Voxel-based mapping of brain hypometabolism in permanent amnesia with PET

In this study, we used voxel-based mapping methods to compare the resting c erebral metabolic rate of glucose (CMRglc) measured with PET in five patien ts with permanent amnesia (three with chronic Wernicke-Korsakoff and two wi th postanoxia syndrome) to that of nine healthy age-matched subjects, We as sessed (i) a group pattern of relative hypometabolism; and (ii) the consist ency of this group pattern, if any, in individual subjects, according to et iology, The results from the group analysis documented that permanent amnes ia is associated with hypometabolism in the thalamus, posterior cingulate c ortex, and mesial prefrontal cortex (near the anterior cingulate gyrus), bi laterally, as well as in the left supramarginal and middle temporal gyri, T he individual analysis showed that this group pattern was found in essentia lly each patient, regardless of the cause of amnesia. Thus, permanent amnes ia is subtended by dysfunction in structures belonging to Papez/limbic circ uits as well as in left-hemisphere areas typically concerned with verbal fu nctions, probably through a mechanism of thalamocortical disconnection and possibly involved in retrograde amnesia. The use of a voxel-based method al lowed us to map a common network of synaptic dysfunction in a neuropsycholo gical syndrome regardless of etiology, Our results indicate that this shoul d be a powerful method in functional neuropsychology. (C) 2001 Academic Pre ss.