Electrodiagnostic study in patients with fibromyalgia: Implication for central sensitization

Background: Fibromyalgia is a syndrome characterized by chronic pain, depression, fatigue, and sleep disturbance. Different hypotheses have emerged about its pathogenesis, but central sensitization, which plays an important role in the development of neuropathic pain, is considered to be the main mechanism. We aim to compare patients with fibromyalgia and healthy controls with different electrodiagnostic testing, and if present, to corroborate whether there is any relationship between electrodiagnostic measures. Also, we sought to test the diagnostic value of some of these measures. Methods: A case-control study of thirty-one patients with fibromyalgia with a duration of illness ranging from 5 months to 10 years were recruited for the study. Full medical history, clinical neurological examination, and electrodiagnostic tests of the upper and lower extremity including nerve conduction studies, needle electromyography, sympathetic skin response, cutaneous silent period and muscle fiber conduction velocity. Results: Sympathetic skin response latency and cutaneous silent period latency were not different between the patients and the control group. Cutaneous silent period duration was prolonged and the muscle fiber conduction velocity is faster in the subjects with fibromyalgia. The latter measures have similar diagnostic value. Sex has no significant impact on electrodiagnostic measures and the latter not correlated with patients' age. Conclusion: A central sensitization and concomitant deregulation of the efferent higher motor centers might be implicated in the pathogenic mechanism of fibromyalgia