Duraplasty Versus Bony Decompression in Adult Chiari I: Comparative Clinical and Morphometric Analysis

Duraplasty Versus Bony Decompression in Adult Chiari I: Comparative Clinical and Morphometric 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 Article Duraplasty Versus Bony Decompression in Adult Chiari I: Comparative Clinical and Morphometric Analysis Recai Engin, Fatih Tomakin, Hasan Şener, Gürkan Gökalp, Vaner Köksal, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8129425/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 Background The optimal surgical technique for Chiari type I malformation (CM-I) remains debated, particularly in patients without syringomyelia. While duraplasty (DP+) may enhance radiological outcomes, it can carry higher complication risks. We compared clinical, radiological, and morphometric outcomes after suboccipital decompression with DP + and without duraplasty (DP–), with prespecified subgroup analyses by syringomyelia status. Methods Ninety-three consecutive adult CM-I underwent DP– (n = 54) or DP+ (n = 39) between 2014 and 2022. Pre- and postoperative MRI and neurological evaluations were obtained at 1 year. Functional recovery was assessed using the Chicago Chiari Outcome Scale (CCOS). Clinical and radiological outcomes, complication rates, and subgroup results (with vs without syringomyelia) were compared. Results Overall clinical improvement was observed in 92.5% of patients (DP–: 94.4%; DP+: 89.7%; p > 0.05). Among patients without syringomyelia, clinical improvement remained high with DP–. Radiological benefit—including syrinx regression and mega cisterna magna formation—was greater with DP+ (64.1% vs 24.1%; p 0.05). Cerebellar slump occurred more often after DP+ (30.8% vs 9.3%; p < 0.05). Complication rates, including CSF-related events, were higher with DP+. Morphometric expansion of the foramen magnum did not correlate with functional outcomes. Conclusion At 1-year follow-up, suboccipital decompression without duraplasty appears to provide comparable clinical improvement to DP+, with fewer complications, in selected CM-I patients without syringomyelia. Duraplasty offers radiological advantages, especially for syringomyelia, but at the cost of increased risk. Longer follow-up is necessary to determine the durability of these findings. Health sciences/Diseases Health sciences/Medical research Health sciences/Neurology Biological sciences/Neuroscience Chiari malformation type I Suboccipital decompression Duraplasty Syringomyelia Chicago Chiari Outcome Scale Morphometric analysis Foramen magnum Figures Figure 1 Figure 2 Figure 3 Introduction Chiari type I malformation (CM-I) is defined as caudal displacement of the cerebellar tonsils through the foramen magnum, frequently associated with altered cerebrospinal fluid (CSF) dynamics and, in many cases, syringomyelia [ 13 , 16 , 25 ]. Clinical presentation is heterogeneous, ranging from headache to cranial nerve dysfunction, and may include syrinx-related symptoms such as motor weakness and sensory changes [ 23 , 26 ]. Recent systematic reviews have also highlighted advances in the epidemiology and pathogenesis of CM-I, underlining its complex and multifactorial nature [ 25 ]. The optimal surgical strategy for CM-I remains controversial. Posterior fossa decompression without duraplasty (DP–) is considered less invasive, with shorter operative time and lower risk of CSF-related complications [ 6 , 9 , 14 , 17 ], whereas decompression with duraplasty (DP+) is thought to achieve more effective restoration of CSF pathways and higher rates of syrinx regression [ 8 , 10 , 18 ]. A large multicenter analysis from the Park-Reeves Syringomyelia Research Consortium demonstrated that surgical technique, particularly the use of duraplasty, significantly influences both complication rates and long-term outcomes in pediatric patients [ 1 ]. Several systematic reviews and meta-analyses have attempted to clarify the relative benefits of these techniques, but the results remain inconsistent [ 3 , 8 , 18 , 27 ]. Consensus recommendations and expert opinion documents have emphasized tailoring the surgical approach to individual patient characteristics, including the presence of syringomyelia and the degree of tonsillar descent [ 7 , 30 ]. Yılmaz et al. proposed a tonsillar-descending grading scale to guide the choice of duraplasty, underscoring the role of morphometric assessment in surgical decision-making [ 31 ]. Clinical outcomes also vary widely across reports. Mueller and Oro found that presenting symptoms can differ substantially between patients with and without syringomyelia [ 23 ]. Pepper et al. reported heterogeneous improvement rates (27–88%) in non-syringomyelia patients following decompression [ 24 ], while Giammattei et al. observed long-term improvement in 87% [ 12 ], and Beretta et al. noted 93% improvement in Chiari-related headache [ 4 ]. Yu et al. recently reported that posterior fossa decompression with duraplasty yielded significantly higher CCOS scores compared with bone-only decompression in a cohort of non-syringomyelia patients [ 32 ]. Durability of results remains an important issue. Krishna et al. documented reoperation rates of 31.9% after DP– at long-term follow-up [ 17 ], whereas Tubbs et al. and Alfieri & Pinna reported markedly lower rates (0–3.2%) after DP+ [ 2 , 29 ]. Mozaffari et al. confirmed that long-term failures are more frequent after DP–, particularly in patients with persistent or progressive syringomyelia [ 22 ]. Recent pediatric series by Hale et al. [ 15 ] and El-Hajj et al. [ 11 ] emphasized the prognostic role of syrinx size and confirmed that complication rates remain broadly comparable between DP– and DP + in high-volume cohorts. Morphometric studies have further suggested that posterior cranial fossa dimensions and syrinx characteristics influence both radiological and clinical outcomes, highlighting the importance of individualized patient selection [ 5 , 31 ]. In this study, we aimed to compare clinical, radiological, and morphometric outcomes of DP + versus DP– in adult CM-I patients, with subgroup analyses by syringomyelia status and age. Functional outcomes were assessed using the Chicago Chiari Outcome Scale (CCOS), which provides disease-specific evaluation superior to generic disability scales. Our hypothesis was that suboccipital decompression without duraplasty may achieve comparable short-term clinical improvement in selected patients without syringomyelia. Materials and Methods Ethical Approval Ethical approval for this study was obtained from the Ondokuz Mayıs University Clinical Research Ethics Committee (Approval No: 2024/571). The study was conducted in accordance with the principles of the Declaration of Helsinki. Written informed consent was obtained from all participants. Patient Selection and Inclusion Criteria This single-center, retrospective, consecutive cohort included adult patients with Chiari type I malformation treated between 2014 and 2022. A total of 100 consecutive patients were screened; 7 were excluded due to prior Chiari surgery (either at our institution or elsewhere), non–Chiari I subtypes, or incomplete 1-year radiological follow-up, leaving 93 patients for analysis. Inclusion criteria were age ≥18 years, radiologically confirmed CM-I, and treatment with suboccipital decompression with (DP+) or without duraplasty (DP–), with available baseline and 1-year postoperative clinical and MRI data. Exclusion criteria were: other Chiari subtypes, incomplete clinical or radiological data, prior CM-I surgery at any institution, or absence of 1-year postoperative imaging. Presence or absence of syringomyelia was recorded but was neither an inclusion/exclusion criterion nor the sole determinant of surgical technique; the rationale for DP+ vs DP– is detailed in the Surgical Technique subsection. Because only 7% of screened patients were excluded, a formal baseline comparison between excluded and included patients was not performed. The screening and inclusion process is summarized in a flow diagram (Figure 1). Radiological Evaluation and Data Collection Demographic data including age and sex were recorded. Preoperative spinal MRI was reviewed for the presence of syringomyelia. The degree of tonsillar herniation was measured from the McRae line and classified as follows: Grade 1 (5–9 mm), Grade 2 (10–14 mm), Grade 3 (15–19 mm), and Grade 4 (≥20 mm). Morphometric analysis included measurement of the anteroposterior diameter of the foramen magnum at the McRae line, both preoperatively and postoperatively (Figure 2). Pre- and postoperative MRI at 1 year was used to assess syringomyelia regression, mega cisterna magna formation, tonsillar descent, and cerebellar slump. Cerebellar slump was defined as cerebellar descent below the McGregor line greater than the preoperative tonsillar herniation. Clinical Outcome Assessment At the 1-year postoperative follow-up, clinical symptoms and MRI findings were reevaluated. Patients who showed a marked reduction in symptoms were considered to have achieved clinical benefit. Radiological benefit was defined as the presence of one or more of the following findings on 1-year postoperative MRI: reduction in tonsillar herniation, formation of a mega cisterna magna (MCM (mega cisterna magna)), resolution or reduction of syringomyelia. Surgical complications such as cerebrospinal fluid (CSF) leakage, wound infection, and meningitis were identified from operative notes and follow-up records. Functional outcomes were evaluated using the Chicago Chiari Outcome Scale (CCOS), which was retrospectively obtained from chart review and follow-up interviews. Surgical technique and group allocation. All patients underwent suboccipital decompression. Among patients with syringomyelia (n=50), 25 received DP+ and 25 received DP–; among those without syringomyelia (n=43), 14 received DP+ and 29 received DP–. The decision to perform duraplasty in non-syringomyelia cases was individualized based on preoperative morphometry (e.g., degree of tonsillar descent, posterior fossa dimensions) and intraoperative findings (dural pulsatility). Bony decompression. In both groups, a midline suboccipital craniectomy of approximately 2.5 × 2.5 cm was performed, followed by a C1 laminectomy. The laminectomy extended ~2 cm laterally from the midline on each side, in line with anatomical and surgical series emphasizing safe decompressive margins without endangering the vertebral arteries or atlanto-axial stability [13,20]. Dural management. In DP–, the inner dural layer was left intact; the outer (parietal) leaf underwent limited “keyhole” dura-splitting incisions to reduce scarring and optimize decompression. In DP+, a Y-shaped durotomy was performed, and the dura was expanded with a watertight graft using either autologous pericranium or a synthetic patch. In all cases, intraoperative ultrasound and/or direct visualization was used to confirm restoration of CSF pulsation at the foramen magnum. Meticulous hemostasis was achieved in every procedure. Closure was performed in anatomical layers, with particular attention to muscle reapproximation and subgaleal drainage when indicated. Postoperative management was standardized across both groups. Statistical Analysis The primary outcome was 12-month CCOS. Continuous variables were compared with independent t-tests (or Mann–Whitney U if