5 migraine questions answered

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Migraines are notorious for causing pain. But what triggers them? How can they be prevented? And what are the best treatments? Here are answers to five questions that will help clear up a few misunderstandings and provide some useful information along the way.

1. What exactly is a migraine?

The "classic" migraine is preceded by aura, which typically consists of strange visual disturbances — zigzagging lines, flashing lights, and, occasionally, temporary vision loss. Numbness and tingling affecting one side of the lips, tongue, face, and the hand on the same side may also occur. But only about a third of migraine sufferers experience aura, and fewer still with every attack.

The migraine headache, with or without aura, often — but not always — produces pain that usually begins (and sometimes stays) on one side of the head. A migraine headache also often has a pulsating quality to it. Many people experience nausea, extreme sensitivity to light or sound, or both.

It's also possible to confuse other sorts of headaches with migraines. Migraines can cause nasal congestion and a runny nose, so they're sometimes mistaken for sinus headaches. And the regular headache that most of us have experienced can have some of the features of a migrainous one, such as unilateral pain and nausea.

In short, arriving at a definition and diagnosis for migraine is complicated. Yet a simple headache diary — keeping track of headaches and factors that might have provoked them — can be very helpful in making a diagnosis.

2. What causes a migraine?

One prevailing theory is that migraines are caused by rapid waves of brain cell activity crossing the cortex, the thin outer layer of brain tissue, followed by periods of no activity. The name for this phenomenon is cortical spreading depression.

Cortical spreading depression makes sense as a cause of aura, but researchers have also linked it to headache. Proponents cite experimental evidence that suggests it sets off inflammatory and other processes that stimulate pain receptors on the trigeminal nerves. This "neurogenic" inflammation and the release of other factors make the receptors — and the parts of the brain that receive their signals — increasingly sensitive, so migraine becomes more likely.

Some leading researchers have expressed doubt about whether migraines start with cortical spreading depression. Experimental drugs that inhibit cortical spreading depression have shown a preventive effect on aura, but not on migraine headache.

So, say some researchers, migraines are best explained as beginning lower in the brain, in the brainstem, which controls basic functions, such as respiration and responses to pain, and modulates many others, including incoming sensory information. The theory is that if certain areas of the brainstem aren't working properly or are easily excited, they're capable of starting cascades of neurological events, including cortical spreading depression, that account for migraine's multiple symptoms.

3. What triggers a migraine?

There are too many triggers to list them all here. Many migraine sufferers are sensitive to strong sensory inputs like bright lights, loud noises, and strong smells. Lack of sleep is a trigger, but so is sleeping too much, and waking up from a sound sleep because of a headache is a distinctive characteristic of migraine. Many women have menstrual migraines associated with a drop in estrogen levels. Alcohol and certain foods can start a migraine.

One of the most common triggers, stress, is one of the hardest to control. Interestingly, migraines tend to start not during moments of great stress but later on, as people wind down.

4. How can migraines be prevented?

If you are prone to migraines, there are many steps to take to prevent or diminish the attacks:

  • Identify triggers so you can avoid them. That can take some time and real detective work.
  • Keep to a regular, stress-reducing schedule that includes a full night's rest, balanced meals, and exercise.
  • Wearing blue- or green-tinted glasses can help fend off an attack in people with light sensitivity.
  • Try medications, such as beta blockers, tricyclic antidepressants, and anticonvulsants. All have side effects, so they should be taken at low doses and only if migraines are frequent.

5. How can they be stopped?

Migraine sufferers can cut an attack short with one of the triptan drugs, a class that includes eletriptan (Relpax), sumatriptan (Imitrex), and zolmitriptan (Zomig). The triptan drugs seem to work by inhibiting pain signaling in the brainstem. They also constrict blood vessels, so people with a history of cardiovascular disease (heart attack, stroke, uncontrolled hypertension) are usually advised not to take them.

Pain relievers like ibuprofen (Advil, Motrin) and naproxen (Aleve) can halt a mild attack, but rebound headaches may develop if they're taken too often. Rebound headache occurs after the body gets used to having a medication in its system; when it's not there, headaches happen. Migraines can quickly snowball into more serious pain, so it's important to treat the headache early, regardless of the medication.

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Is it okay to drink wine if you have a slow heart rate?

Q. If you have a slow heart rate (bradycardia), is it safe to drink wine? If so, how much per day? Does alcohol affect the heart rate?

A. Bradycardia generally refers to a steady but slow heartbeat at rest, under 60 beats per minute (although trained athletes can have much slower resting heart rates). A slow heart rate can cause symptoms such as dizziness, shortness of breath, chest pain, or fainting, but most people don't notice any symptoms unless the heart rate dips below 50 beats per minute.

Small amounts of alcohol can speed up the heart rate. Although that doesn't make it a tonic for bradycardia, moderate drinking is safe for most people with bradycardia. Moderate means one or two drinks a day for men, no more than one drink a day for women.

Larger amounts of alcohol all at once (binge drinking) or over time can be toxic to the heart muscle, leading to heart failure or the common rhythm disorder known as atrial fibrillation.

Around the holidays, emergency rooms see a spike in the number of people having a reaction to too much alcohol. Dubbed the "holiday heart syndrome," symptoms include the sensation that the heart is racing or skipping beats (palpitations), sometimes accompanied by pain, pressure, or heaviness in the chest, or shortness of breath. Although a normal rhythm usually returns on its own within 24 hours, some people need a beta blocker to slow the heart or a medication or procedure to restore a normal rhythm.

The holiday heart syndrome can occur with just a drink or two, but it usually takes five, six, or more drinks to trigger it. Too much caffeine or overuse of over-the-counter decongestants can cause similar rhythm problems.

— Peter Zimetbaum, M.D.
Harvard Heart Letter Editorial Board