Session Type: Abstract Submissions (ACR)
A consistent line of investigation proposes that fibromyalgia is a sympathetically maintained neuropathic pain syndrome (Semin Arthritis Rheum 2000;29:197). This view has been recently reinforced by several controlled studies describing decreased small nerve fiber density in skin biopsies of patients with fibromyalgia (Brain 2013;136:1857).
Small fiber neuropathy is a disorder of the peripheral nerves that primarily affects small somatic fibers and sympathetic fibers resulting in sensory changes and autonomic dysfunction. The cornea receives the densest small fiber innervation of the body. Confocal corneal biomicroscopy is a new noninvasive method to assess small nerve fiber pathology.
The main objective of this cross-sectional investigation was to assess the corneal small nerve fiber morphology in patients with fibromyalgia using confocal microscopy. The secondary objective was to correlate corneal nerve microscopic features with fibromyalgia severity parameters contained in several validated questionnaires.
We studied 17 female patients with fibromyalgia (mean age = 43 ± SD 5) and 17 age-matched healthy female control subjects. A central scan of the total corneal thickness was obtained with a confocal microscope (Confoscan 4, Fortune Technologies, Italy). A single ophthalmologist expert in corneal pathology evaluated stromal nerves morphology and thickness using the Navis v. 3.5.0. Software (NIDEK, Multi-Instrument Diagnostic System, Japan). Nerve thickness was defined as the mean between the widest and the narrowest portion of each analyzed stromal nerve. Nerve smoothness was defined as the difference between the widest and the narrowest portions of each analyzed stromal nerve. Measurements were done without knowledge of the clinical diagnosis. All studied subjects filled out different questionnaires assessing fibromyalgia severity, including a neuropathic symptom questionnaire (LANSS).
Corneal stromal nerves were easily identified as bright linear silvery structures. Patients with fibromyalgia had nerve thickness of 5.9 ± 2.2 micrometers (mean ± SD) significantly different from control’s values (7.4 ± 2.4) p < 0.0001. The difference between widest and narrowest nerve diameter was also dissimilar in patients (1.8 ± 1.3) vs. controls (2.6 ± 1.5) p < 0.0001. Remarkably; when patients and controls were grouped together (n = 34), there was a negative correlation between corneal stromal nerve thickness and LANSS neuropathic symptoms questionnaire score (Spearman’s r = - 0.36, p = 0.03) as well as with tender points number (r = – 0.38, p = 0.02), and other non-pain-related fibromyalgia symptoms.
Conclusion Confocal biomicroscopy demonstrates that women suffering from fibromyalgia have thinner and smoother corneal nerve fibers when compared to healthy controls. When controls and patients are grouped together, there is a correlated continuum between the degree of corneal nerve pathology and fibromyalgia symptoms. Small fiber neuropathy may play a key role in fibromyalgia’s pathogenesis.
L. A. Martinez-Martinez,
E. Hernandez Quintela,
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/small-fiber-neuropathy-in-women-with-fibromyalgia-a-clinical-pathological-correlation-using-confocal-corneal-biomicroscopy/