+Offfj5gw8MfHmELblzzNxYdtthY4lzaYaNMxjYiglqMZBIMJOW3HYgcQMPg2EzDwNbIkHXGUikf5OWnFMH1ML+sfkPcVpyzCQ/NjADtfAYNjMQo0XiRk6ZNMMxoF/O8BTO7DEgwi/8M9K3Sf6oAYZYD/uGDz8qjhEOMRBg5kG481gCUVoYfyDYNcRpGQWjYBSMghEFAMJ/OLuG7eohAAAAAElFTkSuQmCC","orcid":"","institution":"Tokai University","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Han","middleName":"Soo","lastName":"Chang","suffix":""},{"id":101223323,"identity":"bf84944e-f9ab-4c5a-b7c5-d0d092f495a3","order_by":1,"name":"Fumiya Sano","email":"","orcid":"","institution":"Tokai University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Fumiya","middleName":"","lastName":"Sano","suffix":""},{"id":101223324,"identity":"9700bfa2-36f4-476e-8798-7b31c30836da","order_by":2,"name":"Takatoshi Sorimachi","email":"","orcid":"","institution":"Tokai University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Takatoshi","middleName":"","lastName":"Sorimachi","suffix":""},{"id":101223325,"identity":"39e294fb-1cc5-4a0c-bf84-2739f1be4c2f","order_by":3,"name":"Mitsunori Matsumae","email":"","orcid":"","institution":"Tokai University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Mitsunori","middleName":"","lastName":"Matsumae","suffix":""}],"badges":[],"createdAt":"2022-04-16 06:59:14","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-1563436/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-1563436/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":20835409,"identity":"ec33c267-7970-4e1d-ac02-fd5bd604e183","added_by":"auto","created_at":"2022-04-27 16:04:43","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":477078,"visible":true,"origin":"","legend":"\u003cp\u003eSchemes to show the operative technique. A: We make a horizontal skin incision crossing the midline over the appropriate level. B: We make a horizontal incision on the dorsal fascia after unilateral dissection of the spinous processes. C: We expose the unilateral laminae after incising the medial portion of the multifidus muscle. D: We hold the paraspinal muscles with a pair of retractors placed longitudinally, thus obtaining a wide surgical field with an excellent lateral viewing angle.\u003c/p\u003e","description":"","filename":"fig1.png","url":"https://assets-eu.researchsquare.com/files/rs-1563436/v1/c4df55b359d0adeb730e9eaa.png"},{"id":20835267,"identity":"7c96a4ef-4af7-4078-9135-8694782548e4","added_by":"auto","created_at":"2022-04-27 15:59:43","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":291943,"visible":true,"origin":"","legend":"\u003cp\u003ePreoperative MRI of Case 24. A: A T2-weighted sagittal image showing a round, well-demarcated mass at the level of T10. B: A T1-weighted sagittal image after gadolinium administration, and the mass is inhomogeneously enhanced. C: A T1-weighted axial image showing the mass located on the ventral side of the spinal cord, which is severely compressed dorsally.\u003c/p\u003e","description":"","filename":"fig2.png","url":"https://assets-eu.researchsquare.com/files/rs-1563436/v1/b079b2b871d9c5c025be9be1.png"},{"id":20835269,"identity":"92a6a817-bfe3-4bfb-9be5-26b4bac14744","added_by":"auto","created_at":"2022-04-27 15:59:43","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1282246,"visible":true,"origin":"","legend":"\u003cp\u003eOperative images of Case 24. A: Exposure of the right T9 and T10 laminae. B: Exposure of the tumor on the ventral side of the cord. Arrow: tumor, arrowheads: right T10 posterior root, C: Internal decompression of the tumor with an ultrasonic aspirator. D: After removal of the tumor. Arrowhead: right T10 posterior root. Blue arrow: Right T10 motor root (tumor origin)\u003c/p\u003e","description":"","filename":"fig3.png","url":"https://assets-eu.researchsquare.com/files/rs-1563436/v1/98581b8069773d8f44cab9ef.png"},{"id":20835410,"identity":"882c1872-d4d8-4da6-8cde-4e17d5e664bb","added_by":"auto","created_at":"2022-04-27 16:04:43","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":255853,"visible":true,"origin":"","legend":"\u003cp\u003ePostoperative MRI of Case 24. A: T2-weighted sagittal image. B: T2-weighted axial image one month after surgery shows gross total removal. Note the minimal damage to the paraspinal muscles (arrowhead).\u003c/p\u003e","description":"","filename":"fig4.png","url":"https://assets-eu.researchsquare.com/files/rs-1563436/v1/9f2084742e002eaffe6d20aa.png"},{"id":20835272,"identity":"4b6c0131-7d74-4a93-bc9d-bbe536795eef","added_by":"auto","created_at":"2022-04-27 15:59:44","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":518945,"visible":true,"origin":"","legend":"\u003cp\u003ePre- and postoperative images of Case 19. The upper row shows the preoperative, and the lower row shows the postoperative images. A: A sagittal T2-weighted MRI showed cord compression at T10/11. B: An axial T2-weighted MRI showing the cord compression. C. An axial CT showing bilateral ossification of the ligamentum flavum (OLF). D. Postoperative sagittal MRI showing good decompression. E. postoperative axial MRI showing good decompression. F. postoperative CT showing good removal of the bilateral OLF.