Optimizing Initial Shunt Pressure in Idiopathic Normal Pressure Hydrocephalus.

BACKGROUND 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 idiopathic normal pressure hydrocephalus in terms of both efficacy and safety.

MATERIAL AND METHODS Patients with probable iNPH underwent shunt surgery with a programmable valve with a gravitational unit, using either an opening pressure of 3 cm H2O or 6.5 cm H2O, and were prospectively followed for one year. Clinical improvement and complications were recorded.

RESULTS 19 patients with an opening pressure of 3 cm H2O and 37 patients with an opening pressure of 6.5 cm H2O were analyzed. There was no significant difference between the groups. A significant improvement in the iNPH Japanese scale score was observed one 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). 2 patients (10.5%) had subdural effusions that required surgery in the 3 cmH2O group and none in the 6.5 cm H2O group (p= 0.043).

CONCLUSION Patients with iNPH treated with a programmable valve with an initial opening pressure of 6.5 cm H2O showed the same clinical improvement as those treated with an initial opening pressure of 3 cm H2O, but with fewer overdrainage complications.