Acute Korsakoff's Psychosis and Disinhibition Syndrome Triggered by a Cortical Posterior Cerebral Artery Infarction (P07.182)

Objective: We report an unusual case of a dominant hemisphere, medial occipital and medial temporal cortical infarction precipitating Korsakoff9s psychosis and a disinhibition syndrome, reminiscent of a frontal lobe phenotype. A 66 year-old, right handed man, while driving to watch the Monaco Grand Prix, developed acute headache and amnesia accompanied by emotional lability, disinhibited behavior, inappropriate laughter and a right homonymous hemianopia. He had deficits in both episodic and working memory, a mild degree of executive dysfunction and a tendency to confabulate. There were no other focal neurological signs. He had been well previously, except for moderately high alcohol consumption. The cognitive deficits persisted 6 months after presentation, despite thiamine replacement. Acute imaging demonstrated restricted diffusion in the medial occipital and temporal lobes involving the fusiform and parahippocampal gyri with sparing of thalamus and other deeper structures. The rest of the parenchymal structures were normal and there was no evidence of small vessel ischaemia. An occlusion of P2 segment of the left posterior cerebral artery and its cortical branches was seen on vascular imaging. Cognitive deficits associated with posterior cerebral artery infarctions include a constellation of behavioural symptoms including transcortical aphasia, alexia without agraphia, Gerstmann syndrome, episodic memory deficit, visual agnosia, prosopagnosia and rarely acute delirium with/without aggressive behavior. Disinhibition syndromes of frontal phenotype have rarely been reported and may be associated with cortical deafferentation following a non-dominant thalamic lesion. This case demonstrates that behavioural deficits after cortical PCA territory infarction are not restricted to memory, language and vision and may occur without thalamic involvement. We hypothesise that the Korsakoff9s syndrome may have been the result of a functional disruption of mamillothalamic connections, as previously described, whereas the frontal behavioural features may be caused by a disruption of occipito temporal and occipito frontal connectivity. Disclosure: Dr. Agarwal has nothing to disclose. Dr. Manford has received personal compensation for activities with UCB Pharma and Eisai.