Many patients report a delay of more than 5 years in the diagnosis of their cluster headaches. Migraine-like symptoms (light and sound sensitivity, aura, nausea, vomiting) are major reasons for the frequent misdiagnosis. In some cases, patients are inappropriately treated for other types of headaches (like migraine) or health conditions (like sinusitis).
Medical and Personal History
Cluster headache is diagnosed by medical history, including the pattern of recurrent attacks, and by typical symptoms (swollen eyelid, watery eye, runny nose). Keeping a headache diary to record a description of attacks can help the doctor make an accurate diagnosis. The patient should describe to the doctor:
- Frequency of attacks (if keeping a diary, record the date and time of each attack)
- Description of pain (stabbing, throbbing)
- Location of pain
- Duration of pain
- Intensity of pain (using a number scale like the one below)
- Associated symptoms (tearing eyes, nausea and vomiting, sweating)
- Any measures that bring relief (applying pressure, going out for fresh air)
- Any events that preceded or may have triggered the attack
- Any medications you are taking
- Behaviors during a headache (restlessness, agitation)
- Snoring, sleep disturbances, or daytime sleepiness (these could relate to sleep apnea, which is sometimes associated with cluster headache)
Pain may be indicated by using a number system:
1 = Mild, barely noticeable
2 = Noticeable, but does not interfere with work or activities
3 = Distracts from work or activities
4 = Makes work or activities very difficult
5 = Incapacitating
In diagnosing a chronic headache, the doctor will examine the head and neck and perform a neurologic examination, which includes a series of simple exercises to test strength, reflexes, coordination, and sensation. The doctor may also examine the eyes. The doctor may ask questions to test short-term memory and related aspects of mental function.
The doctor may order an imaging test to check for brain abnormalities that may be causing the headaches. For imaging tests, MRIs are preferred over computed tomography (CT) scans because they do not expose patients to radiation.
Ruling Out Other Headaches and Medical Disorders
As part of the diagnosis, a doctor should rule out other headaches and disorders. If the results of the history and physical examination suggest other or accompanying causes of headaches or serious complications, extensive imaging tests are performed.
Migraines. Cluster headaches are often misdiagnosed as migraines but they are quite different:
- Frequency and Duration. Cluster headaches generally last 15 minutes to a few hours and can occur several times a day. A single migraine attack is continuous over the course of one or several days.
- Behavior. Cluster headache sufferers tend to move about while migraine sufferers usually want to lie down.
Nevertheless, in both cases, the headache suffers can be highly sensitive to light and noise, which may make it difficult to distinguish between them.
Other Headaches. Other primary headaches that resemble cluster headaches include SUNCT (short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing) and chronic paroxysmal hemicranias. Cluster headache may also resemble some secondary headaches notably trigeminal neuralgia (TN), temporal arteritis, and sinus headaches. Cluster symptoms, however, are usually precise enough to rule out these other types of headaches.
Tear in the Carotid Artery. A tear in the carotid artery (which carries blood to the brain) can cause pain that resembles a cluster headache. People with this condition may also respond to sumatriptan, a drug used to treat a cluster attack. Doctors should consider imaging tests for patients with a first episode of cluster headache in which this event is suspected.
Orbital Myositis. An unusual condition called orbital myositis, which produces swelling of the muscles around the eye, may mimic symptoms of cluster headache. This condition should be considered in patients who have unusual symptoms such as protrusion of the eyeball, painful eye movements, or pain that does not dissipate within 3 hours.
Headache Symptoms that Could Indicate Serious Underlying Disorders
Headaches indicating a serious underlying problem, such as cerebrovascular disorder or malignant hypertension, are uncommon. (A headache without other neurological symptoms is not a common symptom of a brain tumor.) People with existing chronic headaches may, however, miss a more serious condition believing it to be one of their usual headaches. Such patients should immediately call a doctor if the quality of a headache or accompanying symptoms has changed. Everyone should call a doctor for any of the following symptoms:
- Sudden, severe headache that persists or increases in intensity over the following hours, sometimes accompanied by nausea, vomiting, or altered mental states (possible indication of hemorrhagic stroke, which is also called brain hemorrhage).
- Sudden, very severe headache, worse than any headache ever experienced (possible indication of brain hemorrhage or a ruptured aneurysm).
- Chronic or severe headaches that begin after age 50.
- Headaches accompanied by other symptoms, such as memory loss, confusion, loss of balance, changes in speech or vision, or loss of strength in or numbness or tingling in arms or legs (possibility of stroke).
- Headaches after head injury, especially if drowsiness or nausea are present (possibility of brain hemorrhage).
- Headaches accompanied by fever, stiff neck, nausea and vomiting (possibility of meningitis).
- Headaches that increase with coughing or straining (possibility of brain swelling).
- A throbbing pain around or behind the eyes or in the forehead accompanied by redness in the eye and perceptions of halos or rings around lights (possibility of acute glaucoma).
- A one-sided headache in the temple in elderly people; the artery in the temple is firm and knotty and has no pulse; scalp is tender (possibility of temporal arteritis, which can cause blindness or stroke if not treated).
- Sudden onset and then persistent, throbbing pain around the eye possibly spreading to the ear or neck unrelieved by pain medication (possibility of blood clot in one of the sinus veins of the brain).