Analysis of Factors Associated with Occult Cerebrospinal Fluid Leak Following Lumbar Spine Surgery

Analysis of Factors Associated with Occult Cerebrospinal Fluid Leak Following Lumbar Spine Surgery | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Analysis of Factors Associated with Occult Cerebrospinal Fluid Leak Following Lumbar Spine Surgery Hu Li, Yan Chen, Zhiyong Wang, Guoshi Liu, Huilin Deng This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8443554/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 Introduction: Durotomy-induced occult cerebrospinal fluid (CSF) leak is a common complication of posterior spine surgery. While intraoperatively identified dural tears have been widely reported, data on occult leaks resulting from missed dural injuries remain limited. Most existing studies focus on patient- and procedure-related factors, with few examining the correlation between laboratory findings and postoperative CSF leaks. This study aimed to determine the incidence and associated factors of CSF leak following posterior lumbar spinal surgery through perioperative factor analysis. Materials and methods: A single-institution retrospective study was conducted on patients who underwent posterior lumbar spinal surgery between January 2021 and December 2024. Medical records were reviewed to identify patients with postoperative CSF leaks. Perioperative variables were analyzed using univariate and multivariate regression to identify factors associated with CSF leakage. Results: Among 935 patients included, 46 (4.9%) developed postoperative CSF leaks, of which 12 (1.28%) were occult leaks. American Society of Anesthesiologists (ASA) grade and multiple fusion segments were identified as independent risk factors for occult CSF leak (P=0.033 and P=0.026, respectively). Patients with occult leaks exhibited significantly lower postoperative globulin and glycated serum protein levels, higher postoperative wound drainage volumes, longer drain retention times, longer surgical and anesthesia times, and greater estimated blood loss compared to those without leaks. Conclusion: In this large cohort, ASA grade and multiple fusion segments were independent risk factors for occult CSF leak following posterior lumbar surgery. Occult leak cases were associated with postoperative reductions in globulin and glycated serum protein levels. lumbar surgery cerebrospinal fluid leak risk factors globulin occult dural tear Introduction Cerebrospinal fluid (CSF) leak is a frequent complication after spine surgery, often resulting from intraoperative or postoperative dural tears.[1]¹ Untreated CSF leakage can lead to wound infection, intracranial hypotension, meningitis, and mortality.[2, 3]² , ³ While most dural tears are recognized and repaired intraoperatively, some remain undetected during surgery and present postoperatively as occult CSF leaks. Although intraoperative dural injuries have been well documented, data on occult CSF leaks due to missed dural defects are scarce. Moreover, few studies have investigated the relationship between laboratory parameters and occult CSF leaks after lumbar spinal surgery. Materials and Methods Study Design This retrospective study was approved by the institutional ethics committee, and informed consent was obtained from all participants. Patients who underwent lumbar spinal surgery between January 2021 and December 2024 were enrolled. Inclusion criteria were: (1) diagnosis of lumbar spinal stenosis (LSS), lumbar disc herniation (LDH), or lumbar spondylolisthesis (LS); (2) posterior approach surgery; (3) elective procedures. Exclusion criteria included: (1) lumbar tumor, tuberculosis, or other infectious diseases; (2) history of lumbar trauma or prior lumbar surgery; (3) postoperative complications such as spinal epidural hematoma or systemic infections; (4) incomplete medical records. Diagnosis of CSF Leak CSF leak was defined based on prior literature.[4, 5]⁴ , ⁵ Patients meeting one of the following criteria were diagnosed with CSF leak: (1) intraoperative documentation of dural injury, CSF leakage, or nerve root sleeve injury, followed by postoperative drainage of clear or high-volume pale red fluid; (2) postoperative postural headache, dizziness, or vomiting accompanied by drainage of pale red or clear fluid from the incision. Diagnostic Criteria for Occult CSF Leak Occult CSF leak was defined as meeting the above CSF leak criteria in the absence of documented intraoperative dural injury or observed CSF leakage during surgery, but presenting postoperatively with significant clear or pale red drainage along with symptoms of intracranial hypotension (e.g., headache, dizziness). Data Collection Demographic, clinical, and laboratory data were collected, including: age, sex, smoking status, alcohol use, comorbidities (hypertension, diabetes), diagnosis, surgical approach (PLIF vs. TLIF), postoperative laboratory values (complete blood count, total protein, albumin, globulin, electrolytes, glucose, glycated serum protein), intraoperative variables (operative time, anesthesia time, ASA grade, blood loss, number of fusion segments, urine output), and postoperative drainage volume and duration. Statistical Analysis Statistical analysis was performed using SPSS 25.0 (IBM, Chicago, IL). Continuous normally distributed data are expressed as mean ± standard deviation and compared using Student’s t-test. Categorical data are presented as counts (%) and compared using Chi-square or Fisher’s exact tests. Multivariate logistic regression was performed with occult CSF leak as the dependent variable. A two-sided P-value < 0.05 was considered statistically significant. Results A total of 935 patients (415 male, 520 female; mean age 57.39 ± 7.56 years) were included. Diagnoses included LSS (34.2%), LS (21.1%), and LDH (44.7%). Postoperative CSF leaks occurred in 46 patients (4.92%), of which 12 (1.28%) were occult leaks. Demographic and diagnostic characteristics of occult leak cases are shown in Table 1 . Table 1 Characteristics Distribution of Patients with Postoperative Occult Cerebrospinal Fluid Leak Diagnosis Age (y) Male(n) Female(n) Smoker(n) Surgical Levels Incidence Rate(%) LSS(n) 62.78 ± 10.02 7 1 1 1.89 ± 0.93 75%(9/12) LS(n) 58 1 0 0 2 8.33%(1/12) LDH(n) 56.50 ± 20.51 1 0 1 1.50 ± 0.71 16.67%(2/12) Note: LDH, Lumbar Disc Herniation; LSS, Lumbar Spinal Stenosis; LS, Lumbar Spondylolisthesis Perioperative Factors Univariate analysis (Tables 2 and 3 ) revealed no significant differences in sex, smoking, alcohol use, age, hypertension, diabetes, or surgical approach between leak and no-leak groups. LSS patients had a higher propensity for occult leak compared to LS and LDH patients. Postoperative globulin (P = 0.036) and glycated serum protein (P = 0.018) were significantly lower in the occult leak group. ASA grade, number of surgical levels, drainage volume, and drain duration were significantly higher in the occult leak group (all P < 0.05). Table 4 shows no significant differences between patients with intraoperatively detected dural tears and those with occult leaks. Table 2 Univariate Analysis of Demographic Characteristics in Patients with Postoperative CSF Leak No CSF Leak Group (N = 889) CSF Leak Group (N = 46) t/x 2 value Odds Ratio (OR) 95% CI P-value Gender Male 394 21 0.031 1.055 0.582–1.913 0.859 Female 495 25 Smoking Yes 109 5 0.079 0.873 0.338–2.256 0.779 No 780 41 Alcohol Use Yes 109 2 2.618 0.325 0.078–1.361 0.106 No 780 44 Age(y) ≤ 55 284 20 2.651 0.610 0.335–1.112 0.103 > 55 605 26 Hypertension Yes 226 10 0.314 0.815 0.398–1.669 0.575 No 663 36 Diabetes Mellitus Yes 13 2 3.063 0.670-13.993 0.166 a No 876 44 Diagnosis LSS 297 23 5.348 1.993 1.100-3.612 0.021 LS 184 13 1.504 1.509 0.779–2.926 0.220 LDH 408 10 10.323 0.327 0.161–0.668 0.001 Note: LDH, Lumbar Disc Herniation; LSS, Lumbar Spinal Stenosis; LS, Lumbar Spondylolisthesis, a, Fisher's exact test. Table 3 Correlation Analysis of Perioperative