The effects of greater occipital nerve block and trigger point injection on brush allodynia and pain in migraine.

OBJECTIVE To evaluate the effect of GONB, with or without trigger point injection (TPI), on dynamic mechanical (brush) allodynia (BA) and on head pain in migraine. Background.-Patients with migraine often have cutaneous allodynia that is related to sensitization of central pain neurons. Greater occipital nerve block (GONB) is an effective treatment for migraine headache; however, its effect on cutaneous allodynia in migraine is unknown. METHODS We studied patients with migraine and BA who were treated with GONB with or without TPI. Demographic data, migraine history, and headache features were documented. Allodynia was evaluated using a structured questionnaire and by applying a 4 x 4-inch gauze pad to skin areas in the trigeminal and cervical dermatomes. Degree of allodynia (the allodynia score) was measured on a 100-mm visual analog scale (VAS) before treatment and 10 and 20 minutes thereafter. Headache levels were assessed using an 11-point verbal scale. Allodynia scores, as well as headache levels, before and after treatment were compared. RESULTS Nineteen patients were studied. Mean age was 43.6+/-11.8 years. Twenty minutes after treatment, headache was reduced in 17 patients (89.5%) and did not change in 2 (10.5%). The average headache level was 6.53 before treatment and 3.47, 20 minutes after it. The average allodynia score decreased after 20 minutes in all patients. Average allodynia score per site was reduced by 18.69 mm and 13.74 mm in the trigeminal and cervical areas, respectively. There was a positive correlation between allodynia index, obtained through the questionnaire, and allodynia score, obtained by examination. CONCLUSION GONB, with or without TPI, reduced both head pain and brush allodynia in this migraine patient group.