Peripheral provocation of cranial autonomic symptoms is not sufficient to trigger cluster headache attacks

Background Recently it has been suggested that low frequency stimulation of the sphenopalatine ganglion (SPG) may provoke cluster-like attacks in cluster headache (CH) patients. The question arises whether a robust activation of cranial autonomic symptoms is sufficient to trigger CH attacks. Methods Kinetic oscillation stimulation (KOS) of the nasal mucosa generates ipsilateral marked autonomic symptoms, among which lacrimation is quantitatively measurable. KOS was applied to 29 CH-patients, including both episodic and chronic course. We measured lacrimation at rest and during stimulation, and assessed CH attacks within 24 hours after the experiment. Results Autonomic symptoms including lacrimation were robust and significantly generated, compared to rest. Six patients were lost to follow-up, but did not develop an attack during their stay in the clinic. Of the remaining 23 patients, none developed an attack in the next 4 hours after stimulation, despite marked cranial autonomic symptoms during stimulation. Discussion Peripheral stimulation close to the SPG generated a strong parasympathetic response. However, this stimulation was not sufficient to induce CH attacks, which suggests that a central component is crucial to attack generation.