\u003c/p\u003e","description":"","filename":"fig5.png","url":"https://assets-eu.researchsquare.com/files/rs-1563436/v1/a56aed77c16ac0c9822b5d9e.png"},{"id":20835266,"identity":"a88840f9-fa6d-4425-a560-c305c8dd0a5b","added_by":"auto","created_at":"2022-04-27 15:59:43","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":909836,"visible":true,"origin":"","legend":"\u003cp\u003eImages of Case 4. A. Preoperative sagittal T2-weighted MRI showing a tumor compressing the cord from the ventral side. B. Preoperative sagittal T1-weighted MRI after gadolinium administration. C. Preoperative axial T1-weighted MRI after gadolinium administration shows the tumor’s expansion into the intervertebral foramen. D. Preoperative axial T2-weighted image showing the severe cord compression from the ventral side. E. An intraoperative image after dural opening. The tumor is seen beyond the posterior roots. F. Postoperative axial CT showing the unilateral laminotomy. G. Postoperative sagittal T2-weighted MRI shows good tumor removal inside the canal. H. Postoperative axial T1-weighted image after gadolinium administration.\u003c/p\u003e","description":"","filename":"fig6.png","url":"https://assets-eu.researchsquare.com/files/rs-1563436/v1/1c90c2cd0facd22177216b69.png"},{"id":20835270,"identity":"794da67e-f681-443b-aa8b-40d499c81ab5","added_by":"auto","created_at":"2022-04-27 15:59:43","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":539097,"visible":true,"origin":"","legend":"\u003cp\u003eA. Preoperative T1-weighted MRI after gadolinium enhancement (sagittal view) showing a ventral mass at C2. B. Preoperative T2-weighted MRI (axial view). C. Postoperative T1-weighted MRI after gadolunium enhancement (sagittal view). D. Postoperative T2-weighted MRI (axial view). E. Surgical wound one year after surgery (arrowheads) showing no muscular atrophy.\u003c/p\u003e","description":"","filename":"fig7.png","url":"https://assets-eu.researchsquare.com/files/rs-1563436/v1/f6e910e8968dcbb2f00cebed.png"},{"id":23843456,"identity":"8f65c88e-ceea-431c-8e69-16843861ff69","added_by":"auto","created_at":"2022-07-14 03:59:26","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":6414043,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-1563436/v1/19fd1c8c-20c3-420e-9cae-b73e396949ac.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Posterior Paramedian Approach—A Simple Technique to Obtain a Lateral Viewing Angle for Spinal Lesions","fulltext":[{"header":"Introduction","content":"\u003cp\u003eAlthough the standard posterior midline approach can manage most spinal lesions, it is not free from disadvantages. Removing the midline structures such as spinous processes, supra-spinous ligament, and paraspinal muscle attachments weakens the posterior tension band and affects the spinal stability\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e. Also, laterally retracted skin and the paraspinal muscles block the surgeon\u0026rsquo;s lateral viewing angle\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e,\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e. This blockage is especially disadvantageous for a tumor located ventrally to the spinal cord, where an insufficient lateral viewing angle results in more spinal cord retraction. To compensate, the surgeon must make a longer skin incision and dissect longer spinal segments\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e. This blockage also prohibits the surgeon from approaching bilateral spinal lesions less invasively through a unilateral approach.\u003c/p\u003e \u003cp\u003eWe developed a simple technique to overcome these shortcomings that enabled a surgeon to gain a sufficient lateral viewing angle with minimal invasiveness. The technique consisted of a horizontal skin incision, subperiosteal dissection of the ipsilateral lamina, a horizontal fascial incision, and retraction of the paraspinal muscle longitudinally to the spinal column. So far, we have used this approach in 24 patients with various spinal pathologies and obtained excellent results. We will describe this technique and its application in detail.\u003c/p\u003e"},{"header":"Materials And Methods","content":"\u003ch2\u003eStudy Design\u003c/h2\u003e\n\u003cp\u003eThis study is a retrospective observational study of a consecutive case series at a single teaching hospital. The Tokai University School of Medicine Review Board approved the study protocol (No. 21R179), and informed consent was obtained from all subjects and/or their legal guardians. All methods were performed in accordance with the relevant guidelines and regulations. The first author (a neurosurgeon with over 30 years of experience) operated on all cases from September 2015 to April 2021. Initially, we applied our approach to patients with spinal tumors located ventrally to the spinal cord. Later, as we recognized the usefulness of this approach, we gradually expanded its indication to other pathologies. The first author followed all the patients after surgery at the outpatient clinic. At the last clinical visit, he evaluated the patient\u0026rsquo;s outcome with the modified MacCormick grade4 (Table 1).