non-normal; normality by Shapiro–Wilk); categorical outcomes with Pearson χ² (or Fisher’s exact when expected counts <5). Within-group morphometry (pre/post) used paired t-tests (or Wilcoxon), and correlations with CCOS used Pearson or Spearman as appropriate. All tests were two-sided (α=0.05); no multiplicity adjustment. Table 1 is descriptive only. Analyses were complete-case and conducted in SPSS v26 (IBM, Armonk, NY). Results Study cohort and allocation Of 100 consecutive adults screened (2014–2022), 7 were excluded (prior Chiari surgery, non–CM-I subtype, or incomplete 1-year imaging), leaving 93 patients for analysis (Figure 1). Surgical allocation was DP+ (n=39) and DP– (n=54). Baseline characteristics are summarized in Table 1. The prevalence of syringomyelia at baseline did not differ by technique (DP+ 25/39 [64.1%] vs DP– 25/54 [46.3%], χ²=2.888, p=0.089; Table 2). Illustrative adult cases Both surgical methods applied for Chiari type 1 disorder are shown in illustrative cases (Figure 3A and 3B). Clinical Outcomes At 12 months, clinical improvement exceeded 90% in both groups (DP+ 35/39 [89.7%] vs DP– 51/54 [94.4%], χ²=0.719, p=0.396; Table 4). Mean CCOS scores were similar (DP– 13.77 ± 2.31 vs DP+ 13.00 ± 2.55, p=0.129; Table 5A). By syringomyelia status, CCOS did not differ (no syrinx 13.79 ± 2.09 vs syrinx 13.16 ± 2.67, p=0.215; Table 5B). Radiological Outcomes Composite radiological benefit was more frequent after duraplasty (DP+ 25/39 [64.1%] vs DP– 13/54 [24.1%], χ²=15.015, p<0.001; Table 4). Formation of a mega cisterna magna by 1 year paralleled this pattern (Table 2) and was not associated with clinical benefit (Table 3). Regression of tonsillar herniation did not differ between groups (Table 2). Association between MCM formation and clinical outcome. At 1 year, MCM was observed in 38/93 patients (40.9%). When stratified by MCM status, clinical improvement was similar (94.7% with MCM vs 90.9% without MCM), and the difference was not significant (χ² = 0.473, p = 0.492) (Table 3). These findings indicate that postoperative MCM formation does not reliably predict functional recovery. Complications CSF-related events (including closed pseudomeningocele) occurred more often with duraplasty (DP+ 7/39 [17.9%] vs DP– 2/54 [3.7%], χ²=1.520, p=0.218; Table 4). Overall complication rates were similar (DP+ 9/39 [23.1%] vs DP– 9/54 [16.7%], χ²=0.202, p=0.653; Table 4). Cerebellar slump—defined morphometrically relative to the McGregor line—was more common after DP+ (30.8%) than DP– (9.3%) (p=0.023; Table 2). Subgroup and sensitivity analyses. Age strata were not associated with syrinx regression at 1 year (χ²=5.699, p=0.223; Table 6). Findings were consistent in analyses stratified by syringomyelia status (Table 5B). Morphometric Findings Figüre 3Postoperative foramen magnum diameter increased significantly in both groups; however, neither preoperative nor postoperative diameters correlated with one-year CCOS (p = 0.664 and p = 0.720, respectively), indicating that morphometric expansion alone does not translate into functional recovery. Discussion In this study, we demonstrated that both DP+ and DP– yielded high rates of clinical improvement at 1 year, with no significant difference in CCOS outcomes. In our cohort, mean CCOS was 13.77 ± 2.31 for DP– vs 13.00 ± 2.55 for DP+ (p = 0.129), and ≥1-point clinical improvement occurred in >90% of patients in both groups. This is a key finding, as it suggests that bone-only decompression may provide sufficient short-term clinical benefit in carefully selected CM-I patients without syringomyelia. By applying the CCOS scale, our results provide disease-specific functional insight not captured by generic disability measures [32]. Several studies have reported that in selected cases, suboccipital decompression without duraplasty (DP+–) may yield satisfactory outcomes, but few have objectively compared both techniques in matched cohorts using clinical and radiological metrics. Radiological outcomes, however, clearly favored DP+. O verall radiological benefit was 64.1% with DP+ vs 24.1% with DP– (p < 0.001), and mega cisterna magna formation was more frequent after DP+. Our data showed that syrinx regression and mega cisterna magna formation were significantly more frequent in the DP+ group. This observation aligns with prior studies demonstrating radiological superiority of duraplasty [8,10,18,19], but our work also highlights the dissociation between radiological and clinical outcomes. Similar discrepancies were noted by Pepper et al. [24], Giammattei et al. [12], and Beretta et al. [4], where radiological changes did not always correlate with symptom improvement. Thus, our findings support the notion that radiological benefit should not be equated with guaranteed clinical advantage. Morphometric analysis revealed significant expansion of the foramen magnum in both groups, yet this change did not correlate with CCOS improvement. This aligns with Bogdanov et al. [5], who showed that morphometric variables alone are insufficient predictors of outcome, reinforcing that symptomatology and functional status should guide surgical decision-making rather than radiological thresholds alone. Cerebellar slump occurred more often in the DP+ group in our series, despite standardized decompression size (2.5 × 2.5 cm). We defined slump as descent below the McGregor line greater than preoperative tonsillar herniation, a morphometric definition not uniformly reported in the literature. This finding contrasts with reports suggesting minimal slump when decompression is limited [31]. Our results therefore raise the possibility that individual cranial morphology, rather than decompression size alone, may predispose to slump. Complication rates in our cohort were higher after DP+, particularly for CSF fistulas and pseudomeningocele. CSF fistula/pseudomeningocele developed in 7/39 (17.9%) with DP+ vs 2/54 (3.7%) with DP– (p = 0.218), noting that we counted closed pseudomeningocele within CSF-related events. Our leakage rate exceeds that of many series [1,8,27], but this discrepancy may be partly explained by our inclusion of closed pseudomeningocele under the definition of CSF fistula. The DP– group had a 3.8% rate of CSF leakage, which we attribute to the “keyhole” incision of the parietal dural leaf. This technical nuance aligns with prior reports emphasizing surgical modifications to minimize leakage [20,31]. Moreover, Tam SKP et al. [28] confirmed in a systematic review and meta-analysis that DP+ carries a higher risk of CSF-related complications; notably, in syringomyelia-positive cohorts DP+ tended to achieve superior clinical and radiological endpoints, underscoring a trade-off rather than a uniform advantage. Our analysis of age subgroups revealed no significant correlation between age and syrinx regression, suggesting that in adults, age alone may not determine radiological outcome. This differs from pediatric-focused studies, which have shown better responses in younger patients [11,15]. In addition, El-Hajj et al. [11] highlighted that syrinx characteristics can modulate long-term functional recovery on CCOS, a factor future adult studies should incorporate. Durability remains a critical question. Although our one-year follow-up supports short-term sufficiency of DP–, long-term data consistently caution against overgeneralization. Krishna et al. reported reoperation rates of 31.9% after DP– [17], whereas Tubbs et al. [29] and Alfieri & Pinna [2] observed far lower reoperation rates (0–3.2%) with DP+. Mozaffari et al. [22] similarly confirmed that DP– carries a higher risk of late failure. Taken together, our results should be interpreted as short-term evidence that DP– may suffice in non-syringomyelia patients, while long-term vigilance remains necessary. Another limitation of our study is that we did not stratify syringomyelia cases by size or extent. Holocord versus focal syrinx may influence outcomes differently, and future research should incorporate this parameter. Furthermore, we did not evaluate intradural pathology as Yu et al. [32] did, which may partly explain differences between our findings and theirs. Finally, technique-level choices within DP+ may not dramatically alter global outcomes. Moniruzzaman et al. [21] reported that results did not differ substantially across duraplasty configurations and graft types, supporting individualized technical selection (e.g., graft material, durotomy configuration) according to intraoperative findings and patient-specific anatomy. Furthermore, we did not stratify syringomyelia cases by size or extent. Holocord versus focal syrinx may influence outcomes differently, and future research should incorporate this parameter. We also did not evaluate intradural pathology as Yu et al. [32] did, which may partly explain differences between our findings and theirs. Taken together, our data show that in carefully selected adults without syringomyelia, DP– achieves short-term clinical gains comparable to DP+ while avoiding a higher CSF-event burden, whereas DP+ confers superior radiological endpoints. Limitations This single-centre, retrospective study used surgeon-determined assignment to DP+ or DP– (guided by morphometry and intraoperative dural pulsatility) without multivariable or propensity adjustment, so residual confounding is likely. Follow-up was limited to 12 months, precluding inferences about durability, late reoperation, or delayed radiological change. Imaging endpoints warrant caution: the composite “radiological benefit” combines heterogeneous markers; cerebellar slump was defined by a McGregor-based morphometric threshold without external validation; cine phase-contrast CSF was unavailable; and MRI protocols evolved over time. Complication accounting intentionally included closed pseudomeningocele within CSF-related events, which may overestimate leak rates relative to series reporting overt leaks only, while minor events may be under-ascertained. Phenotyping was incomplete (syrinx morphology/size and intradural anomalies not captured), the cohort was underpowered for small effects, and foramen magnum expansion did not track with CCOS. Subgroup analyses (e.g., the syrinx-positive cohort) were exploratory, and the study was not powered to detect small between-group differences in CCOS at one year; longer follow-up may reveal divergence. Accordingly, generalisability is best limited to adults treated in a tertiary setting using dura-splitting DP– and variable grafts for DP+. Conclusion In adults with Chiari I, bone-only decompression achieved short-term clinical improvement comparable to duraplasty, even though duraplasty conferred clearer radiological change and a higher burden of CSF-related events and cerebellar slump. These findings support an individualized strategy that prioritizes symptom profile, syringomyelia status, age, and morphometric context rather than a uniform preference for duraplasty. For carefully selected adults without syringomyelia, bone-only decompression appears clinically sufficient in the first postoperative year, while duraplasty may be reserved for cases in which radiological objectives predominate. Longer, prospective follow-up—ideally stratifying syrinx morphology and intradural pathology—is needed to refine indications and confirm durability. Abbreviations CCOS – Chicago Chiari Outcome Scale, CM – Chiari Malformation, CM-I – Chiari Malformation Type I, CSF – Cerebrospinal Fluid, DP+ – Duraplasty, FM – Foramen Magnum, MRI – Magnetic Resonance Imaging, MCM – Mega Cisterna Magna. Declarations Future Directions and Recommendations To better isolate the effect of duraplasty, future studies should be prospective, multicentre, pre-registered, and use ≥5-year follow-up with blinded outcome adjudication, preferably randomised or propensity-matched with adjustment for surgeon/centre clustering. Imaging must be standardised across sites/timepoints, incorporating cine phase-contrast CSF and quantitative syrinx morphometrics. Stratification should include syringomyelia phenotype (holocord vs focal; length/diameter; syrinx–cord ratio), tonsillar descent, and posterior fossa morphometry. Outcomes should centre on CCOS (primary) with complementary PROMs, reoperation, CSF-related events, and cost-effectiveness. Technique reporting (durotomy configuration, graft material, sealants, dura-splitting variants) should be explicit to enable meaningful technique-level comparisons. Strengths and Novelty of This Study This adult, consecutive cohort with complete one-year clinical/MRI follow-up uses a disease-specific outcome (CCOS) and a standardised operative protocol, introduces explicit morphometric definitions (including cerebellar slump relative to McGregor’s line), and demonstrates an anatomy–function dissociation whereby foramen magnum expansion does not track with clinical recovery—together providing a transparent, reproducible framework that clarifies technique trade-offs and refines patient selection beyond radiological thresholds. Acknowledgements English language editing support was provided by ChatGPT (OpenAI, San Francisco, CA, USA) for improving clarity and grammar. The authors are fully responsible for the scientific content of this article. Ethical approval All procedures performed in this study involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Ethical approval was obtained from the Ondokuz Mayıs University Clinical Research Ethics Committee (Approval No: 2024/571). Written consent was waived; verbal informed consent was obtained from all participants contacted by telephone. Consent to participate Verbal informed consent was obtained from all patients during follow-up telephone interviews. Formal written consent was waived by the ethics committee due to the retrospective design. Funding This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. Conflict of Interest Statement The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Use of Artificial Intelligence During the preparation of this manuscript, the authors used ChatGPT (OpenAI, San Francisco, CA, USA) to assist in improving the English language and clarity of some technical expressions. After using this tool, the authors reviewed and edited the content as needed and take full responsibility for the integrity and originality of the content. Consent for publication: Not applicable Clinical trial number: Not applicable. Availability of Data and Materials The datasets generated and/or analyzed during the current study are available from the corresponding author upon reasonable request. References Akbari SHA, Yahanda AT, Ackerman LL, Adelson PD, Ahmed R, Albert GW, et al. 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Chiari I malformation: surgical considerations. Neurol India. 2019;67(3):662-663. doi:10.4103/0028-3886.263222. Moniruzzaman S, Kaipainen A, Tervonen J, Huttunen J, Jyrkkänen HK, Huuskonen TJ, et al. Long-term outcome of operated Chiari I patients between 2005 and 2020 in Eastern Finland. Acta Neurochir (Wien). 2024;166(1):115. doi:10.1007/s00701-024-05999-y. Mozaffari K, Davidson L, Chalif E, Phan TN, Sparks AD, Myseros JS, Oluigbo CO, Keating RF. Long-term outcomes of posterior fossa decompression for Chiari malformation type 1: which patients are most prone to failure? Childs Nerv Syst. 2021 Sep;37(9):2891-2898. doi: 10.1007/s00381-021-05280-y. Epub 2021 Jul 7. PMID: 34232379. Mueller DM, Oro’ JJ. Prospective analysis of presenting symptoms among 265 patients with radiographic Chiari I with or without syringomyelia. J Am Acad Nurse Pract. 2004;16:134-138. Pepper J, Magarik JA, Thomas C, et al. Symptom improvement after suboccipital decompression in Chiari I without syringomyelia. J Neurosurg. 2020;132(3):812-819. Rodríguez-Blanque R, Almazán-Soto C, Piqueras-Sola B, Sánchez-García JC, Reinoso-Cobo A, Menor-Rodríguez MJ, et al. Chiari syndrome: advances in epidemiology and pathogenesis—a systematic review. J Clin Med. 2023;12(20):6694. doi:10.3390/jcm12206694. Strahle J, Muraszko KM, Garton HJL. Syrinx location and size according to aetiology: identification of Chiari-associated syrinx. J Neurosurg Pediatr. 2015;16(1):21-29. Tam M, El Tecle NE, El Ahmadieh TY, et al. Complications of posterior fossa decompression in adults and children with Chiari I: systematic review and meta-analysis. Acta Neurochir (Wien). 2020;162(6):1343-1353. doi:10.1007/s00701-020-04403-9. Tam SKP, Brodbelt A, Bolognese PA, Foroughi M. Posterior fossa decompression with duraplasty in Chiari I: a systematic review and meta-analysis. Acta Neurochir (Wien). 2021;163(1):229-238. doi:10.1007/s00701-020-04403-9. Tubbs RS, Beckman J, Naftel RP, Chern JJ, Wellons JC 3rd, Rozzelle CJ, et al. Institutional experience with 500 surgically treated pediatric Chiari I. J Neurosurg Pediatr. 2011;7(3):248-256. doi:10.3171/2010.12.PEDS10379. Visocchi M, Signorelli F, Alves ÓL, Goel A, Parthiban J, Baeesa S, et al. Indications for surgery and surgical options in Chiari malformation: WFNS Spine Committee recommendations. Spine (Phila Pa 1976). 2025;50(11):760-766. doi:10.1097/BRS.0000000000005288. Yilmaz A, Kanat A, Musluman AM, Colak I, Terzi Y, Kayacı S, et al. When is duraplasty required in surgical treatment of Chiari I based on tonsillar descent grading? World Neurosurg. 2011;75(2):307-313. doi:10.1016/j.wneu.2010.09.005. Yu QS, Li T, Wan M, Zhang L, Qiao GY, Yu XG, et al. Clinical outcome of different surgical approaches for symptomatic Chiari malformation without syringomyelia: a 13-year retrospective study. Neurosurg Rev. 2025;48(1):485. doi:10.1007/s10143-025-03640-9. Tables Tablo 1. Demographic and clinical characteristics of patients. Features Gender-n(%) Female 59 (63.4) Male 34 (36.6) Age- Min.-Max (Average±ss) 13-70 (34.53±13.51) Syringomyelia -n(%) No 43 (46.2) Yes 50 (53.8) Herniation Degree-n(%) Grade 1 (5-9 mm) 36 (38.7) Grade 2 (10-14 mm) 39 (41.9) Grade 3 (15-19 mm) 14 (15.1) Grade 4 (>19 mm) 4 (4.3) Applied Surgical Method DP + 39 (41.9) DP - 54 (58.1) Preoperative Clinic Head and neck pain 63 Numbness in extremities 38 Dizziness 15 Difficulty swallowing 12 Loss of balance 10 Loss of strength in extremitie 6 Ringing in the ears 3 ( DP +: suboccipital decompression and duraplasty, DP - : only suboccipital decompression) Table 2. Comparison of post-operative Magnetic Resonance imaging (MRI) findings at the end of the first year according to the preferred surgical method (DP - Vs DP +). DP + DP - χ 2 p No Yes No Yes Syringomyelia 14 (35.9) 25 (64.1) 29 (53.7) 25 (46.3) 2.888 .089 1st year MSM 14 (35.9) 25 (64.1) 41 (75.9) 13 (24.1) 15.015 .000 Decrease in Syringomyelia 10 (40.0) 15 (60.0) 12 (46.2) 13 (50.0) 16.896 .000 Cerebellar Slump 27 (69.2) 12 (30.8) 48 (88.9) 5 (9.3) 7.539 .023 Tonsillar Herniation Reduction 16 (41.0) 23 (59.0) 27 (50.0) 26 (48.1) 1.620 .445 (MCM: Mega cisterna magna) Table 3 . Association Between MCM Formation and Clinical Outcome. Table 4 . Comparison of MRI benefit, CSF fistula development, complications and clinical benefit according to the preferred surgical method. Table 5A. Comparison of CCOS by surgical technique (DP+ vs DP−) Outcome Group N Mean ± SD t p CCOS With duraplasty (DP+) 39 13.00 ± 2.55 −1.532 0.129 Without duraplasty (DP−) 54 13.77 ± 2.31 Notes: Values are mean ± SD. Independent-samples t-test; two-sided p-values. CCOS = Chicago Chiari Outcome Scale. As a result of the independent sample t test (Independent Samples t test) performed to determine whether there was a difference in CCOS values according to the surgical method, it was determined that although the CCOS value was slightly higher in patients who did not undergo Duraplasty, there was no significant difference according to the surgical method (p>0.05). Table 5B. Comparison of CCOS by syringomyelia status Outcome Group N Mean ± SD t p CCOS No syringomyelia 39 13.79 ± 2.09 1.250 0.215 Syringomyelia present 54 13.16 ± 2.67 Notes: Values are mean ± SD. Independent-samples t-test; two-sided p-values. CCOS = Chicago Chiari Outcome Scale. The Independent Samples t test, which was performed to determine whether there was a difference in CCOS values according to the presence or absence of syringomyelia, revealed no significant difference (p>0.05). Table 6. Association between age group and postoperative syrinx regression at 1 year. Age group No regression n (%) Regression n (%) Not evaluable n (%) Total n 45 years 7 (53.8) 5 (38.5) 1 (7.7) 13 Total 22 (43.1) 28 (54.9) 1 (2.0) 51 Statistics: Pearson’s χ² = 5.699, p = 0.223. Percentages are row-wise. ‘Not evaluable’ denotes unavailable or non-assessable 1-year MRI for syrinx change. 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 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-8129425","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":548267696,"identity":"b4dc12de-9ec0-4259-ad73-dc321a4d1362","order_by":0,"name":"Recai Engin","email":"","orcid":"","institution":"Samsun University","correspondingAuthor":false,"prefix":"","firstName":"Recai","middleName":"","lastName":"Engin","suffix":""},{"id":548267697,"identity":"37158a9f-99d8-45cd-9133-8a2f1df8df71","order_by":1,"name":"Fatih Tomakin","email":"","orcid":"","institution":"Samsun University","correspondingAuthor":false,"prefix":"","firstName":"Fatih","middleName":"","lastName":"Tomakin","suffix":""},{"id":548267698,"identity":"3a109e06-1950-4f41-a38c-9d1da1295b00","order_by":2,"name":"Hasan Şener","email":"","orcid":"","institution":"Gazi Mustafa Kemal Occupational and Environmental Disease Hospital","correspondingAuthor":false,"prefix":"","firstName":"Hasan","middleName":"","lastName":"Şener","suffix":""},{"id":548267699,"identity":"5753b78d-d764-41b7-b060-e9258b3e7943","order_by":3,"name":"Gürkan Gökalp","email":"","orcid":"","institution":"Ondokuz Mayıs University","correspondingAuthor":false,"prefix":"","firstName":"Gürkan","middleName":"","lastName":"Gökalp","suffix":""},{"id":548267700,"identity":"5bbc18b7-b856-41a0-ba0b-cf1fc82e06d5","order_by":4,"name":"Vaner Köksal","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABDElEQVRIiWNgGAWjYPCCBAYJBgbGAx/gAmzEaWE4OANZCw8xWg4jVOHRYnD87MHHFQxpcpL9hx8ctvljFy0/I/cAw4eywwz20gewazmTl2x4hiHHWFoizeBwblty7oYbeQmMM84dZuDhS8CqRbIhx0yygaEicZ4EA1BLA3PuBokcA2beNqAWHC6T7H9j/hOshf/4h8MWf+pz588AavmLRwu/RI4ZYwNDTuJshhyDwwxsQItuALUw4tXyxliywSDNWHJGTsHB3rbjuRvOvDE42HMunYfnDHYtbPw5hh8bKpLlJM4f3/jgx5/q3PntOYYPfpRZy7H3YNcCDTc0/gEGgjE5CkbBKBgFowAfAADcElqzXb9QxAAAAABJRU5ErkJggg==","orcid":"","institution":"Samsun University","correspondingAuthor":true,"prefix":"","firstName":"Vaner","middleName":"","lastName":"Köksal","suffix":""},{"id":548267701,"identity":"cad777ef-4d49-43ec-819b-af23a153669d","order_by":5,"name":"Şevki Serhat Baydın","email":"","orcid":"","institution":"Ondokuz Mayıs University","correspondingAuthor":false,"prefix":"","firstName":"Şevki","middleName":"Serhat","lastName":"Baydın","suffix":""},{"id":548267702,"identity":"501ab95f-b625-4aa1-8d3f-fad5eb864a1f","order_by":6,"name":"Mustafa Aras","email":"","orcid":"","institution":"Ondokuz Mayıs University","correspondingAuthor":false,"prefix":"","firstName":"Mustafa","middleName":"","lastName":"Aras","suffix":""},{"id":548267703,"identity":"0e059167-4d03-4af8-a52d-c591efea06de","order_by":7,"name":"Cengiz Cokluk","email":"","orcid":"","institution":"Ondokuz Mayıs University","correspondingAuthor":false,"prefix":"","firstName":"Cengiz","middleName":"","lastName":"Cokluk","suffix":""}],"badges":[],"createdAt":"2025-11-16 20:53:03","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8129425/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8129425/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":96566911,"identity":"b422d7cb-2449-4adb-9052-12352913b5d8","added_by":"auto","created_at":"2025-11-23 15:55:01","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":304349,"visible":true,"origin":"","legend":"\u003cp\u003eFlow diagram of clinical study.