Cluster Headaches

Cluster headache (CH) is a primary headache disorder classified alongside with trigeminal autonomic cephalalgias.  CH still is commonly misdiagnosed and patients can wait many years before receiving proper diagnosis and adequate care.

Typically CH consists of recurrent attacks of unilateral pain, which are very severe and usually involve the orbital or periorbital region innervated by the first (ophthalmic) division of the trigeminal nerve.

The activation of the cranial autonomic pathways causes ipsilateral lacrimation, conjunctival injection, nasal congestion or rhinorrhea (or both), ptosis or miosis (or both), and periorbital edema. Only a few, if any, medical disorders are more painful than CH.

The term cluster headache originates from the tendency of attacks to cluster together into stretches lasting several weeks. In the episodic form the attacks can occur at certain times of year, often with a seasonal predilection separated by periods of remission, which last at least a month. Ten percent of patients have the chronic form and have continuous attacks with no interval.

Imaging studies with functional MRI (FMRI) have detected activation ipsilateral to the pain in the region of the posterior hypothalamus which may have a critical role in integrating the pain, cranial autonomic features, and unique timing of cluster headache.