Acceptance of headache disorders as “real diseases” is now widespread due largely to advances made over the last 50 years in diagnoses, treatment, and the understanding of pathophysiology. Drs. Lipton and Bigal examine the path to acceptance and the impediments that had to be overcome.
Headache is not one disease but a symptom of many different diseases.1,2 Most secondary headache disorders, including those attributed to brain tumors, subarachnoid hemorrhage, and meningitis, are readily accepted as manifestations of real illnesses. Over the last 50 years, the primary headache disorders (including migraine, tension-type headache, and the trigeminal autonomic cephalgias) have also been increasingly accepted as real diseases.1,2
The delayed recognition of primary headaches as real diseases may be due, in part, to the fact that diagnosis rests largely on patient-reported symptoms.1 There is no laboratory study or imaging procedure that establishes the diagnosis of primary headache disorders, though functional imaging findings have been described.3 Investigations serve largely to exclude other causes or establish secondary causes of headache. If an imaging study shows a mass lesion in a patient with headache, the headache will be acknowledged as “real.” In a patient with a similar clinical picture, if studies are negative, the headache disorder may still be met with skepticism.
The advances in headache medicine over the last 50 years, covered elsewhere in this issue, have contributed to the recognition of the primary headaches as real diseases. Real diseases have clear definitions and operational diagnostic criteria (Olesen), a pathophysiological foundation (Moscowitz and Cutrer), a genetic basis (Ferrari), and well-trained specialists credentialed in their diagnosis and treatment (Finkel). Real diseases are relieved by real drugs that act through a specific set of pharmacologic mechanisms (Humphrey and Loder).
In addition to these remarkable advances, other factors have contributed to the recognition of primary headache disorders as real diseases including epidemiologic evidence, health services research, the development of tools to improve diagnosis and treatment, as well as educational interventions directed to clinicians, patients, and other stakeholders. Epidemiologic research has led to an appreciation of the scope and burden of primary headaches and the distinct epidemiologic profiles which characterize these disorders. Health services research has identified the patterns of diagnosis and treatment, clarifying unmet needs. The advances in acute and preventive treatment, coupled with an emerging understanding of the burden of illness, have fueled public and medical education initiatives designed to reduce that burden. Herein, we cover some of the findings that contributed to the recognition of primary headaches as distinct disorders, worthy of diagnosis and treatment.
Epidemiologic research has clarified the scope, distribution, comorbidities, and burden of primary headaches, helping to establish them as real diseases
Over the past 50 years, an enormous number of investigations have focused on the epidemiology of headache.4,5 The modern era of headache epidemiology started with the studies of Waters and O'Connor.6 The firstedition of the International Classification of Headache Disorders (ICHD-1) facilitated epidemiologic research by providing an operational diagnostic criterion for the range of primary headache disorders.7 The Danish group conducted the first epidemiologic studies using the then new ICHD-1 criteria.8 The availability of standard criteria in over 20 languages facilitated the conduct of studies in many countries and in most regions of the world.
The epidemiologic studies of the last 15 years have taught lessons that help establish primary headaches as real diseases.4 These studies have shown that migraine and tension-type headache are common and that they have distinct epidemiological profiles.9,10 Migraine is 3 times more common in women than in men.4,5 Episodic tension-type headache is only slightly more common in women.4,5 Migraine prevalence is inversely related to socioeconomic status.4 Episodic tension-type headache does not show this inverse relationship.4
Epidemiologic studies have also highlighted headache-related disability. Headaches cost US employers about $20 billion per year in lost productive time with about $13 billion attributable to migraine.11,12 This does not include the lost value of household work and chores, the family impact, or the personal impact of pain and suffering.13 Many population studies have shown that migraine disrupts health-related quality of life and that the disruption increases with the frequency and severity of headaches. Headaches cause real burdens on individual headache sufferers and society because they are a real disease.
The studies have shown that migraine is comorbid with a number of disorders including neurologic diseases such as stroke and epilepsy.14,15 These comorbidities support the view that migraine is a brain disease with biological links to other brain diseases.4,16-18
Some headaches progress from an episodic into a chronic state
Some primary headaches (eg, migraine and tension-type headache) start as episodic disorders (occurring less than 15 days per month) and evolve to a stage with headaches more days than not.1,19,20 Headache progression has been better studied for migraine than tension-type headache. The existence of migraine chronification is supported by several lines of evidence. Recent longitudinal population studies have shown that about 3% of episodic headache sufferers develop new onset chronic daily headache over the course of 1 year.21 In a clinic-based study, 14% of episodic migraine sufferers develop chronic daily headache over 1 year.22 A number of risk factors for headache progression have been identified including high baseline headache frequency, overuse of opiates and barbiturates, obesity, snoring, excessive use of caffeine, and stressful life events.21,23-25 The emerging understanding of headache progression highlights the status of headache as a condition which may worsen over time. In addition, neuro-imaging studies have shown that as headache frequency increases, deep white matter lesions and posterior circulation infarcts are more likely.26
The delayed recognition of primary headaches as real diseases may be due, in part, to the fact that diagnosis rests largely on patient-reported symptoms.
