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What Are Cluster Headaches?
Cluster headaches are one of the most painful type of headache. They are marked by excruciating stabbing and penetrating pain, which is usually centered around the eye. Cluster headache attacks occur very suddenly and without warning, with the pain peaking within 15 minutes.
Symptoms of Cluster Headache Attacks
In addition to pain, symptoms of cluster headaches may include:
Who Gets Cluster Headaches?
Treatment of cluster headaches focuses on relieving pain when attacks occur, and on preventive strategies to reduce attack duration and frequency. Oxygen therapy and injections of sumatriptan (Imitrex, generic) are the most effective treatments for acute attacks. Verapamil (Calan, generic), a high blood pressure drug, is typically the first choice of medication used for long-term prevention.
Behavioral treatments can be a helpful supplement to drug therapy. These treatments include relaxation therapy, biofeedback, cognitive-behavioral therapy, and stress management. Patients should also identify and avoid any triggers, such as alcohol use and cigarette smoking, which may provoke cluster headache attacks.
Survey of Cluster Headache Patients
Results from the U.S. Cluster Headache Survey, the largest study of cluster headache patients ever completed in the United States, reveal:
Cluster headaches are among the most painful, and least common, of all headaches. The pain can be so excruciating that they are sometimes referred to as "suicide headaches." Their signature is a pattern of periodic cycles ("clusters") of headache attacks, which may be either:
Timing of an Attack. Cluster headache attacks tend to occur with great regularity at the same time of day. (For this reason, cluster headaches are sometimes referred to as "alarm clock" headaches.) Most attacks occur between early evening and early morning, with peak time of midnight - 3 a.m.
Duration of an Attack. A single cluster attack is usually brief but extremely painful, lasting about 15 minutes – 2 hours if left untreated.
Number of Attacks per Day. During an active cycle, people can experience as few as 1 attack every other day to as many as 8 attacks a day.
Duration of Cycles. Attack cycles typically last 6 - 12 weeks with remissions lasting up to 1 year. In the chronic form, attacks are ongoing, and there is little remission. Attacks cycles tend to occur seasonally, most often in the spring and autumn.
Cluster headaches are a type of primary headache. A headache is considered primary when it is not caused by another disease or medical condition. Other primary headaches that resemble cluster headache include:
Cluster headaches, like migraines, are likely due to an interaction of abnormalities in the blood vessels and nerves that affect regions in the face.
Evidence strongly suggests that abnormalities in the hypothalamus, a complex structure located deep in the brain, play a major role in cluster headaches. Advanced imaging techniques have shown that a specific area in the hypothalamus is activated during a cluster headache attack.
The hypothalamus is involved in the regulation of many important chemicals and nerve pathways, including:
By some not completely understood mechanism, the trigeminal nerve is also involved. The trigeminal nerve carries sensations from the face to the brain.
Circadian Abnormalities. Cluster attacks often occur during specific sleep stages. They also often follow the seasonal increase in warmth and light. Many patients report an increase in attacks when daylight savings time changes occur in the fall and spring. Researchers have therefore focused attention on circadian rhythms, and in particular small clusters of nerves in the hypothalamus that act like biologic clocks. The hormone melatonin is also involved in the body's biologic rhythms.
Cluster headaches are associated with dilation (widening) of blood vessels and inflammation of nerves behind the eye.
What causes these events and how they relate to cluster headaches are still unclear. Because blood vessel dilation appears to follow, not precede, the pain, some action originating in the brain is likely to be part of the process.
Some evidence suggests that abnormalities in the sympathetic (also called autonomic) nervous system may contribute to cluster headaches. This system regulates non-voluntary muscle actions in the body, such as in the heart and blood vessels.
The pain of cluster headaches can be intolerable. In fact, a higher-than-average rate of suicidal thoughts has been reported in men with these headaches. Eventually, as people age, the attacks cease, but doctors cannot predict when or how they will end.
Anxiety and depression are common among people with cluster headaches, which can affect functioning and quality of life.
