Wernicke-Korsakoff syndrome in alcoholic and nonalcoholic patients: clinical and neuropsychological presentation

© 2015 Dr. Simon Joseph ScalzoBackground. Wernicke-Korsakoff syndrome (WKS) is a relatively common neurological disorder due to thiamine deficiency. Approximately 80% of cases with WKS pathology are not diagnosed during life. Untimely diagnosis is associated with poorer patient outcome. WKS most frequently occurs in combination with alcohol use disorder. The relative roles of thiamine deficiency and excessive alcohol consumption in cognitive dysfunction remain unclear. Previous research of WKS in people without alcohol use disorder is limited. Aims. To enhance understanding of nonalcohol-related WKS and WKS in general by demonstrating the presence and variability of the major acute neurological and chronic cognitive symptoms of WKS in cases whether or not related to alcohol. Better understanding and enhanced awareness of the poorly recognised aspects of WKS has clinical and research implications, including for diagnosis and patient management. Methods. The thesis comprises three studies. STUDY ONE was a systematic review of case reports of Wernicke's encephalopathy and WKS in patients without history of alcohol use disorder. Eligible cases totalled 574. Publication dates ranged from 1867 to 2011. Comparisons of patient background and clinical presentation were made with published data on samples comprising, almost exclusively, alcohol-related WKS. STUDY TWO was an analysis of the neuropsychological profiles of nine cases with WKS and alcohol use disorder. One case was recruited prospectively and eight cases were chosen retrospectively on a consecutive basis from a database of patient records. In STUDY THREE, the psychometric test scores of 12 published cases with WKS not related to alcohol were evaluated within the frameworks of the Wechsler and Cattell-Horn-Carroll models of intelligence. Results. STUDY ONE revealed important similarities in clinical presentation between WKS whether or not related to alcohol use disorder. For example, persisting memory impairment was frequently reported in both groups. Several group differences were also identified, such as longer duration of precipitating illness for cases with alcohol-related WKS. STUDY TWO highlighted the variability in neuropsychological profiles in clinical cases with WKS. In contrast to the conventional view of Korsakoff's syndrome, Study Two revealed that a large discrepancy between memory and general intellectual function has poor sensitivity to the detection of chronic WKS. General intellectual function was not always preserved relative to memory function. STUDY THREE found deficits on objective measures of multiple cognitive abilities in published cases of WKS. No case in this small series had a history of alcohol use disorder, therefore the variable range of cognitive deficits could not be attributed to any additional effect of excessive alcohol consumption on the brain. As hypothesised, cognitive profiles included cases with severe, selective memory impairment as well as cases with more generalised cognitive impairment. Conclusions. Consistent with the hypotheses of the thesis, the two primary conclusions were (1) alcohol is not required for any element of WKS, including chronic cognitive impairment and Korsakoff's syndrome, and (2) the range and severity of cognitive deficits in chronic WKS are more variable than is typically appreciated