What are cluster headaches?
Cluster headaches are the most severe headaches. A cluster headache can be many times more
intense than a migraine attack. It has been called the "suicide
headache" because many people have taken their lives either during an
attack or in anticipation of an attack.
The term "cluster headache" refers to headaches that have a
characteristic grouping of attacks. Cluster headaches occur one to three times
per day during a cluster period, which may last 2 weeks to 3 months. The
headaches may disappear completely (go into "remission") for months or
years, only to recur. A cluster headache typically awakens a person from sleep 1
to 2 hours after going to bed. These nocturnal attacks can be more severe than
the daytime attacks.
Who is affected by cluster headaches?
Cluster headaches are the least common type of primary headaches, affecting
less than 1 in 1,000 people. Cluster headaches are a young person’s disease:
the headaches typically start before age 30. Cluster headaches are more common
in men, but more women are starting to be diagnosed with this disorder. The male
to female gender headaches appear to be six times more common in men than women,
especially men in their 20s or 30s.
What causes cluster headaches?
The true biochemical cause of cluster headaches is unknown. However, the
headaches occur when a trigeminal-autonomic reflex pathway in the brainstem is
activated. The trigeminal nerve is the chief sensory nerve of the face. When
activated, the trigeminal nerve leads to the eye pain associated with cluster
headaches. The trigeminal nerve also stimulates the parasympathetic autonomic
system, which causes the eye tearing and redness, nasal congestion and discharge
with cluster attacks. Cluster headaches appear to be generated by the
hypothalamus (the part of the brain that is home to the suprachiasmatic nucleus
or circadian clock). Recent imaging studies have shown activation or stimulation
of the hypothalamus during a cluster attack.
Cluster headaches usually are not caused by an underlying condition such as a
tumor or aneurysm.
What triggers cluster headaches?
The season is the most common trigger for cluster headaches, which often
occur in the spring or autumn. Due to their seasonal nature, cluster headaches
are often mistakenly associated with allergies or business stress. The seasonal
nature of cluster headaches most likely results from stimulation or activation
of the hypothalamus.
Cluster headaches are also common in people who smoke and drink alcohol
frequently.