Some patients with cluster headaches experience migraine-like aura. Research suggests that headaches that are accompanied by aura may increase the risk of stroke or transient ischemic attack (TIA). TIA symptoms are similar to those of stroke, but last only briefly. A TIA is often a warning sign that a person is at risk for having a more severe stroke. Headaches with auras may also increase the risk for eye retinal damage (retinopathy). Aura-related headaches may affect the small blood vessels in the brain and the eyes, thereby increasing the risks for stroke and retinopathy.
Cluster headaches are rare, affecting less than 1% of the population.
Cluster headaches can affect all ages, from children to the elderly, but are most common from young adulthood through middle age. In men, the typical age of onset is in the 30s. In women, cluster headaches often develop in the 60s.
Men are 2 - 3 times more likely to have cluster headaches than women. Unlike with migraines, fluctuations in estrogen and other female hormones do not appear play a role in cluster headaches.
Lifestyle factors, including smoking, alcohol abuse, and stress (in particular stressful work situations), definitely affect cluster headaches. Smoking can trigger attacks. (However, quitting smoking generally does not stop the headaches.) Alcohol, especially beer, is the most common attack trigger.
Cluster headaches tend to run in families, suggesting a genetic component may be involved in some cases.
About half of people with cluster headache have a personal or family history of migraine. About 15% of patients have both kinds of headache.
Head injury with brain concussion appears to increase the risk of cluster headaches, although a causal relationship has not been proven.
Cluster headaches tend to occur during specific sleep stages and have been associated with several sleep disorders, including narcolepsy, insomnia, restless legs syndrome, and sleep apnea.
Sleep apnea, a disorder in which a person's breathing pauses during the night, perhaps hundreds of times, is of particular interest. In some people, apnea may trigger a cluster headache during the first few hours of sleep, making patients susceptible to follow-up attacks during the following midday to afternoon periods. Treating patients who have both disorders with a device called CPAP, which opens the airways, may help improve both conditions.
The following conditions and substances may trigger cluster attacks:
Triggers usually have an effect only during active cluster cycles. When the disorder is in remission, such triggers rarely set off the headaches.
Cluster headaches usually strike suddenly and without warning, although some people have a migraine-type aura before the attack. The pain is deep, constant, boring, piercing, or burning in nature, and located in, behind, or around the eye. The pain then spreads to the forehead, jaw, upper teeth, temples, nostrils, shoulder or neck. The pain and other symptoms usually remain on one side of the head.
The pain generally reaches very severe levels within 15 minutes. Patients may feel agitated or restless during an attack and often want to isolate themselves and then move around. Gastrointestinal symptoms are not very common.
Other typical symptoms include:
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).
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:
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.
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:
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.
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:
Management of cluster headaches focuses on:
The most effective and best-studied treatments for a cluster attack are:
Relief can occur in 5 - 10 minutes. Oxygen and sumatriptan injection are sometimes given together.
Other drugs that may be used for acute attacks are nasal sprays of dihydroergotamine or lidocaine.
Cluster headache attacks are usually short, lasting from 15 - 180 minutes, and the excruciating pain may have subsided by the time a patient reaches a doctor’s office or emergency room.
Because it can be difficult to treat attacks when they occur, treatment efforts focus on the prevention of attacks during cluster cycles. Although certain drugs are standard, preventive therapy needs to be individually tailored for each patient. The doctor may prescribe a combination of drugs.
Verapamil (Calan, generic), a calcium-channel blocker drug, is the mainstay preventive treatment for cluster headaches. However, it can take 2 - 3 weeks for this drug to take effect. During this period, corticosteroids (typically prednisone) may be used as an initial transitional therapy. For long-term treatment of chronic cluster headaches, lithium may be used as an alternative to verapamil.
Although they are not FDA-approved for cluster headache, anti-seizure drugs such as divalproex sodium (Depakote, generic) valproate sodium (Depacon, generic), valproic acid (Depakene, generic), topiramate (Topamax, generic), and gabapentin (Neurontin) are sometimes used for preventive treatment.
