STOWE, VERMONT—Rather than greater headache frequency, a systemic endocrine–metabolic disorder that is associated with frequent headaches may distinguish chronic migraine from episodic migraine, said Egilius L. H. Spierings, MD, PhD, at the 26th Annual Stowe Headache Symposium of the Headache Cooperative of New England.

Egilius L. H. Spierings, MD, PhD

According to the International Headache Society (IHS), a patient with headache on 15 or more days per month for more than three months, and whose headache has the features of migraine on at least eight days per month, fulfills the diagnostic criteria for chronic migraine. A migraineur with headache on 14 or fewer days per month has episodic migraine. The neurology community has accepted this distinction.

The IHS classification is “extremely simple” and “highly arbitrarily defined,” said Dr. Spierings, Director of the Headache and Face Pain Program at Tufts Medical Center in Boston and Clinical Professor of Craniofacial Pain at Tufts University. “There must be more behind that distinction, especially when you look at the question of why Botox works preventively in chronic migraine and not in episodic migraine.”

Taking the perspective of a general practitioner, rather than that of a headache specialist, may clarify the distinction between chronic and episodic migraine, according to Dr. Spierings. A general review of systems suggests that patients with episodic migraine tend to be healthy overall, while patients with chronic migraine tend to have many psychiatric and medical comorbidities. In an exploratory study, Dr. Spierings and colleagues found that women with chronic migraine had a significantly higher prevalence of menstrual cycle disorders (eg, oligomenorrhea and polymenorrhea) and dysmenorrhea, compared with women with episodic migraine.

These findings appear to be consistent with those of previous research. In 2002, Bigal and colleagues found that asthma, allergies, hypertension, and hypothyroidism were significantly more common in patients with chronic migraine than in those with episodic migraine. In 2006, Tietjen et al observed that endometriosis was significantly more common in women with chronic migraine than in women with episodic migraine.

In the most extensive study in this area, Ferrari et al found that psychiatric, gastrointestinal, musculoskeletal, ocular, genitourinary, hematologic, cerebrovascular, and cardiac comorbidities were significantly more common in patients with chronic migraine than in those with episodic migraine. Hypertension, constipation, and insomnia also were more prevalent in chronic migraine.

In addition, data from various studies show that patients with chronic migraine tend to be, on average, 10 to 20 years older than those with episodic migraine. About two-thirds of patients with chronic migraine develop their condition gradually over time out of episodic migraine, a transition that takes, on average, 11.6 years. During this period, these patients may develop the comorbidities that are more frequent in chronic migraine, said Dr. Spierings.

But younger patients with chronic migraine also have more comorbidities than patients of the same age with episodic migraine. One patient of Dr. Spierings was an 18-year-old woman who had had chronic migraine since menarche and whose mother had migraine. The woman’s comorbidities included fatigue, insomnia, anxiety, depression, tight and sore neck and shoulder muscles, reflux disease, and diarrhea. Another patient of Dr. Spierings was a 20-year-old woman who had had chronic migraine since menarche and whose mother had migraine. Among her comorbidities were fatigue, insomnia, depression, tight and sore neck and shoulder muscles, lumbago, polymenorrhea, dysmenorrhea, and hypermenorrhea.

Dr. Spierings also examined a 34-year-old woman without a family history of migraine. She developed a pressure sensation in the temples, but not headaches or migraine, after pregnancy. The woman’s comorbidities included fatigue, anxiety, tight and sore neck and shoulder muscles, fibromyalgia, gastritis, constipation, endometriosis, and hypermenorrhea.

All three patients have a disorder of multiple systems that affects the nervous system, the musculoskeletal system, the gastrointestinal system, and the genitourinary system. “The only unifying diagnosis … is somatic symptom disorder,” said Dr. Spierings. Yet this diagnosis is unsatisfying, he added.

“These people have a systemic endocrine–metabolic disorder centered around energy metabolism that causes the multitude of medical and psychiatric conditions that we tend to see in patients [with chronic migraine] .… It is a syndrome with multiple etiologies, either endocrine or metabolic, genetic or acquired.” The first two patients may have a “genetically determined headache amplifier” that contributed to the development of chronic migraine, Dr. Spierings added. The third patient, who has no family history of migraine, does not have this genetically determined headache amplifier.

In previous research, Dr. Spierings and colleagues concluded that stress, tension, irregular eating times, fatigue, and insufficient sleep were general headache triggers to which everyone is susceptible. “When we do not have that headache amplifier, we get regular headaches that we can combat with a couple of aspirin. When we have that headache amplifier inherited from one or both parents, we need specific antimigraine medications to take care of it,” he said. The inherited headache amplifier “is the essence of migraine” and is related to the threshold at which neurogenic inflammation occurs, said Dr. Spierings. Patients with chronic migraine have the headache amplifier and a systemic disorder not shared by patients with episodic migraine, he concluded.

—Erik Greb

What Distinguishes Chronic Migraine From Episodic Migraine?