Long-term clinical outcome after shunt surgery in idiopathic normal pressure hydrocephalus: a 30-year single-center experience on 307 patients

Background: Idiopathic normal pressure hydrocephalus (iNPH) is an underdiagnosed yet treatable neurological disorder. Although cerebrospinal fluid (CSF) shunting is the standard treatment, the durability of long-term clinical benefit and predictors of sustained postoperative improvement remain incompletely understood. We therefore evaluated long-term clinical outcomes, symptom durability, and complications following shunt surgery in a large consecutive single-center cohort. Methods: We retrospectively analyzed 307 consecutive patients who underwent ventriculoatrial or ventriculoperitoneal shunt implantation after demonstrating clinical improvement during preoperative CSF diversion testing. Clinical outcomes were assessed using hospital records and structured telephone interviews. The mean follow-up duration was 59.9 months. Results: The mean age at surgery was 70.1 ± 9.6 years. Eighteen patients were lost to follow-up. Of the remaining 289 patients, 253 (87.5%) achieved postoperative clinical improvement. Improvement was greatest for gait disturbance (80.6%), followed by cognitive impairment (46.9%) and urinary incontinence (40.8%); 25.6% of patients improved in all three components of Hakim’s triad. Kaplan–Meier analysis estimated a median duration of sustained symptom improvement of 149 months (12.4 years; 95% CI, 96 months to not estimable). The estimated probabilities of sustained improvement were 68.6% (95% CI, 62.0–74.4%) at 5 years and 56.3% (95% CI, 48.1–63.7%) at 10 years. Longer preoperative symptom duration independently predicted shorter postoperative benefit (adjusted HR, 1.16; 95% CI, 1.02–1.32; P = 0.024), whereas age, shunt type, and use of an anti-siphon device were not independently associated with outcome duration. The overall complication rate was 17.3%, the shunt infection rate was 3.3%, and 14.9% of patients required revision surgery. Conclusions: In appropriately selected patients with iNPH, CSF shunt surgery provides durable long-term clinical benefit, particularly for gait disturbance, with improvement persisting for more than two decades in some patients. Although complications and revision procedures remain common, their frequency is comparable to contemporary iNPH series, supporting shunt surgery as an effective long-term treatment option.