\u003c/p\u003e","description":"","filename":"figure1diagram.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8129425/v1/048205e7af1bd61e2f56b5fb.jpg"},{"id":96566912,"identity":"05e5125c-de7d-45ca-a917-661eee0547d5","added_by":"auto","created_at":"2025-11-23 15:55:01","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":58312,"visible":true,"origin":"","legend":"\u003cp\u003ePreoperative and postoperative measurements of the foramen magnum anteroposterior diameter at the McRae line (basion–opisthion distance) are shown.\u003c/p\u003e","description":"","filename":"figure2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8129425/v1/52bfe8d7303de03f3740b92e.jpg"},{"id":96604913,"identity":"dc9b1c61-5909-4f26-afca-101df3a6c15e","added_by":"auto","created_at":"2025-11-24 09:15:57","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":606667,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eA\u003c/strong\u003e (Illustrative case 1) 19-year-old male patient. He complains of headaches and numbness in the arms, especially when sneezing and coughing. a. Preoperative MRI image shows syringomyelia starting from the C3 level and continuing to the thoracic levels with cerebellar tonsillar herniation. b. Syringomyelia is significantly reduced in the 1st year control MRI image after DP–.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eB\u003c/strong\u003e (Illustrative case 2) 45-year-old female patient. She complains of a headache and difficulty swallowing. a. Preoperative MRI shows syringomyelia starting from the C4 level and continuing to the T3 level with cerebellar tonsillar hernation. b. In the 1st year follow-up MRI after DP+, syringomyelia is significantly reduced, and MCM (mega cisterna magna) formation is seen.\u003c/p\u003e","description":"","filename":"figure3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8129425/v1/0e8dc668790e87ebec726978.jpg"},{"id":96607838,"identity":"abe382f9-c95c-4c8c-b7ee-521281e041df","added_by":"auto","created_at":"2025-11-24 09:27:53","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1998240,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8129425/v1/1701979b-4aac-483f-9184-c3f2091d0fe2.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Duraplasty Versus Bony Decompression in Adult Chiari I: Comparative Clinical and Morphometric Analysis","fulltext":[{"header":"Introduction","content":"\u003cp\u003eChiari type I malformation (CM-I) is defined as caudal displacement of the cerebellar tonsils through the foramen magnum, frequently associated with altered cerebrospinal fluid (CSF) dynamics and, in many cases, syringomyelia [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. Clinical presentation is heterogeneous, ranging from headache to cranial nerve dysfunction, and may include syrinx-related symptoms such as motor weakness and sensory changes [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. Recent systematic reviews have also highlighted advances in the epidemiology and pathogenesis of CM-I, underlining its complex and multifactorial nature [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe optimal surgical strategy for CM-I remains controversial. Posterior fossa decompression without duraplasty (DP\u0026ndash;) is considered less invasive, with shorter operative time and lower risk of CSF-related complications [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e], whereas decompression with duraplasty (DP+) is thought to achieve more effective restoration of CSF pathways and higher rates of syrinx regression [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. A large multicenter analysis from the Park-Reeves Syringomyelia Research Consortium demonstrated that surgical technique, particularly the use of duraplasty, significantly influences both complication rates and long-term outcomes in pediatric patients [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eSeveral systematic reviews and meta-analyses have attempted to clarify the relative benefits of these techniques, but the results remain inconsistent [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. Consensus recommendations and expert opinion documents have emphasized tailoring the surgical approach to individual patient characteristics, including the presence of syringomyelia and the degree of tonsillar descent [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. Yılmaz et al. proposed a tonsillar-descending grading scale to guide the choice of duraplasty, underscoring the role of morphometric assessment in surgical decision-making [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eClinical outcomes also vary widely across reports. Mueller and Oro found that presenting symptoms can differ substantially between patients with and without syringomyelia [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Pepper et al. reported heterogeneous improvement rates (27\u0026ndash;88%) in non-syringomyelia patients following decompression [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e], while Giammattei et al. observed long-term improvement in 87% [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e], and Beretta et al. noted 93% improvement in Chiari-related headache [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Yu et al. recently reported that posterior fossa decompression with duraplasty yielded significantly higher CCOS scores compared with bone-only decompression in a cohort of non-syringomyelia patients [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eDurability of results remains an important issue. Krishna et al. documented reoperation rates of 31.9% after DP\u0026ndash; at long-term follow-up [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e], whereas Tubbs et al. and Alfieri \u0026amp; Pinna reported markedly lower rates (0\u0026ndash;3.2%) after DP+ [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Mozaffari et al. confirmed that long-term failures are more frequent after DP\u0026ndash;, particularly in patients with persistent or progressive syringomyelia [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Recent pediatric series by Hale et al. [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e] and El-Hajj et al. [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] emphasized the prognostic role of syrinx size and confirmed that complication rates remain broadly comparable between DP\u0026ndash; and DP\u0026thinsp;+\u0026thinsp;in high-volume cohorts.\u003c/p\u003e\u003cp\u003eMorphometric studies have further suggested that posterior cranial fossa dimensions and syrinx characteristics influence both radiological and clinical outcomes, highlighting the importance of individualized patient selection [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eIn this study, we aimed to compare clinical, radiological, and morphometric outcomes of DP\u0026thinsp;+\u0026thinsp;versus DP\u0026ndash; in adult CM-I patients, with subgroup analyses by syringomyelia status and age. Functional outcomes were assessed using the Chicago Chiari Outcome Scale (CCOS), which provides disease-specific evaluation superior to generic disability scales. Our hypothesis was that suboccipital decompression without duraplasty may achieve comparable short-term clinical improvement in selected patients without syringomyelia.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cp\u003e\u003cstrong\u003eEthical Approval\u003c/strong\u003e\u003cbr\u003eEthical approval for this study was obtained from the Ondokuz Mayıs University Clinical Research Ethics Committee (Approval No: 2024/571). The study was conducted in accordance with the principles of the Declaration of Helsinki. Written informed consent was obtained from all participants.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePatient Selection and Inclusion Criteria\u003c/strong\u003e\u003cstrong\u003e\u003cbr\u003e\u003c/strong\u003eThis single-center, retrospective, consecutive cohort included adult patients with Chiari type I malformation treated between 2014 and 2022. A total of 100 consecutive patients were screened; 7 were excluded due to prior Chiari surgery (either at our institution or elsewhere), non\u0026ndash;Chiari I subtypes, or incomplete 1-year radiological follow-up, leaving 93 patients for analysis. Inclusion criteria were age \u0026ge;18 years, radiologically confirmed CM-I, and treatment with suboccipital decompression with (DP+) or without duraplasty (DP\u0026ndash;), with available baseline and 1-year postoperative clinical and MRI data. Exclusion criteria were: other Chiari subtypes, incomplete clinical or radiological data, prior CM-I surgery at any institution, or absence of 1-year postoperative imaging. Presence or absence of syringomyelia was recorded but was neither an inclusion/exclusion criterion nor the sole determinant of surgical technique; the rationale for DP+ vs DP\u0026ndash; is detailed in the Surgical Technique subsection. Because only 7% of screened patients were excluded, a formal baseline comparison between excluded and included patients was not performed. The screening and inclusion process is summarized in a flow diagram (Figure 1).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eRadiological Evaluation and Data Collection\u003cbr\u003e\u003c/strong\u003eDemographic data including age and sex were recorded. Preoperative spinal MRI was reviewed for the presence of syringomyelia. The degree of tonsillar herniation was measured from the McRae line and classified as follows: Grade 1 (5\u0026ndash;9 mm), Grade 2 (10\u0026ndash;14 mm), Grade 3 (15\u0026ndash;19 mm), and Grade 4 (\u0026ge;20 mm). Morphometric analysis included measurement of the anteroposterior diameter of the foramen magnum at the McRae line, both preoperatively and postoperatively (Figure 2). Pre- and postoperative MRI at 1 year was used to assess syringomyelia regression, mega cisterna magna formation, tonsillar descent, and cerebellar slump. Cerebellar slump was defined as cerebellar descent below the McGregor line greater than the preoperative tonsillar herniation.