Fractional Anisotropy Predicts Shunt Responsiveness in Normal Pressure Hydrocephalus: A Diffusion Tensor Imaging-Based Clinical Study.

Abstract

Normal pressure hydrocephalus (NPH) is a treatable form of dementia that can mimic other neurodegenerative disorders. Diffusion tensor imaging (DTI) has emerged as a promising tool to assess white matter alterations in NPH. This study investigated the diagnostic role of fractional anisotropy (FA) values and their relationship with clinical outcome. Preoperative magnetic resonance imaging with diffusion tensor imaging sequences and cerebrospinal fluid lumbar puncture were performed in 19 patients with probable NPH. Responders were treated with shunt surgery. FA maps were generated, and regions of interest were placed in the periventricular white matter, corpus callosum (genu and splenium), and cerebral peduncles. Of 19 patients, 14 responded to lumbar puncture, and 12 underwent shunting. FA values were significantly lower in nonresponders. Among responders, hydrocephalus with triventricular-shaped ventricular enlargement showed higher FA values than the communicating type. The corpus callosum demonstrated the lowest FA values among responders, whereas triventricular enlargement correlated with better postoperative outcomes. FA represents a reliable marker of white matter integrity in NPH. Higher values, particularly in triventricular enlargement, were associated with favorable surgical outcomes. Incorporating FA analysis into routine magnetic resonance imaging protocols could improve diagnostic accuracy and guide treatment planning in patients with NPH.