Factors in Postoperative Occult CSF Leak Parameter Control Group (N = 889) Occult CsF Leak Group (N = 12) P-value Leukocytes(*10 12 /L) 12.28 ± 3.46 11.16 ± 3.44 0.286 Erythrocytes (*10 12 /L) 3.54 ± 0.51 3.49 ± 0.60 0.767 Hemoglobin(g/L) 108.04 ± 15.19 104.17 ± 19.58 0.410 Total Protein(g/L) 54.06 ± 7.15 50.89 ± 4.54 0.134 Albumin(g/L) 33.38 ± 3.55 31.71 ± 3.41 0.118 Globulin (g/L) 21.11 ± 4.49 18.32 ± 2.76 0.036 Serum Calcium(mmol/L) 2.165 ± 0.153 2.100 ± 0.163 0.160 Serum Potassium(mmol/L) 3.829 ± 0.393 3.855 ± 0.411 0.830 Platelets(*10 9 /L) 187.44 ± 66.45 168.67 ± 50.56 0.342 Glucose(mmol/L) 6.39 ± 1.66 5.81 ± 1.22 0.239 Glycated Serum Protein(mmol/L) 1.79 ± 0.30 1.58 ± 0.26 0.018 Operation Time (h) 3.40 ± 1.0 4.23 ± 1.98 0.179 Anesthesia Time (h) 5.42 ± 1.32 6.44 ± 2.14 0.130 ASA Physical Status 2..31 ± 0.51 2.67 ± 0.49 0.022 Intraoperative Blood Loss (ml) 445.80 ± 344.02 775.00 ± 565.89 0.071 Surgical Approach (n, %) 0.264 PLIF 361 7 TLIP 528 5 Number of Surgical Levels 1.33 ± 0.66 1.83 ± 0.83 0.014 Intraoperative Urine Output (ml) 481.16 ± 322.47 608.33 ± 494.44 0.122 Day 1 Drainage (ml) 208.73 ± 126.58 470.83 ± 246.30 0.004 Day 2 Drainage (ml) 77.03 ± 90.78 364.17 ± 238.20 0.002 Drainage Day Before Removal (ml)) 40.33 ± 15.58 102.50 ± 49.57 0.001 Time to Drain Removal (days) 2.49 ± 0.79 5.42 ± 2.19 0.001 Table 4 Comparison Between intraoperatively Detected Dural Tear CSf Leak and Occult CSf Leak Parameter CSF Leak with Detected Dural Tear (N = 34) Occult CSF Leak (N = 12) P-value Leukocytes (*10 9 /L) 11.99 ± 3.33 11.16 ± 3.44 0.481 Erythrocytes (*10 12 /L) 3.29 ± 0.55 3.49 ± 0.60 0.301 Hemoglobin(g/L) 96.53 ± 16.92 104.17 ± 19.58 0.204 Total Protein (g/L) 51.28 ± 7.40 50.89 ± 4.54 0.867 Albumin(g/L) 31.04 ± 3.70 31.71 ± 3.41 0.584 Globulin(g/L) 19.66 ± 4.85 18.32 ± 2.76 0.370 Serum Calcium (mmol/L) 2.106 ± 0.155 2.1 ± 0.163 0.919 Serum Potassium (mmol/L) 3.767 ± 0.416 3.855 ± 0.411 0.534 Platelets(*10 9 /L) 171.35 ± 57.49 168.67 ± 50.56 0.887 Glucose (mmol/L) 6.04 ± 1.30 5.81 ± 1.22 0.593 Glycated Serum Protein (mmol/L) 1.70 ± 0.33 1.58 ± 0.26 0.265 Operation Time (h) 4.03 ± 1.51 4.23 ± 1.98 0.724 Anesthesia Time (h) 5.97 ± 1.61 6.44 ± 2.14 0.429 ASA Physical Status 2.694 ± 0.849 2.667 ± 0.492 0.916 Intraoperative Blood Loss (ml) 633.82 ± 410.97 775.00 ± 565.89 0.360 Number of Surgical Levels 2.41 ± 1.18 1.83 ± 0.83 0.127 Intraoperative Urine Output (ml) 557.35 ± 340.26 608.33 ± 494.44 0.695 Postoperative Day 1 Drainage (ml) 379.12 ± 206.98 470.83 ± 246.30 0.216 Postoperative Day 2 Drainage (ml) 287.65 ± 222.71 364.17 ± 238.19 0.343 Time to Drain Removal (days) 4.71 ± 2.13 5.42 ± 2.19 0.343 Table 5: Logistic Regression Analysis of Risk Factors for Postoperative Occult CSF Leak Factor Standard Error(SE) Wald X 2 Odds Ratio(OR) 95% CI P-value Lower Upper ASA Physical Status 0.526 4.569 3.075 1.098 8.614 0.033 Number of Surgical Levels 0.328 4.957 2.074 1.091 3.942 0.026 Multivariate Analysis Multivariate logistic regression ( Table 5) confirmed ASA grade (OR = 3.075, P = 0.033, 95% CI 1.098–8.614) and multiple fusion segments (OR = 2.074, P = 0.026, 95% CI 1.091–3.942) as independent risk factors for occult CSF leak. Discussion This study retrospectively analyzed perioperative factors associated with occult cerebrospinal fluid (CSF) leak following posterior lumbar spinal surgery in a cohort of 935 patients. The overall incidence of postoperative CSF leak was 4.92%, with occult leaks—defined as leaks without intraoperatively documented dural injury—accounting for 1.28% of all cases (12 patients). Through multivariate analysis, a higher American Society of Anesthesiologists (ASA) physical status grade and surgery involving multiple fusion segments were identified as independent risk factors for occult CSF leakage. Furthermore, patients with occult leaks demonstrated significantly lower postoperative levels of globulin and glycated serum protein, alongside markedly higher postoperative wound drainage volumes and longer drain retention periods. The reported incidence of CSF leak after lumbar spine surgery varies widely in the literature, ranging from 1% to 15%, depending on surgical indications and techniques.[6–11] Our observed overall rate of 4.92% falls within this spectrum and aligns with data from large registries. The occult leak rate of 1.28% is notably higher than the 0.28% reported by Cammisa et al. in a mixed spine surgery population,[10] potentially reflecting differences in patient selection, surgical complexity, or diagnostic vigilance. The stratification by diagnosis revealed that patients with lumbar spinal stenosis (LSS) had the highest occult leak rate (2.81%), significantly greater than those with lumbar disc herniation (LDH) or spondylolisthesis (LS). This finding is consistent with previous studies suggesting that chronic compression in LSS leads to dural adhesion, thinning, and loss of epidural fat, rendering the dura more vulnerable to subtle, intraoperatively undetectable injury during decompression.[12, 13] The older average age of LSS patients in our cohort further supports the role of degenerative changes and prolonged pathological stress in increasing dural fragility. A principal finding of this study is the identification of ASA grade as an independent predictor of occult CSF leak. The ASA classification is a validated surrogate for a patient’s systemic physiological reserve and comorbid burden.[14] A higher ASA grade signifies poorer baseline health status, which is often associated with impaired wound healing, diminished immune response, and slower metabolic recovery. These systemic factors can compromise the delicate process of dural repair following an undetected injury.[14–16] Most patients in our occult leak group had comorbidities such as hypertension or diabetes, conditions frequently linked to microvascular dysfunction and poor tissue regeneration, thereby providing a plausible pathophysiological link to the observed association. This underscores the critical importance of comprehensive preoperative optimization in patients with higher ASA scores undergoing complex spinal procedures. The second independent risk factor was surgery involving multiple fusion segments. This aligns with established literature indicating that increased surgical levels correlate with a higher risk of dural tears and CSF leakage.[17–19] Multi-level procedures are inherently more complex, involving greater soft tissue dissection, longer operative times, and increased epidural scarring and adhesion, all of which elevate the risk of incidental dural injury.¹³ , ¹⁸ Prolonged operative time and exposure can lead to surgeon fatigue and subtle technical errors, while increased blood loss may obscure the surgical field, making small dural defects more likely to be missed. Interestingly, while the occult leak group had fewer surgical levels on average than the group with intraoperatively detected tears, they experienced longer operative times and greater blood loss. This suggests that the complexity and technical difficulty within a given surgical level, rather than the absolute number of levels alone, may be a key driver of occult injury. Our analysis also revealed distinctive postoperative laboratory profiles in patients with occult leaks. Significantly lower levels of globulin and glycated serum protein were observed. The reduction in globulin may reflect a combination of factors: a systemic inflammatory or catabolic response to more extensive surgical trauma, potential nutritional deficits in patients with higher comorbidity burdens, or even loss of immunoglobulin-rich CSF. The lower glycated serum protein level, an indicator of intermediate-term glycemic control, might result from greater intraoperative metabolic stress and glucose consumption, or altered protein turnover post-injury. While these findings are associative and do not imply causation, they suggest that postoperative laboratory derangements may serve as indirect markers of significant occult physiological stress or fluid shift, warranting closer clinical scrutiny. The significantly higher postoperative drainage volume and prolonged drain retention in the occult leak group are clinically intuitive findings. They directly reflect the ongoing egress of CSF from an unsealed dural defect into the surgical bed.