Central sensitization and chronic pain: study for migraine

Refractory chronic headaches greatly impair the quality of life of migraine patients and also reduce social productivity. To elucidate the pathophysiology of the supersensitive brain state of refractory migraine attacks, and to discover the treatment and prophylaxis for the refractory chronic migraine, we analyzed a brain electric field under the light stimulation–induced brain supersensitivity. As a result, we found suppression of the cortical hyperexcitation only in patients with migraine without aura. This result suggested that the suppression of the cortical hyperexcitation by cortical spreading depression may have a role for inhibition of excitation in limbic system, vestibular system and the vomiting center. Next, cranial autonomic symptoms in patients with migraine have recently received attention. We showed that central sensitization, assessed by central sensitization inventory questionnaire, was more prevalent in migraine patients with cranial autonomic symptoms compared with those without cranial autonomic symptoms, suggesting a possible role of central sensitization in comorbid autonomic symptoms in migraine. Central sensitization is postulated to participate in not only severe pain but also in various symptoms such as fatigue, sleep disturbances, anxiety and depres sion in chronic pain syndrome. We believe our study results from migraine patients shed some light on the role of central sensitization in pathophysiology of chronic pain syndrome, but the elucidation of these relationships require further studies.