Abstract and Introduction
Objective: To provide an overview of the current available literature on peripheral nerve blocks for the management of migraine and other headache disorders in adults.
Background: Peripheral nerve blocks have been commonly performed in the headache practice for migraine, cluster headache, occipital neuralgia, and other headache disorders, despite a paucity of evidence supporting their use historically. In the past decade, there has been an effort to explore the efficacy and safety of peripheral nerve blocks for the management of headache, with the greatest interest centered around greater occipital blocks.
Design: We performed a search in PubMed using key words including "occipital nerve blocks," "peripheral nerve blocks," "occipital nerve," "migraine," "cluster headache," and "neuralgia." We reviewed the randomized controlled trials (RCTs), observational studies, and case series, and summarized the anatomy, techniques, and the evidence for the use of peripheral nerve blocks in different headache disorders, with particular focus on available RCTs. Case reports were included for a detail review of adverse events.
Results: Of 12 RCTs examining the use of greater occipital nerve blocks for migraine, all but one demonstrate efficacy with reduction in headache frequency, intensity, and/or duration compared to placebo. Studies have not demonstrated a difference in clinical outcomes with the use of corticosteroids for nerve blocks compared to blocks with local anesthetic in the treatment of migraine. There are two RCTs supporting the use of greater occipital blockade for cluster headache, both showing benefit of suboccipitally injected corticosteroid. One RCT suggests benefit of greater occipital nerve blocks for cervicogenic headache. Observational studies and case series/reports show that greater occipital nerve block may be effective in prolonged migraine aura, status migrainosus, post-dural puncture headache, and occipital neuralgia. Overall, peripheral nerve blocks are well tolerated. Serious side effects are rare but have been reported, including acute cerebellar syndrome and infection.
Conclusions: Peripheral nerve blocks, especially occipital nerve blocks, are a viable treatment option for migraine and may be helpful in cluster headache as a transitional therapy or rescue therapy. Additional prospective studies are needed to investigate the efficacy and safety of occipital nerve blocks for long-term migraine prevention, as well as for other headache disorders, such as occipital neuralgia.
Peripheral nerve blocks have been used for decades in the treatment of cranial neuralgias and multiple headache disorders, including migraine,[1–4] cluster headache,[5–8] and cervicogenic headache.[9–11]
Nerve blocks are generally well tolerated and may provide rapid pain relief that can last up to days or weeks. Technique varies but nerve blocks usually involve administration of local anesthetic with or without corticosteroid. When nerve blocks are used for headache disorders, the greater occipital nerve (GON) is the most common target. Some centers will block the lesser occipital nerve (LON) together with the GON. The supraorbital (SON), supratrochlear (STN), and auriculotemporal (ATN) nerves are also common nerve targets. Local anesthetics inhibit conduction in the sensory nerve fibers within mixed nerves, but headache relief often far outlasts the duration of action of local anesthesia.
The precise mechanism underlying prolonged headache relief following nerve blocks is unknown, but may involve central pain modulation.[14–16] The upper cervical nerve roots are anatomically and functionally connected to trigeminal pathways,[14,17] with convergence in the trigeminal cervical complex. Recent studies suggest Lamina I in the dorsal horn may play a significant role in the trigeminocervical integration, with upper cervical Lamina I projection neurons and local-circuit neurons receiving diverse input from trigeminal and cervical C-fibers and A-delta fibers.[19,20] Interestingly, anesthetic blockade of the GON, from the posterior division of C2, has been demonstrated by electrophysiology and functional imaging to reduce activation of trigeminal nociceptors,[16,21] though changes in trigeminal function do not always translate into direct clinical benefit.
The literature for peripheral nerve blocks varies widely in trial design, technique of blockade, duration of follow-up, and primary outcomes studied. Until recently, there were only a handful of randomized controlled trials (RCTs) to support the use of nerve blocks for any headache disorder.[2,23] However, in the last decade, there has been a concentrated effort to expand our understanding of the efficacy of nerve blocks for head and face pain, with the greatest efforts devoted to GON blocks. This review starts with an overview of the relevant nerve anatomy and technique for nerve blocks, then highlights the accruing evidence for the use of GON blocks in adult patients with migraine, cluster headache, and additional select headache disorders, with special attention to RCTs. Finally, we discuss pertinent topics of interest, including the current understanding of the need for the use of corticosteroids in nerve blocks.
Headache. 2022;62(9):1077-1092. © 2022 Blackwell Publishing