[20, 21] While subfascial drainage is a standard measure to prevent fluid accumulation and potential complications, persistently high output is a hallmark of CSF leakage.[20] Our data reinforce that meticulous monitoring of drain output in the early postoperative period is a simple yet crucial practice for the timely detection of occult leaks, especially in high-risk patients. This study has several limitations. Its retrospective, single-center design may limit the generalizability of the findings. The definition of occult leak, while based on clinical and drainage criteria, could be subject to diagnostic subjectivity. Furthermore, the small absolute number of occult leak events, though statistically significant in this cohort, necessitates validation in larger, prospective multi-center studies. Despite these limitations, our analysis provides clinically relevant insights into the risk profile for this specific complication. Conclusions In conclusion, this study highlights that patients with a higher ASA physical status and those undergoing multi-level lumbar fusion are at increased independent risk for developing an occult CSF leak postoperatively. Surgeons should maintain a high index of suspicion for this complication in such patients, particularly those diagnosed with lumbar spinal stenosis. Vigilant postoperative monitoring of wound drainage and consideration of the patient’s overall metabolic and nutritional status may aid in early identification and management. Declarations Compliance with Ethical Standards Conflict of Interest The authors declare no conflict of interest. Ethical Approval This study was approved by the institutional medical research ethics committee. Informed Consent Informed consent was obtained from all participants. Funding This work was supported by the Science and Technology Plan Project of Jiangxi Provincial Health Commission, China (SKJP2202228668). Author Contribution Hu Li (First Author): Conceptualization, Methodology, Software, Investigation, Formal Analysis, Writing - Original Draft;Yan Chen: Data Curation, Writing - Original Draft;Zhiyong Wang: Visualization, Investigation;Guoshi Liu: Resources, Supervision;HuiLin Deng (Corresponding Author):Conceptualization, Funding Acquisition, Resources, Supervision, Writing - Review and Editing. References Yee TJ, Swong K, Park P (2020) Complications of anterior cervical spine surgery: a systematic review of the literature. 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Surg Neurol Int 15:8. doi: 10.25259/sni_934_2023 Martínez-Manrique JJ, Palacios-Rodríguez RA, Rodríguez-Hernández LA, Aragón-Arreola JF, Sangrador-Deitos MV, Gómez-Amador JL (2025) Continuous sitting position during the postoperative period as an intervention to reduce risk of cerebrospinal fluid leak after endoscopic endonasal surgery. Neurocirugia (Engl Ed) 36:500658. doi: 10.1016/j.neucie.2025.500658 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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Deng","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA70lEQVRIiWNgGAWjYBACNvnDx38kVLDVz2fv//gg4YcNYS18EmwJEh/O8DFu7DlgbPCwJ42wFjkJHgPJmS1yjA03HMwkH7AdJsJh0g0GxrwNZsyMMxjSKhJ4DjPwt3cn4NcicyAhmXdHGhu7dMOxGwkW6QwSZ85uwK+FIeHAYd4zx3gY5xxsu5HAY81gIJFLSEtiYzNv238JhhvJbAUJbMxEaJFIZmac2cZmwHAjDWgjmzMRWniOsTF8OMOWYNhzhlkisSeNh6Bf5Nv7vzEAozJBnr2H8eOPHzZy/O29+LVgAB7SlI+CUTAKRsEowAoAY7VItV5oH9kAAAAASUVORK5CYII=","orcid":"","institution":"Gaoxin Hospital Of The First Affiliated Hospital Of Nanchang University","correspondingAuthor":true,"prefix":"","firstName":"Huilin","middleName":"","lastName":"Deng","suffix":""}],"badges":[],"createdAt":"2025-12-24 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12:37:52","extension":"xml","order_by":4,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":67718,"visible":true,"origin":"","legend":"","description":"","filename":"659680a14df34d50a016de73b58000101structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-8443554/v1/c76985d709fcbd41b8ac6bef.xml"},{"id":99612015,"identity":"6cc1af10-3a93-42fb-b261-e6b0041be1b5","added_by":"auto","created_at":"2026-01-06 12:37:52","extension":"html","order_by":5,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":75488,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-8443554/v1/652ce1e60ba0ddb508010451.html"},{"id":102295836,"identity":"60d4c9ea-dd3a-45cf-b49b-a92fbdf4cc02","added_by":"auto","created_at":"2026-02-10 10:15:22","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":806937,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8443554/v1/29aa9412-eca3-45b8-a243-4639ae45641e.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Analysis of Factors Associated with Occult Cerebrospinal Fluid Leak Following Lumbar Spine Surgery","fulltext":[{"header":"Introduction","content":"\u003cp\u003eCerebrospinal fluid (CSF) leak is a frequent complication after spine surgery, often resulting from intraoperative or postoperative dural tears.[1]\u0026sup1; Untreated CSF leakage can lead to wound infection, intracranial hypotension, meningitis, and mortality.[2, 3]\u0026sup2;\u003csup\u003e,\u003c/sup\u003e\u0026sup3; While most dural tears are recognized and repaired intraoperatively, some remain undetected during surgery and present postoperatively as occult CSF leaks. Although intraoperative dural injuries have been well documented, data on occult CSF leaks due to missed dural defects are scarce. Moreover, few studies have investigated the relationship between laboratory parameters and occult CSF leaks after lumbar spinal surgery.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy Design\u003c/h2\u003e \u003cp\u003eThis retrospective study was approved by the institutional ethics committee, and informed consent was obtained from all participants. Patients who underwent lumbar spinal surgery between January 2021 and December 2024 were enrolled. Inclusion criteria were: (1) diagnosis of lumbar spinal stenosis (LSS), lumbar disc herniation (LDH), or lumbar spondylolisthesis (LS); (2) posterior approach surgery; (3) elective procedures. Exclusion criteria included: (1) lumbar tumor, tuberculosis, or other infectious diseases; (2) history of lumbar trauma or prior lumbar surgery; (3) postoperative complications such as spinal epidural hematoma or systemic infections; (4) incomplete medical records.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eDiagnosis of CSF Leak\u003c/h3\u003e\n\u003cp\u003eCSF leak was defined based on prior literature.[4, 5]⁴\u003csup\u003e,\u003c/sup\u003e⁵ Patients meeting one of the following criteria were diagnosed with CSF leak: (1) intraoperative documentation of dural injury, CSF leakage, or nerve root sleeve injury, followed by postoperative drainage of clear or high-volume pale red fluid; (2) postoperative postural headache, dizziness, or vomiting accompanied by drainage of pale red or clear fluid from the incision.\u003c/p\u003e\n\u003ch3\u003eDiagnostic Criteria for Occult CSF Leak\u003c/h3\u003e\n\u003cp\u003eOccult CSF leak was defined as meeting the above CSF leak criteria in the absence of documented intraoperative dural injury or observed CSF leakage during surgery, but presenting postoperatively with significant clear or pale red drainage along with symptoms of intracranial hypotension (e.g., headache, dizziness).\u003c/p\u003e\n\u003ch3\u003eData Collection\u003c/h3\u003e\n\u003cp\u003eDemographic, clinical, and laboratory data were collected, including: age, sex, smoking status, alcohol use, comorbidities (hypertension, diabetes), diagnosis, surgical approach (PLIF vs. TLIF), postoperative laboratory values (complete blood count, total protein, albumin, globulin, electrolytes, glucose, glycated serum protein), intraoperative variables (operative time, anesthesia time, ASA grade, blood loss, number of fusion segments, urine output), and postoperative drainage volume and duration.