Usefulness of CT and MR imaging in the diagnosis of acute Wernicke's encephalopathy.

Abstract

In this study, we analyzed the sensitivity and specificity of CT and MR imaging in the diagnosis of acute Wernicke's's encephalopathy. Three groups of subjects were studied: 15 patients with acute Wernicke's encephalopathy; 15 asymptomatic alcoholics; and 15 control subjects. Studies included clinical and laboratory examinations as well as CT and MR imaging of the brain. On CT scans, two patients with Wernicke's encephalopathy (13%) and no asymptomatic alcoholics showed low-density abnormalities in the paraventricular regions of the thalamus (p = .2414). On MR imaging, increased T2 signal of paraventricular regions of the thalamus was observed in seven patients (46%) with Wernicke's encephalopathy and one asymptomatic alcoholic (6%) (p < .01), and increased T2 signal of periaqueductal regions of the midbrain in six patients (40%) with Wernicke's encephalopathy and one asymptomatic alcoholic (6%) (p < .05). However, no significant differences were observed in the prevalence of mamillary body shrinkage between alcoholics with Wernicke's encephalopathy (six [40%]) and asymptomatic chronic alcoholics (four [27%]). The sensitivity of MR imaging in revealing evidence of this disease was 53% and the specificity, 93%. MR imaging is useful in confirming the diagnosis of acute Wernicke's encephalopathy. However, the absence of abnormalities on MR imaging does not exclude this diagnosis. CT proved not useful in the diagnosis of Wernicke's encephalopathy.