Curr Treat Options Neurol. 2003 Nov;5(6):483-492.   
 
The Use of Botulinum Toxins for Chronic Pain and Headaches.

Argoff CE.

Cohn Pain Management Center, North Shore University Hospital and New York University School of Medicine, 4300 Hempstead Turnpike, Bethpage, NY 11714, USA. pargoff@optonline.net

The use of botulinum toxin in the management of various neurologic and non-neurologic disorders has grown considerably over the past decade. At the same time, new information regarding the mechanism of action of these toxins has evolved allowing for a greater understanding of the versatility of these agents. Although two types of botulinum toxin (type A Botox and type B Myobloc ) are commercially available in the US, most studies of the use of these toxins for the management of chronic pain and headache have been completed with type A. Data from open-label and retrospective studies as well as clinical practice suggest as strongly as possible that there is a role for these agents, especially Botox, in the management of several chronic headache disorders, including chronic migraine, chronic tension-type, cervicogenic, and cluster headache. Emerging data regarding the use of these agents for so-called "analgesic-rebound" headache also appear impressive; however, as of yet, no multicenter, randomized, controlled studies for any headache type have been published that confirm the results seen in noncontrolled studies. Nevertheless, the benefit that some patients experience from this agent is impressive, and this drug appears for many to modify the disorder in a very positive manner. In a similar fashion, data for other pain states are often restricted to open-label and case study approaches; however, clinical experience and some of the available studies (even small controlled studies) suggest a role for the toxins in the management of various chronic pain states, such as myofascial pain, low back pain, and neuropathic pain. One of the greatest challenges ahead for all interested in this area is confirming the benefit seen clinically through appropriately designed multicenter, randomized, controlled studies.

PMID: 14516525 
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J Headache Pain. 2007 Sep;8(4):236-241. Epub 2007 Sep 24.
Botulinum toxin type-A therapy in cluster headache: an open study.

Sostak P, Krause P, Förderreuther S, Reinisch V, Straube A.

Department of Neurology, Klinikum Großhadern, Ludwig-Maximilians University, Marchioninistr. 15, 81377, Munich, Germany, Petra.Sostak@med.uni-muenchen.de.

The objective of this open single-centre study was to evaluate the efficacy and tolerability of botulinum toxin type-A (BTX-A) as add-on in the prophylactic treatment of cluster headache (CH). Twelve male patients with episodic (n=3) or chronic (n=9) CH, unresponsive to common prophylactic medications, were treated with a cumulative dose of 50 International Units (IU) BTX-A according to a standardised injection scheme into the ipsilateral pericranial muscles. One patient with chronic CH experienced a total cessation of attacks and in 2 patients attack intensity and frequency improved. In another patient with chronic CH typical attacks were not influenced, but an ipsilateral continuous occipital headache significantly improved. Patients with episodic CH did not benefit from BTX-A treatment. Tolerability was excellent. THESE FINDINGS PROVIDE EVIDENCE THAT BTX-A MAY BE BENEFICIAL AS AN ADD-ON PROPHYLACTIC THERAPY FOR A LIMITED NUMBER OF PATIENTS WITH CHRONIC CH.

PMID: 17901920 [PubMed}
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Curr Pain Headache Rep. 2009 Apr;13(2):164-7.

The role of nerve blocks and botulinum toxin injections in the management of cluster headaches.
Ailani J, Young WB.

Jefferson Headache Center, Gibbon Building, 111 South 11th Street, Suite 8130, Philadelphia, PA 19107, USA. jessica.ailani@gmail.com

Cluster headache (CH) is a primary headache syndrome that is classified with the trigeminal autonomic cephalalgias. CH treatment involves three steps: acute attack management, transitional therapy, and preventive therapy. Greater occipital nerve block has been shown to be an effective alternative bridge therapy to oral steroids in CH.

BOTULINUM TOXIN TYPE A HAS RECENTLY BEEN STUDIED AS A NEW PREVENTIVE TREATMENT FOR PATIENTS WITH CHRONIC CH, WITH LIMITED SUCCESS.

PMID: 19272284 [PubMed]