Idiopathic Normal Pressure Hydrocephalus and Shunt Complications per Valve Type: A Meta-Analysis of Proportions

BACKGROUND: Idiopathic normal pressure hydrocephalus is classically recognized by the triad of gait disturbance, cognitive dysfunction, and urinary incontinence. Since ventricular shunting may be affected by valve type, we conducted a meta-analysis to assess the relationship between valve characteristics and outcomes. METHODS: English language studies that reported valve types, outcomes, and associated complications were included. Data were extracted and analyzed using R, version 4.3.2. RESULTS: Thirteen studies were included. With gravitational valves, meta- analysis yielded 0.04 [0.02, 0.07] for subdural effusions (SDEs), 0.00 [0.00, 0.00] for surgical SDEs, 0.06 [0.03, 0.09] for proximal revisions, and 0.06 [0.03, 0.09] for distal. With differential pressure valves (DPVs) with antisiphon control, meta- analysis showed an incidence of 0.10 [0.07, 0.13] for SDEs, 0.02 [0.01, 0.04] for surgical SDEs, 0.03 [0.01, 0.05] for proximal and 0.04 [0.02, 0.07] for distal revisions. With DPVs without antisiphon control, there was an incidence of 0.17 [0.11, 0.23] for SDEs, 0.11 [0.06, 0.19] for surgical SDEs, 0.00 [0.00, 0.02] for proximal shunt revisions, and 0.05 [0.02, 0.10] for distal shunt revisions. With flow regulated valves, there was an incidence of 0.05 [0.01, 0.12] for SDEs, 0.01 [0.00, 0.05] for surgical SDEs, 0.06 [0.02, 0.11] for proximal revisions, and 0.01 [0.00, 0.05] for distal. CONCLUSIONS: Gravitational valves and NPVs are associated with fewer SDEs while DPVs with and without ASDs are associated with more while there were no differences in proximal or distal revisions.