Prognostic Factors for Neurological Outcome After Surgery for Idiopathic Spinal Cord Herniation: A Systematic Review and Published Individual Patient Data Analysis.

objectiveIdiopathic spinal cord herniation (ISCH) is a rare cause of progressive thoracic myelopathy, for which surgical management is widely accepted for symptomatic patients, but prognostic determinants remain poorly defined. This study aimed to synthesize the available surgical literature on ISCH, through a systematic review of published individual patient data (IPD), and to identify clinical, anatomical, and intraoperative factors associated with postoperative motor and sensory outcomes.

methodsA systematic review of the literature was performed in accordance with PRISMA guidelines and prospectively registered in PROSPERO (CRD420251273863). Studies reporting surgically treated cases of ISCH were identified, from database inception to December 2024. Stringent inclusion criteria were applied. For the enrolled patients, demographic, clinical, radiological, surgical, and postoperative outcome variables were harmonized. Postoperative motor and sensory outcomes were dichotomized as improved versus stable or worsened. Associations were explored using univariate and multivariable logistic regression models to identify factors independently associated with neurological outcomes.

resultsA total of 154 studies were included, providing published IPD for 285 surgically treated patients. The cohort consisted predominantly of middle-aged individuals with a slight female predominance, and Brown-Séquard syndrome represented the most frequent neurological presentation. Dural patch reconstruction and primary dural closure were adopted in 68.8% and 31.2% of patients, respectively. Overall, postoperative motor and sensory improvement were observed in 79.2% and 63% of patients, respectively. No significant association was found between dural patch adoption and postoperative motor or sensory improvement. Multivariable logistic regression identified preoperative paraparesis/plegia as independently associated with both motor and sensory stableness or worsened function (p = 0.041; p = 0.014, respectively). The presence of a posterior arachnoid cyst was independently associated with a higher probability of stable/worsened motor outcome (p = 0.033). Duplication of dura mater was associated with a lower probability of stable/worsened sensory outcome (p = 0.036), while dural patch reconstruction was associated with a higher probability of stable/worsened sensory outcome (p = 0.015). Intraoperative neurophysiological monitoring showed significant associations in both motor (p = 0.020) and sensory (p = 0.007).

conclusionsSurgical treatment of ISCH resulted in neurological improvement in a substantial proportion of patients. This IPD analysis identified preoperative neurological impairment and specific anatomical characteristics as factors associated with postoperative recovery, suggesting that advanced neurological deterioration may reduce the probability of functional improvement.These findings should be regarded as exploratory and underscore the need for prospective studies with standardized outcome assessment to refine surgical decision-making in ISCH.