Neurotoxins: Expanding Uses of Neuromodulators in Medicine--Headache.

Over the course of the past 17 years, since the initial discovery of the association between botulinum toxin-A (BT-A) and the reduction of headache symptoms, the use of this neurotoxin has greatly evolved. BT-A has emerged as an alternative to prophylactic pharmacological therapies in the prevention of chronic migraine headaches, with an excellent safety profile and proven efficacy, and is Food and Drug Administration-approved for on-label use since October 2010. The mechanism of BT-A involves its effect at the neuromuscular junction, inhibition of neuropeptide and neurotransmitter release in peripheral sensory neurons, and retrograde axonal transport allowing for its direct effect on inhibiting central sensitization. Through its diagnostic and therapeutic utility, BT-A has proven to be an integral part in the treatment of chronic headache disorders.