Central hyperexcitability in fibromyalgia

Hyperalgesia to pressure stimuli combined with spontaneous muscle pain are present in fibromyalgia [FMS]. If increased responses to painful stimuli ar e found in muscles without spontaneous pain, it could indicate involvement of central hyperexcitability in FMS. In the present study, experimental pai nful stimulation of a pain-free muscle in FMS patients resulted in exaggera ted referred pain patterns compared to controls. Moreover, repeated painful electrical muscle stimulation caused facilitated pain in FMS patients comp ared to controls [i.e., increased gain of temporal summation]. Temporal sum mation of skin stimuli above the painful muscle was not affected. These fin dings probably reflect involvement of central hyperexcitability [muscular h yperalgesia] in the FMS patients.