Differential central pain processing following repetitive intramuscular proton/prostaglandin E₂ injections in female fibromyalgia patients and healthy controls.

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 E(2) (PGE(2)) 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/PGE(2) has the advantage that it is not prone to tachyphylaxis compared to capsaicin and hypotonic saline solution.