Preoperative biomarkers in patients with idiopathic normal pressure hydrocephalus showing a favorable shunt surgery outcome.

INTRODUCTION: Idiopathic normal pressure hydrocephalus (INPH) is known to be a potentially treatable neurologic condition. The neurocognitive outcomes after surgery, however, have been variable. It is important to define preoperative characteristics of patients that predicts the shunting outcome. We aimed to compare baseline differences between shunt-responsive and unresponsive patients after 1year from surgery in order to identify preoperative predictors showing favorable clinical outcomes.

METHODS: Among 69 candidates, 31 patients with probable INPH completed the study. Patients were divided into two groups, responsive group (n=17) and unresponsive group (n=14), according to the clinical outcomes on INPH grading scale and modified Rankin score (MRS). Preoperative cerebrospinal (CSF) Aß, tau levels, MRI findings, and clinical characteristics were compared between the groups. Correlations between shunt responsiveness and preoperative characteristics were also assessed.

RESULTS: After 1year from shunt, gait problem was the most likely to improve. Shunt-responsive group showed lower CSF p-tau/Aß, fewer lacunes, and higher incidence of disproportionately enlarged subarachnoid space (DESH) signs on MRIs compared to those in unresponsive group. Favorable outcome was related with positive DESH sign and fewer lacunes.

CONCLUSIONS: Our results suggest that biomarkers representing non-INPH related pathology including Alzheimer's disease and small vessel disease might show less favorable clinical outcomes after 1year from surgery.