Dysfunction in the processing of the spinal cord may be responsible for pain in patients with fibromyalgia (FM), a study entitled “Cutaneous silent period prolonged fibromyalgia suggesting a central sensitization as pathogenesis” and published in the journal PLoS One.
The Fibromyalgia is characterized by chronic widespread pain, among other symptoms, but the underlying cause responsible for chronic pain in FM remains unclear. Recent and cumulative evidence suggests that central pain amplification is key to the pathogenesis of fibromyalgia: a process characterized by increased pain and sensory processing in the spinal cord and brain, also known as “central sensitization.”
The researchers compared the silent skin period (CSP), a spinal reflex mediated by A-delta skin afferents used to evaluate pain processing in the central and peripheral nervous system, between patients with fibromyalgia and normal healthy controls. A total of 24 patients with fibromyalgia (diagnosed according to the classification system of the American College of Rheumatology 1990) and 24 healthy controls matched for age and sex were analyzed. Researchers measured the CSP of the short abductor muscle of the thumb (located in the hand between the wrist and the base of the thumb) using standard electrodiagnostic equipment, along with patient parameters including demographic data, number of tender points, visual analog scale and Fibromyalgia impact questionnaire scores.
The mean duration of CSP was significantly longer in patients with fibromyalgia compared to healthy controls. Previous studies investigating CSP in patients with central nervous system disorders had found that the duration of CSP was prolonged in brachial dystonia, Parkinson’s disease, and multisystem atrophy. These findings suggest that the duration of CSP may reflect dysfunction of the supraspinal control, which will cause an impact on spinal excitability.
These findings suggest that fibromyalgia is associated with dysfunction of pain modulation mechanisms in the central nervous system. In particular, the researchers found no correlation between CSP and clinical parameters, such as VAS score, K-FIQ score, age and height, raising questions about whether to use CSP to assess the severity of the disease. Consequently, the researchers emphasize that additional studies are required to further evaluate the relationship between CSP parameters and clinical data.
“In conclusion, dysfunction of supraspinal control may be responsible for pain in FM, providing more evidence that central sensitization underlies the pathogenesis of the disease,” the authors write in their report.