Connectional diaschisis associated with acute psychosis after right thalamic stroke: A case report.

We report a rare case of sudden-onset psychiatric syndrome following a right thalamic ischemic event. Potential mechanisms involving both structural and functional thalamic disconnection are considered. A 51-year-old man was admitted to the Neurology Unit at the Azienda Ospedale-Università of Padova with sudden-onset confusion and amnesia, accompanied by visual and auditory hallucinations and emotional lability. An initial head CT scan showed no evidence of stroke; however, a follow-up MRI revealed a recent ischemic lesion in the right mediodorsal nucleus (MDN) of the thalamus. A brain [18F]FDG PET-MRI scan identified a small hypometabolic area in the right anterolateral frontal cortex. The prefrontal cortex was structurally and functionally disconnected by the thalamic lesion. Neuropsychological testing revealed deficits of executive functions, particularly in planning and abstract reasoning, as well as impairments in long-term verbal and visuospatial memory and deficits in the visuoperceptual domain. The patient was treated with risperidone and venlafaxine, leading to an improvement in psychotic symptoms at both discharge and follow-up. Understanding these network-level disruptions may offer valuable insights into therapeutic approaches and prognostic evaluation.