"Chronic daily headache" (CDH) refers to the unhappy situation in which headaches are present at least fifteen days per month. Headaches can even occur every day or almost every day. CDH is more of a category than a final diagnosis, and different, recognizable patterns of headache are included in this category. It is important to distinguish among the different patterns because, once recognized, they can indicate the underlying cause and dictate appropriate treatment.

CDH can occur in the form of either "primary headaches" or "secondary headaches." Secondary headache means that the headache is a symptom of some other disease or process. In this case, the best treatment is one that addresses the underlying cause. Primary headache means that the headache disorder itself is the disease and is not a symptom of something else.

The most common primary headache condition is "tension-type headaches." Generally affecting the left and right sides equally, tension-type headaches often involve the back of the head and neck, but can also include the front of the head. These headaches are usually mild to moderate in intensity and have pressing or tightening qualities. Nausea, photosensitivity and sound sensitivity are not prominent in this headache disorder and tension-type headaches do not usually worsen with exertion.

Migraine is another common primary headache disorder which, when present more days than not, is also categorized as CDH. Migraine attacks typically last 4-72 hours when untreated. They are of moderate to severe intensity and often have a pulsating quality. They show increased tendency to affect just one side of the head and to include the associated symptoms of nausea, light sensitivity and sound sensitivity. They usually worsen with exertion.

While some people have frequent, individual, migraine attacks that span more than 15 days per month and are therefore categorized as CDH, another form of migraine involves a blending together of attacks into a more continuous, never-ending pattern. This usually occurs in people who previously had the more recognizable pattern of distinct, individual, migraine attacks. Just what happens in these cases--or even what to call it when it does happen--is a source of great debate among headache experts. One camp of experts calls it "chronic migraine" and another camp calls it "transformed migraine."

To make matters even more interesting, a person can have more than one type of headache, for example, a mixture of migraine and tension-type headaches. When this occurs, the mixture can be difficult to distinguish from the previously mentioned chronic (or transformed) migraine.

Two other kinds of primary headache are rarer than migraine and tension-type headaches, and show quite different characteristics. These are "hemicrania continua" and "chronic cluster." Hemicrania continua ("hemicrania" means half-headed and "continua" means continuous) is a strictly one-sided headache which can wax and wane in intensity without resolving. It does not include migraine's usual associated symptoms of nausea, light sensitivity, sound sensitivity and exertional aggravation. Chronic cluster, like its less-frequent "episodic" form, involves intense, recurring pain in or around just one eye that lasts for only 15-180 minutes per attack, but which can occur more than once per day. Unlike its episodic cousin, chronic cluster does not go into remission without treatment.

Secondary headaches taking the form of CDH can be due to numerous causes. Among them are head injury, arthritis of the neck bones, arthritis of the jaw joints (TMJs), sinus disease, breathing problems during sleep, tumors or other conditions causing increased pressure within the braincase, and leakages of the cerebrospinal fluid that surrounds the brain and spinal cord.

Two secondary forms of CDH deserve special mention--giant cell arteritis and medication overuse headaches. Giant cell arteritis (previously called temporal arteritis) occurs in people who are at least 50 years old and becomes more common in subsequent decades of life. It involves inflammation of larger-diameter arteries supplying blood to the brain and the rest of the head and, untreated, can lead to stroke or blindness. So it is important to recognize and treat this source of headaches before these complications occur. Classically, people with giant cell arteritis show a swollen, stiff, tender artery just beneath the skin of one or both temples. When this occurs, it facilitates diagnosis, but giant cell arteritis can still be present in the absence of this tell-tale sign. As a rule of thumb, giant cell arteritis should be considered as a possible diagnosis in every new headache disorder starting at the age of 50 or older.

Medication overuse headaches (also known as rebound headaches) occur when a primary headache disorder becomes transformed into an even worse secondary headache disorder via too many doses of as-needed medication. Typically, the primary headache disorders involved are either migraine or tension-type headaches, and the transformation occurs when the headache-sufferer takes need-driven medication for them at least two to three days each week. When the as-needed medication is a painkiller this syndrome is called "analgesic rebound" and when a triptan drug is used, it is called "triptan rebound." Triptans are newer drugs, which include sumatriptan (Imitrex) and rizatriptan (Maxalt), that interact with specific chemical receptors and halt the generation of migraine attacks. The bottom line with medication overuse headaches is that they don't get better until the drug that caused them is withdrawn and, even then, can take up to two months to wash out.

The group of disorders known as chronic daily headache afflicts 3-5% of the worldwide population and is a source of major disability in the form of lost or decreased functioning at home and at work. While many people with CDH treat them on their own, medical management can reduce suffering and improve quality of life.

(C) 2005 by Gary Cordingley

Gary Cordingley

Gary Cordingley graduated from Purdue University with a B.S. in chemistry and biology in 1971. He attended Duke University where he earned a Ph.D. in physiology and pharmacology in 1976, and an M.D. in 1977. He received internship training in internal medicine at the University of Michigan Hospitals 1977-1978, residency training in neurology at the Neurological Institute of Columbia-Presbyterian Medical Center in New York, 1978-1981, and fellowship training as a pharmacology research associate in the National Institute of General Medical Sciences in Bethesda, Maryland, 1981-1983.

He has practiced neurology in Athens, Ohio, since 1983. He is an associate professor of neurology at the Ohio University College of Osteopathic Medicine and a medical staff member of O'Bleness Memorial Hospital in Athens, Ohio.

Dr. Cordingley has been certified in neurology by the American Board of Psychiatry and Neurology. He is a fellow of the American Academy of Neurology and a member of the American Headache Society. He is also a member of the Ohio Academy of Medical History and was president of this organization 1994-1997. Dr. Cordingley's articles on neurology, neuroscience and medical history have appeared in numerous professional and general publications.