Open label experience of repeated OnabotulinumtoxinA injections towards the sphenopalatine ganglion in patients with chronic cluster headache and chronic migraine. - Simmonds L; Jamtøy KA; Aschehoug I; Hara S; Meisingset TW; Matharu MS; Tronvik E; Bratbak DF (Cephalalgia : an international journal of headache, 2024)