Claude syndrome unveiled in a case of thalamic-midbrain infarction

Claude syndrome is a rare mesencephalic syndrome characterized by third-nerve palsy and contralateral cerebellar symptoms. We present the case of a 52-year-old man with sudden diplopia, right-sided ptosis, drowsiness, and gait instability. Examination revealed anisocoria with a mydriatic right pupil that was non-reactive to light stimuli, left-sided dysdiadochokinesia and dysmetria, and restricted eye movements with impaired intorsion of the right eye, suggesting possible fourth cranial nerve palsy. Magnetic resonance imaging revealed an acute stroke in the right thalamus and ipsilateral midbrain. This is among the first cases in South America to describe the clinical-radiological correlation of a thalamic-midbrain stroke with Claude syndrome.