Definition and Characteristics of Migraine Headache

Definition and Characteristics of Migraine Headache

Migraine is a Neurological Condition, best defined as a Neurovascular Disorder.  Migraine is characterized by recurrent attacks of severe headache that may be accompanied by various neurological signs and symptoms.  Migraine is thus not just a headache but an important central nervous system disorder which affects 38 million people in the U.S. Medical studies estimate that about 14% of adults in the U.S. suffer from migraine and that 2-3 million sufferers manifest a chronic form of migraine characterized by chronic daily headaches which are associated with significant quality of life issues, marked disability and other important neurological consequences.

Nearly 1 in 4 U.S. households includes someone with migraine.  About 5 million Americans experience at least one migraine attack per month while more than 11 million people in the U.S. blame migraines for causing moderate to severe disability.  91% of migraineurs miss work or cannot function normally during a migraine attack. 59% with migraine miss family or social events while another 53% with migraine show some disability requiring reducing activities or even bedrest.  49% of migraineurs indicate that they had to restrict activities for at least one day during a migraine. Probably related to hormonal issues, migraine is more common in women. 70% of all migraine sufferers are women.

In the American Migraine Study 11, conducted in 2001, 92% of women and 89% of men with severe migraine had some headache related disability.  About half of the migraineurs were severely disabled and required bedrest. Because migraine headaches strike most commonly during the more productive working years, the disease state also takes a financial toll.  The World Health Organization (WHO) rates migraine as one of the 19th most common reason for disability.  The average migraine sufferer misses 2 days of work per year.  Others may work during a migraine attack but report much lower productivity.  In a 1998 study, in the U.S. the total costs of disability attributed to migraine was estimated to exceed $13 Billion per year.  In a 2002 study, the cost of decreased productivity related to migraine was $19.6 Billion. While more updated studies are in progress, in the U.S. the overall economic cost related to the burden of migraine is staggering.

Headache as an isolated symptom is best defined as a universal experience.  Headache is one of the most common symptoms in the general population. Headache disorders are among the most common disorders of the central nervous system.   For some, the symptoms of headache may just be an episodic nuisance. For others the headache symptoms may be manifestations of a chronic significant disabling disease.  Yet in others headache may also be the first symptom of a more serious, even life-threatening condition. Headache is therefore also a variable experience. Of the primary headache disorders, migraine, tension-type headache and medication-overuse headache are of public health importance since they are responsible for the high population levels of disability and ill-health.   

Migraine headache involves different mechanisms of action within the brain and cranium.  The diagnosis of migraine is usually based upon retrospective patient reporting of their headache characteristics, signs and symptoms.  Most laboratory tests as well as the physical examination are usually normal. In specific migraineurs, neuroimaging may reveal abnormalities on MRI which are related to the migraine syndrome.  While childhood migraine is an important early diagnosis, migraine more often begins in puberty and statistically is most prevalent between the ages of 35 and 45 years. The migraine attack is divided into four potential phases. 1.  The Premonitory Phase (Prodrome). 2. The Aura Phase. 3. The Headache Phase. 4. The Resolution Phase (Postdrome).

The Premonitory Phase (Prodrome):  The Prodrome, which is characteristically a change in mood or behavior may also present with nonspecific poorly characterized feelings that a migraine attack is about to occur.  These premonitory features are quite variable among migraineurs but may be consistent within an individual. The premonitory phenomena may include such things as a feeling of depression, hyperactivity, irritability, food cravings, cognitive dysfunction, diarrhea or constipation and other signs or symptoms involving one’s mental state, neurological state and/or more general perceptions.  A prodrome may occur between 20% to 60% of migraineurs and may be manifested hours to days before the migraine headache.

The Aura Phase:  The migraine aura is the most common migraine syndrome associated with neurological symptoms.  Most symptoms develop over a 5 to 10-minute period. Most auras last less than 30 minutes but may persist to over 60 minutes or more.  The most common auras are visual abnormalities but aura may include sensory or motor phenomena. In some instances, an aura may be even more complex and include language disturbances or brief or sometimes prolonged sensory motor abnormalities.  Auras may vary in their complexity. Migraine aura usually occur within an hour before the migraine headache. Sometimes migraine with aura occurs with little or no headache, especially in people age 50 or older. Migraine aura may also occur off and on during the headache phase of migraine.  Migraine aura is usually related to pathophysiological changes occurring within the central nervous system during a migraine attack.

The Headache Phase:  About 60% of headaches in migraine are predominantly unilateral.  A headache can even switch sides during the same attack. But it is important to emphasize that a bilateral headache does not exclude the diagnosis of migraine.  About 40%-45% of migraine patients will present with bilateral headache. 85% of patients with migraine describe a throbbing, pulsating headache which may also be exacerbated by any physical activity or even simple movements of the head.  Therefore, typically, during migraine, the patient does not prefer to move and may desire to lie down without much movement of the head or body. Associated symptoms during the headache phase may include nausea (90% of patients), vomiting (30% of patients), light sensitivity (80% of patients), and sound sensitivity (76% of patients).  Because of light sensitivity (photophobia) and sound sensitivity (Phonophobia), patients with migraine often seek a dark, quiet room during an attack.

Resolution Phase (Postdrome):  Following a migraine attack, the patient may feel tired, fatigued, washed out, irritable, listless and may manifest scalp tenderness and even significant mood changes.  Some individuals may report a feeling of being refreshed or even euphoric. Others may experience depression or malaise. In some individuals, this postdrome, or after affects of the migraine attack, may persist for hours to days.

Migraine is not just a headache but is an extremely incapacitating collection of signs and symptoms which have their origin within the central nervous system and result in dysfunction and disability.  Migraine is a condition involving the brain. Migraine is not a diagnosis of exclusion but a neurological condition defined by specific clinical markers identified by performing a careful and detailed neurological history and physical examination.  

Because everyone is unique and migraine symptoms may vary by occurrence and even within attacks, a careful evaluation by an experienced headache medicine specialist is often necessary.  It is important for patients to consult a headache specialist if headache symptoms are disabling, interfere with normal life activities or work, are associated with neurological abnormalities, increase in frequency or severity, or if the patient is not responsive to the usual and customary medical care.  Patients experiencing headaches with migraine features two or more days a week should consider further headache medicine consultation. Pregnant women and nursing mothers would also benefit if their medication management were under the supervision of a headache medicine specialist for treatment of their migraines.