Expectations of cerebrospinal fluid shunt treatment outcome in idiopathic normal pressure hydrocephalus: a combined cross-sectional and prospective cohort study.

INTRODUCTION: Idiopathic normal pressure hydrocephalus (iNPH) is increasingly relevant in the aging population. Despite improved diagnostic criteria, postoperative outcome remains variable and difficult to predict. Preoperative expectations may substantially influence perceived treatment success, and caregivers often play a key role in the decision-making process. RESEARCH QUESTION: This study evaluated whether physicians assess postoperative outcomes more accurately than primary caregivers. MATERIAL AND METHODS: This single-centre study combined a prospective pre-post interventional cohort design with a cross-sectional component. Patients with iNPH undergoing first-time ventriculoperitoneal shunt surgery were included. Symptom severity was assessed preoperatively and at follow-up using standardized grading scales. Primary caregivers (PCGs), neurosurgical residents, and board-certified neurosurgeons independently predicted postoperative outcomes, which were subsequently compared with observed treatment results. RESULTS: Forty-one patients were screened between January 2022 and June 2025. The study cohort had a mean age of 74.1 years (SD 7.3), 57% male, mean symptom duration 23.9 months (SD 14.1) and a mean Charlson comorbidity index of 4.1 (SD 1.3). At a median follow-up of 48 days (range 36-118) after ventriculoperitoneal shunt surgery, mean symptom improvement was Δ 2.2 points (95% CI 1.6-2.7; p < 0.001), with the greatest improvement observed in gait disturbance and urinary incontinence. Revision surgery was required in 17% of patients. Correlation between predicted and observed outcome was strongest among neurosurgical specialists (r = 0.79), followed by residents (r = 0.74), while PCGs demonstrated only moderate agreement (r = 0.56). DISCUSSION AND CONCLUSION: Our study supports the efficacy of CSF shunt surgery in iNPH and demonstrates that neurosurgical expertise aligns more closely with actual postoperative outcome than the expectations of PCGs. Structured preoperative counselling may help improve expectation management and reduce discrepancies between anticipated and observed treatment benefit.