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 some 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 up to eight
times per day during a cluster period, which may last 2 weeks to 3 months, or
longer. The headaches may disappear completely (go into "remission") for months
or years, only to recur at a later date. 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 an uncommon type of primary
headaches (i.e., a headache that has no structural cause), affecting less than 1
in 1,000 people. Cluster headaches are a young person’s disease, and 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. Thus, they are considered to
be a form of ‘primary’ headache.
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
sinusitis. The seasonal nature of cluster headaches most likely results from
stimulation or activation of the hypothalamus.