\u003c/p\u003e\n\u003ch2\u003eOperative Technique\u003c/h2\u003e\n\u003cp\u003eFigure 1 shows the detail of this approach. With the patient in the prone position under general anesthesia, we determined the appropriate level on a lateral X-ray. We then made a 7 to 10-cm horizontal skin incision crossing the midline so that about one-third of the incision lay on the contralateral side (Figure 1A). A more prolonged longitudinal exposure required a longer skin incision. We then subperiosteally dissected the multifidus muscles off the ipsilateral spinous processes and laminae (Figure 1B). Next, we made a horizontal incision on the dorsal fascia covering the ipsilateral paraspinal muscles (Figure 1B). This fascial incision facilitated the lateral retraction of the muscles. We then made a horizontal incision on the most medial portion of the multifidus muscle as needed to obtain good exposure to the laminae. Finally, we placed a pair of self-retaining retractors to hold the surgical field (Figure 1C). We placed these retractors longitudinally to the spinal column so that there would be no obstacles to a lateral viewing angle (Figure 1D). We then approached the spinal canal through ipsilateral partial or complete hemilaminectomy.\u003c/p\u003e\n\u003ch2\u003eEstimation of postoperative pain\u003c/h2\u003e\n\u003cp\u003eFrom June 2016 to August 2017, we performed a short survey of postoperative pain. We asked patients who underwent spinal tumor surgery (intradural schwannomas or meningiomas) in this period to evaluate the maximal postoperative wound pain with the visual analog scale (VAS). We compared the scores between two groups: those who underwent the posterior paramedian approach and those who underwent the standard bilateral laminectomy. The first author determined the surgical approach (standard or paramedian) individually. We performed Student\u0026rsquo;s t-test using a statistical software package (R version 4.0.6, R Foundation for Statistical Computing, Vienna, Austria. https://www.R-project.org/\u003cstrong\u003e)\u003c/strong\u003e. A p-value less than 0.05 was considered statistically significant.\u003c/p\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eCase Series\u003c/h2\u003e \u003cp\u003eTwenty-four patients underwent spinal surgery with the posterior paramedian approach during the study period. Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e shows the detailed information about the series. There were ten men and fourteen women with a mean age of 61.5 years and a standard deviation (SD) of 4.4. The mean follow-up period was 36.8 (SD 4.3) months. The series included nine schwannomas, five meningiomas, four OLF, three malignant tumors, and three others, of which nine were cervical, twelve thoracic, two lumbar, and one sacral lesion. The location of the tumors in the spinal canal was ventral or dumbbell/ventral in 10 cases, lateral or dumbbell/lateral in three cases, and dorsolateral in three cases. We previously reported Case 2 as a case report\u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eRepresentative Cases\u003c/h2\u003e \u003cdiv id=\"Sec9\" class=\"Section3\"\u003e \u003ch2\u003eCase 24\u003c/h2\u003e \u003cp\u003eThis 50-year-old man complained of severe pain radiating to his bilateral flank areas, and he also had mild gait disturbance. Neurological exams showed hypesthesia below the level of T9, hyperreflexia in both lower extremities, and positive Babinski signs on both sides. Thoracic-spine MRI revealed a mass lesion on the ventral side of the spinal cord at T9/10 (Fig.\u0026nbsp;2A). This lesion was inhomogeneously enhanced after gadolinium administration (Fig.\u0026nbsp;2B, C).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eWe chose the right posterior paramedian approach for this ventrally located tumor (Fig.\u0026nbsp;3A). After unilateral partial laminotomy of T9 and T10, the spinal cord still covered most of the tumor (Fig.\u0026nbsp;3B). We removed the tumor through a small space on the lateral side of the cord, repeating internal decompression and slight pulling out (Fig.\u0026nbsp;3C). The approach provided a wide and bright operative field with an excellent lateral viewing angle for the gross total removal of the tumor with minimal cord retraction (Fig.\u0026nbsp;3D). We removed only the medial portion of the facet joint, so fixation was unnecessary.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003ePostoperatively, the patient immediately made a good neurological recovery. There was minimal wound-related pain either in the postoperative period or later. We could confirm gross total removal on a postoperative MRI (Fig.\u0026nbsp;4). The patient returned to his normal activities and was doing well six months after surgery.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section3\"\u003e \u003ch2\u003eCase 19\u003c/h2\u003e \u003cp\u003eThis 75-year-old woman gradually worsened her gait with bilateral leg numbness. On exam, she had hyperreflexia in both lower extremities with positive Babinski signs. A thoracolumbar spine MRI showed spinal canal stenosis at T10/11 with thickening of the shadow of the yellow ligament (Fig.\u0026nbsp;5A, B). A thoracic-spine CT showed bilateral ossification of the yellow ligament at this level (Fig.\u0026nbsp;5C). We planned to remove the OYL through a unilateral laminotomy to avoid unnecessary spine fusion. For this purpose, we chose the posterior paramedian approach.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eWith a horizontal skin incision, we dissected the multifidus muscle off the left side of the spinous processes of T10 and T11. We exposed the ossified yellow ligament with partial hemilaminectomy at T10 and 11. We carefully removed bilateral OLF with an ultrasonic aspirator (SONOPET, Stryker, Kalamazoo, MI, U.S.A.) under an operating microscope.\u003c/p\u003e \u003cp\u003eThe patient made an uneventful recovery after surgery. Her gait disturbance fully recovered after a month of rehabilitation. Some numbness in both lower extremities remained. Postoperative MRI and CT showed good cord decompression (Fig.