Behavioral Treatments. Behavioral therapies are a helpful accompaniment to drug treatment. These approaches can help with pain management and enable patients to feel more in control of their condition.
Behavioral approaches include:
Lifestyle Changes. Patients should avoid the following triggers that may provoke cluster headache attacks:
Breathing pure oxygen (by face mask, for 15 minutes or less) is one of the most effective and safest treatments for cluster headache attacks. It is often the first choice treatment. Inhalation of oxygen raises blood oxygen levels, therefore relaxing narrowed blood vessels.
Triptans are drugs that are usually used to treat migraine headaches. They can also help stop a cluster attack. An Injection of sumatriptan (Imitrex, generic) is the standard triptan treatment and is FDA-approved for cluster headaches. Sumatriptan injections usually work within 15 minutes. The nasal spray form may also be effective for some patients, and generally provides relief within 30 minutes. The spray seems to work best for attacks that last at least 45 minutes, although some people find it does not work as well as the injectable form.
Zolmitriptan (Zomig) is another triptan drug used for cluster headache treatment. It is given in either oral or nasal spray form. Zolmitriptan may have fewer side effects than sumatriptan.
Side Effects. Side effects of sumatriptan may include:
Complications and Contraindications of Triptans. The following are potentially serious problems with triptans:
Injections of the ergotamine-derived drug known as dihydroergotamine (DHE, Migranal) can stop cluster attacks within 5 minutes in many patients, offering benefits similar to injectable sumatriptan. Ergotamine is also available in the form of a nasal spray, rectal suppositories, and tablets.
Ergotamine can have dangerous drug interactions with many medications, including sumatriptan. All ergotamine products approved by the Food and Drug Administration (FDA) contain a "black box" warning in the prescription label explaining these drug interactions. Because ergotamine constricts blood vessels, patients with peripheral vascular disease should not use this drug.
Lidocaine, a local anesthetic, may be useful in nasal-spray or nasal-drop form for stopping cluster attacks. It usually takes effect within about 40 minutes. Lidocaine can have an unpleasant taste. Some doctors recommend that patients try a nasal application of lidocaine to see if it helps ease pain.
Capsaicin is a compound derived from hot pepper. Some patients who have not found relief through other medications use it to treat or prevent cluster headaches by applying it intranasally. There have been few studies to confirm its effectiveness. It can cause an intense burning sensation.
Calcium-channel blockers, commonly used to treat high blood pressure and heart disease, are important drugs for preventing episodic and chronic cluster headaches. Verapamil (Calan, generic) is the standard calcium-channel blocker used for cluster headache prevention. It can take 2 - 3 weeks to have a full effect, and a corticosteroid drug may be used in combination during this transitional period. Constipation is a common side effect.
People taking calcium-channel blockers should not stop taking the drug abruptly. Doing so can dangerously increase blood pressure. Overdose can cause dangerously low blood pressure and slow heart beats.
Lithium (Eskalith, generic), commonly used for bipolar disorder, may also help prevent cluster headaches. The benefits of lithium usually appear within 2 weeks of starting the drug, and often within the first week. Lithium may be used alone or with other drugs. Lithium can have many side effects including trembling hands, nausea, and increased thirst. Weight gain is a common side effect with long-term use.
Corticosteroid drugs (also called steroids) are very useful as transitional drugs for stabilizing patients after an attack until a maintenance drug, such as verapamil, begins to take effect. Prednisone (generic) and dexamethasone (Decadron, generic) are the standard steroid drugs used for short-term cluster headache transitional treatment. These drugs are typically taken for a week and then gradually tapered off. If headaches return, the patient may start taking the steroid again. Unfortunately, long-term use of steroids can lead to serious side effects so they cannot be taken for on-going prevention.
Steroid injections may also provide short-term relief. Some patients are helped by an occipital nerve block in which an anesthetic and a corticosteroid are injected into the occipital nerve in the back of the head. Researchers are also investigating suboccipital injections where a steroid is injected into the base of the skull on the same side as the headache attack.
