Fibromyalgia Found to Result in Reduced Neuronal Density in the Cornea

Fibromyalgia Found to Result in Reduced Neuronal Density in the Cornea

Fibromyalgia is normally defined as a kind of myopathy that leads to weakness, stiffness, joint pains, fatigue, bowel and bladder movement difficulties among other symptoms. In short, it is a disease that causes painful responses to pressure stimuli.

A group of researchers in Mexico, including Manuel Ramírez, MD, Laura-Aline Martínez-Martínez, Everardo Hernández-Quintela, MD, Jorge Velazco-Casapía, MD, Angélica Vargas, MD, Manuel Martínez-Lavín from the Asociación para Evitar la Ceguera and Instituto Nacional de Cardiología Ignacio Chávez. México, performed a study to observe whether fibromyalgia is a neuropathic condition as suggested recently by researchers. The concept was developed after a series of skin biopsies from fibromyalgia patients showed that small nerve fiber densities were reduced considerably.

Because the cornea is known to be innervated by the maximum number of small nerve fibers, researchers studied their condition in affected patients using confocal microscopy and comparing them to healthy controls in order to test their hypothesis.

A total of 17 females with fibromyalgia were selected for the study along with an equal number of healthy controls. Their medical assessments were made after a series of questions with regard to fibromyalgia, its symptoms and a survey based on neuropathic pain.

The corneal nerve measurements formed the basis of this study. Corneal thickness was measured by confocal microscopy. Stromal nerves and sub-basal plexus nerves were analyzed by an ophthalmologist who was completely unaware of the medical histories of these patients, in order to get an unbiased response.

It was observed that the stromal nerve thickness (defined as the mean value between the widest and narrowest portion of each stromal nerve fiber analyzed) was considerably lesser than those in healthy controls. Sub-basal plexus nerve densities were also lesser for the test population as compared to the controls. When statistical correlation (Fischer’s exact test) was applied, there was a significant relationship between reduced corneal nerve density and the reports of neuropathic pain in the test population.

This study proved that women suffering from fibromyalgia had slender nerve density, which contributed to neuropathic pain and may be a contributing factor towards pathogenesis of fibromyalgia. Also, confocal microscopy was established to be useful tool in studying patients with fibromyalgia.