Optimizing Initial Shunt Pressure in Idiopathic Normal Pressure Hydrocephalus

Although setting a low initial opening pressure in a programmable valve with a gravitational unit seems to be the gold standard treatment for idiopathic normal pressure hydrocephalus (iNPH) patients, there are no studies in the literature describing the optimal initial low-pressure setting. Here, we sought to describe the optimal initial opening pressure setting for iNPH in terms of both efficacy and safety.

Patients with probable iNPH underwent shunt surgery with a programmable valve with a gravitational unit, using either an opening pressure of 3 or 6.5 cmH₂O, and were prospectively followed for 1 year. Clinical improvement and complications were recorded.

Nineteen patients with an opening pressure of 3 cmH₂O and 37 patients with an opening pressure of 6.5 cmH₂O were analyzed. There was no significant difference between the groups. A significant improvement in the iNPH Japanese scale score was observed 1 year following shunt placement in both the 3.0 cmH₂O (p = 0.001) and 6.5 cmH₂O groups (p < 0.001), but there was no statistical difference between groups (p = 0.708). Two patients (10.5%) had subdural effusions that required surgery in the 3 cmH₂O group and none in the 6.5 cmH₂O group (p = 0.043).

Patients with iNPH treated with a programmable valve with an initial opening pressure of 6.5 cmH₂O showed the same clinical improvement as those treated with an initial opening pressure of 3 cmH₂O but with fewer overdrainage complications.