Peripheral Nerve Blocks for Headache Disorders: Expert Roundtable

For many years, clinicians have used peripheral nerve blocks (PNBs) in the treatment of several types of headache disorders, and research supports their efficacy in both adult and pediatric patients.^1,2

For example, in a double-blind placebo-controlled 2005 study, a greater occipital nerve block was found to alleviate cluster headache in 80% of patients (vs no patients in the control group), an effect that was sustained for ≥4 weeks in most patients.³

In a 2014 retrospective cohort study of children with post-traumatic headache, 71% of patients receiving a greater occipital nerve block experienced complete headache resolution vs 32% of children receiving intravenous metoclopramide.⁴

However, high-quality studies on PNBs are scarce and no official guidelines pertaining to their use have been formulated. The American Headache Society Special Interest Section for PNBs and other Interventional Procedures published expert consensus recommendations in 2013 regarding the use of PNBs in the treatment of headache disorders.⁵ These recommendations were partly based on responses from a physician survey on PNB drug dosages, injection volumes and schedules, and other aspects of PNBs.

The guideline authors provided recommendations for nerves most commonly targeted in PNBs for headache, as highlighted below. In addition to the points noted here, the article also includes specific guidance on injection location and techniques for each site.

Greater occipital nerve. This is the most common target for PNB in the treatment of headache disorders. Unilateral or bilateral injections may be performed using a 3 mL- or 5 mL-syringe ( 25‐, 27‐, or 30‐gauge and 0.5‐ or 1‐inch needle). Lidocaine 1% to 2% (10 to 20 mg/mL) and/or bupivacaine 0.25% to 0.5% (2.5 to 5 mg/mL) may be used; if combined, a volume ratio (lidocaine/bupivacaine) of 1:1 to 1:3 is recommended, with an injection volume of 1.5 mL to 3 mL per nerve.

Lesser occipital nerve. The drugs and injection technique used for a lesser occipital nerve block are similar to those used in blocks targeting the greater occipital nerve. The recommended injection volume is 1 mL to 2 mL per nerve.

Trigeminal Nerve Blocks

• Supratrochlear nerve. Lidocaine 1% to 2% (10 to 20 mg/mL) and/or bupivacaine 0.25% to 0.5% (2.5 to 5 mg/mL) may be injected using a 1 mL-syringe (30-gauge; 0.5-inch needle). If combined, a volume ratio (lidocaine/bupivacaine) of 1:1 to 1:3 is recommended. The recommended injection volume is 0.2 mL to 1.0 mL per nerve.
• Supraorbital nerve. Recommendations for needle size, drugs, and injection volume are the same as those for supratrochlear nerve block.
• Auriculotemporal nerve. Using the same needle size and drugs recommended for the previously mentioned blocks, the recommended injection volume is 0.5 mL to 1.0 mL for an injection at the proximal part of the nerve. A greater injection volume should be used when also injecting the superior branches, and an extra 0.25 mL should be used for each additional nerve injected.

“It should be noted that there is a paucity of evidence from controlled studies for the use of PNBs in the treatment of primary and secondary headache disorders, with the exception of [greater occipital nerve] blockade for cluster headache,” noted the guideline authors. The consensus recommendations may be revised as additional study results are reported.

To further explore the current state of practice and remaining research needed on the use PNBs for headache disorders, Clinical Pain Advisor interviewed 3 experts: one of the authors of the consensus recommendations, Matthew S. Robbins, MD, FAAN, FAHS, associate professor of neurology at Albert Einstein College of Medicine and chief of neurology at the Jack D. Weiler Hospital of Montefiore Medical Center in New York; Nauman Tariq, MD, assistant professor of neurology and director of the Headache Center at Johns Hopkins School of Medicine in Baltimore, Maryland; and Megan Donnelly, DO, headache specialist and assistant professor of medicine at Cleveland Clinic in Ohio.

Clinical Pain Advisor: What are the main benefits of PNBs in the treatment of headache disorders?

Dr Robbins: PNBs seem to be a safe and effective treatment in a variety of headache disorders. The best evidence is for greater occipital nerve blocks in the short-term prevention of migraine, with 5 clinical trials having been reported, most of which show safety and efficacy. There are 2 double-blind trials with greater occipital injections with steroids — not blocks per se — in the short-term prevention of cluster headache, and thus the latest guideline on cluster headache treatment by the American Headache Society stated it has Level A evidence for their use.

Dr Tariq: Trigeminal nerve branch block and occipital nerve blocks can be easily done in the clinician’s office, and it takes 5 to 10 minutes to perform either one of these procedures. They are considered safe, and complications are rare but may include risk of infection due to needle penetration; this is the same risk patients take when they go for a lab draw.

