The practice of headache medicine has evolved over time, and the use of peripheral nerve blocks has been gradually increasing among practitioners. Peripheral nerve blocks are generally safe, well-tolerated office-based procedures that can be performed for the acute treatment of numerous headache disorders. For reasons that are less clear, nerve blocks can have prolonged effects beyond the duration of the injected anesthetic, at times lasting weeks to months.1 As such, nerve blocks can also be used for preventive treatment.
Although peripheral nerve blocks target peripheral nerves, the duration of benefit in some cases suggests that these procedures likely also have effects on central pain–modulating structures. One study that supports the theory of peripheral nerve blocks causing central pain modulation demonstrated that after performing occipital nerve blocks in the setting of an acute migraine, migraine pain, brush allodynia in the trigeminal nerve distribution, and photophobia improved.2
In a survey study conducted by the American Headache Society, occipital neuralgia and chronic migraine were the most common indications for performing peripheral nerve blocks. Clinicians were more likely to perform nerve blocks if the patient had local tenderness in the region where the nerve block was performed.3
The greater occipital nerve is the most commonly targeted nerve for peripheral nerve blockade. Some other common peripheral nerve block targets are the lesser occipital nerve, supratrochlear nerve, supraorbital nerve, and auriculotemporal nerve. Nerve blocks can be performed using various techniques, volumes, and drugs. Lidocaine and bupivacaine are the most commonly used anesthetics for these procedures.3 These anesthetics can be injected with or without steroids. The use of steroids in peripheral nerve blocks is controversial for different headache disorders, but some of the most compelling evidence for steroid use is for the treatment of both episodic and chronic cluster headaches.4 In addition to the use of anesthetic combined with steroid, one study demonstrated that betamethasone injections without anesthetic were more effective than placebo for the treatment of cluster headache.5 The use of anesthetic combined with steroids is usually preferred because this combination tends to generate a more rapid analgesic effect than steroids alone.
Steroids should be used with caution given the potential for Cushing's syndrome, glaucoma, cutaneous atrophy, and alopecia.6,7 Because of these possible complications, steroid use should be avoided in nerve blocks around face, especially given the risk of significant cosmetic disfigurement. These local cutaneous changes can have an additive effect when serial nerve blocks with steroids are performed within a relatively short time period. If repeat injections with steroids are indicated based a beneficial patient response, examination of the injection site should be performed before the procedure is repeated to look for signs of cutaneous atrophy and alopecia. If present, steroid use should be avoided. In clinical practice, steroids are typically used in nerve blocks no more frequently than once every three months.