Background Two cases of bilateral thalamic infarction are discussed. Bothpatients presented similarly with decreased consciousnessand visual disturbance within a 5-month period of a strokerotation. Summary Although infarcts restricted to the thalamus were reportedfor the first time more than 100 years ago by Dejerine andRoussy, they remain an uncommon presentation of strokeand account for only 11% of all vertebrobasilar infarcts.Bilateral thalamic infarction is rare, accounting for only 0.6%of all cerebral infarctions, and results from a combination ofpredisposing factors and anatomic variations. The patternof bilateral thalamic stroke is usually seen after paramedianartery infarct of the so-called artery of Percheron (AOP); thisis a rare anatomical variant of thalamic blood supply arisingfrom the posterior cerebral artery, providing bilateral arterialsupply to the paramedian thalami and the rostral midbrain.AOP occlusion accounts for 4–18% of all thalamic strokesand 0.1–2% of all ischaemic strokes. The thalamus is involved in several functions of the bodyincluding regulation of sleep and wakefulness, motor control,receiving auditory, somatosensory and visual sensory signals,and relaying sensory signals to the cerebral cortex. Thalamocortico-thalamiccircuits are involved in consciousness, arousal,level of awareness, and activity. Patients may take days to weeksto recover from a thalamic infarct and seem to be in a sleep-likestate. In these cases, both patients were noted to be sleeping forthe entire day and, as somnolence cleared, vertical gaze palsybecame apparent.
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