Unraveling the Mystery of Migraine

As printed in Hearing Health, volume 20:3, Fall 2004

Richard E. Gans, Ph.D., FAAA

According to the American Academy of Neurology, nearly 28 million Americans suffer from migraine. The most disruptive effects of this neurological disorder are excruciating headache pain and/or other disorienting symptoms. Because these symptoms are often so overwhelming, migraine is estimated to cost the economy about $13 billion
annually in lost productivity.

Most people have heard the term migraine but even experts have some difficulty
defining it. There is such variability across cases that providing an all-inclusive definition is challenging.

The International Headache Society (IHS) provides a descriptive framework that defines migraine by specific characteristics. According to the IHS, the disorder displays: recurrent attacks; limited duration of each attack (from four to 72 hours); sensitivity to physical activity; and pain that has a unilateral location, a pulsating quality and intensity sufficient to interrupt daily activities. Associated symptoms include nausea, vomiting and hypersensitivity to light and sound.

The society goes on to classify migraine into several subgroups (see Table 1). The vast majority of cases are made up of migraine with aura and migraine without aura. Auras generally are considered to be abnormal sensory perceptions. Visual auras are the most frequent type and may occur in many forms, including hallucinations.

People who have migraine may experience it in various ways throughout their lives
(see Table 2). Although most often it is associated with an acutely painful headache, migraine can also have audiovestibular symptoms. These include vertigo (spinning dizziness), tinnitus (ringing in the ears), hypersensitivity to light and sound and/or hearing loss. One or more may precede or accompany a headache or occur in the absence of any headache pain.

What Causes Migraine?
The conclusive answer is that no one knows for sure … yet. Numerous theories exist on the underlying physical causes of migraine. One implies that a vascular condition may cause spasms in blood vessels in the head that are outside of the skull, resulting in headaches. It also is speculated other symptoms and auras result if this atypical opening and dilation action occurs in specific vessels within the brain.

Yet another theory suggests that symptoms arise due to a slow spreading of these spasms across the cerebral cortex of the brain, leading to visual auras in particular. Proponents of the theory point to an alteration in the normal metabolic processes surrounding the blood vessels as the cause. The vasospasms may also spread to the peripheral sensory organs, such as the eye or inner ear, or may occur within the brainstem.

The ion channel disorder theory may provide an explanation for this spreading action. It describes a defect in the processing of calcium ions which results in increased potassium outside the cells that initiate the spasms. The relationship between calcium and potassium is critical in maintaining the potassium-rich fluid (endolymph) within the inner ear, for example. Ion channel disorder in either the brain or ear could lead to sensory dysfunction that affects hearing and/or balance and other vestibular functions.

These theories are the best science currently has to offer. However, it should be encouraging to people who have migraine that scientific and medical speculation continues and new theories constantly emerge.

Who Is Most Likely to Have Migraine?
The short answer is women more than men – in a three-to-one ratio – and adults between the ages of 25 and 55. In the U.S. and Europe, 50 percent of women and 40 percent of men have likely experienced at least one severe, debilitating headache during their lives. Following the IHS criteria, estimates are that about 18 percent of women and seven percent of men experience some form of migraine disorder.

Women often have their first migraine attack during puberty and as they approach menopause, the frequency of episodes and the intensity of symptoms lessen, probably due to hormonal influences. Similarly, pregnancy often provides a respite from migraine. Somewhat surprisingly, research among women with migraine who experience premature menopause due to surgery shows that they subsequently have symptoms that are more severe.

Also, migraine does “run in the family.” There are a variety of types for which strong genetic links have been identified.

What Are the Auditory and Vestibular Symptoms?
Approximately 30 percent of people who visit healthcare providers to seek treatment for migraine have symptoms affecting their ears and/or sense of balance. Although less common than other audiovestibular symptoms, hearing loss does sometimes occur as a fluctuating, sensorineural loss in the low frequencies. It is also possible to have a
permanent hearing loss or vestibular dysfunction following a migraine attack.

Because these symptoms are common to other disorders as well, it can be difficult to diagnose migraine based on their presence alone. At first, particularly in people with recurring episodes or attacks, clinicians may think that the symptoms indicate Meniere’s disease or other types of inner ear conditions. Making a correct diagnosis often presents a quandary complicated by the fact that 60 percent of people who suffer from migraine report a lifelong history of motion sensitivity. In addition, the incidence of Meniere’s disease is twice as high among people with migraine as in the general population.

Diagnosis can be further complicated if multiple sclerosis (MS) is a possible consideration. An initial attack of acute, debilitating vertigo appears as the first symptom of MS in five percent of cases and 50 percent of people with MS experience at least one episode of vertigo during the course of the disease. Another complicating factor is that one in ten people with MS have partial or complete hearing loss that often recovers, similar to those with migraine or Meniere’s.

How Is Migraine Treated?
As many as half of all people with migraine will never link their symptoms with the disorder, receive an official diagnosis or have the opportunity to undergo treatment. No doubt this is due in part to the fact that many of the non-headache symptoms are not typically thought to be related to migraine.

Since there is not one specific diagnostic test, if you have vertigo, tinnitus, hearing loss, etc., you may be asked to have audiovestibular testing and possibly an MRI to help better differentiate migraine from other disorders.

Historically, neurologists have taken the lead in migraine management but family doctors and internists can also play a role. Some types of migraine can be managed with medication but finding the right ones can take several trials of different medicines. It also calls for a close collaboration between doctor and patient to identify the drug(s) that provides the greatest results.

Migraine can be triggered or aggravated by certain conditions or substances (see Table 3). It is important to explore with the doctor any lifestyle habits or foods and beverages that may be contributing to the onset of attacks or exacerbating symptoms. Many specialists recommend a weekly workout regimen and increased physical activity prior to bedtime for stress reduction with quite successful results.

Vestibular Rehabilitation Therapy (VRT) can be used to treat vestibular damage following a migraine. For people who suffer from chronic vestibular symptoms, such as blurred vision with head movement, exaggeration of motion and increased motion intolerance, VRT will successfully remedy their symptoms. It is important to remember, however, that VRT does not treat the migraine itself; instead, it helps the brain to see the vestibular problem and correct the faulty signals.

If you are among the millions of people who experience any of the variety of symptoms that can result from migraine, your first step to finding relief is to discuss your condition with your physician who may then refer you to a migraine specialist. Be patient but assertive when looking for assistance. Now more than ever, you do not have to “just live with it!”

For more information about migraine and treatment options, visit www.thebrainmatters.org, www.migraines.org and www.achenet.org.

Richard Gans, Ph.D., FAAA, executive director of the American Institute of Balance in Seminole, Fla., is president of the American Academy of Audiology. His teaching positions are adjunct faculty for Univ. of South Florida, Univ. of Florida, Nova Southeastern Univ. and guest instructor for the Univ. of Pittsburgh. Readers can contact him at www.dizzy.com.

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