Ultrasound-Guided Greater Occipital Nerve Block: An Efficient Technique in Chronic Refractory Migraine Without Aura?

Background: The effectiveness of greater occipital nerve block (GONB) in patients with primaryheadache syndromes is controversial. Few studies have been evaluated the usefulness of GONB inpatients with migraine without aura (MWOA).Objective: To compare the effectiveness of ultrasound-guided GONB using bupivacaine 0.5%and placebo on clinical improvement in patients with refractory MWOA in a randomized, doubleblinded clinical trial.Study Design: A prospective, randomized, placebo-controlled, double-blind pilot trial.Setting: Physical medicine and rehabilitation and neurology departments of a University Hospital.Methods: Thirty-two patients with a diagnosis of MWOA according to the InternationalClassification of Headache Disorders-II criteria were included in the study. Twenty-three patients(2 men, 21 women) completed the study. They were randomly assigned to receive either GONBwith local anesthetic (bupivacaine 0.5% 1.5 mL) or greater occipital nerve (GON) injection withnormal saline (0.9% 1.5 mL). Ultrasound-guided GONB was performed to more accurately locatethe nerve. All procedures were performed using a 7 – 13 MHz high-resolution linear ultrasoundtransducer. The treatment group was comprised of 11 patients and the placebo group wascomprised of 12 patients. The primary outcome measure was the change in the headache severityscore during the one-month post-intervention period. Headache severity was assessed with a visualanalogue scale (VAS) from 0 (no pain) to 10 (intense pain).Results: In both groups, a decrease in headache intensity on the injection side was observedduring the first post-injection week and continued until the second week. After the second week,the improvement continued in the treatment group, and the VAS score reached 0.97 at the endof the fourth week. In the placebo group after the second week, the VAS values increased againand nearly reached the pre-injection levels. The decrease in the monthly average pain intensityscore on the injected side was statistically significant in the treatment group (P = 0.003), but notin the placebo group (P = 0.110). No statistically significant difference in the monthly average painintensity score was observed on the uninjected side in either group (treatment group, P = 0.994;placebo group, P = 0.987). No serious side effect was observed after the treatment in either group.Only one patient had a self-limited vaso-vagal syncope during the procedure.Limitations: This trial included a relatively small sample. This may have been the result ofthe inclusion of only those patients who correctly completed their pain diaries. Another majorlimitation is the short follow-up duration. Patients were followed for one month after the injection,thus relatively long-term effects of the injection have not been observed.Conclusions: Ultrasound guided GONB with 1.5 mL of 0.5% bupivacaine for the treatmentof migraine patients is a safe, simple, and effective technique without severe adverse effects. Toincrease the effectiveness of the injection, and to implement the isolated GONB, ultrasonographyguidance could be suggested.Key words: Migraine, greater occipital nerve, occipital nerve block, ultrasound-guided