Small-diameter nerve fiber neuropathy in systemic lupus erythematosus.

BACKGROUND: Systemic lupus erythematosus (SLE) is an inflammatory, autoimmune, multiorgan disease often involving the central and peripheral nervous systems.

OBJECTIVE: To determine whether there is a selective small-diameter nerve fiber neuropathy in patients with SLE.

DESIGN: Cross-sectional study.

SETTING: Stavanger University Hospital, Stavanger, Norway. Patients Sixty patients with SLE, aged 43.2 +/- 13.5 years (mean +/- SD).

INTERVENTIONS: Skin biopsies, nerve conduction studies, and clinical neurologic examinations.

MAIN OUTCOME MEASURES: Density of intraepidermal small-diameter nerve fibers in skin biopsy specimens and large-diameter nerve fiber function as determined by nerve conduction studies and clinical examinations.

RESULTS: The mean density of intraepidermal small-diameter nerve fibers in patients with SLE was 7.5 +/- 3.8/mm. Eight patients (13%) had densities below reference values, consistent with small-diameter nerve fiber neuropathy, and results of nerve conduction studies were normal in 6 of them. Eleven patients (18%) had abnormal results of nerve conduction studies, reflecting large-diameter nerve fiber neuropathy, and 4 patients (7%) were classified by an experienced neurologist as having polyneuropathy after the clinical examination.

CONCLUSIONS: An abnormal reduction in intraepidermal small-diameter nerve fiber densities is evident in some patients despite normal function of their larger nerve fibers. This adds further support to the theory that a pure small-diameter nerve fiber neuropathy may occur in SLE.