Greater occipital nerve (GON) blockade is a safe, effective cluster headache (CH) prevention strategy, but its use lacks standardized protocols, a systematic review published in Journal of Neurology, Neurosurgery & Psychiatry shows. Researchers also suggest that higher injectate volumes improve the odds that a patient will respond to the preventative therapy approach, and that methylprednisolone can improve its safety.
Patients with CH often report the associated pain as severe. The short-term prevention strategy greater occipital nerve blockade consists of injecting corticosteroid or local anesthetics, or both, into the suboccipital region. Despite use in clinical practice, there is no consensus on optimal treatment techniques and some data suggests effects vary.
This systematic review evaluated 22 studies of greater occipital nerve blockade in CH that were published prior to the literature search in October 2020.
Overall, 595 patients with CH received greater occipital nerve blockade, among whom 224 had episodic CH and 315 chronic CH. The GON block was administered as a preventative strategy in 19 studies, used as an acute strategy during an attack in 2 studies, and both strategies were used in 1 study. Most studies (n=16) used a combined corticosteroid and local anesthesia injection whereas 4 studies used only corticosteroids and 3 used only a local anesthetic.
As a preventative treatment, a randomized trial reported a significant reduction in the average number of attacks per day following greater occipital nerve blockade in the 15 days after the first injection compared with controls.
Similarly, all open-label studies reported a reduction in attack frequency following blockade compared with baseline. In general, pain scores were reduced after treatment, with a study reporting significant effects on pain scores up to 6 months postintervention. The blockade of the greater occipital nerve was also associated with a reduction in attack duration in 4 studies of between 19.8 and 58.2 minutes.
The duration of change in frequency, severity, and duration of attacks differed between studies. The proportion of responders in the studies ranged between 46.7% and 100% and the duration of response between 0-3 and 129.5 days, the study shows.
As an acute treatment, 16 out of 20 patients reported immediate relief of headache activity for up to 2.6 hours following injection of a local anesthetic alone.
In 18 studies that reported adverse events, 1 reported that greater occipital nerve blockade increased risk for adverse events by 4.39 times compared with controls. Immediate effects of dizziness, blurred vision, and tenderness were reported whereas local alopecia or subcutaneous atrophy could take up to a month to develop. Few studies reported the time to resolution of adverse effects, however, 1 study shows headache and facial hypogastria resolved within 24 hours and resolution of injection site pain took between 5 days and 3 months.
In general, there were no clear trends in patient characteristics or response to greater occipital nerve blockade. Similarly, intervention characteristics did not show clear trends, for example, response rates were high with all reported corticosteroid agents. However, evidence from 2 studies may indicate a relationship between injectate volume and degree of response.
“Improved knowledge of how GON blockade can be made more effective requires studies that better control confounding factors and have standardised reporting of injection technique,” according to the researchers. “More standardised reporting and measurement are also needed to establish determinants of potentially irreversible adverse effects.”
Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.
Gordon A, Roe T, Villar-Martínez MD, Moreno-Ajona D, Goadsby PJ, Hoffmann J. Effectiveness and safety profile of greater occipital nerve blockade in cluster headache: a systematic review. J Neurol Neurosurg Psychiatry. 2023;jnnp-2023-331066. doi:10.1136/jnnp-2023-331066