\u003c/p\u003e\n\u003cp\u003eClinical Outcome Assessment\u003c/p\u003e\n\u003cp\u003eAt the 1-year postoperative follow-up, clinical symptoms and MRI findings were reevaluated. Patients who showed a marked reduction in symptoms were considered to have achieved clinical benefit. Radiological benefit was defined as the presence of one or more of the following findings on 1-year postoperative MRI: reduction in tonsillar herniation, formation of a mega cisterna magna (MCM (mega cisterna magna)), resolution or reduction of syringomyelia. Surgical complications such as cerebrospinal fluid (CSF) leakage, wound infection, and meningitis were identified from operative notes and follow-up records. Functional outcomes were evaluated using the Chicago Chiari Outcome Scale (CCOS), which was retrospectively obtained from chart review and follow-up interviews.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSurgical technique and group allocation.\u003c/strong\u003e\u003cbr\u003eAll patients underwent suboccipital decompression. Among patients with syringomyelia (n=50), 25 received DP+ and 25 received DP\u0026ndash;; among those without syringomyelia (n=43), 14 received DP+ and 29 received DP\u0026ndash;. The decision to perform duraplasty in non-syringomyelia cases was individualized based on preoperative morphometry (e.g., degree of tonsillar descent, posterior fossa dimensions) and intraoperative findings (dural pulsatility).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eBony decompression.\u003c/strong\u003e\u003cbr\u003eIn both groups, a midline suboccipital craniectomy of approximately 2.5 \u0026times; 2.5 cm was performed, followed by a C1 laminectomy. The laminectomy extended ~2 cm laterally from the midline on each side, in line with anatomical and surgical series emphasizing safe decompressive margins without endangering the vertebral arteries or atlanto-axial stability [13,20].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDural management.\u003c/strong\u003e\u003cbr\u003eIn DP\u0026ndash;, the inner dural layer was left intact; the outer (parietal) leaf underwent limited \u0026ldquo;keyhole\u0026rdquo; dura-splitting incisions to reduce scarring and optimize decompression. In DP+, a Y-shaped durotomy was performed, and the dura was expanded with a watertight graft using either autologous pericranium or a synthetic patch.\u003c/p\u003e\n\u003cp\u003eIn all cases, intraoperative ultrasound and/or direct visualization was used to confirm restoration of CSF pulsation at the foramen magnum. Meticulous hemostasis was achieved in every procedure. Closure was performed in anatomical layers, with particular attention to muscle reapproximation and subgaleal drainage when indicated. Postoperative management was standardized across both groups.\u003c/p\u003e\n\u003ch2\u003eStatistical Analysis\u003c/h2\u003e\n\u003cp\u003eThe primary outcome was 12-month CCOS. Continuous variables were compared with independent t-tests (or Mann\u0026ndash;Whitney U if non-normal; normality by Shapiro\u0026ndash;Wilk); categorical outcomes with Pearson \u0026chi;\u0026sup2; (or Fisher\u0026rsquo;s exact when expected counts \u0026lt;5). Within-group morphometry (pre/post) used paired t-tests (or Wilcoxon), and correlations with CCOS used Pearson or Spearman as appropriate. All tests were two-sided (\u0026alpha;=0.05); no multiplicity adjustment. Table 1 is descriptive only. Analyses were complete-case and conducted in SPSS v26 (IBM, Armonk, NY).\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cstrong\u003eStudy cohort and allocation\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eOf 100 consecutive adults screened (2014\u0026ndash;2022), 7 were excluded (prior Chiari surgery, non\u0026ndash;CM-I subtype, or incomplete 1-year imaging), leaving 93 patients for analysis (Figure 1). Surgical allocation was DP+ (n=39) and DP\u0026ndash; (n=54). Baseline characteristics are summarized in Table 1. The prevalence of syringomyelia at baseline did not differ by technique (DP+ 25/39 [64.1%] vs DP\u0026ndash; 25/54 [46.3%], \u0026chi;\u0026sup2;=2.888, p=0.089; Table 2).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eIllustrative adult cases\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBoth surgical methods applied for Chiari type 1 disorder are shown in illustrative cases (Figure 3A and 3B). \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eClinical Outcomes\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAt 12 months, clinical improvement exceeded 90% in both groups (DP+ 35/39 [89.7%] vs DP\u0026ndash; 51/54 [94.4%], \u0026chi;\u0026sup2;=0.719, p=0.396; Table 4). Mean CCOS scores were similar (DP\u0026ndash; 13.77 \u0026plusmn; 2.31 vs DP+ 13.00 \u0026plusmn; 2.55, p=0.129; Table 5A). By syringomyelia status, CCOS did not differ (no syrinx 13.79 \u0026plusmn; 2.09 vs syrinx 13.16 \u0026plusmn; 2.67, p=0.215; Table 5B).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eRadiological Outcomes\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eComposite radiological benefit was more frequent after duraplasty (DP+ 25/39 [64.1%] vs DP\u0026ndash; 13/54 [24.1%], \u0026chi;\u0026sup2;=15.015, p\u0026lt;0.001; Table 4). Formation of a mega cisterna magna by 1 year paralleled this pattern (Table 2) and was not associated with clinical benefit (Table 3). Regression of tonsillar herniation did not differ between groups (Table 2).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAssociation between MCM formation and clinical outcome.\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAt 1 year, MCM was observed in 38/93 patients (40.9%). When stratified by MCM status, clinical improvement was similar (94.7% with MCM vs 90.9% without MCM), and the difference was not significant (\u0026chi;\u0026sup2; = 0.473, p = 0.492) (Table 3). These findings indicate that postoperative MCM formation does not reliably predict functional recovery.\u003c/p\u003e\n\u003cp\u003eComplications\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eCSF-related events (including closed pseudomeningocele) occurred more often with duraplasty (DP+ 7/39 [17.9%] vs DP\u0026ndash; 2/54 [3.7%], \u0026chi;\u0026sup2;=1.520, p=0.218; Table 4). Overall complication rates were similar (DP+ 9/39 [23.1%] vs DP\u0026ndash; 9/54 [16.7%], \u0026chi;\u0026sup2;=0.202, p=0.653; Table 4). Cerebellar slump\u0026mdash;defined morphometrically relative to the McGregor line\u0026mdash;was more common after DP+ (30.8%) than DP\u0026ndash; (9.3%) (p=0.023; Table 2).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSubgroup and sensitivity analyses.\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAge strata were not associated with syrinx regression at 1 year (\u0026chi;\u0026sup2;=5.699, p=0.223; Table 6). Findings were consistent in analyses stratified by syringomyelia status (Table 5B).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMorphometric Findings\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFig\u0026uuml;re 3Postoperative foramen magnum diameter increased significantly in both groups; however, neither preoperative nor postoperative diameters correlated with one-year CCOS (p = 0.664 and p = 0.720, respectively), indicating that morphometric expansion alone does not translate into functional recovery.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eIn this study, we demonstrated that both DP+ and DP\u0026ndash; yielded high rates of clinical improvement at 1 year, with no significant difference in CCOS outcomes.\u0026nbsp;In our cohort, mean CCOS was 13.77 \u0026plusmn; 2.31 for DP\u0026ndash; vs 13.00 \u0026plusmn; 2.55 for DP+ (p = 0.129), and \u0026ge;1-point clinical improvement occurred in \u0026gt;90% of patients in both groups.\u0026nbsp;This is a key finding, as it suggests that bone-only decompression may provide sufficient short-term clinical benefit in carefully selected CM-I patients without syringomyelia. By applying the CCOS scale, our results provide disease-specific functional insight not captured by generic disability measures [32]. Several studies have reported that in selected cases, suboccipital decompression without duraplasty (DP+\u0026ndash;) may yield satisfactory outcomes, but few have objectively compared both techniques in matched cohorts using clinical and radiological metrics.\u003c/p\u003e\n\u003cp\u003eRadiological outcomes, however, clearly favored DP+. O verall radiological benefit was 64.1% with DP+ vs 24.1% with DP\u0026ndash; (p \u0026lt; 0.001), and mega cisterna magna formation was more frequent after DP+. Our data showed that syrinx regression and mega cisterna magna formation were significantly more frequent in the DP+ group. This observation aligns with prior studies demonstrating radiological superiority of duraplasty [8,10,18,19], but our work also highlights the dissociation between radiological and clinical outcomes. Similar discrepancies were noted by Pepper et al. [24], Giammattei et al. [12], and Beretta et al. [4], where radiological changes did not always correlate with symptom improvement. Thus, our findings support the notion that radiological benefit should not be equated with guaranteed clinical advantage.\u003c/p\u003e\n\u003cp\u003eMorphometric analysis revealed significant expansion of the foramen magnum in both groups, yet this change did not correlate with CCOS improvement. This aligns with Bogdanov et al. [5], who showed that morphometric variables alone are insufficient predictors of outcome, reinforcing that symptomatology and functional status should guide surgical decision-making rather than radiological thresholds alone.\u003c/p\u003e\n\u003cp\u003eCerebellar slump occurred more often in the DP+ group in our series, despite standardized decompression size (2.5 \u0026times; 2.5 cm). We defined slump as descent below the McGregor line greater than preoperative tonsillar herniation, a morphometric definition not uniformly reported in the literature. This finding contrasts with reports suggesting minimal slump when decompression is limited [31]. Our results therefore raise the possibility that individual cranial morphology, rather than decompression size alone, may predispose to slump.\u003c/p\u003e\n\u003cp\u003eComplication rates in our cohort were higher after DP+, particularly for CSF fistulas and pseudomeningocele. CSF fistula/pseudomeningocele developed in 7/39 (17.9%) with DP+ vs 2/54 (3.7%) with DP\u0026ndash; (p = 0.218), noting that we counted closed pseudomeningocele within CSF-related events. Our leakage rate exceeds that of many series [1,8,27], but this discrepancy may be partly explained by our inclusion of closed pseudomeningocele under the definition of CSF fistula. The DP\u0026ndash; group had a 3.8% rate of CSF leakage, which we attribute to the \u0026ldquo;keyhole\u0026rdquo; incision of the parietal dural leaf. This technical nuance aligns with prior reports emphasizing surgical modifications to minimize leakage [20,31]. Moreover, Tam SKP et al. [28] confirmed in a systematic review and meta-analysis that DP+ carries a higher risk of CSF-related complications; notably, in syringomyelia-positive cohorts DP+ tended to achieve superior clinical and radiological endpoints, underscoring a trade-off rather than a uniform advantage.\u003c/p\u003e\n\u003cp\u003eOur analysis of age subgroups revealed no significant correlation between age and syrinx regression, suggesting that in adults, age alone may not determine radiological outcome. This differs from pediatric-focused studies, which have shown better responses in younger patients [11,15]. In addition, El-Hajj et al. [11] highlighted that syrinx characteristics can modulate long-term functional recovery on CCOS, a factor future adult studies should incorporate.