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Everything You Need to Know About Cluster Headache Diagnosis

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    They are the worst headaches known to medical science and one of the worst pains of any kind known to medical science. Those who have experienced them will agree. Those who haven’t think of the usual sorts of headaches and wonder what the fuss is about.

    They are NOT the usual sort of headache. They are NOT migraines. Those who suffer from cluster headaches wish they were called something else besides “headache,” some name that would indicate how severe they are. Some call them “attacks” rather than headaches. Some call them suicide headaches, because they have been known to drive people to this desperate treatment. The severity of the attacks, the way they seem to regularly return and the tenacity with which they defy treatment inspire sufferers to personify them into some kind of animate evil: The Beast.

    What causes cluster headache is ultimately unknown, but it seems to involve the hypothalamus, a small but very important organ deep in the center of the brain. It controls the autonomic functions of the body, the stuff we don’t have too think about. It serves as the body’s time clock and controls body temperature, blood vessel status, digestion and many other things.

    Scientists think a malfunction or abnormality of the hypothalamus causes the carotid arteries that feed the brain to enlarge and press on the trigeminal nerves, causing incredible pain. The trigeminal is a bundle of nerves, one bundle on each side of the head, that split into three to serve the upper jaw, face, forehead and temple. This idea got complicated, though, when researchers found that the pain of cluster headache seems to start before the artery expands and touches the trigeminal.

    The Cycle

    “Cluster” means the attacks seem to occur in groups called “cycles,” lasting a few weeks to several months. The cluster cycle is followed by a period with no attacks. A typical cycle of attacks might last one to three months, with one to several months in between clusters. Often, clusters show a pattern, with cluster cycles recurring every year or twice a year at roughly the same time, early spring and early fall, for example. Within a cycle, the individual cluster attacks can show a pattern, recurring every day at about the same time.

    Some sufferers – 10 percent or so – get no significant breaks between cycles of attacks, they simply go on and on, month-to-month and year-to-year. This is the chronic form, and officially this means there is not more than a 30-day period without an attack in any one year.

    The Attack

    Attacks can come regular as clockwork but they can also be unpredictable, striking out of the blue. They can also be triggered by substances or conditions. Alcohol is a common trigger, as are nitroglycerin and other nitrogen-based drugs or food additives. Overheated rooms, hot sun, and changes in barometric pressure (an airplane trip or an advancing storm front, for example), can trigger attacks in some. An odd trigger is the relief of stress. Relaxing after a hard day at work or feeling relief after some crisis may be followed, infuriatingly, by a cluster attack. Triggers vary widely among sufferers, and can seem to change from cycle to cycle. Clusters sufferers in general don’t have as many triggers as people suffering from migraines.

    Attacks last from 15 minutes to three hours or more; most typically they last 45 to 90 minutes. The attacks come on quickly, with warning signs appearing one to several minutes before the severe attack strikes. The pain can ramp up from mild warning pains to agony in less than a minute. The attacks can end just as quickly, though some may trail off slowly, with mild after-effects lasting for hours.

    The attack usually involves severe pain on just one side of the head, apparently centered behind the eye or between the eye and the ear, or between the eye and the top of the head. The pain is a steady and severe burning and penetrating sensation, as if a red-hot spike were being thrust through the eye and into the brain, and then twisted.

    Other symptoms accompany the pain. On the same side as the pain, the eye may become red and flow copious tears, the eyelid may droop and the pupil may become smaller. A very runny nose and/or heavy congestion is common.

    There are cluster attack behaviors that distinguish them from migraines or other types of headache. Cluster sufferers cannot lie down or remain still, but feel they have to pace around or move in some way. In the worst attacks, they may crawl or roll on the floor, pound their fists on their heads or the floor, or even pound their heads on the floor or wall. Muttering, swearing and screaming is common, escalating with the severity of the pain.

    Life with Clusters

    Beyond the physical symptoms of this disease, there are mental and social symptoms. They are significant. They can ruin your marriage, your career and your life.

    Attacks are completely debilitating – there is simply no way to function while being hit with a cluster attack. Some employers are sympathetic and flexible, others are not. In many jobs and professions, it is simply unacceptable to frequently stop work for an hour or more until an attack passes.

    This disease is scary. The sight and sound of someone in a severe attack can be alarming to strangers and distressing to loved ones. Clusterheads often don’t want to be seen or touched or helped during an attack, and this increases the distance from loved ones and their feelings of helplessness. Divorce and alienation can be the result. Coworkers can become uncomfortable, not knowing how to relate to what seems like a catastrophic disease. Some simply don’t want to be around someone who might go into a screaming fit at any time. The clusterhead can end up effectively ostracized.

