Reintervention rate of arachnolysis versus shunting for nonforaminal syringomyelia.

OBJECTIVE Surgical treatment for nonforaminal syringomyelia related to spinal arachnoiditis is still controversial. The authors sought to assess respective outcomes and rates of reintervention for shunting and spinal cord untethering (arachnolysis) in spinal arachnoiditis with syringomyelia. METHODS This retrospective cohort study was conducted at a single reference center for syringomyelia. Patients undergoing arachnolysis and/or shunting interventions for nonforaminal syringomyelia were screened. RESULTS The study included 75 patients undergoing 130 interventions. Arachnolysis without shunting was performed in 48 patients, while 27 patients underwent shunting. The mean follow-up between the first surgery and the last outpatient visit was 65.0 months (range 12-379 months, median 53 months). At the last follow-up, the modified McCormick score was improved or stabilized in 83.4% of patients after arachnolysis versus 66.7% after shunting. Thirty-one (41.3%) patients underwent reintervention during follow-up, with a mean delay of 33.2 months. The rate of reintervention was 29.2% in the arachnolysis group versus 63.0% in the shunting group (chi-square = 8.1, p = 0.007). However, this difference was largely driven by the extension of the arachnoiditis: in patients with focal arachnoiditis (≤ 2 spinal segments), the reintervention rate was 21.6% for arachnolysis versus 57.1% for shunting; in patients with extensive arachnoiditis, it was 54.5% versus 65.0%, respectively. Survival analysis assessing the time to the first reintervention demonstrated a better outcome in both the arachnolysis (p = 0.03) and the focal arachnoiditis (p = 0.04) groups. CONCLUSIONS Arachnolysis led to fewer reinterventions than shunting in patients with nonforaminal syringomyelia. There was a high risk of reintervention for patients with extensive arachnopathies, irrespective of the surgical technique.