\u003c/p\u003e\n\u003cp\u003eDurability remains a critical question. Although our one-year follow-up supports short-term sufficiency of DP\u0026ndash;, long-term data consistently caution against overgeneralization. Krishna et al. reported reoperation rates of 31.9% after DP\u0026ndash; [17], whereas Tubbs et al. [29] and Alfieri \u0026amp; Pinna [2] observed far lower reoperation rates (0\u0026ndash;3.2%) with DP+. Mozaffari et al. [22] similarly confirmed that DP\u0026ndash; carries a higher risk of late failure. Taken together, our results should be interpreted as short-term evidence that DP\u0026ndash; may suffice in non-syringomyelia patients, while long-term vigilance remains necessary.\u003c/p\u003e\n\u003cp\u003eAnother limitation of our study is that we did not stratify syringomyelia cases by size or extent. Holocord versus focal syrinx may influence outcomes differently, and future research should incorporate this parameter. Furthermore, we did not evaluate intradural pathology as Yu et al. [32] did, which may partly explain differences between our findings and theirs.\u003c/p\u003e\n\u003cp\u003eFinally, technique-level choices within DP+ may not dramatically alter global outcomes. Moniruzzaman et al. [21] reported that results did not differ substantially across duraplasty configurations and graft types, supporting individualized technical selection (e.g., graft material, durotomy configuration) according to intraoperative findings and patient-specific anatomy. Furthermore, we did not stratify syringomyelia cases by size or extent. Holocord versus focal syrinx may influence outcomes differently, and future research should incorporate this parameter. We also did not evaluate intradural pathology as Yu et al. [32] did, which may partly explain differences between our findings and theirs. Taken together, our data show that in carefully selected adults without syringomyelia, DP\u0026ndash; achieves short-term clinical gains comparable to DP+ while avoiding a higher CSF-event burden, whereas DP+ confers superior radiological endpoints.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eLimitations\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis single-centre, retrospective study used surgeon-determined assignment to DP+ or DP\u0026ndash; (guided by morphometry and intraoperative dural pulsatility) without multivariable or propensity adjustment, so residual confounding is likely. Follow-up was limited to 12 months, precluding inferences about durability, late reoperation, or delayed radiological change. Imaging endpoints warrant caution: the composite \u0026ldquo;radiological benefit\u0026rdquo; combines heterogeneous markers; cerebellar slump was defined by a McGregor-based morphometric threshold without external validation; cine phase-contrast CSF was unavailable; and MRI protocols evolved over time. Complication accounting intentionally included closed pseudomeningocele within CSF-related events, which may overestimate leak rates relative to series reporting overt leaks only, while minor events may be under-ascertained. Phenotyping was incomplete (syrinx morphology/size and intradural anomalies not captured), the cohort was underpowered for small effects, and foramen magnum expansion did not track with CCOS.\u0026nbsp;Subgroup analyses (e.g., the syrinx-positive cohort) were exploratory, and the study was not powered to detect small between-group differences in CCOS at one year; longer follow-up may reveal divergence. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAccordingly, generalisability is best limited to adults treated in a tertiary setting using dura-splitting DP\u0026ndash; and variable grafts for DP+.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIn adults with Chiari I, bone-only decompression achieved short-term clinical improvement comparable to duraplasty, even though duraplasty conferred clearer radiological change and a higher burden of CSF-related events and cerebellar slump. These findings support an individualized strategy that prioritizes symptom profile, syringomyelia status, age, and morphometric context rather than a uniform preference for duraplasty. For carefully selected adults without syringomyelia, bone-only decompression appears clinically sufficient in the first postoperative year, while duraplasty may be reserved for cases in which radiological objectives predominate. Longer, prospective follow-up\u0026mdash;ideally stratifying syrinx morphology and intradural pathology\u0026mdash;is needed to refine indications and confirm durability.\u003c/p\u003e\n"},{"header":"Abbreviations","content":"\u003cp\u003eCCOS \u0026ndash; Chicago Chiari Outcome Scale, CM \u0026ndash; Chiari Malformation, CM-I \u0026ndash; Chiari Malformation Type I, CSF \u0026ndash; Cerebrospinal Fluid, DP+ \u0026ndash; Duraplasty, FM \u0026ndash; Foramen Magnum, MRI \u0026ndash; Magnetic Resonance Imaging, MCM \u0026ndash; Mega Cisterna Magna.\u003c/p\u003e\n"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eFuture Directions and Recommendations\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTo better isolate the effect of duraplasty, future studies should be prospective, multicentre, pre-registered, and use \u0026ge;5-year follow-up with blinded outcome adjudication, preferably randomised or propensity-matched with adjustment for surgeon/centre clustering. Imaging must be standardised across sites/timepoints, incorporating cine phase-contrast CSF and quantitative syrinx morphometrics. Stratification should include syringomyelia phenotype (holocord vs focal; length/diameter; syrinx\u0026ndash;cord ratio), tonsillar descent, and posterior fossa morphometry. Outcomes should centre on CCOS (primary) with complementary PROMs, reoperation, CSF-related events, and cost-effectiveness. Technique reporting (durotomy configuration, graft material, sealants, dura-splitting variants) should be explicit to enable meaningful technique-level comparisons.\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStrengths and Novelty of This Study\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis adult, consecutive cohort with complete one-year clinical/MRI follow-up uses a disease-specific outcome (CCOS) and a standardised operative protocol, introduces explicit morphometric definitions (including cerebellar slump relative to McGregor\u0026rsquo;s line), and demonstrates an anatomy\u0026ndash;function dissociation whereby foramen magnum expansion does not track with clinical recovery\u0026mdash;together providing a transparent, reproducible framework that clarifies technique trade-offs and refines patient selection beyond radiological thresholds.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eEnglish language editing support was provided by ChatGPT (OpenAI, San Francisco, CA, USA) for improving clarity and grammar. The authors are fully responsible for the scientific content of this article.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical approval \u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll procedures performed in this study involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Ethical approval was obtained from the Ondokuz Mayıs University Clinical Research Ethics Committee (Approval No: 2024/571).\u0026nbsp;Written consent was waived; verbal informed consent was obtained from all participants contacted by telephone.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to participate \u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eVerbal informed consent was obtained from all patients during follow-up telephone interviews. Formal written consent was waived by the ethics committee due to the retrospective design.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding \u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of Interest Statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eUse of Artificial Intelligence \u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDuring the preparation of this manuscript, the authors used ChatGPT (OpenAI, San Francisco, CA, USA) to assist in improving the English language and clarity of some technical expressions. After using this tool, the authors reviewed and edited the content as needed and take full responsibility for the integrity and originality of the content.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication:\u003c/strong\u003e Not applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eClinical trial number:\u003c/strong\u003e Not applicable.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003cstrong\u003eAvailability of Data and Materials\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets generated and/or analyzed during the current study are available from the corresponding author upon reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAkbari SHA, Yahanda AT, Ackerman LL, Adelson PD, Ahmed R, Albert GW, et al. Complications and outcomes of posterior fossa decompression with duraplasty versus without duraplasty for pediatric Chiari I with syringomyelia: a Park-Reeves Syringomyelia Research Consortium study. J Neurosurg Pediatr. 2022;30(1):39-51. doi:10.3171/2022.2.PEDS21446.\u003c/li\u003e\n\u003cli\u003eAlfieri A, Pinna G. Long-term results after posterior fossa decompression in syringomyelia with adult Chiari Type I malformation. J Neurosurg Spine. 2012 Nov;17(5):381-7. doi: 10.3171/2012.7.SPINE12272. Epub 2012 Aug 31. PMID: 22938552.\u003c/li\u003e\n\u003cli\u003eAntkowiak Ł, Tabakow P. Comparative assessment of posterior fossa decompression techniques in Chiari I malformation: a systematic review. World Neurosurg. 2021;152:31-43.\u003c/li\u003e\n\u003cli\u003eBeretta E, Vetrano IG, Curone M, Chiapparini L, Furlanetto M, Bussone G, et al. Chiari malformation-related headache: outcome after surgical treatment. Neurol Sci. 2017;38(Suppl 1):95-98.\u003c/li\u003e\n\u003cli\u003eBogdanov EI, Heiss JD, Salamat MS, et al. Morphometric assessment of posterior cranial fossa and spinal canal in Chiari malformation type I. Neuroradiology. 2021;63(3):403-411.\u003c/li\u003e\n\u003cli\u003eButensky S, Rodgers S, Baron S, Schneider S, Mittler M. Comparison of surgical outcomes in Chiari I receiving posterior fossa decompression with and without duraplasty. Childs Nerv Syst. 2020;36(7):1399-1405. doi:10.1007/s00381-020-04667-7.\u003c/li\u003e\n\u003cli\u003eCiaramitaro P, Massimi L, Bertuccio A, Solari A, Farinotti M, Peretta P, et al. Diagnosis and treatment of Chiari malformation and syringomyelia in adults: international consensus document (Milan, 2019). Neurol Sci. 2022;43(2):1327-1342.\u003c/li\u003e\n\u003cli\u003eChang TW, Zhang X, Maoliti W, Yuan Q, Yang XP, Wang JC. Outcomes of dura-splitting decompression versus decompression with duraplasty in Chiari I: systematic review and meta-analysis. World Neurosurg. 2021;147:105-114.\u003c/li\u003e\n\u003cli\u003eChotai S, Medhkour A. Surgical outcomes after posterior fossa decompression with and without duraplasty in Chiari malformation I. Clin Neurol Neurosurg. 2014;125:182-188.\u003c/li\u003e\n\u003cli\u003eDeng X, Zhang L, Zhang Y, et al. Posterior fossa decompression with duraplasty for Chiari I: a retrospective study of 152 cases. World Neurosurg. 2015;84(5):1428-1435.