A Research Study to Examine Cutaneous Allodynia and Cluster Headache

Inclusion Criteria: * Male and female patients aged 18-75, inclusive * Diagnosis of cluster headache, episodic or chronic. * Patients with episodic CH can be either in active cluster period or not. * Ability to read and understand an informed consent form, where the study protocol is described. Exclusion Criteria: * Patients with abnormal sensory findings on examination, or any known neurological disease that may affect skin sensation (peripheral neuropathy, multiple sclerosis, stroke, etc). * Patients who are cognitively impaired, as determined by investigator * Patients with significant psychiatric disorder that may affect their understanding of the study protocol and/or their cooperation with the investigators. * Patients who had taken an acute pain medication within 24 hours prior to allodynia testing. * Patients with skin diseases that may cause abnormal skin sensation. * Patients who had been treated with a nerve block in the 4 week period prior to allodynia testing * Patients who had been treated with Botulinum neurotoxin within the 4 month period prior to allodynia testing