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.
Reis et al. (Thu,) studied this question.