Treatment of adult-onset obstructive hydrocephalus with low- or medium-pressure CSF shunts.

Nine patients with nontumor obstructive hydrocephalus of adult onset underwent 13 shunt placements; low-pressure valves (closing pressure, 20 to 50 mm H2O) were employed for 5 placements, and medium-pressure valves (closing pressure, 55 to 85 (mm H2O) were employed for 8 placements. The use of a low-pressure valve was followed by objective improvement in all five instances, whereas the use of a medium-pressure valve was followed by objective improvement in only two of eight instances (p = 0.021). The treatment of adult-onset obstructive hydrocephalus may require low-pressure shunts because of the high outflow resistance that characterizes this condition.