Mechanical Complications of Sophysa SM8 Shunt in Adult Hydrocephalus: A Monocentric Experience

BACKGROUND: Sophysa SM8 is widely used by neurosurgeons in France. Published studies report shunt malfunction rates in adults between 18% and 29%. However, these studies included multiple valve types and thus entailed a serious confounding factor. OBJECTIVE: To ascertain the incidence the Sophysa SM8 cerebrospinal fluid (CSF) shunt malfunctions in adults. METHODS: We present a retrospective series of adult patients who underwent CSF shunt placement between 2000 and 2013 with Sophysa SM8. RESULTS: In total, 599 patients (329 males and 270 females) were included. The mean age at surgery was 64.15 years (19-90) (SD 16.17; median 68.0). The causes of hydrocephalus were normal pressure hydrocephalus (49%), traumatic hemorrhages (26.5%), tumors (15.7%), cerebral aqueduct stenoses (3%), and arachnoid cysts (2%). The mean follow-up was 3.9 years (0-16) (SD 4.10; median 3 years). The rate of complications was 22.04% (132 of 599). Most frequent causes of complications were disconnection (25%), migration (12.9%), overdrainage (9.1%), and proximal obstruction (6.8%). In 17 cases (12.9%), no failure was diagnosed during revision. Seven infections (5.3%) were reported. The mean delay for the first revision was 1.70 years (0-13.93) (SD 2.67, median 0.35). The risk of shunt failure was 36% at 10 years. Seventeen percent of revisions occurred during the first year after shunt placement. CONCLUSION: Disconnections are a very frequent complication of Sophysa SM8 valve. They are related to the 2-connector system of this valve. Based on these results, we recommend using 1-piece valves.