Botulinum Toxin Type A Block of the Otic Ganglion in Chronic Cluster Headache: Safety Issues

Cluster headache (CH) is the most common of the trigeminal autonomic cephalalgias and one of the most severe pains known to man, having a large impact on the sufferer's quality of life. A parasympathetic dysfunction in CH has been suggested. The sphenopalatine ganglion has been a target for treatment of primary headache disorders for more than a century but there are several anatomic and physiologic studies that suggest that another cranial parasympathetic ganglion, the otic ganglion (OG), might be also relevant in CH. In this study OG will be blocked with botulinum toxin type A in a pilot study in 10 patients with chronic cluster headache. Recruitment of patients will be solely in Norway. There is no data available to determine the correct dosage of botulinum toxin. A similar neural structure that has been blocked with botulinum toxin in humans is the sphenopalatine ganglion. The investigators injected 10 patients suffering from intractable chronic cluster headache with botulinum toxin in the sphenopalatine ganglion. 5 patients were given 25 IU and 5 patients were given 50 IU. Even though the number of treated patients is low, there did not appear to be differences in the adverse events profile between those who received 25 Iu and those who received 50 IU. The investigators also previously injected 25 IU botulinum toxin towards the sphenopalatine ganglion bilaterally (i.e. 25 IU in each side) in 10 patients suffering from intractable chronic migraine. Doses of up to 25 IU have been injected in structures adjacent to the otic ganglion, for instance in dystonia towards the lateral pterygoid muscle. Thus it was decided for this study on injection towards the otic ganglion, to explore the safety of 12.5 and 25 IU of botulinum toxin.