Long-term outcome and prognostic factors of syringo-subarachnoid shunt for syringomyelia

Syringo-subarachnoid shunt (SSS) is often considered a rescue procedure or a second-line treatment option for syringomyelia. However, the clinical efficacy of SSS in treating this condition remains controversial.To evaluate the long-term outcome of the SSS and its relationship with the syrinx area, as well as to investigate the factors that influence the prognosis.This retrospective study included twenty-seven consecutive patients who underwent SSS between 2014 and 2020. The study evaluated several independent variables such as age, sex, duration of progressive symptoms, morphological characteristics of the syrinx, changes in the syrinx area, and Chiari malformation. The long-term follow-up (>2 years) Japanese Orthopaedic Association (JOA) score was used to assess neurological function and outcome. Statistical analysis was performed using a stepwise logistic regression test.All patients were followed up for an average of 48.6 ± 14.8(26.8 to 78.0) months. Follow-up magnetic resonance imaging showed syrinx collapse to different degrees occurred in 96.3% (26 of 27) patients. The JOA score was improvedinonly6patients (22.2%), remained stable in 5 patients (18.5%),and deteriorated in 16 patients(59.3%).A logistic regression test showed that the tension syrinx (odds ratio 0.111) and early shunting intervention (odds ratio 0.138) were favorable independent prognostic factors.It is important to note that the shrinkage of the syrinx does not necessarily translate to an improvement in clinical outcomes. Therefore, the decision to perform SSS should be made with caution and considered as a last resort.