Predictors of shunt responsiveness and outcomes in idiopathic normal pressure hydrocephalus: a retrospective cohort study

Abstract Background Idiopathic Normal Pressure Hydrocephalus (iNPH) remains a challenging clinical diagnosis with variable treatment response. Objectives This study aimed to identify clinical, imaging, and CSF biomarkers associated with favorable outcomes following shunt placement. Methods All patients evaluated for iNPH at the Tel-Aviv Medical Center (TLVMC) between 2020 and 2022 were included. Participants underwent clinical, cognitive, and imaging assessments, high-volume lumbar puncture (LP). LP responders were referred for shunt placement, and outcomes assessed at one year. Results 183 patients were evaluated; 167 met criteria for suspected iNPH and underwent LP. Sixty-two (37%) patients showed improvement after CSF drainage and were referred for shunting. Of these, 38 (61%) underwent shunt placement. Gait disturbance was the most common presenting symptom (68%), and more frequent in LP responders ( p = 0.007), whereas cognitive symptoms were more common among non-responders (29.5% vs. 10%). LP responders had lower CSF total tau (t-tau) (222.6 ± 99.1 vs. 256 ± 107.1, p = 0.045) and protein (41.1 ± 17.1 vs. 49.1 ± 25.7, p = 0.032) and were more likely to exhibit a disproportionately enlarged subarachnoid-space hydrocephalus (DESH) pattern (73% vs. 46%, p < 0.001). Among the 38 shunted patients, 21 (55%) had a favourable outcome at one year, which was associated with lower t-tau ( p = 0.056) and more frequent DESH ( p = 0.026). Conclusions Over half of patients who underwent shunt placement experienced favorable clinical outcomes at one year. Lower t-tau and DESH pattern were associated with better outcomes.