Diffusion-weighted MR in reversible Wernicke encephalopathy

Diffusion-weighted images (DWI) of a patient with Wernicke encephalopathy w ere obtained during routine MR examination. Mammillary bodies were hyperint ense on T2-weighted and enhanced on T1-weighted images; on DWI, a mild hype rintensity was noticed. Calculation of the apparent diffusion coefficient ( ADC) demonstrated an increased diffusion on the affected regions; the hyper intensity on DWI was probably due to a "T2-shine-through" effect. These fin dings are consistent with the presence of extracellular oedema, without sig nificant neuronal damage. The patient recovered promptly after thiamine adm inistration, and MR alterations disappeared. The favourable evolution indic ates that no relevant neuronal death occurred. This is consistent with DWI findings. DWI are more sensitive than ordinary T1- and T2-weighted images t o neuronal irreversible damage, and may differentiate between neuronal necr osis and extracellular oedema in various brain pathologies. The demonstrati on of a limited neuronal damage may represent a favourable prognostic facto r in patients with WE.