\u003c/p\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis\u003c/h2\u003e \u003cp\u003eStatistical analysis was performed using SPSS 25.0 (IBM, Chicago, IL). Continuous normally distributed data are expressed as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation and compared using Student\u0026rsquo;s t-test. Categorical data are presented as counts (%) and compared using Chi-square or Fisher\u0026rsquo;s exact tests. Multivariate logistic regression was performed with occult CSF leak as the dependent variable. A two-sided P-value\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eA total of 935 patients (415 male, 520 female; mean age 57.39\u0026thinsp;\u0026plusmn;\u0026thinsp;7.56 years) were included. Diagnoses included LSS (34.2%), LS (21.1%), and LDH (44.7%). Postoperative CSF leaks occurred in 46 patients (4.92%), of which 12 (1.28%) were occult leaks. Demographic and diagnostic characteristics of occult leak cases are shown in Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\u0026nbsp;\u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eCharacteristics Distribution of Patients with Postoperative Occult Cerebrospinal Fluid Leak\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003ccolgroup cols=\"7\"\u003e\u003c/colgroup\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eDiagnosis\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eAge (y)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMale(n)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eFemale(n)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSmoker(n)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSurgical Levels\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eIncidence Rate(%)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLSS(n)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e62.78\u0026thinsp;\u0026plusmn;\u0026thinsp;10.02\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.89\u0026thinsp;\u0026plusmn;\u0026thinsp;0.93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e75%(9/12)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLS(n)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.33%(1/12)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLDH(n)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e56.50\u0026thinsp;\u0026plusmn;\u0026thinsp;20.51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.50\u0026thinsp;\u0026plusmn;\u0026thinsp;0.71\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e16.67%(2/12)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"7\"\u003eNote: LDH, Lumbar Disc Herniation; LSS, Lumbar Spinal Stenosis; LS, Lumbar Spondylolisthesis\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003ch3\u003ePerioperative Factors\u003c/h3\u003e\n\u003cp\u003eUnivariate analysis (Tables\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e and \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e) revealed no significant differences in sex, smoking, alcohol use, age, hypertension, diabetes, or surgical approach between leak and no-leak groups. LSS patients had a higher propensity for occult leak compared to LS and LDH patients. Postoperative globulin (P\u0026thinsp;=\u0026thinsp;0.036) and glycated serum protein (P\u0026thinsp;=\u0026thinsp;0.018) were significantly lower in the occult leak group. ASA grade, number of surgical levels, drainage volume, and drain duration were significantly higher in the occult leak group (all P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e shows no significant differences between patients with intraoperatively detected dural tears and those with occult leaks.\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n \u003cdiv align=\"left\" class=\"colspec\"\u003e\u003cbr\u003e\u003c/div\u003e\u0026nbsp;\u003ctable id=\"Tab2\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eUnivariate Analysis of Demographic Characteristics in Patients with Postoperative CSF Leak\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003ccolgroup cols=\"8\"\u003e\u003c/colgroup\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eNo CSF Leak\u003c/p\u003e\n \u003cp\u003eGroup (N\u0026thinsp;=\u0026thinsp;889)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eCSF Leak\u003c/p\u003e\n \u003cp\u003eGroup (N\u0026thinsp;=\u0026thinsp;46)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003et/x\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e\n \u003cp\u003evalue\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eOdds\u003c/p\u003e\n \u003cp\u003eRatio\u003c/p\u003e\n \u003cp\u003e(OR)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e95% CI\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eP-value\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003eGender\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e394\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.031\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.055\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.582\u0026ndash;1.913\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.859\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFemale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e495\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003eSmoking\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eYes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e109\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.079\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.873\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.338\u0026ndash;2.256\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.779\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e780\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003eAlcohol Use\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eYes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e109\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.618\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.325\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.078\u0026ndash;1.361\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.106\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e780\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e44\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAge(y)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026le;\u0026thinsp;55\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e284\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.651\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.610\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.335\u0026ndash;1.112\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.103\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026gt;\u0026thinsp;55\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e605\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003eHypertension\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eYes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e226\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.314\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.815\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.398\u0026ndash;1.669\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.575\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e663\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003eDiabetes\u003c/p\u003e\n \u003cp\u003eMellitus\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eYes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.063\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.670-13.993\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.166\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e876\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e44\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eDiagnosis\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLSS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e297\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e5.348\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.993\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.100-3.612\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.021\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e184\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.504\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.509\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.779\u0026ndash;2.926\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.220\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLDH\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e408\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10.323\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.327\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.161\u0026ndash;0.668\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.001\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"8\"\u003eNote: LDH, Lumbar Disc Herniation; LSS, Lumbar Spinal Stenosis; LS, Lumbar Spondylolisthesis, a, Fisher\u0026apos;s exact test.\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cdiv class=\"gridtable\"\u003e\n \u003cdiv align=\"char\" class=\"colspec\"\u003e\u003cbr\u003e\u003c/div\u003e\u0026nbsp;\u003ctable id=\"Tab3\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eCorrelation Analysis of Perioperative Factors in Postoperative Occult CSF Leak\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003ccolgroup cols=\"4\"\u003e\u003c/colgroup\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eParameter\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eControl Group (N\u0026thinsp;=\u0026thinsp;889)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eOccult CsF Leak Group (N\u0026thinsp;=\u0026thinsp;12)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eP-value\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLeukocytes(*10\u003csup\u003e12\u003c/sup\u003e/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.28\u0026thinsp;\u0026plusmn;\u0026thinsp;3.46\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11.16\u0026thinsp;\u0026plusmn;\u0026thinsp;3.44\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.286\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eErythrocytes (*10\u003csup\u003e12\u003c/sup\u003e/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.54\u0026thinsp;\u0026plusmn;\u0026thinsp;0.51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.49\u0026thinsp;\u0026plusmn;\u0026thinsp;0.60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.767\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eHemoglobin(g/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e108.04\u0026thinsp;\u0026plusmn;\u0026thinsp;15.19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e104.17\u0026thinsp;\u0026plusmn;\u0026thinsp;19.58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.410\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTotal Protein(g/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e54.06\u0026thinsp;\u0026plusmn;\u0026thinsp;7.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e50.89\u0026thinsp;\u0026plusmn;\u0026thinsp;4.54\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.134\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAlbumin(g/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e33.38\u0026thinsp;\u0026plusmn;\u0026thinsp;3.55\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e31.71\u0026thinsp;\u0026plusmn;\u0026thinsp;3.41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.118\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eGlobulin (g/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e21.11\u0026thinsp;\u0026plusmn;\u0026thinsp;4.49\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e18.32\u0026thinsp;\u0026plusmn;\u0026thinsp;2.76\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.036\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSerum Calcium(mmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.165\u0026thinsp;\u0026plusmn;\u0026thinsp;0.153\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.100\u0026thinsp;\u0026plusmn;\u0026thinsp;0.163\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.160\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSerum Potassium(mmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.829\u0026thinsp;\u0026plusmn;\u0026thinsp;0.393\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.855\u0026thinsp;\u0026plusmn;\u0026thinsp;0.411\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.830\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePlatelets(*10\u003csup\u003e9\u003c/sup\u003e/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e187.44\u0026thinsp;\u0026plusmn;\u0026thinsp;66.45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e168.67\u0026thinsp;\u0026plusmn;\u0026thinsp;50.56\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.342\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eGlucose(mmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.39\u0026thinsp;\u0026plusmn;\u0026thinsp;1.66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.81\u0026thinsp;\u0026plusmn;\u0026thinsp;1.22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.239\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eGlycated Serum Protein(mmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.79\u0026thinsp;\u0026plusmn;\u0026thinsp;0.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.58\u0026thinsp;\u0026plusmn;\u0026thinsp;0.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.018\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eOperation Time (h)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.40\u0026thinsp;\u0026plusmn;\u0026thinsp;1.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.23\u0026thinsp;\u0026plusmn;\u0026thinsp;1.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.179\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAnesthesia Time (h)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.42\u0026thinsp;\u0026plusmn;\u0026thinsp;1.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.44\u0026thinsp;\u0026plusmn;\u0026thinsp;2.14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.130\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eASA Physical Status\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2..31\u0026thinsp;\u0026plusmn;\u0026thinsp;0.51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.67\u0026thinsp;\u0026plusmn;\u0026thinsp;0.49\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.022\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eIntraoperative Blood Loss (ml)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e445.80\u0026thinsp;\u0026plusmn;\u0026thinsp;344.02\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e775.00\u0026thinsp;\u0026plusmn;\u0026thinsp;565.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.071\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSurgical Approach (n, %)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.264\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePLIF\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e361\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTLIP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e528\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNumber of Surgical Levels\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.33\u0026thinsp;\u0026plusmn;\u0026thinsp;0.66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.83\u0026thinsp;\u0026plusmn;\u0026thinsp;0.83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.014\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eIntraoperative Urine Output (ml)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e481.16\u0026thinsp;\u0026plusmn;\u0026thinsp;322.47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e608.33\u0026thinsp;\u0026plusmn;\u0026thinsp;494.44\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.122\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eDay 1 Drainage (ml)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e208.73\u0026thinsp;\u0026plusmn;\u0026thinsp;126.58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e470.83\u0026thinsp;\u0026plusmn;\u0026thinsp;246.