Pharmacology of Interventional Headache Management

Abstract

Local anesthetics, corticosteroids, and botulinum toxin are the drugs widely used in interventional headache management. Local anesthetics are used in peripheral nerve blocks, trigger point injections, and sphenopalatine ganglion block. Local anesthetics preferentially bind to voltage-gated sodium channels when they are in the inactivated state, prolong the duration of inactivation, prevent the firing and propagation of the action potentials, and consequently block sensory information. Analgesia longer than the anesthetic effect could be achieved with peripheral nerve blocks due to central pain modulation. The most widely used local anesthetics for peripheral nerve blocks and trigger point injections are bupivacaine and lidocaine. The duration of the analgesia caused by a peripheral nerve block is prolonged by adding steroids to local anesthetics. Corticosteroids show their effects in interventional headache management via their anti-inflammatory, weak membrane stabilizer properties and by inhibiting unmyelinated C-fiber transmission. Botulinum toxin, approved for chronic migraine, prevents acetylcholine release at the neuromuscular junction or neuroeffector junctions by cleaving one of the SNARE proteins and by rendering this protein useless. A suggested mechanism for the efficacy of BoNT in chronic migraine is the inhibition of peripheral sensitization and indirectly reduced central sensitization. BoNT inhibits the release of neuropeptides such as substance P and calcitonin gene-related peptide that are associated with pain. It is essential to follow the PREEMPT onabotulinum toxin A injection protocols of fixed-site/fixed-dose or follow-the-pain to achieve maximum efficacy in chronic migraine.