Small fiber impairment in patients with Fibromyalgia: a neurophysiological and skin biopsy study

Fibromyalgia (FM) is a disorder of uncertain origin associated with widespread pain, tenderness, muscular spam, fatigue, sleep disturbance and cognitive dysfunction. A dysfunction of pain processing at central and peripheral level was reported. In this study we aimed to explore the presence of signs of impairment of the peripheral nervous system in a cohort of patients with FM. Fifty-one FM patients underwent Laser Evoked Potentials (LEPs) and sympathetic skin response (SSR) by the right hand, knee and foot and skin biopsy from the right thigh and right ankle. In 15 (29%) patients we found alterations of LEPs in at least two of the 3 stimulated seats (hand, knee, foot). The SSR was impaired in 15 patients by stimulation of the hand, in 9 patients for both stimulated sites. Epidermal density was reduced in 46 (90%) patients and in 41 of these there was only an interest in the proximal site. In 5 subjects (10%) neurophysiological evaluation and skin biopsy were normal. Skin biopsy in patient with FM reveals a prominent peripheral nervous system involvement in FM patients with a prevalent picture of non-length-dependent sensory neuropathy.