\u0026nbsp;5D, E, F). After 19 months of follow-up, her condition was stable with well-kept alignment. She had no complaint of back pain.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section3\"\u003e \u003ch2\u003eCase 4\u003c/h2\u003e \u003cp\u003eThis two-year-old boy had a right upper extremity weakness, which rapidly progressed to complete paralysis of his right arm. A cervical-spine MRI showed an ovoid-shaped mass on the ventral side of the spinal cord at the level of C5 and 6 (Fig.\u0026nbsp;6A, B), which extended into the right C5/6 foramen and exited along with the right longus colli muscle (Fig.\u0026nbsp;6C, D). We took the patient to the operating room on a semi-emergency basis.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eBecause of the age and size of this boy, an anterior approach did not seem to be feasible. If we approached posteriorly, however, because of the tumor\u0026rsquo;s location on the ventral side, a lateral viewing angle seemed to be necessary. Thus, we chose the posterior paramedian approach, which could give us an excellent lateral viewing angle to the ventral side of the cord. Its unilateral approach seemed less invasive than the standard laminectomy, even if there was some inevitable muscle damage on the ipsilateral side.\u003c/p\u003e \u003cp\u003eWith C5, 6 hemilaminectomies, we could achieve a good exposure of the ventral tumor with a comfortably wide surgical field despite the unilateral approach on a two-year-old boy (Fig.\u0026nbsp;6E). The tumor was malignant and seemed to extend along the C7 motor root. Thanks to the good lateral viewing angle, we could carefully dissect the tumor from the ventral side of the spinal cord under direct microscopic vision. We could completely remove the tumor inside the spinal canal through unilateral laminectomy (Fig.\u0026nbsp;6F). We removed the tumor in the medial part of the foramen but left its lateral part.\u003c/p\u003e \u003cp\u003eThe patient made an uneventful recovery from surgery. Postoperative MRI showed good spinal cord decompression (Fig.\u0026nbsp;6G, H). His right upper-extremity weakness gradually improved, and he recovered full strength in about a month. The pathology was a desmoplastic small round cell tumor, and he was transferred to our pediatric oncology service and received chemotherapy. However, the patient died one year after surgery because of the spread of the malignant tumor.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section3\"\u003e \u003ch2\u003eCase 2\u003c/h2\u003e \u003cp\u003eThis 79-year-old woman presented with weakness in her right hand and gait disturbance. Cervical-spine MRI showed a mass located on the ventral side of the cord at the level of C2 (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e7\u003c/span\u003eA, B). We selected the posterior paramedian approach because the surgery required a wide lateral viewing angle.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe tumor was removed using the right-sided posterior paramedian approach through a C2 hemilaminectomy. The patient achieved full neurological recovery after surgery with no surgical complication. Postoperative MRI showed gross total removal of the tumor (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e7\u003c/span\u003eC, D). The patient complained of no neck pain or shoulder fatiguability postoperatively. There was no detectable muscle atrophy one year after surgery (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e7\u003c/span\u003eE).\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eOutcomes and Complications\u003c/h2\u003e \u003cp\u003eWe could achieve MacCormick grade I in 18 cases and grade II in four cases (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). One patient (Case 22) with dissemination from a germ cell tumor had an outcome of grade IV. One patient (Case 3) died one year after surgery because of a malignant tumor. We could achieve gross total removal in all five meningiomas. We achieved gross total removal in three of the five dumbbell-shaped schwannomas and left a portion of the tumor outside the foramen in two. The unilateral laminotomy achieved good bilateral decompression for the four OLF cases. We could obtain MacCormick grade I results in 14 of the 17 tumor cases. One patient (Case 3) with cervical schwannoma originating from a motor root developed postoperative biceps weakness, which recovered to a nearly normal level in three months. There was no CSF leak or wound problem, and no patient complained of significant wound pain during the follow-up period.\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\u003eModified MacCormick Scale\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"2\"\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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eI\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eIntact neurologically, normal ambulation, minimal dysesthesia\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eII\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMild motor or sensory deficit, functional independence\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIII\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eModerate deficit, limitation of function, independent w/external aid\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIV\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSevere motor or sensory deficit, limited function, dependent\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eV\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eParaplegia or quadriplegia, even w/flickering movement\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \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\u003eSummary of the Series\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=\"char\" char=\".