Insights Into the Mechanism of OnabotulinumtoxinA in Chronic Migraine
Article first published online: 14 NOV 2011
© 2011 American Headache Society
Headache: The Journal of Head and Face Pain
Volume 51, Issue 10, pages 1573–1577, November/December 2011
How to Cite
Durham, P. L. and Cady, R. (2011), Insights Into the Mechanism of OnabotulinumtoxinA in Chronic Migraine. Headache: The Journal of Head and Face Pain, 51: 1573–1577. doi: 10.1111/j.1526-4610.2011.02022.x
- Issue published online: 14 NOV 2011
- Article first published online: 14 NOV 2011
- Accepted for publication September 1, 2011.
- chronic migraine;
- peripheral sensitization;
- central sensitization;
- trigger point;
OnabotulinumtoxinA has recently been approved by regulatory agencies in the UK and United States for treatment of chronic migraine based on data generated from the PREEMPT studies. As such, onabotulinumtoxinA is the only prophylactic therapy specifically approved for chronic migraine. Most headache clinicians would agree that acute episodic migraine and chronic migraine differ in their pathophysiology, etiology, diagnosis, and response to pharmacological as well as nonpharmacological therapies. Of the 7 botulinum neurotoxin serotypes, botulinum neurotoxin type A (onabotulinumtoxinA) has been the most thoroughly investigated in preclinical and clinical studies. Based on preclinical studies, onabotulinumtoxinA is known to inhibit the release of excitatory neurotransmitters from both motor and sensory neurons by preventing vesicle fusion to the cell membrane. In addition to the well-documented myorelaxant effects of this neurotoxin, onabotulinumtoxinA can exert a direct analgesic effect that likely involves inhibition of primary and secondary nociceptive neurons. The inhibitory effects of onabotulinumtoxinA are also likely to involve suppressing the activity of myogenic trigger points and decreasing the persistent nociceptive barrage that promotes and maintains central sensitization. This article describes possible mechanisms to explain how onabotulinumtoxinA functions as a therapy for chronic migraine and considers why treatment with the neurotoxin is not effective in some chronic migraineurs.