\u003c/li\u003e\n\u003cli\u003eEl-Hajj F, Ben Nsir A, Haddad A, et al. Long-term outcomes in pediatric Chiari I malformation: a multicentre cohort analysis. J Neurosurg Pediatr. 2024;33(1):1-10.\u003c/li\u003e\n\u003cli\u003eGiammattei L, Messerer M, Daniel RT, Aghakhani N, Parker F. Long-term outcome of surgical treatment of Chiari malformation without syringomyelia. J Neurosurg Sci. 2020;64(4):364-368.\u003c/li\u003e\n\u003cli\u003eGoel A, Milhorat TH, Kula RW, Mandell M. 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Decompression with vs without duraplasty for Chiari I: systematic review and meta-analysis. World Neurosurg. 2018;110:460-474.e5.\u003c/li\u003e\n\u003cli\u003eLu VM, Phan K, Crowley SP, Daniels DJ. Addition of duraplasty to posterior fossa decompression in pediatric Chiari I: systematic review and meta-analysis. J Neurosurg Pediatr. 2017;20:439-449.\u003c/li\u003e\n\u003cli\u003eMassimi L, Frassanito P, Chieffo D, Tamburrini G, Caldarelli M. Bony Decompression for Chiari Malformation Type I: Long-Term Follow-Up. Acta Neurochir Suppl. 2019;125:119-124. doi: 10.1007/978-3-319-62515-7_17. PMID: 30610311.\u003c/li\u003e\n\u003cli\u003eMohanty A. Chiari I malformation: surgical considerations. Neurol India. 2019;67(3):662-663. doi:10.4103/0028-3886.263222.\u003c/li\u003e\n\u003cli\u003eMoniruzzaman S, Kaipainen A, Tervonen J, Huttunen J, Jyrkk\u0026auml;nen HK, Huuskonen TJ, et al. Long-term outcome of operated Chiari I patients between 2005 and 2020 in Eastern Finland. Acta Neurochir (Wien). 2024;166(1):115. doi:10.1007/s00701-024-05999-y.\u003c/li\u003e\n\u003cli\u003eMozaffari K, Davidson L, Chalif E, Phan TN, Sparks AD, Myseros JS, Oluigbo CO, Keating RF. Long-term outcomes of posterior fossa decompression for Chiari malformation type 1: which patients are most prone to failure? Childs Nerv Syst. 2021 Sep;37(9):2891-2898. doi: 10.1007/s00381-021-05280-y. Epub 2021 Jul 7. PMID: 34232379.\u003c/li\u003e\n\u003cli\u003eMueller DM, Oro\u0026rsquo; JJ. Prospective analysis of presenting symptoms among 265 patients with radiographic Chiari I with or without syringomyelia. J Am Acad Nurse Pract. 2004;16:134-138.\u003c/li\u003e\n\u003cli\u003ePepper J, Magarik JA, Thomas C, et al. Symptom improvement after suboccipital decompression in Chiari I without syringomyelia. J Neurosurg. 2020;132(3):812-819.\u003c/li\u003e\n\u003cli\u003eRodr\u0026iacute;guez-Blanque R, Almaz\u0026aacute;n-Soto C, Piqueras-Sola B, S\u0026aacute;nchez-Garc\u0026iacute;a JC, Reinoso-Cobo A, Menor-Rodr\u0026iacute;guez MJ, et al. Chiari syndrome: advances in epidemiology and pathogenesis\u0026mdash;a systematic review. J Clin Med. 2023;12(20):6694. doi:10.3390/jcm12206694.\u003c/li\u003e\n\u003cli\u003eStrahle J, Muraszko KM, Garton HJL. Syrinx location and size according to aetiology: identification of Chiari-associated syrinx. J Neurosurg Pediatr. 2015;16(1):21-29.\u003c/li\u003e\n\u003cli\u003eTam M, El Tecle NE, El Ahmadieh TY, et al. Complications of posterior fossa decompression in adults and children with Chiari I: systematic review and meta-analysis. Acta Neurochir (Wien). 2020;162(6):1343-1353. doi:10.1007/s00701-020-04403-9.\u003c/li\u003e\n\u003cli\u003eTam SKP, Brodbelt A, Bolognese PA, Foroughi M. Posterior fossa decompression with duraplasty in Chiari I: a systematic review and meta-analysis. Acta Neurochir (Wien). 2021;163(1):229-238. doi:10.1007/s00701-020-04403-9.\u003c/li\u003e\n\u003cli\u003eTubbs RS, Beckman J, Naftel RP, Chern JJ, Wellons JC 3rd, Rozzelle CJ, et al. Institutional experience with 500 surgically treated pediatric Chiari I. J Neurosurg Pediatr. 2011;7(3):248-256. doi:10.3171/2010.12.PEDS10379.\u003c/li\u003e\n\u003cli\u003eVisocchi M, Signorelli F, Alves \u0026Oacute;L, Goel A, Parthiban J, Baeesa S, et al. Indications for surgery and surgical options in Chiari malformation: WFNS Spine Committee recommendations. Spine (Phila Pa 1976). 2025;50(11):760-766. doi:10.1097/BRS.0000000000005288.\u003c/li\u003e\n\u003cli\u003eYilmaz A, Kanat A, Musluman AM, Colak I, Terzi Y, Kayacı S, et al. When is duraplasty required in surgical treatment of Chiari I based on tonsillar descent grading? World Neurosurg. 2011;75(2):307-313. doi:10.1016/j.wneu.2010.09.005.\u003c/li\u003e\n\u003cli\u003eYu QS, Li T, Wan M, Zhang L, Qiao GY, Yu XG, et al. Clinical outcome of different surgical approaches for symptomatic Chiari malformation without syringomyelia: a 13-year retrospective study. Neurosurg Rev. 2025;48(1):485. doi:10.1007/s10143-025-03640-9.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003e\u0026nbsp;Tablo 1. Demographic and clinical characteristics of patients. \u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 48.8263%;\"\u003e\n \u003cp\u003eFeatures\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.1737%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 48.8263%;\"\u003e\n \u003cp\u003eGender-n(%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.1737%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 48.8263%;\"\u003e\n \u003cp\u003eFemale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.1737%;\"\u003e\n \u003cp\u003e59 (63.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 48.8263%;\"\u003e\n \u003cp\u003eMale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.1737%;\"\u003e\n \u003cp\u003e34 (36.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 48.8263%;\"\u003e\n \u003cp\u003eAge- Min.-Max (Average\u0026plusmn;ss)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.1737%;\"\u003e\n \u003cp\u003e13-70 (34.53\u0026plusmn;13.51)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 48.8263%;\"\u003e\n \u003cp\u003eSyringomyelia -n(%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.1737%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 48.8263%;\"\u003e\n \u003cp\u003eNo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.1737%;\"\u003e\n \u003cp\u003e43 (46.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 48.8263%;\"\u003e\n \u003cp\u003eYes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.1737%;\"\u003e\n \u003cp\u003e50 (53.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 48.8263%;\"\u003e\n \u003cp\u003eHerniation Degree-n(%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.1737%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 48.8263%;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; Grade 1 (5-9 mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.1737%;\"\u003e\n \u003cp\u003e36 (38.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 48.8263%;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; Grade 2 (10-14 mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.1737%;\"\u003e\n \u003cp\u003e39 (41.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 48.8263%;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; Grade 3 (15-19 mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.1737%;\"\u003e\n \u003cp\u003e14 (15.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 48.8263%;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; Grade 4 (\u0026gt;19 mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.1737%;\"\u003e\n \u003cp\u003e4 (4.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 48.8263%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eApplied Surgical Method\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.1737%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 48.8263%;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;DP +\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.1737%;\"\u003e\n \u003cp\u003e39 (41.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 48.8263%;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; DP -\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.1737%;\"\u003e\n \u003cp\u003e54 (58.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 48.8263%;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePreoperative Clinic\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.1737%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 48.8263%;\"\u003e\n \u003cp\u003eHead and neck pain\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.1737%;\"\u003e\n \u003cp\u003e63\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 48.8263%;\"\u003e\n \u003cp\u003eNumbness in extremities\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.1737%;\"\u003e\n \u003cp\u003e38\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 48.8263%;\"\u003e\n \u003cp\u003eDizziness\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.1737%;\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 48.8263%;\"\u003e\n \u003cp\u003eDifficulty swallowing\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.1737%;\"\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 48.8263%;\"\u003e\n \u003cp\u003eLoss of balance\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.1737%;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 48.8263%;\"\u003e\n \u003cp\u003eLoss of strength in extremitie\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.1737%;\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 48.8263%;\"\u003e\n \u003cp\u003eRinging in the ears\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.1737%;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e( DP +: suboccipital decompression and duraplasty, DP - : only suboccipital decompression)\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTable 2. Comparison of post-operative Magnetic Resonance imaging (MRI) findings at the end of the first year according to the preferred surgical method (DP - Vs DP +).\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 28px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 27px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eDP +\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 28px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eDP -\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" style=\"width: 9px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026chi;\u003csup\u003e2\u003c/sup\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" style=\"width: 6px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ep\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 28px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNo\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eYes\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNo\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 15px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eYes\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 28px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSyringomyelia\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e14 (35.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e25 (64.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13px;\"\u003e\n \u003cp\u003e29 (53.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 15px;\"\u003e\n \u003cp\u003e25 (46.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 9px;\"\u003e\n \u003cp\u003e2.888\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 6px;\"\u003e\n \u003cp\u003e.089\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 28px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e1st year MSM\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e14 (35.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e25 (64.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13px;\"\u003e\n \u003cp\u003e41 (75.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 15px;\"\u003e\n \u003cp\u003e13 (24.