Epidemiologic studies have shown a pattern of underconsultation, underdiagnosis, and undertreatment motivating efforts in public education
In 1989, the American Migraine Study 1 examined patterns of headache diagnosis and treatment in the US population.4,27 The study showed that in any given year, most headache sufferers do not consult healthcare professionals for their headaches. Many active migraine sufferers are not currently seeking medical care and about half of them have never received a medical diagnosis.27 As a consequence, most migraine sufferers treat with over-the-counter medications or prescription analgesics rather than migraine-specific medications. The studies reveal that when migraine sufferers consult for headache, they usually do so in primary care settings. In aggregate, these data demonstrate the need to encourage consultation among those with disabling headache, and to improve diagnosis, initial treatment, as well as follow-up. These data helped motivate the educational and public health efforts described below.
The use of tools designed to improve the diagnosis and treatment of headache disorders highlights headache as a symptom of real diseases
Over the past 20 years, many tools have been developed to improve the diagnosis and treatment of headache disorders.28,29 Some of these tools have focused on diagnosis. One simple migraine-specific diagnostic tool intended for use in primary care is known as ID-migraine.28 This tool identifies individuals in primary care with significant headache and is over 90% accurate based on questions which address photophobia, nausea, and disability. Other diagnostic aids include a 4-question screener intended to find chronic daily headache, medication overuse, and migraine.29
In addition, tools have been developed to improve measurement and communication about headache-related disability. The Migraine Disability Assessment measures lost time due to headache over 3 months in several domains.30 Two other widely used tools, the Headache Impact Test31 and the Henry Ford DisabilityInventory, cover broader aspects of headache impact using an arbitrary measurement scale.32 Current treatment guidelines, which consider illness severity in the selection of treatment, provide great hope for improving patient outcomes.
These instruments helped to establish headache as a real disease since they highlighted accurate diagnosis and focused on illness severity and burden.
Medical Education Initiatives Designed to Improve the Diagnosis and Treatment
Over the past 20 years, there have been many educational initiatives directed both to healthcare professionals and to patients. On the professional side, the American Headache Society (AHS) has played a leadership role with our annual scientific meeting (with over 8000 registered attendees over the past decade), teaching courses and special programs. To mention a few special programs, the “Neurology Ambassadors Program,” led by Stephen Silberstein, is a series of day-long comprehensive headache course jointly sponsored by the AHS and the American Academy of Neurology (AAN). This program was attended by over 2500 healthcare professionals. Studies demonstrate that the program increased knowledge of headache diagnosis and treatment. “Brainstorm” is an AHS course directed to primary care doctors. An educational evaluation showed that the program had a significant immediate impact on the knowledge, beliefs, and attitudes of participants. This program is currently offered as part of regional or state meetings for primary care physician, nurse practitioner, or physician assistants.
The AHS's Neurology Resident Curriculum is a comprehensive, consequence-based, interactive program designed to provide headache education to neurology residents while meeting the 6 core competencies of the American College of Graduate Medical Education. The program has been recognized for its educational merit and has been reviewed and endorsed by the AAN.
The AHS journal Headache has enjoyed great success under a series of editors including John Edmeads, Keith Campbell, and, most recently, John Rothrock. Under David Dodick's leadership, a review journal, Headache Currents, was established as a joint project of the AHS and the International Headache Society. It is now included in both Headache and Cephalalgia and brings relevant headache science to interested clinicians.
In addition to the AHS, the AAN, the International Headache Society, European Headache Federation, and the Migraine Trust are among the organizations that have been leaders in headache medical education. There have been innumerable teaching courses, symposia, electronic educational initiatives, dinner programs, slide kits, and grand rounds programs. The Primary Care Network, under the leadership of Roger Cady, has played a major role in educating and mobilizing clinicians to prioritize headache. All of these efforts communicated both implicitly and explicitly that headache is a real disease worthy of medical attention. The National Institutes of Health has organized 2 conferences on headache and migraine intended to increase awareness of headache disorders. Nonetheless, public funding for headache research in the USA and Europe lags behind the scope and importance of the problem.33,34
Patient and public education initiatives designed to improve the diagnosis and treatment of headache and to reduce its burden
Enormous efforts have also been made in the area of patient education. There are national organizations for headache sufferers in many countries. In the USA, the American Council on Headache Education (ACHE) and the National Headache Foundation have organized local chapters and support groups, published newsletters, developed websites, and organized public relations initiatives, all designed to improve the lives of headache sufferers. Both ACHE and the World Headache Alliance were established as an international consortium of voluntary organizations for headache sufferers, under the auspices of the International Headache Society. The World Headache Alliance, led for many years by Fred Sheftell, did much to improve the lives of headache sufferers.
Several years ago, the World Health Organization in collaboration with the World Headache Alliance, the International Headache Society, and the European Headache Federation launched its Global Campaign to Lift the Burden of Headache. This initiative, led by Dr. Timothy Steiner, has summarized the world literature on epidemiology and burden of headache5 and is now developing outcome tools, workplace studies, clinical tool boxes, and a variety of other programs (http://www.l-t-b.org; referenced January 15, 2008).5 Many of these efforts contain as key messages that headache disorders are real medical problems with a biological and genetic basis and that they are amenable to treatment. This program endeavors to reach not just headache sufferers and clinicians, but governmental and nongovernmental organizations that fund research and patient care.
There is now widespread acceptance of headache disorders as “real diseases.” Coupled with the many advances over the last 50 years in the diagnosis, the treatment, and the understanding of pathophysiology, our progress is a cause for celebration. Treatment has never been better. More people than ever get excellent medical care for their headaches. On the other hand, headache has not fully lost its stigma. Headache disorders remain underdiagnosed, undertreated, and relatively neglected in medical education. Headache research remains underfunded. It is proper that we celebrate our remarkable accomplishments even as we commit to the next wave of progress over the next 50 years.