Neurological outcome and frequency of overdrainage in normal pressure hydrocephalus directly correlates with implanted ventriculo-peritoneal shunt valve type.

BACKGROUND: The correlation between neurological outcome and frequency of overdrainage in the management of idiopathic normal pressure hydrocephalus (iNPH) using different ventriculoperitoneal shunt valve types is under investigation. Thus, we retrospectively compared one group of iNPH patients implanted with a programmable differential pressure valve (DPV) with another group treated by implantation of a DPV in combination with a flow-regulated anti-siphon device valve (ASD).

METHODS: A retrospective evaluation of clinical outcome and frequency of overdrainage of 40 consecutive iNPH patients following surgical management between 08/2010 and 08/2014 was performed. Within the first 2 years of the study, a programmable DPV was implanted in 21 patients (DPV-group, 14 males, 7 females, mean age 74.0 ± 6.0 years). In the following two years, a programmable DPV with a flow-regulated ASD was implanted in 19 patients (ASD- group, 12 males, 7 females, mean age 73.3 ± 4.2 years). Neurological outcome was assessed by employing the NPH recovery rate (comparison of pre- and postoperative Kiefer-score). Mean follow-up period was 12.4 ± 9.8 months.

RESULTS: In the DPV-group, three patients (14.3%) experienced severe overdrainage needing surgical intervention despite initial higher valve opening pressures (175 ± 11 mmH2 O), compared to one non surgical overdrainage in the ASD-group despite significant lower valve opening pressure (144 ± 22 mmH2 O). Excellent/good clinical outcome was found in 78.9% of the patients implanted with ASD compared to 44.4% of patients in the DPV group (p < 0.05).

CONCLUSION: Our results clearly demonstrate reduction in surgical over-drainage frequency and resulting complications in iNPH patients, with significantly better clinical outcome following insertion of a flow regulated ASD VP shunt compared to a DPV VP shunt, despite both systems comprised a programmable opening pressure mechanism.