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.004\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eDay 2 Drainage (ml)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e77.03\u0026thinsp;\u0026plusmn;\u0026thinsp;90.78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e364.17\u0026thinsp;\u0026plusmn;\u0026thinsp;238.20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.002\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eDrainage Day Before Removal (ml))\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e40.33\u0026thinsp;\u0026plusmn;\u0026thinsp;15.58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e102.50\u0026thinsp;\u0026plusmn;\u0026thinsp;49.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.001\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTime to Drain Removal (days)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.49\u0026thinsp;\u0026plusmn;\u0026thinsp;0.79\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.42\u0026thinsp;\u0026plusmn;\u0026thinsp;2.19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.001\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cdiv class=\"gridtable\"\u003e\n \u003cdiv align=\"left\" class=\"colspec\"\u003e\u003cbr\u003e\u003c/div\u003e\n \u003cdiv align=\"left\" class=\"colspec\"\u003e\u003cbr\u003e\u003c/div\u003e\u0026nbsp;\u003ctable id=\"Tab4\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eComparison Between intraoperatively Detected Dural Tear CSf Leak and Occult CSf Leak\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003ccolgroup cols=\"11\"\u003e\u003c/colgroup\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eParameter\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003eCSF Leak with Detected Dural Tear (N\u0026thinsp;=\u0026thinsp;34)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003eOccult CSF Leak (N\u0026thinsp;=\u0026thinsp;12)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eP-value\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eLeukocytes (*10\u003csup\u003e9\u003c/sup\u003e/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003e11.99\u0026thinsp;\u0026plusmn;\u0026thinsp;3.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003e11.16\u0026thinsp;\u0026plusmn;\u0026thinsp;3.44\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.481\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eErythrocytes (*10\u003csup\u003e12\u003c/sup\u003e/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003e3.29\u0026thinsp;\u0026plusmn;\u0026thinsp;0.55\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003e3.49\u0026thinsp;\u0026plusmn;\u0026thinsp;0.60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.301\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eHemoglobin(g/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003e96.53\u0026thinsp;\u0026plusmn;\u0026thinsp;16.92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003e104.17\u0026thinsp;\u0026plusmn;\u0026thinsp;19.58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.204\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eTotal Protein (g/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003e51.28\u0026thinsp;\u0026plusmn;\u0026thinsp;7.40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003e50.89\u0026thinsp;\u0026plusmn;\u0026thinsp;4.54\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.867\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eAlbumin(g/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003e31.04\u0026thinsp;\u0026plusmn;\u0026thinsp;3.70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003e31.71\u0026thinsp;\u0026plusmn;\u0026thinsp;3.41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.584\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eGlobulin(g/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003e19.66\u0026thinsp;\u0026plusmn;\u0026thinsp;4.85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003e18.32\u0026thinsp;\u0026plusmn;\u0026thinsp;2.76\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.370\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eSerum Calcium (mmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003e2.106\u0026thinsp;\u0026plusmn;\u0026thinsp;0.155\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003e2.1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.163\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.919\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eSerum Potassium (mmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003e3.767\u0026thinsp;\u0026plusmn;\u0026thinsp;0.416\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003e3.855\u0026thinsp;\u0026plusmn;\u0026thinsp;0.411\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.534\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003ePlatelets(*10\u003csup\u003e9\u003c/sup\u003e/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003e171.35\u0026thinsp;\u0026plusmn;\u0026thinsp;57.49\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003e168.67\u0026thinsp;\u0026plusmn;\u0026thinsp;50.56\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.887\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eGlucose (mmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003e6.04\u0026thinsp;\u0026plusmn;\u0026thinsp;1.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003e5.81\u0026thinsp;\u0026plusmn;\u0026thinsp;1.22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.593\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eGlycated Serum Protein (mmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003e1.70\u0026thinsp;\u0026plusmn;\u0026thinsp;0.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003e1.58\u0026thinsp;\u0026plusmn;\u0026thinsp;0.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.265\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eOperation Time (h)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003e4.03\u0026thinsp;\u0026plusmn;\u0026thinsp;1.51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003e4.23\u0026thinsp;\u0026plusmn;\u0026thinsp;1.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.724\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eAnesthesia Time (h)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003e5.97\u0026thinsp;\u0026plusmn;\u0026thinsp;1.61\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003e6.44\u0026thinsp;\u0026plusmn;\u0026thinsp;2.14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.429\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eASA Physical Status\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003e2.694\u0026thinsp;\u0026plusmn;\u0026thinsp;0.849\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003e2.667\u0026thinsp;\u0026plusmn;\u0026thinsp;0.492\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.916\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eIntraoperative Blood Loss (ml)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003e633.82\u0026thinsp;\u0026plusmn;\u0026thinsp;410.97\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003e775.00\u0026thinsp;\u0026plusmn;\u0026thinsp;565.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.360\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eNumber of Surgical Levels\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003e2.41\u0026thinsp;\u0026plusmn;\u0026thinsp;1.18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003e1.83\u0026thinsp;\u0026plusmn;\u0026thinsp;0.83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.127\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eIntraoperative Urine Output (ml)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003e557.35\u0026thinsp;\u0026plusmn;\u0026thinsp;340.