Treatment of normal pressure hydrocephalus with low versus medium pressure cerebrospinal fluid shunts.

In a retrospective study, 39 patients received a low pressure (20 to 50 mm H2O) shunt and 33 received a medium pressure (55 to 85 mm H2O) shunt for the treatment of normal pressure hydrocephalus (NPH). Pre- and postoperative computed tomographic scans were obtained in 32 patients, permitting us to determine the influence of shunt pressure on ventricular size. A reduction in 3rd ventricle width was found to correlate with clinical improvement and was observed more frequently after the placement of a low pressure shunt than after the placement of a medium pressure shunt. When results were evaluated in patients who did not have advanced NPH or develop postoperative complications, gait was markedly improved in 60% of those receiving a low pressure shunt as opposed to 23% of those receiving a medium pressure shunt (P less than 0.05).