Greater occipital nerve (GON) block appears to be effective for acute treatment of migraine headache pain, according to new research published in Journal of the American Board of Family Medicine.
“We undertook this retrospective cohort study to assess the efficacy of GON block in the acute treatment of migraine headache, having anecdotally experienced good results in our clinical practice,” wrote corresponding author Martina Mookadam, MD, Mayo Clinic, Scottsdale, AZ, and coauthors.
No current clinical guidelines for the treatment of migraine headache include GON block, yet there has been much research on the subject with mixed findings.
In this study, 562 patients (average age 58.6 years; 75% women) fulfilled inclusion criteria: age between 18 and 100 years; diagnosis of migraine headache; previous administration of at least one GON block; and went to at least one follow-up visit. Exclusion criteria included: inadequate documentation concerning follow-up and response to treatment; administration of botulinum toxin injection at the same time as GON block; and headache not defined as migraine using diagnostic criteria.
The GON procedure involves injecting a local anesthetic plus a corticosteroid at the level of the inferolateral aspect of the occipital protuberance.
Researchers obtained pain scores before GON block and during a follow-up visit, which occurred between 1 and 4 weeks after the procedure. They used the 11-point Numeric Pain Rating Scale (NPRS) to assess pain, with a score of 0 indicating pain free and a score of 10 indicating worst pain imaginable.
Researchers assessed improvement based on percentage change from baseline NPRS pain score. Improvement was categorized as:
- minimal (<30% point reduction)
- moderate (31%–50% point reduction)
- significant (>50% point reduction)
At the time of the procedure, 91% of participants were in acute migraine pain, with the rest complaining of migraine pain within 3 days before the procedure.
At the follow-up visit, a total of 82% of participants reported pain reduction as moderate (23%) or significant (58%), as categorized by the researchers.
Additionally, 61% of patients less than age 65 experienced a significant response to treatment compared with that of 54% of patients aged 65 years and older (P = 0.03). Furthermore, 74% of patients who received two or more GON blocks had a significant response compared with 36% of patients given only one GON block (P < 0.001).
Overall, GON block worked equally well across all ages and sexes, regardless of previous treatments, administration of single or multiple GON blocks, and type of specialist performing the procedure. Previous treatments included medications, physical therapy, botulinum toxin, acupuncture, or some combination of therapies.
“The suggested biological mechanism by which GON block works to treat the symptoms of migraine,” wrote the researchers, “relates to modulation of afferent signals to the trigeminal nucleus caudalis, which bridges the gap between sensory regions of the ophthalmic branch of the trigeminal nerve and the greater occipital nerve. Injecting this region with local anesthetic and corticosteroids decreases sensory input to the trigeminal nucleus caudalis.”
The main strength of this study is its large sample size, which researchers suggest is substantially more powerful than previous trials.
GON block appears to yield higher rates of clinical response in patients with migraine headache when used as sole or adjunct treatment, the researchers concluded. But, they added, higher power placebo-controlled trials are still needed to confirm the use of GON block in patients with migraines. Further research could also support the inclusion of GON block in clinical guidelines for the treatment of migraine headache.