Subclinical peripheral nerve involvement in patients with rheumatoid arthritis.

OBJECTIVE: Clinical involvement of the peripheral nervous system is uncommon in rheumatoid arthritis (RA); the most common disorders are multiple mononeuritis, sensorimotor neuropathy, and entrapment neuropathy. This study was undertaken to investigate the occurrence of electrophysiologically evident peripheral nerve involvement in RA patients without a clinical history of peripheral nerve involvement. METHODS: Forty RA patients were examined neurologically and electrophysiologically, and sural nerve biopsies were performed in 4. RESULTS: No patient reported symptoms or signs of peripheral nerve involvement. Twenty-six patients (65%) exhibited electrophysiologic findings consistent with a sensorimotor neuropathy (in 2 of them a carpal tunnel syndrome was also present), while 3 patients showed isolated carpal tunnel syndrome. There was a moderate loss of myelinated fibers in 3 of the 4 nerve biopsy samples, and all showed an increased number of endo- and perineurial vessels and some signs of axonal degeneration. CONCLUSION: Patients with RA may have electrophysiologic and histologic findings of peripheral nerve damage, even in the absence of clinical evidence of peripheral nerve involvement.