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Matthew Lawrence, MD PhD
Simmons Lessell, MD
Massachusetts Eye and Ear Infirmary, Harvard Medical School
October 15, 2002

What are migraines?
Migraines are characterized by recurrent attacks of throbbing headache lasting four to seventy-two hours, typically starting on one side of the head, which become worse with exertion and maybe associated with nausea, vomiting and loss of appetite and increased sensitivity to light, sound or smell. Migraines may vary widely in intensity, duration and frequency of recurrence. Migraine sufferers may additionally experience a premonition that migraine events are about to occur. This takes the form of an aura that precedes the headache by no more than sixty minutes consisting of visual changes, or less commonly, reversible mood disturbances, tactile sensory deficits or weakness.

What different types of migraines are there?
Common migraines are headaches accompanied by symptoms such as nausea, without visual or other neurologic changes. The pain may feel as though it radiates FROM a specific point, sometimes behind the eye, for which reason it can be confused with eye pain.

Classic migraines share all of the characteristics of common migraine with the additional defining feature of neurologic changes preceding or accompanying the headache, including visual changes and sensory or motor disturbances such as tingling in the arm or muscle weakness.

Complicated migraines are much less common and are accompanied by various neurologic changes including paralysis of the eye, paralysis of the body in one side, more widespread loss of sensation over one side of the body, and memory loss. There can additionally be changes in behavior and loss of the ability to read and write. These more profound disturbances are distinguished FROM similar changes seen in stroke by their transient nature. Complicated migraines may or may not be accompanied by headache. Transient visual changes lasting ten to thirty minutes without an accompanying headache, termed acephalgic migraines, are the most frequent form of complicated migraine.

What are the visual changes associated with migraine?
The visual changes associated with migraine are described as "positive" and "negative" phenomena, both of which are alarming to those who have not previously experienced them. "Positive" changes often begin as flashes of light in one area of the visual field in both eyes, usually in the medial or lateral periphery. These flashes may appear as sparkles of different colors, geometric patterns or zig zag lines, which often progressively expand to fill a larger and larger area. "Negative" changes can include the onset of tunnel vision where objects can no longer be seen in the periphery, or there may be smaller more discrete areas of central or peripheral vision loss. In some instances vision loss can expand to involve half of the visual field in both eyes or there can be a sudden and complete blindness in both eyes. Both "positive" and "negative" changes usually last FROM ten to thirty minutes and have no known lasting effect on visual function.

What can migraines be confused with?
The perception of flashes of light can occur in other conditions. The most common is a posterior vitreous detachment in which the gel within the center of the eye tugs on the retina. Retinal tears can also cause flashes, which may herald the onset of a retinal detachment. The flashes associated with both of these conditions affect only one eye and tend not to have the progressing angular geometric pattern or ten to thirty minute duration characteristic of migraine.

What would a doctor do to diagnose a migraine?
As with many medical conditions, the diagnosis of migraines is based on the history elicited by the doctor. Any headache preceded by bright flashes or loss of vision lasting approximately fifteen minutes is highly suggestive of a classic migraine. A detailed history can lead to a confident diagnosis even in less typical cases. The importance of an eye examination in the evaluation of a suspected migraine is to rule out other possible causes of either the visual changes or headache. In this instance, a dilated eye examination should be performed by an ophthalmologist to rule out a posterior vitreous detachment, retinal tear or retinal detachment. Persistent throbbing headache in a person with no prior history of migraine would warrant evaluation by a neurologist and possible brain imaging to rule out tumor or intracranial bleeding. Should you suspect a migraine, the first point of contact with a medical care provider should be your primary care physician.

Who gets migraines?
It is estimated that twenty-four million Americans get migraines. Migraines may occur at any age but most frequently in those between ten and forty years old, and more often in woman than men. In those who suffer migraines a family history can often be elicited.

What causes migraines?
The exact cause of migraines is unknown. Changes in blood flow to different regions of the brain are associated with migraines and may be responsible for triggering their onset. Further specific triggers, such as estrogen, are likely, given the much higher incidence of migraines in postpubertal and premenopausal woman. The constellation of symptoms in any given migraine are determined by which brain regions are affected. Disturbances in the occipital lobe, the area in the back of the brain responsible for visual processing, cause the visual changes associated with migraines. Changes in blood perfusion in the eye itself, termed an ocular migraine, occur very infrequently.

What can be done to prevent or stop migraines?
Migraines with visual symptoms and minimal or no headache require no treatment. Migraine headaches can be alleviated with common over the counter pain relievers such as acetaminophen, aspirin or ibuprofen. Medications specifically designed to abort severe headaches, such as serotonin receptor blocking agents, can be obtained following evaluation by a primary care physician or neurologist. Beta-blockers, calcium channel blockers, tricyclic antidepressants or anticonvulsants can be taken prophylactically to prevent migraines in those suffering one or more episodes per week. Again, such medications should only be initiated following evaluation be a primary care physician or neurologist. As a general measure, the avoidance of stress and other potential precipitating factors can reduce the frequency of migraines. Such factors include hyperglycemia, smoking, hypertension, birth control pills, high altitude and certain dietary items such as monosodium glutamate.

The information and recommendations appearing on these pages are informational only and is not intended to be a basis for diagnosis, treatment or any other clinical application. For specific information concerning your personal medical condition, the DJO suggests that you consult your physician.