Systemic lupus erythematosus (SLE) may have an early effect on peripheral nerve function before the development of electrophysiologic or clinical neuropathy, according to study results published in Rheumatology International.

Researchers evaluated data from nerve conduction studies (NCS) in patients with SLE without clinical or electrophysiologic neuropathy and healthy control participants matched by age and sex. Data included sensory nerve action potential (SNAP), sensory nerve conduction velocities, (SNCV), and demographics. Investigators aimed to determine whether SLE could have an even earlier effect on peripheral nerve function before the development of electrophysiologic abnormalities.

A total of 61 patients with SLE without electrophysiologic neuropathy (88.5% women; median disease duration, 8 years) were included in the study. Patients had a median SLE Disease Activity Index (SLEDAI) score of 3 (range, 0-16). A total of 49.2% of patients had mild disease activity (score, 1-5), and 32.8% showed no active disease (score, 0).

Although NCS results were within the normal range, the researchers found statistically significant differences in several motor and sensory parameters between the patient and control group. Compared with control participants, among patients with SLE, distal compound muscle action potential was significantly lower in the ulnar, fibular, and posterior tibial nerves and motor nerve conduction velocities were significantly slower in the median, ulnar, and fibular nerves. In the sensory NCS, patients with SLE vs control participants showed significantly lower SNAP amplitudes in the sural nerves and slower SNCV in the median, ulnar, and sural nerves. Patients with SLE also had longer minimum F-wave latencies and their H reflexes more frequently absent.


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No significant correlations were found between NCS parameters and SLEDAI or disease duration among patients with SLE; however, there were correlations between disease relapses and motor conduction velocities, specifically of the tibial and fibular nerves (r=-0.315; P =.013 and r=-0.426; P =.001).

Researchers noted that NCS measure the function of only large nerve fibers, which may represent a limitation of the study, because small peripheral nerve fibers have also been recognized to be involved in SLE.

Overall, despite having NCS results within a normal range, the data show that patients with SLE without other known causes of neuropathy experienced worse peripheral nerve function. This could suggest that SLE has early negative effects on peripheral nerve function, which supports the possibility that SLE polyneuropathy may gradually progress to development of clinical peripheral neuropathy.

Reference

Fong S-Y, Raja J, Wong K-T, Goh K-J. Systemic lupus erythematosus may have an early effect on peripheral nerve function in patients without clinical or electrophysiological neuropathy: comparison with age- and gender-matched controls [published online June 2, 2020]. Rheumatol Int. doi:10.1007/s00296-020-04610-8