What is a Cluster Headache?
Cluster headaches are much less common than migraines. They occur in young adulthood, usually in men. These excruciatingly severe stabbing headaches are usually located behind one eye or the other, often accompanied by redness and tearing of the eye, and nasal congestion. The eyelid may droop, and the pupil may change size. The headaches are usually more brief and more intense than migraines.
While a migraine patient may want to lie still, a cluster headache patient may display more agitated behavior, such as wanting to pace.
Cluster headaches usually begin as intermittent headaches that occur over a “cluster” of several weeks, followed by many months or even years of no symptoms. The individual headaches that occur are often circadian, meaning that they may occur at the same time every day, often an hour or so after going to sleep. A patient may have anywhere from one to five attacks per day.
How is a cluster headache diagnosed?
During a physical examination, patients may show signs of irritation of nerves going to the affected eye (small pupil, droopy eyelid, numbness or tenderness of the forehead), even between attacks.
Rarely, a cluster-like headache may be caused by unusual disorders that will show up on MRI imaging, but in most cases, routine brain scans are normal. In a few research studies, specialized imaging in some patients has demonstrated very subtle abnormalities in the hypothalamus on the side of the attacks.
How is a cluster headache treated?
A cluster headache responds to similar migraine preventative drugs and can often be brought under better control temporarily by steroids or nerve blocks. The individual headaches are tricky to treat, as they may be too brief for a pill to be properly absorbed before the attack begins to go away on its own. Many patients respond remarkably well within minutes to inhaled 100 percent oxygen. Others may benefit from topical anesthetic applied inside the nose, injected or nasal triptans, or, in appropriate cases, nasal or mouth-absorbed narcotics.
In some patients cluster headaches go on to become chronic, occurring throughout the year, often more than once a day. Treatments to reduce the function of the trigeminal or occipital nerves may help in certain cases. These treatments are briefly mentioned in the section on trigeminal neuralgia and occipital neuralgia.
There is evidence from research MRI and PET scans that a cluster headache involves dysfunction in the hypothalamus region of the brain. This tiny but important brain structure controls or influences a wide variety of bodily functions, including the biological clock. Investigations are underway to treat this abnormal area using deep brain stimulators (electrode needles placed surgically in the brain, connected to a pacemaker-like box). Currently, it is considered highly experimental, but deep brain stimulation may hold future promise for patients who do not benefit from other therapies.