Operational criteria for the classification of chronic alcoholics: identification of Wernicke's encephalopathy.
OBJECTIVES: To establish better operational criteria for the diagnosis of Wernicke's encephalopathy. Current criteria for diagnosing Wernicke's encephalopathy require the presence of three clinical signs (oculomotor abnormalities, cerebellar dysfunction, and an altered mental state), although it has often been reported that most patients do not fulfil all these criteria. METHODS: The clinical histories of 28 alcoholics with neurological and neuropsychological assessments and definitive neuropathological diagnoses were examined to determine clinical signs for use in a screening schedule. Operational criteria were then proposed for differentiating patients with Wernicke's encephalopathy alone or in combination with Korsakoff's psychosis or hepatic encephalopathy. The new criteria for Wernicke's encephalopathy require two of the following four signs; (1) dietary deficiencies, (2) oculomotor abnormalities, (3) cerebellar dysfunction, and (4) either an altered mental state or mild memory impairment. Reproducibility and validity testing of these criteria were performed on 106 alcoholics screened from a large necropsy sample. RESULTS: Despite rater variability with regard to specific symptoms, within and between rater reliability for diagnostic classification using the criteria retrospectively on patient records was 100% for three independent raters. Validity testing showed that Wernicke's encephalopathy was underrecognized only when occurring with hepatic encephalopathy (50% sensitivity). CONCLUSIONS: By contrast with current criteria, the proposed operational criteria show that the antemortem identification of Wernicke's encephalopathy can be achieved with a high degree of specificity.