Met-enkephalin increase in patients with fibromyalgia under local treatment.

Fibromyalgia is a chronic debilitating condition of unknown etiology. The clinical picture suggests increased activity and/or supersensitivity in nociceptive pathways or inadequate activity in endogenous pain attenuation mechanisms. One therapeutic approach in the treatment of this syndrome is the administration of serial local injections of lidocaine hydrochloride in the painful points. To evaluate the effect of this treatment on plasma met-enkephalin (ME) levels we studied 15 patients, all women with fibromyalgia under local treatment in the tender points, grouped as follows: 5 were treated with local injection of lidocaine hydrochloride, 5 were treated with local injection of saline and 5 treated with dry needling. Significant increases in plasma ME concentrations were observed in all groups in the last sampling of each session studied. These results show an increase in plasma ME levels 10 minutes after finishing each session, which is independent of the maneuver employed.