PURPOSE: The fibromyalgia syndrome (FMS) is known to be associated with symptoms of peripheral paresthesias, and a recent study found electodiagnostic EDX evidence suggesting polyneuropathy. Therefore, we systematically studied a series of FMS patients for clinical and laboratory evidence of immune mediated neuropathic disease. We report here a surprisingly high prevalence of CIDP-like findings in these patients.

METHODS: 58 FMS patients (53 female: mean age 63 years, range 18-92) meeting 1990 ACR criteria were questioned to find the prevalence of paresthesias and weakness, and examined for proximal muscle strength and stocking-type hypesthesia. Sixteen other rheumatic disease patients (11 males; mean age 64 yrs, range 33-80) without FMS (Rheum non-FMS) served as controls. Neural autoimmunity was assessed in patients and controls using four complement assays (C’3, C’4, FactorB, CH50), eight neural tissue auto antibody assays (GM1, Asialo-GM1, MAG IgM, SGPG IgM, GD1a, GD1b, GQ1b, Hu), and immunofixation electropheresis (IFE). FMS subjects also underwent EDX with emphasis on detection of demyelination. Approximately 70% of FMS and Rheum non-FMS subjects had concomitant RA or similar connective tissue disease (CTD).

RESULTS: Low C was seen only in RA or CTD. Anti Neural antibody titers, other than GQ1b, did not differ significantly from controls. All IFE paraproteins were benign. Demyelination was significantly associated with FMS and older age, but not with RA, OA, or gender.

CONCLUSIONS: Some FMS patients have clinical and laboratory findings suggestive of a demyelinating polyneuropathy which may have an immune mediated component. It is possible that this represents a CIDP-like illness. This observation has implications for better understanding the etiopathogenesis and treatment of a subset of FMS patients and deserves further attention.

CLINCIAL AND LAB VALUES IN FMS SUBJECTS AND CONTROLS AND EDX RESULTS IN FMS SUBJECT