Jaynee Handelsman, PhD, and Hussam El-Kashlan, MD
Dizziness is one of the most common complaints in medicine and is reported to affect 20%–30% of the general population. Migraine is also a very common disorder, with prevalence in the general population ranging from 6%–20% in men and 17%–29% in women. Thus, 3%–4% of the population can be expected to experience both dizziness and migraine. In reality, however, the cooccurrence of symptoms is much higher than that. Specifically, vertigo, which is the sensation of perceived motion without actually moving, is reported by up to one third of people who have migraine, and general dizziness or unsteadiness is reported by up to three quarters of all patients with migraine.
Unfortunately, although migraine is a common cause of dizziness, it is often not correctly diagnosed until years after the patient initially seeks medical care for complaints of dizziness. The delay is due, in part, to the fact that most patients and many physicians think of migraine only in terms of headache, when it is actually an organic neurological syndrome. The result is that even in patients with headaches, migraine is often misdiagnosed as sinus headache or tension-type headache. Less than half of all migraine sufferers have received a diagnosis of migraine from their health care provider. Furthermore, vertigo is not included in the International Headache Society classification system as a symptom of migraine except as a part of basilar migraine, so most patients who have migrainous vertigo (MV) cannot be classified using the existing criteria. Recently, diagnostic criteria have been proposed that separate definite MV from probable MV and that conceptualize MV as an episodic vestibular disorder.
Migraine is now believed to be a genetically based neurological disorder in which certain triggers start a series of events including functional changes in the trigeminal nerve system and imbalances in brain chemicals, such as serotonin, that regulate pain. As a result, the trigeminal nerve releases chemicals that irritate and cause swelling of blood vessels on the surface of the brain, sending pain signals to the brainstem. MV may occur at any age and has a female preponderance with a probable autosomal dominant inheritance pattern with decreased penetrance in men. Typically, migraine begins earlier in life than does MV, and it is not unusual for vertigo to replace headaches in women around menopause.
Various factors have been identified as being migraine triggers, including foods, stress, hormones, physical activity, sensory stimuli, and environmental factors. Individuals with migraine are often aware of the things that serve as triggers for them, since part of migraine management is avoidance of triggers. Some of the more common triggers are detailed below:
Like migraine and many vestibular disorders, MV is diagnosed primarily on the basis of history. Specifically, risk factors for MV include family history or remote personal history of migraine; long history of motion intolerance with tendency toward motion sickness; visual motion sensitivity where visually challenging environments, such as supermarket aisles, feel uncomfortable; dislike of bright lights (photophobia); dislike of loud sounds (phonophobia); and increased tendency for nausea. In fact, the proposed criteria for both definite and probable MV include the combination of episodic vestibular symptoms of at least moderate severity coupled with a personal history of migraine and/or a relationship between the vestibular symptoms and some aspect of migraine (e.g., triggers, response to medications). Additionally, the criteria specify that other causes have been ruled out by appropriate investigations.
Dizziness due to migraine can present in different forms. Patients may actually feel vertigo, they may just feel lightheaded and unsteady, or they may simply feel that their head is not right. These sensations may occur individually or in combination, and can last seconds, minutes, hours, or days. The duration of symptoms typically varies across episodes. With MV, dizziness is not usually associated with auditory symptoms such as fluctuating hearing loss or unilateral tinnitus. In addition, it is important to realize that there is not necessarily a timing relationship between headaches and dizziness. In fact, as mentioned earlier, headache may be absent.
Because dizziness can be caused by numerous factors, reaching a correct diagnosis can be quite challenging. The single most important element in reaching a correct diagnosis is obtaining an accurate history. The diagnosis of MV is usually made when the patient has the traditional risk factors for migraine and the dizziness fits the characteristics mentioned above. Other disorders can usually be ruled out by accurate analysis of the history given by the patient. Although MV is often confused with Meniere's disease (MD), the diagnosis of MD should be limited to individuals experiencing fluctuating hearing loss, tinnitus, and aural fullness in one ear together with vertigo lasting less than 24 hours. It should be noted that vestibular function testing can be abnormal in about 25% of patients with MV. Other potential diagnoses (e.g., vestibular schwannoma) should be ruled out by the appropriate imaging studies such as MRI.
Treatment of migraine-related dizziness is usually accomplished by migraine prevention. Medications to stop the progression of headaches do not have an effect on the dizziness. Migraine prevention should be a multitiered approach. Keeping a headache diary to record events that may contribute to the headache can be helpful. Avoiding known trigger factors is also helpful in managing the migraine. Management includes a healthy lifestyle with regular exercise and balanced meals, in addition to healthy sleep habits. Medications can be used if these measures alone are not enough. Most preventive migraine medications were first developed to treat other disorders such as high blood pressure, depression, or seizures. Although the mechanism of action of these medications is not completely understood, they are thought to work by affecting the balance of certain chemicals in the brain. The major groups of medication used for migraine prevention include beta-blockers, calcium channel blockers, tricyclic antidepressants, and anti-epileptic (anti-seizure) medicines. Each patient with migraine is unique, and not every medication will work for every patient. In addition, since each of these medications has its own side effects as well as possible drug interactions, the choice of medication should be discussed carefully with the patient's primary health care provider.
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