Botulinum toxins are neurotoxins which inhibit the release of acetylcholine from presynaptic nerve terminals resulting in muscle relaxation.  Another mechanism of action is blocking the release of CGRP and Substance P from nerve terminals, thereby inhibiting the sterile neurogenic inflammation.  BoNT-A was discovered serendipitously by Dr. William Binder who was using it to treat wrinkles.  Many patients returned and reported a significant amelioration of their headaches. Thereafter, small controlled trials were performed showing moderate efficacy.²⁸⁵

Botulinum toxin type A (BoNT-A) shows significant promise in the management of a variety of headache types.  Pivotal double-blind placebo-controlled trials are currently underway to establish the potential efficacy in the management of headache.  It is now recognized that BoNT-A is an effective prophylactic treatment in the primary headache disorders.^243,244

My personal experience^62,242,286 is based upon experience with over 600 patients and 2200 injection cycles.  The majority of these patients (>95%) had previously failed three or more of the preventive pharmacologic therapies for migraine previously discussed.  Outcome was measured on a 1 to 5 scale from no change to excellent improvement.  Overall, 91% of the patients noted some level of improvement and, after three treatments, 75% of the patients reported improvement as good to excellent.⁶²  The mechanism of action is based upon two factors:  BoNT-A is a focally acting neurotoxin that inhibits release of acetylcholine and other neurotransmitters from presynaptic nerve endings.  At the neuromuscular junction this results in reduced muscle tone, but there is good evidence now that BoNT-A affects pain signaling and reduces the local release of nociceptive neuropeptides.^287-289

In our experience, patients with migraine with aura usually experience reduction in headaches along with reduction in aura.  Menstrual migraine associated headache is also reduced following the use of botulinum toxin, prompting us to consider whether there is central desensitization from the peripheral muscle and scalp injections of botulinum toxin.

Our results and those of others suggest that BoNT-A may be an effective and safe prophylactic treatment variety of moderate to severe chronic headache types.²⁴³

As pointed out by Silberstein and Lipton,⁹ the goals of treatment are to relieve or prevent  pain in the associated symptoms of migraine and optimize the patient’s ability to function normally.  The patient should learn to identify and avoid headache triggers.  The wide variety of drug therapies available, numbering over 400, attest to the fact that no particular therapy or combination of drugs is completely effective.  The management of the patient with migraine is a complex problem requiring evaluation and elimination of possible precipitating factors, including psychogenic ones, as well as vigorous management of the acute attack and attempts at prevention of recurrent episodes.  The care of the migraine patient continues to represent, in many instances, a major therapeutic challenge.