Imaging Biomarkers in Idiopathic Normal Pressure Hydrocephalus: Associations with Symptoms and 1-Year Treatment Outcomes.

BACKGROUND AND PURPOSE:Idiopathic normal pressure hydrocephalus (iNPH) is a neurological disorder that primarily affects older adults and is typically characterized clinically by a triad of symptoms: gait disturbance, urinary urgency or incontinence, and cognitive decline. The relationship between clinical presentation and iNPH imaging biomarkers remains unclear, as does the ability of these markers to predict outcomes following cerebrospinal fluid diversion. Additionally, the association between fecal incontinence (FI) and iNPH, as well as the relationship between FI and iNPH imaging biomarkers, is poorly understood. METHODS:A retrospective review was conducted on 125 consecutive iNPH patients treated by a single surgeon at Brigham and Women's Hospital between 2015 and 2023. Patients were treated with the placement of a ventriculoperitoneal (VP) shunt. Patient demographics, symptoms, and clinical improvement were recorded at 3 and 12 months post-shunt placement. Imaging biomarkers, including Evans Index (EI), callosal angle (CA), anteroposterior diameter of the lateral ventricle index (ALVI), and disproportionately enlarged subarachnoid space hydrocephalus score, were measured using preoperative imaging. RESULTS:Of 125 patients (mean age 74.8 years, 71 males), 124 presented with gait disturbance, 113 with urinary dysfunction, and 111 with cognitive decline. FI was present in 24 patients. Patients with preoperative FI had higher EI and ALVI. Patients with improved FI at 3-month follow-up had larger CA. Patients with improved gait at 12-month follow-up had smaller EI and ALVI scores. Patients with preoperative urinary symptoms had a higher EI. CONCLUSIONS:Imaging biomarkers can have both diagnostic utility and predictive potential for outcomes related to specific symptoms following CSF diversion with VP shunts.