Cluster Headaches

What are Cluster Headaches?

Cluster headache is pain that occurs along one side of the head. It's frequently described as pain that occurs around, behind, or above the eye and along the temple in cyclic patterns or clusters. The pain of a cluster headache is very severe. Many patients describe a “drilling” type of sensation.

For classification as a true cluster headache, associated autonomic features such as tearing/watering of the eye, redness of the conjunctiva, rhinorrhea or nasal stuffiness, eyelid drooping,sweating on one side of the face, or changes in pupil size (with the pupil on the affected side becoming notably smaller) are usually present. The headache lasts from 15 minutes to a maximum duration of about 3 hours. However, the headache can recur up to eight times daily. [1]

What Causes Cluster Headaches?

The cause of cluster headaches is unknown. However, the headaches occur when a nerve pathway in the base of the brain (the trigeminal-autonomic reflex pathway) is activated. The trigeminal nerve is the main nerve of the face responsible for sensations (such as heat or pain.)

When activated, the trigeminal nerve causes the eye pain associated with cluster headaches. The trigeminal nerve also stimulates another group of nerves that causes the eye tearing and redness, nasal congestion, and discharge associated with cluster attacks.

The activation of the trigeminal nerve appears to come from a deeper part of the brain called the hypothalamus. The hypothalamus is home to our "internal biologic clock," which regulates our sleep and wake cycles on a 24-hour schedule. Recent imaging studies have shown activation or stimulation of the hypothalamus during a cluster attack.[2]

Source; [1] [2]