Background/Purpose: To assess patients with primary fibromyalgia (pFM) for small fibre neuropathy (SFN) and to correlate biopsy results between groups and with known causes of SFN

Methods: A total of 21 patients with pFM (M:F=19:2) had 3mm skin punch biopsies from 2 leg sites-proximal and distal (20cm below right iliac crest and 10cm above right lateral malleolus) following appropriate consent. PGP-5 has been used as a pan axonal marker. Clinical assessments obtained on pain, sleep disturbance, effect of the disease on well being past week and past month , FM pain and FM fatigue ( all on a VAS 0-10; 10=worse positive). Fabro fatigue scale (0-90), Rotterdam emotional scale (30-120) ability to perform activities ( 8-32; 8 best ability). Each patient from the pFM group was examined for conditions known to be associated with SFN [1]: namely: Thyroid disease (hypo and hyper), metabolic syndrome, insulin resistance, diabetes, Family history (Fx) of diabetes, impaired Glucose tolerance, sarcoid, coeliac disease, B12 deficiency, chemotherapy drugs, para-neoplastic syndrome, antiviral drugs, Human Immunodeficiency Virus (HIV), Neurotoxins, palindromic rheumatism, Fx of psoriasis, hepatitis, Systemic Lupus Erythematosus, Sjogren’s, amyloidosis, restless syndrome, Guillain Barre, demyelinating polyneuropathy, complex regional pain syndrome and alcoholism. Demographic, ethnic, clinical, laboratory and disease associated comparisons between SFN(+) and SFN(-) biopsy groups took place.

Results: Age (mean) of the group was of 44.48 years (y) sd (+10.9) range (20-73). Age of symptoms onset was of 32.7 y (+ 10.9)(range 12-50) while mean age of diagnosis was 40.5 y (+ 8.9)(range 21-55). Data on tender point evaluation showed that all 21 patients were fulfilling 2011 criteria for FM while 18 of 21 patients were fulfilling the 1999 criteria having >11 tender points. Biopsy results showed 14 patients of 21 (66.6%) of pFM patients to be positive for SFN while 7 patients (33.3%) were negative. Looking at SFN associations, a total of 19 of 21 patients with pFM( 90.4%) had an associated cause from those listed related to SFN. More specifically 7 patients had metabolic syndrome (including diabetes and Fx of diabetes), 5 patients had hypothyroidism, 4 had B12 deficiency and 3 patients had family history of psoriasis. No predominant distribution according to biopsy results was found. Similarly no difference between the demographic, ethnic, clinical or laboratory characteristics between SFN (+) and SFN( -) found.

Conclusion: Metabolic syndrome along with other known causes of SFN is related to pFM. Reference: [1]. Hovaguimian A, Gibbons C. Diagnosis and treatment of pain in small fibre neuropathy. Curr Pain Headache Rep. 2011;15(3)193-200.

ACR Meeting Abstracts - https://acrabstracts.org/abstract/small-fibre-neuropathy-biopsies-sfn-in-primary-fibromyalgia-revealed-predominant-association-with-metabolic-syndrome-in-addition-to-other-known-treatable-causes-of-sfn/