[An unusual case of peroneal muscular atrophy with rigidity, polyneuropathy, mental retardation, and diabetes mellitus developed in familial Parkinson's disease]

Abstract

Familial polyneuropathy mimicking Charcot-Marie-Tooth disease associated with parkinsonism and dementia has been reported in literature. We present with similar peroneal muscular atrophy, rigidity of upper extremities, severe peripheral neuropathy, mental retardation and diabetes mellitus. The patient, a 42-year-old man, developed progressive muscle weakness, mental retardation and difficulty in walking in childhood. Because of his pes cavus, he had three surgical operations. At the age of 20 years, he developed distal muscular atrophy of lower limbs. On neurological examination, all limb muscles were atrophic, especially in lower one third of the thigh. Rigidity was noted in the upper extremities. Deep tendon reflexes were hyperactive in the upper and diminished in the lower extremities. Muscle CT revealed low density areas in all the muscles examined, specially in the gastrocnemius and anterior tibial muscles. Needle EMG showed neurogenic change in the forearm, but not in the lower limbs, because of no voluntary contractions obtained due to severe muscle atrophy. Marked slowing of motor conduction velocity with muscle action potentials of very low amplitude was found in the ulnar nerve. Muscle action potentials were not elicited in the median and peroneal nerves. Sensory action potentials were not elicited from the median, ulnar and sural nerves. These findings were consistent with axonal polyneuropathy. In the sural nerve biopsy, the densities of myelinated fibers were markedly decreased. However, unmyelinated fiber densities were relatively preserved. Onion bulb formation was not found. This patient may be classified into hereditary motor-sensory neuropathy (HMSN) type II based on the clinical findings delayed nerve conduction velocities and axonal degeneration in the sural nerve. He has also diabetes mellitus. CT of the brain revealed nothing particular. He is one of members with familial Parkinson's disease (PD) developed in Sagamihara. Peroneal muscular atrophies are not necessarily associated with PD, though it has been occasionally complicated in various neuro-degenerative diseases including parkinsonism. We are now following the patient to detect the symptom of Parkinson's disease for early treatment.