Substantia Nigra Involvement: An Unusual Finding in Heat Stroke.

A 20-year-old man without medical history but with septic shock developed neuroleptic malignant syndrome after being treated with loxapine for delirium. He had been admitted to the intensive care unit 2 weeks earlier for septic shock. An MRI done 27 days after admission for persistent unresponsiveness despite weaning of sedation revealed symmetric and bilateral involvement of the substantia nigra, globi pallidi, and hippocampi (figure). The radiologic differential diagnosis includes carbon monoxide poisoning, viral (West Nile, Saint Louis) encephalitides,1 and heatstroke.2 Heatstroke is usually associated with symmetric lesions in the cerebellum (dentate nuclei, cerebellar peduncles, cerebellar cortex), cerebral cortex, lenticular nuclei, thalami, and hippocampi.2