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003e608.33\u0026thinsp;\u0026plusmn;\u0026thinsp;494.44\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.695\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003ePostoperative Day 1 Drainage (ml)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003e379.12\u0026thinsp;\u0026plusmn;\u0026thinsp;206.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003e470.83\u0026thinsp;\u0026plusmn;\u0026thinsp;246.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.216\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003ePostoperative Day 2 Drainage (ml)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003e287.65\u0026thinsp;\u0026plusmn;\u0026thinsp;222.71\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003e364.17\u0026thinsp;\u0026plusmn;\u0026thinsp;238.19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.343\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eTime to Drain Removal (days)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003e4.71\u0026thinsp;\u0026plusmn;\u0026thinsp;2.13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003e5.42\u0026thinsp;\u0026plusmn;\u0026thinsp;2.19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.343\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\u003c/table\u003e\u003cbr\u003e\u003ctable\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"10\"\u003e\n \u003cp\u003e\u003cstrong\u003eTable\u0026nbsp;5: Logistic Regression Analysis of Risk Factors for Postoperative Occult CSF Leak\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"1\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFactor\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eStandard Error(SE)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWald X\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eOdds Ratio(OR)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e95% CI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eP-value\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"1\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eLower Upper\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"1\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eASA Physical Status\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.526\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.569\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e3.075\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.098\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.614\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.033\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"1\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNumber of Surgical Levels\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.328\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.957\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e2.074\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.091\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.942\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.026\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"1\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003ch3\u003eMultivariate Analysis\u003c/h3\u003e\n\u003cp\u003eMultivariate logistic regression (\u003cstrong\u003eTable\u0026nbsp;5)\u003c/strong\u003e confirmed ASA grade (OR\u0026thinsp;=\u0026thinsp;3.075, P\u0026thinsp;=\u0026thinsp;0.033, 95% CI 1.098\u0026ndash;8.614) and multiple fusion segments (OR\u0026thinsp;=\u0026thinsp;2.074, P\u0026thinsp;=\u0026thinsp;0.026, 95% CI 1.091\u0026ndash;3.942) as independent risk factors for occult CSF leak.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study retrospectively analyzed perioperative factors associated with occult cerebrospinal fluid (CSF) leak following posterior lumbar spinal surgery in a cohort of 935 patients. The overall incidence of postoperative CSF leak was 4.92%, with occult leaks\u0026mdash;defined as leaks without intraoperatively documented dural injury\u0026mdash;accounting for 1.28% of all cases (12 patients). Through multivariate analysis, a higher American Society of Anesthesiologists (ASA) physical status grade and surgery involving multiple fusion segments were identified as independent risk factors for occult CSF leakage. Furthermore, patients with occult leaks demonstrated significantly lower postoperative levels of globulin and glycated serum protein, alongside markedly higher postoperative wound drainage volumes and longer drain retention periods.\u003c/p\u003e \u003cp\u003eThe reported incidence of CSF leak after lumbar spine surgery varies widely in the literature, ranging from 1% to 15%, depending on surgical indications and techniques.[6\u0026ndash;11] Our observed overall rate of 4.92% falls within this spectrum and aligns with data from large registries. The occult leak rate of 1.28% is notably higher than the 0.28% reported by Cammisa et al. in a mixed spine surgery population,[10] potentially reflecting differences in patient selection, surgical complexity, or diagnostic vigilance. The stratification by diagnosis revealed that patients with lumbar spinal stenosis (LSS) had the highest occult leak rate (2.81%), significantly greater than those with lumbar disc herniation (LDH) or spondylolisthesis (LS). This finding is consistent with previous studies suggesting that chronic compression in LSS leads to dural adhesion, thinning, and loss of epidural fat, rendering the dura more vulnerable to subtle, intraoperatively undetectable injury during decompression.[12, 13] The older average age of LSS patients in our cohort further supports the role of degenerative changes and prolonged pathological stress in increasing dural fragility.\u003c/p\u003e \u003cp\u003eA principal finding of this study is the identification of ASA grade as an independent predictor of occult CSF leak. The ASA classification is a validated surrogate for a patient\u0026rsquo;s systemic physiological reserve and comorbid burden.[14] A higher ASA grade signifies poorer baseline health status, which is often associated with impaired wound healing, diminished immune response, and slower metabolic recovery. These systemic factors can compromise the delicate process of dural repair following an undetected injury.[14\u0026ndash;16] Most patients in our occult leak group had comorbidities such as hypertension or diabetes, conditions frequently linked to microvascular dysfunction and poor tissue regeneration, thereby providing a plausible pathophysiological link to the observed association. This underscores the critical importance of comprehensive preoperative optimization in patients with higher ASA scores undergoing complex spinal procedures.\u003c/p\u003e \u003cp\u003eThe second independent risk factor was surgery involving multiple fusion segments. This aligns with established literature indicating that increased surgical levels correlate with a higher risk of dural tears and CSF leakage.[17\u0026ndash;19] Multi-level procedures are inherently more complex, involving greater soft tissue dissection, longer operative times, and increased epidural scarring and adhesion, all of which elevate the risk of incidental dural injury.\u0026sup1;\u0026sup3;\u003csup\u003e,\u003c/sup\u003e\u0026sup1;⁸ Prolonged operative time and exposure can lead to surgeon fatigue and subtle technical errors, while increased blood loss may obscure the surgical field, making small dural defects more likely to be missed. Interestingly, while the occult leak group had fewer surgical levels on average than the group with intraoperatively detected tears, they experienced longer operative times and greater blood loss. This suggests that the complexity and technical difficulty within a given surgical level, rather than the absolute number of levels alone, may be a key driver of occult injury.