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Overview of Cluster Headache
Neurologists diagnose headaches according to the International Headache Society (I.H.S.) Classification System {Cephalgia 2004;24 (Suppl 1)}. This system recognizes four primary headache types. The phrase, "primary headache type" means that the headache is not caused by some other disease process. Primary headache types include:
- Migraine Headache
- Tension Headache
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Cluster Headache and Chronic Paroxysmal Hemicrania,
- Other Headaches not Otherwise Explained
Cluster headaches are, by far, the most severe headache. The headache intensity has been severe enough to make some patients contemplate suicide.
These headaches are called “cluster” because the patient experiences a group or series of headaches a period of time and then the headaches will disappear for several months before they recur. Cluster headaches were initially described by an allergist named Horton and were felt to be allergic-or histamine-related because Horton had a series of patients that had these horrible headaches the same time every year. Histamine, known to be important for allergic reactions, also triggers a headache in a susceptible patient. Other known triggers include red wines and nitroglycerin-containing medications.
Characteristics of a Cluster Headache:
- A typical cluster headache will be described as an "ice-pick" type pain in the eye or just above one eye.
- It is typically a relatively short headache.
- Most patients would rather walk around during the headache than lie down.
- They tend to occur at night and will wake patients from their sleep.
- A cluster headache is sometimes associated with eye findings on the affected side with the pain. Eye findings may include redness, tearing, and pupil changes.
Paroxsmal hemicrania is a separate condition that mimics cluster headache and shares many of the same symptoms. This disease however responds completely to the drug indocin. However since both are very similar, they are grouped together in the cluster section.
Cluster and migraines headaches are sometimes referred to as vascular headaches. Dr. Loftus does not like this categorization because research is demonstrating that these headache types are clearly different entities and grouping them causes unneeded confusion. Patients will sometimes be told that they have "cluster migraines" and this is the worst label since it fails to convey to the patient which diagnosis they have - i.e., cluster or migraine. While a rare patient has both cluster headaches and migraine headaches, the typical patient who uses the term "cluster migraines" even from their physician, has migraine headaches that need prevention.
If you are unsure if you have cluster type headaches, then read the page about the definition of cluster headache. If you know you have cluster and you are in the middle of a cluster cycle, you may want to start on the cluster prevention page. If you are not currently taking an effective treatment when you have an acute attack, then please see the acute cluster treatment page.