Objective: Evaluate the advantages, results and drawbacks of the Sophy adjustable valve (SV) in the treatment of hydrocephalus in the adult.
Material and methods: One-hundred and forty-seven adult hydrocephalic patients (mean age = 64.5 years) shunted with a SV between 1990 and 1997 were retrospectively reviewed. Etiologies of hydrocephalus were: "normal pressure" chronic hydrocephalus (NPH) in 124 and tumoral hydrocephalus with intracranial hypertension in 23 patients. One-hundred fifty shunts were established in 147 patients: 14 ventriculoatrial and 136 ventriculoperitoneal shunts. The initial pressure settings of the SV were: high pressure: 12 times (8%), medium pressure: 136 times (90.6%) and low pressure: 2 times (1.3%).
Results: Sixteen patients were lost to follow-up. Two patients died within hours following the procedure. So, the results were analyzed in the 129 remaining patients, with a follow-up of 16.7 months (+/- 17.8). Three patients died from shunted-related causes (2.3%). Eighty-four patients had good results (65%), 25 had fair results (19.5%) and 20 failed to improve or deteriorated (15.5%) after shunting. Fifty-three reoperations were performed in 44 patients (34%), including 37 procedures for mechanical obstruction and 6 for septic complications. Subdural effusions (SDE) occurred in 16 patients (12.5%): 10 surgical evacuations were required in 7 patients; 8 patients were successfully treated using uprating of the SV pressure alone; one was managed conservatively. Fifty-eight pressure readjustments were performed in 47 patients. The pressure settings were uprated 28 times in patients showing clinical or computerized tomographic (CT) features suggesting overdrainage; 20 of those proved to be successful (71.5%). The pressure settings were lowered 30 times in patients showing a lack of improvement after shunting, attributed to underdrainage; only 12 of those proved to be successful (40%). Spontaneous changes of the pressure settings were observed in 14 patients (10.8%). After a MRI exposure, SV pressure changes were observed in 64% of patients.
Discussion: The technological refinements that have been proposed to eliminate the overdrainage which occurs in most usual cerebrospinal fluid shunts are reviewed. The SV valve has allowed non-invasive adjustments of its opening pressure in patients showing complications ascribed to inappropriate drainage. The need for additional surgery was eliminated in 20% to 25% of patients of the present series. Because of frequent spontaneous and magnetic resonance-induced pressure changes, the need for repeated controls of valve pressure is to be reemphasized.
Conclusion: This experience suggests that the SV represents a substantial improvement over standard fixed-pressure valves.