\u003c/p\u003e \u003cp\u003eOur analysis also revealed distinctive postoperative laboratory profiles in patients with occult leaks. Significantly lower levels of globulin and glycated serum protein were observed. The reduction in globulin may reflect a combination of factors: a systemic inflammatory or catabolic response to more extensive surgical trauma, potential nutritional deficits in patients with higher comorbidity burdens, or even loss of immunoglobulin-rich CSF. The lower glycated serum protein level, an indicator of intermediate-term glycemic control, might result from greater intraoperative metabolic stress and glucose consumption, or altered protein turnover post-injury. While these findings are associative and do not imply causation, they suggest that postoperative laboratory derangements may serve as indirect markers of significant occult physiological stress or fluid shift, warranting closer clinical scrutiny.\u003c/p\u003e \u003cp\u003eThe significantly higher postoperative drainage volume and prolonged drain retention in the occult leak group are clinically intuitive findings. They directly reflect the ongoing egress of CSF from an unsealed dural defect into the surgical bed.[20, 21] While subfascial drainage is a standard measure to prevent fluid accumulation and potential complications, persistently high output is a hallmark of CSF leakage.[20] Our data reinforce that meticulous monitoring of drain output in the early postoperative period is a simple yet crucial practice for the timely detection of occult leaks, especially in high-risk patients.\u003c/p\u003e \u003cp\u003eThis study has several limitations. Its retrospective, single-center design may limit the generalizability of the findings. The definition of occult leak, while based on clinical and drainage criteria, could be subject to diagnostic subjectivity. Furthermore, the small absolute number of occult leak events, though statistically significant in this cohort, necessitates validation in larger, prospective multi-center studies. Despite these limitations, our analysis provides clinically relevant insights into the risk profile for this specific complication.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eIn conclusion, this study highlights that patients with a higher ASA physical status and those undergoing multi-level lumbar fusion are at increased independent risk for developing an occult CSF leak postoperatively. Surgeons should maintain a high index of suspicion for this complication in such patients, particularly those diagnosed with lumbar spinal stenosis. Vigilant postoperative monitoring of wound drainage and consideration of the patient\u0026rsquo;s overall metabolic and nutritional status may aid in early identification and management.\u003c/p\u003e"},{"header":"Declarations","content":" \u003ch2\u003eCompliance with Ethical Standards\u003c/h2\u003e \u003cp\u003e \u003cb\u003eConflict of Interest\u003c/b\u003e The authors declare no conflict of interest.\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eEthical Approval\u003c/strong\u003e \u003cp\u003eThis study was approved by the institutional medical research ethics committee.\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eInformed Consent\u003c/strong\u003e \u003cp\u003eInformed consent was obtained from all participants.\u003c/p\u003e \u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eThis work was supported by the Science and Technology Plan Project of Jiangxi Provincial Health Commission, China (SKJP2202228668).\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eHu Li (First Author):\u0026nbsp;Conceptualization, Methodology, Software, Investigation, Formal Analysis, Writing - Original Draft;Yan Chen: Data Curation, Writing - Original Draft;Zhiyong Wang: Visualization, Investigation;Guoshi Liu:\u0026nbsp;Resources, Supervision;HuiLin Deng (Corresponding Author):Conceptualization, Funding Acquisition, Resources, Supervision, Writing - Review and Editing.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eYee TJ, Swong K, Park P (2020) Complications of anterior cervical spine surgery: a systematic review of the literature. 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Surg Neurol Int 15:8. doi: 10.25259/sni_934_2023\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMart\u0026iacute;nez-Manrique JJ, Palacios-Rodr\u0026iacute;guez RA, Rodr\u0026iacute;guez-Hern\u0026aacute;ndez LA, Arag\u0026oacute;n-Arreola JF, Sangrador-Deitos MV, G\u0026oacute;mez-Amador JL (2025) Continuous sitting position during the postoperative period as an intervention to reduce risk of cerebrospinal fluid leak after endoscopic endonasal surgery. Neurocirugia (Engl Ed) 36:500658. doi: 10.1016/j.neucie.2025.500658\u003c/span\u003e\u003c/li\u003e\u003c/ol\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":"lumbar surgery, cerebrospinal fluid leak, risk factors, globulin, occult dural tear","lastPublishedDoi":"10.21203/rs.3.rs-8443554/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8443554/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eIntroduction: \u003c/strong\u003eDurotomy-induced occult cerebrospinal fluid (CSF) leak is a common complication of posterior spine surgery. While intraoperatively identified dural tears have been widely reported, data on occult leaks resulting from missed dural injuries remain limited. Most existing studies focus on patient- and procedure-related factors, with few examining the correlation between laboratory findings and postoperative CSF leaks. This study aimed to determine the incidence and associated factors of CSF leak following posterior lumbar spinal surgery through perioperative factor analysis.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMaterials and methods: \u003c/strong\u003eA single-institution retrospective study was conducted on patients who underwent posterior lumbar spinal surgery between January 2021 and December 2024. Medical records were reviewed to identify patients with postoperative CSF leaks. Perioperative variables were analyzed using univariate and multivariate regression to identify factors associated with CSF leakage.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults: \u003c/strong\u003eAmong 935 patients included, 46 (4.9%) developed postoperative CSF leaks, of which 12 (1.28%) were occult leaks. American Society of Anesthesiologists (ASA) grade and multiple fusion segments were identified as independent risk factors for occult CSF leak (P=0.033 and P=0.026, respectively). Patients with occult leaks exhibited significantly lower postoperative globulin and glycated serum protein levels, higher postoperative wound drainage volumes, longer drain retention times, longer surgical and anesthesia times, and greater estimated blood loss compared to those without leaks.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion: \u003c/strong\u003eIn this large cohort, ASA grade and multiple fusion segments were independent risk factors for occult CSF leak following posterior lumbar surgery. Occult leak cases were associated with postoperative reductions in globulin and glycated serum protein levels.\u003c/p\u003e","manuscriptTitle":"Analysis of Factors Associated with Occult Cerebrospinal Fluid Leak Following Lumbar Spine Surgery","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-01-06 12:37:47","doi":"10.21203/rs.3.rs-8443554/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":"56ad77df-3a15-4a2d-9c1d-389fb9d4057d","owner":[],"postedDate":"January 6th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-02-06T22:53:46+00:00","versionOfRecord":[],"versionCreatedAt":"2026-01-06 12:37:47","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8443554","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8443554","identity":"rs-8443554","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}