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 9px;\"\u003e\n \u003cp\u003e15.015\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 6px;\"\u003e\n \u003cp\u003e.000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 28px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eDecrease in Syringomyelia\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e10 (40.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e15 (60.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13px;\"\u003e\n \u003cp\u003e12 (46.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 15px;\"\u003e\n \u003cp\u003e13 (50.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 9px;\"\u003e\n \u003cp\u003e16.896\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 6px;\"\u003e\n \u003cp\u003e.000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 28px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCerebellar Slump\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e27 (69.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e12 (30.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13px;\"\u003e\n \u003cp\u003e48 (88.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 15px;\"\u003e\n \u003cp\u003e5 (9.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 9px;\"\u003e\n \u003cp\u003e7.539\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 6px;\"\u003e\n \u003cp\u003e.023\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 28px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTonsillar Herniation Reduction\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e16 (41.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e23 (59.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13px;\"\u003e\n \u003cp\u003e27 (50.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 15px;\"\u003e\n \u003cp\u003e26 (48.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 9px;\"\u003e\n \u003cp\u003e1.620\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 6px;\"\u003e\n \u003cp\u003e.445\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e(MCM: Mega cisterna magna)\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3\u003c/strong\u003e. Association Between MCM Formation and Clinical Outcome. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003cimg 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\"\u003e\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003cstrong\u003eTable 4\u003c/strong\u003e. Comparison of MRI benefit, CSF fistula development, complications and clinical benefit according to the preferred surgical method.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cimg 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\"\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 5A. Comparison of CCOS by surgical technique (DP+ vs DP\u0026minus;)\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eOutcome\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGroup\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eN\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMean \u0026plusmn; SD\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u003cstrong\u003et\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ep\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003eCCOS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003eWith duraplasty (DP+)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e13.00 \u0026plusmn; 2.55\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026minus;1.532\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e0.129\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003eWithout duraplasty (DP\u0026minus;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e54\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e13.77 \u0026plusmn; 2.31\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eNotes: Values are mean \u0026plusmn; SD. Independent-samples t-test; two-sided p-values. CCOS = Chicago Chiari Outcome Scale.\u003c/p\u003e\n\u003cp\u003eAs a result of the independent sample t test (Independent Samples t test) performed to determine whether there was a difference in CCOS values according to the surgical method, it was determined that although the CCOS value was slightly higher in patients who did not undergo Duraplasty, there was no significant difference according to the surgical method (p\u0026gt;0.05).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 5B. Comparison of CCOS by syringomyelia status\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eOutcome\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGroup\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eN\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMean \u0026plusmn; SD\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u003cstrong\u003et\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ep\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003eCCOS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003eNo syringomyelia\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e13.79 \u0026plusmn; 2.09\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e1.250\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e0.215\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003eSyringomyelia present\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e54\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e13.16 \u0026plusmn; 2.67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eNotes: Values are mean \u0026plusmn; SD. Independent-samples t-test; two-sided p-values. CCOS = Chicago Chiari Outcome Scale.\u003c/p\u003e\n\u003cp\u003eThe Independent Samples t test, which was performed to determine whether there was a difference in CCOS values according to the presence or absence of syringomyelia, revealed no significant difference (p\u0026gt;0.05).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 6. Association between age group and postoperative syrinx regression at 1 year.\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAge group\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNo regression\u003cbr\u003e\u0026nbsp;n (%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eRegression\u003cbr\u003e\u0026nbsp;n (%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNot evaluable\u003cbr\u003e\u0026nbsp;n (%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTotal n\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026lt;18 years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e2 (22.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e7 (77.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e0 (0.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e19\u0026ndash;45 years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e13 (44.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e16 (55.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e0 (0.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e29\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026gt;45 years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e7 (53.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e5 (38.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e1 (7.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e13\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003eTotal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e22 (43.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e28 (54.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e1 (2.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e51\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eStatistics: Pearson\u0026rsquo;s \u0026chi;\u0026sup2; = 5.699, p = 0.223. Percentages are row-wise. \u0026lsquo;Not evaluable\u0026rsquo; denotes unavailable or non-assessable 1-year MRI for syrinx change.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"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":"Chiari malformation type I, Suboccipital decompression, Duraplasty, Syringomyelia, Chicago Chiari Outcome Scale, Morphometric analysis, Foramen magnum","lastPublishedDoi":"10.21203/rs.3.rs-8129425/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8129425/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003eThe optimal surgical technique for Chiari type I malformation (CM-I) remains debated, particularly in patients without syringomyelia. While duraplasty (DP+) may enhance radiological outcomes, it can carry higher complication risks. We compared clinical, radiological, and morphometric outcomes after suboccipital decompression with DP\u0026thinsp;+\u0026thinsp;and without duraplasty (DP\u0026ndash;), with prespecified subgroup analyses by syringomyelia status.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003eNinety-three consecutive adult CM-I underwent DP\u0026ndash; (n\u0026thinsp;=\u0026thinsp;54) or DP+ (n\u0026thinsp;=\u0026thinsp;39) between 2014 and 2022. Pre- and postoperative MRI and neurological evaluations were obtained at 1 year. Functional recovery was assessed using the Chicago Chiari Outcome Scale (CCOS). Clinical and radiological outcomes, complication rates, and subgroup results (with vs without syringomyelia) were compared.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eOverall clinical improvement was observed in 92.5% of patients (DP\u0026ndash;: 94.4%; DP+: 89.7%; p\u0026thinsp;\u0026gt;\u0026thinsp;0.05). Among patients without syringomyelia, clinical improvement remained high with DP\u0026ndash;. Radiological benefit\u0026mdash;including syrinx regression and mega cisterna magna formation\u0026mdash;was greater with DP+ (64.1% vs 24.1%; p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), but this did not translate into higher CCOS scores (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05). Cerebellar slump occurred more often after DP+ (30.8% vs 9.3%; p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Complication rates, including CSF-related events, were higher with DP+. Morphometric expansion of the foramen magnum did not correlate with functional outcomes.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e\u003cp\u003eAt 1-year follow-up, suboccipital decompression without duraplasty appears to provide comparable clinical improvement to DP+, with fewer complications, in selected CM-I patients without syringomyelia. Duraplasty offers radiological advantages, especially for syringomyelia, but at the cost of increased risk. Longer follow-up is necessary to determine the durability of these findings.\u003c/p\u003e","manuscriptTitle":"Duraplasty Versus Bony Decompression in Adult Chiari I: Comparative Clinical and Morphometric Analysis","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-11-23 15:54:57","doi":"10.21203/rs.3.rs-8129425/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":"19767136-f801-4f45-995d-44a9c5464bf2","owner":[],"postedDate":"November 23rd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":58339583,"name":"Health sciences/Diseases"},{"id":58339584,"name":"Health sciences/Medical research"},{"id":58339585,"name":"Health sciences/Neurology"},{"id":58339586,"name":"Biological sciences/Neuroscience"}],"tags":[],"updatedAt":"2025-11-23T15:54:57+00:00","versionOfRecord":[],"versionCreatedAt":"2025-11-23 15:54:57","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8129425","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8129425","identity":"rs-8129425","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}