The cause of cluster headache is unknown.
Cluster headaches were historically described as vascular headaches, with the belief that intense pain was caused by dilation of blood vessels which in turn, was thought to create pressure on the trigeminal nerve.
The vascular theory has been called into question  and other mechanisms are being considered.
The Third Edition of the Internal Classification of Headache disorders classifies CH as belonging to the trigeminal autonomic cephalalgias.
The cause of cluster headache is unknown. Cluster headaches were historically described as vascular headaches, with the belief that intense pain was caused by dilation of blood vessels which in turn, was thought to create pressure on the trigeminal nerve. The vascular theory has been called into question  and other mechanisms are being considered. The Third Edition of the Internal Classification of Headache disorders classifies CH as belonging to the trigeminal autonomic cephalalgias.
Cluster headache