White matter diffusion is higher in Binswanger disease than in idiopathic normal pressure hydrocephalus.

Objectives: To explore diagnostic differences in periventricular white matter (PWM) and deep white matter (DWM) diffusion patterns in patients diagnosed with Binswanger disease (BD) and in patients diagnosed with probable idiopathic normal pressure hydrocephalus (INPH) using diffusion-weighted imaging (DWI).

Materials And Methods: Apparent diffusion coefficient (ADC) values were calculated in the PWM and DWM in patients with INPH (n = 14) and BD (n = 9) and in controls (n = 10) using an spin echo echo planar imaging single-shot diffusion sequence and region of interest (ROI) analysis.

Results: Patients with BD had higher ADC values than patients with INPH in the PWM and DWM in the frontal and occipital regions (P < 0.05) and higher values than controls in the frontal PWM and DWM (P < 0.01). After shunt surgery, ADC values were reduced in the frontal PWM in patients with INPH (P < 0.05).

Conclusions: Increased diffusion in the PWM and DWM in patients with BD may reflect irreversible breakdown of axonal integrity caused by the subcortical ischaemic vascular disease. By contrast, the normal white matter diffusion in patients with INPH indicates structurally intact axons, compatible with the reversibility of this disorder. DWI may be an important non-invasive diagnostic tool for differentiating between INPH and BD and identifying shunt responders and reversible brain damage in patients with INPH. However, the overlap between patients with INPH and BD in this study restricts the predictive value of the method.