    A clusterhead tends to withdraw from society during cycles. They don’t want to risk having an attack in public. Not wanting to be seen is part of it. The reactions of strangers is a bigger problem. Some want to help a fellow human in the throes of an attack, others can become afraid.

    Some might call an ambulance, or want to rush the clusterhead to an emergency room, but this usually is not a good idea and rarely results in an effective treatment for the attack. Some call the police, and this is an even worse idea – some police officers might insist the cluster sufferer “calm down,” which is a lawful order the clusterhead cannot follow. At best, the police officer will call an ambulance.

    The drugs clusterheads take have side effects, some of them severe. Pain killers are usually ineffective and can be addictive. Steroids can be effective, but their use is limited by the damage they can do to the body. Triptans such as Imitrex can affect the heart, and some say they prolong the cluster cycle or cause rebound headaches. Anti-convulsant drugs can affect mental acuity. Some medications are expensive enough to drive the sufferer into bankruptcy.

    In the end, the recurring cluster attack severely limits the life one can lead, and tends to drive away those who make life worth living.

    The Official Symptoms

    There is an official description of the symptoms of clusters and the diagnostic criteria, developed by the International Headache Society.

    General Description

    Attacks of severe, strictly unilateral (one-sided) pain which is orbital (the area of your eye socket “behind your eye”), supraorbital (the area around your eye socket), temporal (area of your temple to the side of your eye) or in any combination of these sites, lasting 15-180 minutes and occurring from once every other day to 8 times a day. Pain is maximal orbitally, supraorbitally, temporally or in any combination of these sites, but may spread to other regions of the head. Pain almost invariably recurs on the same side during an individual cluster period. During the worst attacks, the intensity of pain is excruciating. Patients are usually unable to lie down and characteristically pace the floor. The attacks are associated with one or more of the following, all of which are ipsilateral (on the same side of the head as the headache pain): conjunctival injection (the mucous membrane that covers the front of the eye and lines the inside of the eyelids looks red/inflamed: “red eye”), lacrimation (the flow of tears), nasal congestion, rhinorrhea (nasal discharge/”runny nose”), forehead and facial sweating, miosis (excessive constriction/tightening of the eye’s pupil), ptosis (drooping of the upper eyelid), eyelid edema (swelling/”puffiness” of the eyelid from excessive watery fluid collection). Most patients are restless or agitated during an attack.

    General Diagnostic Criteria

    Severe or very severe unilateral orbital, supraorbital and/or temporal pain lasting 15-180 minutes if untreated.

    Headache is accompanied by at least one of the following (all medical terms defined above):

    1.  ipsilateral conjunctival injection and/or lacrimation
    2. ipsilateral nasal congestion and/or rhinorrhoea
    3. ipsilateral eyelid edema
    4. ipsilateral forehead and facial sweating
    5. ipsilateral miosis and/or ptosis
    6. a sense of restlessness or agitation

    Attacks have a frequency from one every other day to 8 per day.

    Attacks cannot attributed to another disorder.


    1. During part (but less than half) of the time-course of cluster headache, attacks may be less severe and/or of shorter or longer duration.
    2. During part (but less than half) of the time-course of cluster headache, attacks may be less frequent.

    Description of Episodic Cluster Headache

    Cluster headache attacks occurring in cycles lasting 7 days to 1 year separated by pain-free periods lasting 1 month or longer.

    Diagnostic criteria for Episodic Cluster Headache

    Attacks fulfilling criteria A-E above.

    At least two cluster cycles lasting 7-365 days and separated by pain-free remission periods of one month or more. Note: Cluster cycles usually last between 2 weeks and 3 months.

    Comment: The duration of the remission period has been increased in the most recent edition of HIS diagnostic criteria to a minimum of 1 month.

    Description of Chronic Cluster Headache

    Cluster headache attacks occurring for more than one year without remission or with remissions lasting less than one month.

    Diagnostic criteria for Chronic Cluster Headache

    Attacks fulfilling criteria above

    Attacks recur over one year or more without remission periods or with remission periods lasting less than one month.

    Comment: chronic cluster headache may arise de novo (come first – previously referred to as primary chronic cluster headache) or evolve from the episodic subtype (previously referred to as secondary chronic cluster headache). Some patients may switch from chronic to episodic cluster headache.

    Strengthen your vocabulary

    For those who aren’t doctors, here are some definitions of the medical terms used by the IHS:

    • conjunctival injection – red eye
    • edema – swelling or puffiness from fluid collection
    • ipsilateral – on the same side
      lacrimation – tears
    • miosis – pupil shrinks
    • orbital – the area of the eye socket “behind” the eye
    • ptosis – eyelid droops
    • rhinorrhea – runny nose
    • supraorbital – around the eye socket
    • temporal – the temple area
    • unilateral – one sided

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