Differential central pain processing following repetitive intramuscular proton/prostaglandin E2 injections in female fibromyalgia patients and healthy controls - 04/08/11
, Marcus T. Schley b, 1, Mariela Rance a, Pinar Yilmaz a, Lydia Lauer b, Roman Rukwied b, Martin Schmelz b, Herta Flor a
Corresponding author. Address: Department of Clinical and Cognitive Neuroscience, Central Institute of Mental Health, University of Heidelberg, J 5, D-68159 Mannheim, Germany. Tel.: +49 621 1703 6311; fax: +49 621 1703 6305.Abstract |
Background |
While the etiology of fibromyalgia syndrome (FMS) remains unclear, it is assumed that both peripheral and central components are involved.
Aims/methods |
To investigate central activation patterns following chemically-induced muscle pain we repetitively injected protons (low pH) and prostaglandin E2 (PGE2) in isotonic solution into the left extensor carpi radialis brevis muscle of female FMS patients and female healthy control subjects (HC). The injection of protons/PGE2 has the advantage that it is not prone to tachyphylaxis compared to capsaicin and hypotonic saline solution. During the repetitive injections continuous pain ratings were recorded and functional magnetic resonance imaging measurements were conducted.
Results |
Injection of protons/PGE2 led to activation of the anterior and medial cingulate cortices, contralateral primary sensory cortex, bilateral insula and thalamus, left basal ganglia, left orbitofrontal cortex and the cerebellum in FMS patients. In HC, activations were found only in the anterior, medial, and posterior cingulate cortices, and the primary somatosensory cortex. The contrast between the groups revealed significantly stronger activation for FMS patients in the left anterior insula. Peak pain ratings were comparable between HC and FMS patients, but pain duration (sustained pain) was prolonged in FM.
Conclusion |
Repetitive proton/PGE2-induced excitation of muscle tissue led to a more prolonged perception of pain and more wide-spread activation in pain-related brain areas in FMS, especially in the left (ipsilateral) insula, whereas acute protons/PGE2-induced pain processing was similar in the two groups. These data provide further evidence for enhanced central pain processing in FMS patients.
Le texte complet de cet article est disponible en PDF.Keywords : Fibromyalgia, fMRI, Tonic and transient muscle pain, Prostaglandin E2, Proton
Plan
Vol 15 - N° 7
P. 716-723 - août 2011 Retour au numéro
Article précédent
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