peroneal muscular atrophy, a condition characterized by symmetric weakening or atrophy of the foot and ankle muscles and the development of hammertoes. This disease is a dominantly inherited condition that occurs in a hypertrophic neuropathy form or in a neuronal form. The hypertrophic neuropathy form results in demyelination of nerve fibers and characteristic onion bulb formations. Affected individuals usually have high plantar arches and an awkward gait caused by weak ankle muscles. In the neuronal form this condition usually starts in the second decade of life and causes muscle weaknesses similar to those associated with the hypertrophic neuronal form. Both forms of the disease may also involve mild sensory loss in the lower limbs. Affected individuals may be helped by corrective surgery and leg braces that stabilize weak ankle joints.