Anti-seizure drugs, which are used for epilepsy treatment, may be helpful for preventing cluster headaches in some patients. They include older drugs such as divalproex (Depakote, generic), valproate (Depacon, generic), and valproic acid (Depakene, generic) and newer drugs such as topiramate (Topamax, generic) and gabapentin (Neurontin, generic). More research needs to be done to evaluate how effective these drugs are at preventing cluster headaches.These drugs can have significant side effects. Some anti-seizure drugs, particularly valproate products, can increase the risk for birth defects and should not be taken by pregnant women. All anti-seizure drugs can increase the risks of suicidal thoughts and behavior (suicidality).
Botulinum. Botulinum toxin A (Botox) injections are typically used to smooth wrinkles. Botox is also being studied for treatment of headaches, and is approved for prevention of chronic migraine. Research on its use for cluster headache prevention is still preliminary, and there is not sufficient evidence to support its efficacy.
Melatonin. Small reports indicate that melatonin, a brain hormone that helps to regulate the sleep-wake cycle, may help prevent episodic or chronic cluster headaches. Melatonin supplements are sold in health food stores, but as with most natural remedies, the quality of different preparations varies, and they have not been rigorously tested for safety or effectiveness. More studies are needed.
In rare cases, surgical intervention may be considered for patients with chronic cluster headaches that do not respond to other treatments. Patients whose headaches have not gone into remission for at least a year may also be candidates for surgery. Most surgical approaches for cluster headache are still considered experimental, having been tested only on a relatively small number of patients. Surgery has shown limited success and can have distressing side effects. However, some surgical techniques, such as deep brain electrical stimulation, are showing promise.
Deep brain stimulation (also called neurostimulation) may relieve chronic cluster headaches in some patients who do not respond to drug therapy. A similar technique is approved for treating the tremors associated with Parkinson's disease. The surgeon implants a tiny wire in a specific part of the hypothalamus. The wire receives electrical pulses from a small generator implanted under the collarbone.
Although only a small number of patients have been treated, results to date are promising. Some patients have remained completely free of pain for an average of more than 7 months when the electrode is switched on. When the device is turned off, headaches reappear within days to weeks. The procedure is reversible and appears to be generally safe, although a few cases of fatal cerebral hemorrhage have occurred.
Occipital nerve stimulation is being investigated as a less invasive and less risky alternative to deep brain hypothalamus stimulation. Recent studies have reported promising results in a small group of patients with cluster headaches. Some patients became pain-free, while others had reduced frequency of headache attacks.
The vagus nerve runs between the brain and the abdomen. Vagus nerve stimulation (VNS) is a surgical procedure in which a small generator is placed under the skin on the left side of the chest. A surgeon makes a second incision in the neck and connects a wire from the generator to the vagus nerve. A doctor programs the generator to send mild electrical pulses at regular intervals. These pulses stimulate the vagus nerve.
VNS is sometimes used to treat epilepsy and depression that does not respond to drugs. It is also being investigated as a possible treatment for chronic migraine and cluster headaches.
Percutaneous Radiofrequency Retrogasserian Rhizotomy. Percutaneous radiofrequency retrogasserian rhizotomy (PRFR) generates heat to destroy pain-carrying nerve fibers in the face. Unfortunately complications are common and include numbness, weakness during chewing, changes in tearing and salivation, and facial pain. In severe, but rare, cases, complications include damage to the cornea and vision loss.
Percutaneous Retrogasserian Glycerol Rhizolysis. Percutaneous retrogasserian glycerol rhizolysis (PRGR) is a less invasive technique than PRFR and has fewer complications. It involves injections of glycerol to block the facial nerves that cause the pain. Cluster headaches usually recur.
Microvascular Decompression of the Trigeminal Nerve. Microvascular decompression frees the trigeminal nerve from any blood vessels that are pressing against it. The procedure is risky, and possible complications include nerve and blood vessel injury and spinal fluid leakage. There is reasonably good evidence that it is not effective for treatment of cluster headaches.
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