Neuronal intranuclear inclusion disease in a child: diagnosis by rectal biopsy.

A 15-year-old boy presented with progressive pyramidal and extrapyramidal signs, anterior horn cell dysfunction, and behavioral disturbances suggesting a diagnosis of neuronal intranuclear inclusion disease. The diagnosis was confirmed by examination of a rectal biopsy specimen that showed typical intranuclear inclusions in the neurons of the myenteric plexus. Diagnosis of neuronal intranuclear inclusion disease during life appears to be possible.