Polyneuropathy and systemic vasculitis. An electrophysiological study.

A review of cases of systemic vasculitis followed for one year in a rheumatology department resulted in the detection of 18 patients who on the clinical and electrophysiological evidence had symmetrical distal polyneuropathy. A moderate impairment of the motor conduction velocity was present in 7 patients, with electromyographic neurogenic changes in the distal lower limbs of all but one patient. The sensory action potential of the sural nerve was bilaterally absent in one case, and its amplitude was reduced in 14 out of 16 patients, with a decreased sensory conduction velocity in 9 cases. The sural nerve biopsy, performed in 6 patients, was prevalently suggestive of previous axonal degeneration. This investigation illustrates the spectrum of diffuse peripheral nerve involvement associated with systemic vasculitis. A variable impairment of the sensory action potential, ranging from slight decrease of amplitude to no response, is the most common finding. Conduction velocities appear to be relatively spared.