Postoperative Spinal Subdural Lesions Following Lumbar Spine Surgery: Prevalence and Risk Factors

STUDY DESIGN: Retrospective case–control study PURPOSE: To clarify the prevalence and risk factors for spinal subdural lesions (SSDLs) following lumbar spine surgery. OVERVIEW OF LITERATURE: Because SSDLs, including arachnoid cyst and subdural hematoma, that develop following spinal surgery are seldom symptomatic and require reoperation, there are few reports on these pathologies. No study has addressed the prevalence and risk factors for SSDLs following lumbar spine surgery. METHODS: We conducted a retrospective analysis of the magnetic resonance (MR) images and medical records of 410 patients who underwent lumbar decompression surgery with or without instrumented fusion for degenerative disorders. SSDLs were classified into three grades: grade 0, no obvious lesion; grade 1, cystic lesion; and grade 2, lesions other than a cyst. Grading was based on the examination of preoperative and postoperative MR images. The prevalence of SSDLs per grade was calculated and risk factors were evaluated using multivariate logistic regression analysis. RESULTS: Postoperative SSDLs were identified in 123 patients (30.0%), with 50 (12.2%) and 73 (17.8%) patients being classified with grade 1 and 2 SSDLs, respectively. Among these, one patient was symptomatic, requiring hematoma evacuation because of the development of incomplete paraplegia. Bilateral partial laminectomy was a significantly independent risk factor for SSDLs (odds ratio, 1.52; 95% confidence interval, 1.20–1.92; p<0.001). In contrast, a unilateral partial laminectomy was a protective factor (odds ratio, 0.11; 95% confidence interval, 0.03–0.46; p=0.002). CONCLUSIONS: The prevalence rate of grade 1 SSDLs was 30%, with no associated clinical symptoms observed in all but one patient. Bilateral partial laminectomy increases the risk for SSDLs, whereas unilateral partial laminectomy is a protective factor.

Comparison of the Japanese Orthopaedic Association Score and the Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire Scores: Time-Dependent Changes in Patients with Cervical Spondylotic Myelopathy and Posterior Longitudinal Ligam

STUDY DESIGN: Prospective cohort study. PURPOSE: To identify differences in time-dependent perioperative changes between the Japanese Orthopaedic Association (JOA) score and the JOA Cervical Myelopathy Evaluation Questionnaire (JOACMEQ) score in patients with cervical spondylotic myelopathy (CSM) and posterior longitudinal ligament (OPLL) who underwent cervical laminoplasty. OVERVIEW OF LITERATURE: The JOA score does not take into consideration patient satisfaction or quality of life. Accordingly, the JOACMEQ was designed in 2007 as a patient-centered assessment tool. METHODS: We studied 21 patients who underwent cervical laminoplasty. We objectively evaluated the time-dependent changes in JOACMEQ scores and JOA scores for all patients before surgery and at 2 weeks, 3 months, 6 months, and 1 year after surgery. RESULTS: The average total JOA score and the recovery rate improved significantly after surgery in both groups, with a slightly better recovery rate in the OPLL group. Cervical spine function improved significantly in the CSM group but not in the OPLL group. Upper- and lower-extremity functions were more stable in the CSM group than in the OPLL group. The effectiveness rate of the JOACMEQ for measuring quality of life was quite low in both groups. In both groups, the Spearman contingency coefficients were dispersed widely except for upper- and lower-extremity function. CONCLUSIONS: Scores for upper- and lower-extremity function on the JOACMEQ correlated well with JOA scores. Because the JOACMEQ can also assess cervical spine function and quality of life, factors that cannot be assessed by the JOA score alone, the JOACMEQ is a more comprehensive evaluation tool.