The use of these techniques can break a continuous cycle of headaches. Some physicians believe that repeating these procedures every few weeks may have a potentiated effect in terms of decreasing the intensity of chronic migraine. They are a reasonable alternative to oral medicines, which some patients avoid due to concerns of gastrointestinal-related adverse events. Patients generally prefer a one-time treatment over the use of daily medications. 

Dr Donnelly: PNBs have been used for decades to treat various headache disorders. They offer nearly immediate analgesia and can provide lasting relief beyond that of the anesthesia, with effects often lasting weeks to months. PNBs are generally safe, well-tolerated by patients, and relatively easy to perform when done by a well-trained clinician. There is no good data to either support or refute the use of nerve blocks, but clinical practice suggests that it can be helpful.

Clinical Pain Advisor: What do you anticipate clinicians will find most helpful about the consensus recommendations?

Dr Robbins: The most helpful recommendations are those that provide details on how to perform PNBs and specifics on injections — ie, what, where, how much, and how often to inject. Since there is no abundant evidence for trigeminal branch nerve blocks, it is important to have an expert consensus so that clinicians can apply these techniques in their practice and researchers can use them when designing future studies.

Dr Tariq: It is a nice and brief introduction to the use of PNBs for headaches. Interested physicians will still need to do hands-on training a few times before they are able to perform them independently. 

Dr Donnelly: I think providing a more standardized approach to the utilization of PNBs is an important step forward. As with many older procedures or medicines, these techniques currently lack much evidence, as quality research in the form of large prospective randomized controlled trials have just not been performed. To put it simply, PNBs have been “grandfathered” into practice. Information on the selection of the ideal patient population based on the identification of indications and contraindications, the procedural technique, specific medication choices, and dosage is a helpful and important step.

Clinical Pain Advisor: What should be the focus of future research in this area?

Dr Robbins: Future research should explore how effective and safe nerve blocks are to treat migraine acutely, a treatment which is performed in clinical practice often. Our institution has interesting studies on nerve blocks in the emergency department, which is a practical place to study them. Also, many headache and pain specialists use occipital plus trigeminal nerve blocks, but it is not known whether the combination is more effective than occipital nerve blocks alone, or if the injections should be tailored to the site of the pain.

Dr Tariq: I think we need 2 things. First, a high-powered randomized double-blind clinical trial, which could tell us whether steroids should be used in combination with anesthetic drugs or not during these procedures. At this time, the data is conflicting. 

The second thing is the availability of an injectable anesthetic and a steroid with an ultra-long half-life. This could potentially give patients longer-lasting relief compared with  relief time periods (achieved with current formulations) which, realistically, vary from a couple of days to a few weeks. 

Dr Donnelly: Regarding research for PNBs, there have only been limited prospective randomized controlled trials for cluster headache, chronic daily headache, and cervicogenic headaches, but not for other headache disorders for which we commonly use nerve blocks. I think future research should more rigorously test each form of PNB for each primary headache disorder, specifically looking at efficacy, measured as length of pain relief. 

The use of standardized techniques outlined in the consensus recommendations should lead to “standardized” research, which can be replicated. Furthermore, as the article points out, the utility of the addition of corticosteroids to nerve blocks has not really been touched upon, although it is routinely included in clinical practice. Therefore, this is also an area that is ripe for research.

Clinical Pain Advisor: Any other point you would like to make?

Dr Robbins: Pain specialists may utilize ultrasound or fluoroscopic guidance for PNBs, but it is not known if that technology really improves outcomes.

Dr Tariq: In headache sufferers who have tried and not responded to oral drugs, have sensitivities, or contraindications to the use of oral drugs, PNBs are a reasonable alternative. They can be performed in children and elderly patients with relative ease. 

Dr Donnelly: PNBs can be helpful in the clinical setting for medically complex patients who are on multiple medications —and I would rather not add to their polypharmacy — as well as in women who are pregnant or lactating, so as to limit fetal or breast milk exposure to systemic medications. But again, further research in these more sensitive and complex patient populations is needed.

 

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References

1. Levin M. Nerve blocks in the treatment of headache. Neurotherapeutics. 2010; 7(2):197-203.
2. Dubrovsky AS. Nerve blocks in pediatric and adolescent headache disorders. Curr Pain Headache Rep. 2017; 21(12):50.
3. Ambrosini A, Vandenheede M, Rossi P, et al. Suboccipital injection with a mixture of rapid- and long-acting steroids in cluster headache: a double-blind placebo-controlled study. Pain. 2005; 118(1-2): 92-96.
4. Dubrovsky S, Friedman D, Kocilowicz H. Pediatric post-traumatic headaches and peripheral nerve blocks of the scalp: a case series and patient satisfaction survey. Headache. 2014; 54(5):878-887.
5. Blumenfeld A, Ashkenazi A, Napchan U, et al. Expert consensus recommendations for the performance of peripheral nerve blocks for headaches–a narrative review. Headache. 2013; 53(3):437-446.