Object: Idiopathic normal pressure hydrocephalus (iNPH) is the only variant of dementia disorders possibly treatable by neurosurgical intervention. iNPH is a neurodegenerative condition clinically characterized by gait ataxia, urinary incontinence, and memory disturbance. We present one of the largest single-center studies, which was designed to prove efficacy of our low-pressure setting of gravitational valve at all three symptoms of iNPH and to find statistically significant cut-off time for best clinical improvement according to the duration of symptoms.
Methods: Sixty-one consecutive patients (mean age 74.9 ± 5.3) with iNPH were prospectively observed from the time of surgery with minimal 6 months follow-up. All patients underwent implantation of the same type of gravitational valve with the same setting-pro GAV with low opening pressure at 5 cm H2O-and were operated by the same team of 2 neurosurgeons. We statistically evaluated gait disturbance, psychological changes, and incontinence preoperatively and at 6 months after surgery and timing of the surgery according to the duration of symptoms and to the age.
Results: Paired t test showed a statistically significant increase in MMSE, a statistically significant decrease in 10-m walk test and 360 deg. rotation test (p < 0.0001). The correlation among the change of the MMSE, the walk test, and the rotation test, and the age and time of symptoms' duration was verified by Pearson's correlation coefficient. Pearson's correlation coefficient showed a medium strong correlation between the change of MMSE and the time of symptoms (r = - 0.580; p < 0.0001) and between the change of the number of steps and the time of symptoms (r = 0.517, p < 0.0001). There was a statistically significant weak (poor) correlation between the change of the walk test and the time of symptoms (r = 0.351, p = 0.006). All 3 ROC tests confirmed optimal cut-off for the best improvement of symptoms as 9.5 months of the symptom duration.
Conclusions: We proved statistical significant optimal cut-off for the best improvement of the symptoms as 9.5 months of the symptom duration. This study also confirmed successful treatment of iNPH with VP shunting using low pressure setting of gravitational valve with overall improvement in 75% and low over drainage complications in 5% We proved statistically significant increase in MMSE, decrease in 10 m walk test and number of steps test, p < 0.0001.
Keywords: Normal pressure hydrocephalus; VP shunt; prospective study.