Submitted and Edited by Clark Pinyan, MD
Reduction of Skin Innervation is Associated with a Severe Fibromyalgia Phenotype.
Evdokimov D et al, Ann Neurol.
Patients with clinical diagnosis of fibromyalgia underwent extensive testing of small and sensory nerve fibers, including proximal and distal lower extremity skin biopsy, corneal nerve microscopy, quantitative sensory testing, pain-related evoked potentials and microneurography. Patients with other neuropathic or potentially neuropathic diseases were excluded. Controls included patients with a clinical diagnosis of major depressive disorder with pain (MD-P) as well as lab normative values for skin biopsy. 63% of fibromyalgia syndrome patients had reduced intraepidermal nerve fiber density compared to 10% of MD-P patients and 18% of controls. Those with reduced fiber density had higher pain intensity, higher impairment due to pain, higher disease burden, more stabbing pain and paresthesias, and more anxiety. Therefore the extent of small fiber pathology may correlate with symptom severity in fibromyalgia.
The diagnosis of “fibromyalgia” is very complex, especially how it is often applied in clinical practice. It is sometimes difficult to distinguish or separate from other possible causes of body pain, fatigue, and hyperalgesia. This article helps elucidate the detectable, physiologic differences between fibromyalgia syndrome and other painful disorders such as MD-P, as well as attempt to find a basis for symptom severity in some patients. It certainly may not apply to all patients with this clinically diverse syndrome, but could give us some hints as to causation as well as help direct therapy or develop new therapies.
Anything that hints at a physiologic basis or reproducible changes in fibromyalgia would be helpful for clinicians who encounter this common syndrome.