Valve Selection and Long-Term Outcomes in idiopathic Normal Pressure Hydrocephalus (iNPH): A Comparative Study of Programmable Shunt Technologies

BACKGROUND: Valve technology for ventriculoperitoneal shunting in idiopathic normal pressure hydrocephalus (iNPH) has evolved considerably, yet the comparative clinical impact of programmable flow-regulated valve (FV) versus gravitational valve (GV) remains unclear. We aimed to assess the long-term safety, effectiveness, and complication rates of these 2 valve types over a 3-year follow-up in a large cohort of iNPH patients. METHODS: We retrospectively analyzed 212 adults diagnosed with probable iNPH and treated with adjustable VPS using either FV (n = 136) or GV (n = 76). The primary outcome was clinical improvement based on the iNPH grading scale. Secondary outcomes included postoperative complications, valve dysfunction, number of setting adjustments, changes in differential pressure unit values, and the influence of preoperative factors on outcomes. RESULTS: Significant clinical improvement was observed in both groups (P < 0.001), with no significant difference in iNPH grading scale scores between valves (P = 0.124). However, patients treated with FV had a significantly higher rate of postoperative complications (P = 0.019), particularly valve dysfunction (P = 0.029). Postoperative pressure adjustments led to greater differential pressure unit reductions in the GV group (P < 0.05), though the number of adjustments was similar. Preoperative factors (age, sex, and initial pressure) were not associated with outcome differences. CONCLUSIONS: In our institutional experience, both FV and GV were effective in the treatment of iNPH, with comparable clinical outcomes. GV were associated with fewer late complications, suggesting a potentially more favorable long-term safety profile. However, given the observational nature of this study, causal inference is limited, and prospective studies are required to validate these findings.