Thyroid crisis mimicking clinically mild encephalitis/encephalopathy with a reversible splenial lesion: A pediatric...

Reversible lesions in the splenium of the corpus callosum (SCC) with viral infections are associated mainly with clinically mild encephalitis/encephalopathy with a reversible splenial lesion (MERS). We report a pediatric patient in thyroid crisis with reversible SCC lesions.

We diagnosed a 9-year-old girl with thyroid crisis. She had presented with fever, tachycardia, and impaired consciousness. Magnetic resonance imaging revealed hyperintense signals in the splenium and genu of the corpus callosum and a white matter lesion of the left hemisphere in diffusion-weighted imaging. The initial, tentative diagnosis was clinically mild encephalitis/encephalopathy with a reversible splenial lesion (MERS). We initiated intravenous methylprednisolone pulse therapy; thereafter, her level of consciousness rapidly improved. On admission, thyroid function studies revealed elevation of free thyroxine and a low level of thyroid stimulating hormone with thyroid-related autoantibodies. She was begun on thiamazole and was discharged without neurological sequelae.

Thyroid crisis is similar to acute encephalitis or encephalopathy associated with viral infection, especially with MERS, because the clinical and radiological features resemble those of thyroid crisis; therefore, thyroid diseases should be considered as a possible cause of reversible lesions in the splenium of the corpus callosum.