\" 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\u003eCase\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAge/Sex\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePathology\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eLocation\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eType\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eResection\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eFollow-up\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eMacCormick Scale\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e38/m\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eschwannoma\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ethoracic\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003edumbbell/lateral\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003egross total\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e73\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eI\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e79/f\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003emeningioma\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ecervical\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eventral\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003egross total\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eI\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e69/f\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eschwannoma\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ecervical\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003edumbbell/ventral\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003esubtotal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e58\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eII\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2/m\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDSRCT\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ecervical\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003edumbbell/ventral\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003esubtotal*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eDead\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e62/f\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003emeningioma\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ecervical\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003edorsolateral\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003egross total\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eI\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e76/f\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eschwannoma\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ecervical\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eventral\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003egross total\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eI\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e67/m\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eschwannoma\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003esacral\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003edumbbell/dorsal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eGross total\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e53\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eI\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e81/f\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eschwannoma\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ethoracic\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003edorsolateral\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eGross total\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eI\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e73/f\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eOLF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ethoracic\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003edorsal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eGross total\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eI\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e60/f\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003emeningioma\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ecervical\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eventral\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eGross total\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eI\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e56/m\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eschwannoma\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003elumbar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003elateral\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eGross total\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eI\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e77/f\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003emeningioma\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ethoracic\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003edorsolateral\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eGross total\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eI\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e70/f\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003emeningioma\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ethoracic\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003elateral\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eGross total\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e46\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eI\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e37/f\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eschwannoma\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003elumbar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003elateral\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eGross total\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eI\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e74/f\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eOLF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ethoracic\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003edorsal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eGross total\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eII\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e78m\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003earachnoid cyst\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ecervical\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eventral\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003esubtotal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eII\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e31f\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003egerm cell tumor\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ethoracic\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eventral\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003esubtotal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eIV\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e60f\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eschwannoma\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ecervical\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003edumbbell/ventral\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003esubtotal*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eI\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e75f\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eOLF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ethoracic\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003edorsal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eGross total\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eI\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e85m\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eOLF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ethoracic\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003edorsal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eGross total\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eII\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e80m\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCSM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ecervical\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003en/a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003en/a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eI\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e18m\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003egerm cell tumor\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ethoracic\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eventral\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003esubtotal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eI\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e78m\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003edural AVF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ethoracic\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003elateral\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003en/a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eI\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e50m\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eschwannoma\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ethoracic\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eventral\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eGross total\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eI\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"8\"\u003eDSRCT: desmoplastic small round cell tumor\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eCSM: cervical spondylotic myelopathy\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003ePostoperative Pain\u003c/h2\u003e \u003cp\u003eSix patients underwent the posterior paramedian approach (cervical 3, thoracic 1, lumbar 2), and seven patients underwent the standard bilateral laminectomy (cervical 3, thoracic 2, lumbar 1). The mean VAS score was significantly smaller (p\u0026thinsp;=\u0026thinsp;0.04) in the paramedian approach group (mean 3.1, SD 2.0) compared to the standard approach group (mean 5.6, SD 2.0).