Diffusion tensor imaging of idiopathic normal-pressure hydrocephalus and the cerebrospinal fluid tap test

Abstract

We evaluated relationships between diffusion tensor imaging (DTI) findings and clinical profiles in idiopathic normal-pressure hydrocephalus (INPH) patients, along with differences in DTI parameters between cerebrospinal fluid tap test (CSFTT) responders and non-responders. Fifty-four INPH patients constituted the final group for analysis. Fractional anisotropy (FA), axial diffusivity, radial diffusivity, and mean diffusivity were assessed using atlas-based tract-mapping methods on 20 different fiber tracts. Uncorrected results revealed that CSFTT non-responders, when compared to responders, exhibited lower FA in the left anterior thalamic radiation (ATR), left cingulum-hippocampus (CgH), and left inferior fronto-occipital fasciculus (IFO) and higher axial diffusivity, radial diffusivity, and mean diffusivity in the left CgH and left inferior longitudinal fasciculus (ILF). FA values in the ATR (bilateral), corticospinal tract (right), IFO (bilateral), and ILF (bilateral) were negatively correlated with Unified Parkinson's Disease Rating Scale motor scores. In the right CgH, FA values showed significant positive correlations with Korean-Mini Mental State Examination scores and negative correlations with Clinical Dementia Rating Scale scores. Our findings may suggest a possibility for considering microstructural changes of white matter in patients with ventriculomegaly as potential imaging markers for the prediction of CSFTT responders. Unique patterns of white matter microstructural changes, as measured using DTI, might underlie impairments in distinct symptom domains in patients with INPH.

Keywords: CSF tap test; Diffusion tensor imaging; Normal-pressure hydrocephalus.