Functional alterations of pain processing pathway in migraine patients with cutaneous allodynia.

Abstract

Cutaneous allodynia (CA) is a characteristic of central sensitization, predicting migraine progression, and poor response to therapy. The present study aimed to find out the cerebral functional alterations related to the establishment of central sensitization in migraineurs using functional magnetic resonance imaging (fMRI). The experiment was performed in 15 migraineurs with Cutaneous allodynia (MWCA) and 19 patients without Cutaneous allodynia (MWoCA) in the interictal phase, and 20 matched healthy controls. Blood oxygen level dependent-fMRI was applied in all subjects when they were given transcutaneous electrical nerve stimulation at the left medial forearm, achieving to a predetermined level of pain sensation (i.e., visual analogue scale [VAS] = 40). Contrast images were then produced to determine whether this disorders present functional changes in the brain during pain processing. Demographic and headache characteristics were balanced between groups. The contrast images of both migraine groups comparing to healthy controls exhibited weaker activation of various brain regions (e.g., cerebellum and insulae), which might be relevant to the pathophysiological procedure of migraine. The direct comparison between the two migraine groups revealed that activation in the dorsal pons and contralateral (right) inferior parietal lobule of MWCA subjects were significantly lower than it in MWoCA ones. The interictal dysfunction of pain processing pathway may be responsible for (at least relevant to) central sensitization in migraine patients, via abnormal modulations of nociceptive transmission.