Clinical outcomes of resection of thoracic arachnoid webs: patient series

BACKGROUND: Spinal arachnoid web (SAW) is a rare pathology of the intradural arachnoid layer that can cause progressive neurological symptoms including pain, numbness, weakness, imbalance, and incontinence. Surgical fenestration is the primary treatment and has shown generally favorable outcomes. OBSERVATIONS: This retrospective case series includes 18 patients who underwent SAW fenestration at a tertiary care center between 2015 and 2024. The mean age was 54.7 years, and the mean BMI was 34.0 kg/m2. Preoperative symptoms included back pain (n = 15), sensory changes (n = 15), gait instability (n = 14), and lower extremity weakness (n = 14). Most patients experienced symptom improvement postoperatively, although 5 (27.8%) reported worsening in at least one domain. Of the 15 patients with a preoperative scalpel sign, 46.7% showed radiographic resolution following surgery. LESSONS: The authors present one of the largest single-center series of surgically treated SAW to date. While a subset of patients experienced persistent or worsened symptoms, the majority demonstrated both clinical and radiological improvement. These findings support surgical fenestration as a generally effective intervention for symptomatic SAW. Given the progressive nature of the condition and its potential impact on function, early recognition and surgical referral are critical to optimize patient outcomes. https://thejns.org/doi/10.3171/CASE25910.