Chronic idiopathic axonal polyneuropathy and successful aging of the peripheral nervous system in elderly people.

BACKGROUND Chronic idiopathic axonal polyneuropathy (CIAP) is a frequent neurologic disorder in elderly persons. In view of the aging population, it is important to know the long-term prognosis of CIAP. OBJECTIVES To determine if CIAP is influenced by the superposition of the effects of aging and to evaluate the severity of CIAP according to the disease duration. DESIGN Controlled cohort study. SETTING Outpatient clinic for neuromuscular diseases at the University Medical Center Utrecht, Utrecht, the Netherlands. PARTICIPANTS AND METHODS One hundred twenty-seven patients with CIAP and 108 age-matched control subjects were included. We defined CIAP on the basis of symmetrical distal sensory or sensorimotor symptoms and signs with evolution over at least 6 months, exclusion of causes by history taking, results of clinical and laboratory investigations, and electrophysiologic findings that agreed with the diagnosis of axonal polyneuropathy. RESULTS No important neurologic or electrophysiologic differences were found between patients with early-onset (before the age of 65 years) and late-onset (at or after the age of 65 years) CIAP, but patients with early-onset CIAP who had a short disease duration (<10 years) experienced more disability than patients with late-onset CIAP who had a similar disease duration. Old controls (age of 65 years or older) more often had symptoms, sensory signs in the legs, absent ankle jerks, and lower mean distal amplitudes of compound muscle action potentials and sensory nerve action potentials than young controls (aged <65 years). Absence of the sural nerve sensory nerve action potentials or presence of spontaneous muscle fiber activity in the anterior tibial muscle was common in patients with CIAP (51% and 60%, respectively), but exceptional (both 2%) in controls. CONCLUSIONS Neither aging of the peripheral nervous system nor disease duration affects CIAP to a considerable degree, but CIAP has a greater influence on the daily life of nonretired patients with early-onset CIAP. The diagnosis of axonal polyneuropathy is probably supported best by either the absence of the sural nerve sensory nerve action potentials or the presence of spontaneous muscle fiber activity in the anterior tibial muscle.