A clinical, electrophysiological, and pathological study of neuropathy in rheumatoid arthritis

Neuropathy in rheumatoid arthritis (RA) may result secondary to entrapment, vasculitis, and drug toxicity. We aimed to study clinical and electrophysiological neuropathy and pathological changes in sural nerve in patients with RA. One hundred eight patients of RA, fulfilling American College of Rheumatology 1987 criteria (mean age, 45.83 years; M/F 1:3, 80.3% seropositive) were examined clinically and electrophysiologically for evidence of peripheral neuropathy. Sural nerve biopsies were performed in the involved cases. In all RA patient medications, disease activity, results of blood tests, and X-rays of affected joints were recorded. Twenty-three patients complained of paresthesias in the extremities. Vibration sensations were decreased in 9, and tendon reflexes were decreased or absent in 28 patients. Sixty-two (57.4%) patients had electrophysiologic evidence of neuropathy. Of these 53 (85.5%) patients had pure sensory or sensory motor axonal neuropathy (mononeuritis multiplex, n = 7), while 9 (14.5%) had demyelinating neuropathy (chronic inflammatory demyelinating polyneuropathy, n = 1). Carpal tunnel syndrome was seen in 11 (10.1%) patients (associated with neuropathy in 6). Of 23 sural nerve biopsies available, perineurial thickening (n = 5, amyloid deposits n = 4), perivascular lymphomononuclear cell infiltrate (n = 4), loss of myelin fibers (n = 2), and necrotizing vasculitis (n = 1) were found. Clinically, however, seven patients had evidence of cutaneous vasculitis. Comparing the clinical characteristics of the patients with or without electrophysiological neuropathy, absence of deep tendon jerks (p < 0.005) and presence of extra articular manifestations (p < 0.01) were conspicuous in the neuropathic group. There was no relation of neuropathy with the duration of RA, seropositivity, joint erosions, joint deformities, prior disease-modifying anti-rheumatic drugs or glucocorticoid intake, and 28-joint disease activity score. Neuropathy in RA was mostly subclinical and predominantly axonal. Pathologically, neuropathy secondary to amyloid infiltration was second only to vasculitic neuropathy. Absence of deep tendon jerks and presence of vasculitis were more commonly observed in patients with neuropathy.