Infantile neuroaxonal dystrophy: axonal changes in biopsied muscle tissue.

Dystrophic axons were found in the biopsied muscle tissue of a 17-month-old hypotonic infant after confirmation of a diagnosis of infantile neuroaxonal dystrophy (INAD) by subsequent peripheral nerve biopsy. He manifested gradual deterioration and had brief tonic seizures. The sural nerve biopsy, performed at age 42 months, confirmed INAD. Intensive ultrastructural investigation of the preceding muscle biopsy specimens demonstrated infrequent but definite findings of axonal degeneration in the musculature. Ultrastructural investigation of muscle biopsy should include a careful search for neural tissue because in INAD axonal changes occur primarily in the presynaptic region.