\u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003e We have described a simple surgical technique for spine surgery that provided a wide operative field and an excellent lateral viewing angle. We used this technique for 24 cases of various spinal pathologies, including spinal tumors and OLF, with excellent results. In spinal tumors located ventrally, the wide lateral viewing angle reduced the amount of spinal cord retraction. It also provided an excellent surgical field for removing bilateral OLF through a unilateral approach preserving the midline structures.\u003c/p\u003e \u003cp\u003eWhen a tumor is located on the ventral side of the spinal cord, a posterior approach requires some spinal cord retraction. However, retracting an already compressed spinal cord poses some risk of postoperative neurological deficits\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e,\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e. To reduce this spinal cord retraction, one needs to have a lateral viewing angle. However, with the midline skin incision, the skin and the paraspinal muscles block the lateral viewing angle.\u003c/p\u003e \u003cp\u003eWe could solve this problem by incising the skin and the dorsal fascia horizontally. With a horizontal skin incision, the skin was no more an obstacle. Incising the dorsal fascia and the medial portion of the multifidus muscle, we could easily retract the paraspinal muscles, which presented no more obstacles. The skin incision could be elongated laterally during surgery, making this technique flexible. Also, our approach required shorter exposure segments because of its good lateral viewing angle.\u003c/p\u003e \u003cp\u003eRecently, a few clinical series have shown that minimally invasive surgery (MIS) can provide a satisfactory outcome for patients with intradural extramedullary tumors.\u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e,\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/sup\u003e Our approach may be considered a modification of MIS. Both approaches use the less invasive unilateral laminectomy, and MIS makes a smaller paraspinal skin incision, incises the fascia, and retracts the muscle with a tubular retractor. Our technique uses unilateral subperiosteal dissection, fascial incision, minimal muscle incision, and longitudinal retraction. Although dissection is more expansive in our approach, actual damage to the muscle may be comparable to that of MIS. In MIS, however, a narrow tubular retractor makes microsurgical manipulation technically challenging\u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e, while our approach provides a wide operative field for comfortable surgical maneuvers. Also, MIS may not be currently indicated for ventrally located intradural tumors6, while our approach is feasible.\u003c/p\u003e \u003cp\u003eSome cases may require more complex approaches such as posterolateral approaches and their variations (costotransversectomy and extracavitary approaches\u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e,\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e), usually with facet removal\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e,\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e, and anterior or lateral approaches (anterior or lateral approaches to the cervical spine\u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e,\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e, transthoracic approach\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e, retroperitoneal approach\u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e). However, these approaches are more invasive and often associated with complications. For example, unilateral facet removal tends to cause postoperative instability\u003csup\u003e\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e, and corpectomy in anterior approaches requires fixation with cages and plates\u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e,\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e. Also, their approach routes are often not familiar to ordinary spine surgeons. On the other hand, the unilateral midline dissection in our approach provides straightforward anatomy familiar to spine surgeons, and it also preserves the facet joint ensuring postoperative stability.\u003c/p\u003e \u003cp\u003eThere is a trade-off between the better exposure attainable by an approach and its invasiveness and complexity. The best strategy will be to adopt the most straightforward and least invasive technique that enables the surgeon to remove the lesion safely. As far as the arachnoid membrane is well-defined between the tumor and the cord, most intradural extramedullary tumors located ventrally can be removed safely from the posterolateral angle3. Thus, those cases that require complex and invasive approaches will be relatively rare. We believe that our approach provides a well-balanced solution with its good exposure combined with simple, familiar, and less-invasive techniques for most ventrally located tumors.