“Vascular” Korsakoff Syndrome With Bilaterally Damaged Mammillothalamic Tracts: Insights Into the Pathogenesis of “Acute” Korsakoff Syndrome As Acute-Onset Irreversible Anterograde Amnesia

The structural pathogenesis of Wernicke-Korsakoff syndrome remains debatable. Wernicke encephalopathy is acute and often reversible whereas Korsakoff syndrome (KS) is chronic and may be irreversible. The cognitive deficits observed in KS are considered to be primarily due to damage to the anterior nucleus of the thalamus, mammillary bodies, and corpus callosum. We present an extremely rare case of non-alcoholic “vascular” KS (vKS) as acute-onset amnesia. A 97-year-old man living alone was brought to our hospital, complaining of sudden-onset behavioral changes with amnesia. Diffusion-weighted images (DWIs) showed fresh cerebral infarction in the right thalamus involving the right mammillothalamic tract (MTT). T2*-weighted images (T2*WIs), in addition, revealed a microbleed scar over the left MTT. This case supports the hypothesis that bilateral MTT dysfunction can lead to KS. Furthermore, in collaboration with a prior report about non-alcoholic “acute” KS due to cerebral infarction, this case supports the existence of vascular KS as an acute-onset amnestic syndrome, as well as insight into the pathogenesis of KS as an irreversible amnestic syndrome.