Incidence and management of subdural hematoma/hygroma with variable- and fixed-pressure differential valves: a randomized, controlled study of programmable compared with conventional valves

Abstract

Thirty-two patients with normal-pressure hydrocephalus were managed using the lumboperitoneal (LP) shunt system in which the Codman Hakim programmable valve was utilized. The initial opening pressure was set at 100 mm H(2)O in three cases, 80 mm H(2)O in two, 70 mm H(2)O in three cases, 50 mm H(2)O in 23, and 30 mm H(2)O in one case (mean pressure 57.8 mm H(2)O). In 12 patients the valve pressure required reprogramming. The final valve pressure was 30 mm H(2)O in four cases, 50 mm H(2)O in 19, 70 mm H(2)O in three, 80 mm H(2)O in one, 100 mm H(2)O in two, 130 mm H(2)O in one, 140 mm H(2)O in one, and 170 mm H(2)O in one case (mean 62.5 mm H(2)O). Lumboperitoneal shuntography was performed in five patients by injection of contrast medium into the prechamber. In two patients a shunt obstruction developed between the valve and the lumbar catheter. Complications occurred in eight patients. Low-pressure symptoms such as headache and vomiting were observed in four patients but disappeared after increasing the valve pressure. One patient, whose shunt pressure was set at 50 mm H(2)O developed a slight asymptomatic subdural effusion, which resolved after increasing the valve pressure to 100 mm H(2)O. Convulsions developed in two aged patients but were easily controlled with anticonvulsant medication. Surgery-related wound infection was observed in one patient. The major advantage in the use of this valve is the ability to modify the pressure noninvasively. Another important advantage of the LP shunt system in which this valve is incorporated is the lower pressure of 30 mm H(2)O that can improve symptoms caused by underdrainage of cerebrospinal fluid.