\u003c/p\u003e \u003cp\u003eOne may be concerned that our approach damages the ipsilateral paraspinal muscles resulting in short-term or long-term complications. Our experience did not support this concern, and none of our patients had a stability problem or outstanding complaints related to paraspinal muscles. Our survey on postoperative pain suggested that our approach caused less postoperative pain than the standard technique. Thus, we believe that our technique has more advantages: less invasiveness of a short-segment unilateral approach, a wider lateral viewing angle, and familiar anatomy, compared to its minor disadvantage: the limited damage to the multifidus muscle.\u003c/p\u003e \u003cp\u003eOur approach can be applied not only to spinal tumors but also to other pathologies. It was beneficial for bilateral removal of OLF through a unilateral laminotomy. Surgery on OLF is associated with a relatively high complication rate\u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e, and the unilateral approach, albeit its better preservation of stability, poses a further technical challenge\u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e. For this problem, our approach was quite valuable.\u003c/p\u003e \u003cp\u003eThere are some shortcomings of this study. It is a retrospective observational study at a single center without a comparative group, and the responsible pathology is inhomogeneous. The outcome measurement was surgeon-oriented. A detailed MRI analysis of the postoperative paraspinal muscle will be necessary for the future.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eWe described a simple, less-invasive unilateral approach to spinal lesions with a wide lateral viewing angle. This approach can be a valuable addition to the spine surgeon\u0026rsquo;s armamentarium.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eData Availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data generated or analysed during this study are included in this published article.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eIguchi T, Kurihara A, Nakayama J, Sato K, Kurosaka M, Yamasaki K. Minimum 10-year outcome of decompressive laminectomy for degenerative lumbar spinal stenosis. Spine (Phila Pa 1976). 2000;25(14):1754\u0026ndash;1759. doi:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1097/00007632-200007150-00003\u003c/span\u003e\u003cspan address=\"10.1097/00007632-200007150-00003\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSlin\u0026rsquo;ko EI, Al-Qashqish II. Intradural ventral and ventrolateral tumors of the spinal cord: surgical treatment and results. Neurosurg Focus. 2004;17(1):ECP2. doi:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3171/foc.2004.17.1.9\u003c/span\u003e\u003cspan address=\"10.3171/foc.2004.17.1.9\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAngevine PD, Kellner C, Haque RM, McCormick PC. Surgical management of ventral intradural spinal lesions. 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Microendoscopic posterior decompression for the treatment of thoracic myelopathy caused by ossification of the ligamentum flavum: a technical report. \u003cem\u003eEur Spine J\u003c/em\u003e. 2016;25(6):1912\u0026ndash;1919. doi:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s00586-015-4158\u003c/span\u003e\u003cspan address=\"10.1007/s00586-015-4158\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"case series, ossification of ligamentum flavum, spinal meningioma, spinal schwannoma, spinal tumor, surgical technique","lastPublishedDoi":"10.21203/rs.3.rs-1563436/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-1563436/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eA wide lateral viewing angle is often necessary for spinal surgery. However, the skin and paraspinal muscles limit this angle in the traditional posterior midline approach.\u003c/p\u003e \u003cp\u003eThis article describes a simple, less-invasive approach that provides good lateral viewing angles to spinal lesions.\u003c/p\u003e \u003cp\u003eThe approach consisted of (1) a horizontal skin incision, (2) unilateral dissection and exposure of the laminae, (3) a horizontal fascial incision, and (4) application of retractors in the longitudinal direction with a minimal incision on the multifidus muscle.\u003c/p\u003e \u003cp\u003eWe successfully used this approach on 24 patients with various spinal diseases. The pathology of the lesions included nine schwannomas, five meningiomas, four ossification of ligamentum flavum (OLF), three malignant tumors, and three others. There were nine cervical, twelve thoracic, two lumbar, and one sacral lesions. We could achieve gross total removal in most cases without significant complications. The approach provided an excellent surgical field for removing ventrally located tumors with minimal cord retraction.\u003c/p\u003e \u003cp\u003eThis simple technique will be a valuable addition to the armamentarium of spine surgeons.\u003c/p\u003e","manuscriptTitle":"Posterior Paramedian Approach—A Simple Technique to Obtain a Lateral Viewing Angle for Spinal Lesions","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2022-04-27 15:59:41","doi":"10.21203/rs.3.rs-1563436/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"ea9e1a16-edef-445a-b493-1ad73b2ff026","owner":[],"postedDate":"April 27th, 2022","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2022-07-14T03:59:16+00:00","versionOfRecord":[],"versionCreatedAt":"2022-04-27 15:59:41","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-1563436","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-1563436","identity":"rs-1563436","version":["v1"]},"buildId":"zQwnuV7TCBrMSSSToR1PI","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}