The thalamus and midbrain in Reye syndrome.

A previously healthy 5 1/2-year-old male had Reye syndrome. He presented in coma with apnea 1 week after a viral infection and following 2 days of vomiting and progressive obtundation. He was in coma with dystonic posturing and intact brainstem function. Laboratory evaluation revealed initial hypoglycemia, and markedly elevated liver enzymes, prolonged clotting times, and elevated ammonia levels. No underlying metabolic disorder was present, and the patient completely recovered. On a modified diffusion-weighted image magnetic resonance imaging scan, restriction of diffusion in the thalamus and midbrain was observed. While abnormalities of the thalamus and midbrain have previously been reported, this is the first report of diffusion-weighted imaging indicating early impairment of water diffusion, a finding more commonly observed with stroke.