Small nerve fiber involvement in systemic lupus erythematosus: A controlled study

OBJECTIVE: To determine if patients with systemic lupus erythematosus (SLE) may have a peripheral neuropathy involving unmyelinated and small, myelinated nerve fibers, by immunostaining epidermal nerve fibers (ENF) in skin biopsy samples for the panaxonal marker, protein gene product 9.5 (PGP 9.5). METHODS: Fifteen consecutive and nonselected SLE patients and 15 age- and sex-matched controls were included in the study. The age of the patients ranged from 25 years to 65 years, with a mean +/- SD age of 47.3 +/- 10.2 years and a disease duration of 2-28 years (mean +/- SD 14.8 +/- 8.6 years). Two 3-mm skin biopsy samples were obtained with a punch needle approximately 10 cm superior to the lateral malleolus of the right leg and immunostained with 0.1% rabbit polyclonal antibodies to human PGP 9.5. The number of ENF per millimeter was counted and recorded as the mean +/- SD of counts in six 50-microm sections, 3 from each of the 2 biopsy samples. RESULTS: The mean number of ENF per mm in patients with SLE was 8.0 +/- 1.5 (range 5.0-9.9), while the matched controls had 12.2 +/- 3.8 ENF per mm (range 6.8-18.6) (P = 0.0006). CONCLUSION: This study indicates that a small fiber involvement in patients with SLE may be responsible for the prevalent neuropathic symptoms and impaired warm sense that is observed in such patients.