Acute necrotizing encephalopathy presenting as a basal ganglia syndrome

Acute necrotizing encephalopathy is a relatively new disease. The characteristic clinical findings are of febrile illness followed by rapid deterioration in mental status and seizures. The hallmark of the disease is multifocal bilateral symmetric lesions affecting the thalamus, hypothalamus, brainstem tegmentum, cerebral white matter, and cerebellum. The etiology is unknown, but immune-mediated mechanism was suggested. We present a 12-year-old previously healthy girl who developed increased sleepiness progressing to stupor and coma. Magnetic resonance imaging (MRI) of the brain showed the characteristic findings previously described in acute necrotizing encephalopathy. Her mental status improved dramatically with steroid treatment, and the MRI findings resolved completely within 6 months. Following the acute illness, she developed a complex neuropsychiatric disorder consistent with basal ganglia syndrome.