Does Botox reduce the frequency of chronic migraine?

Paul Rizzoli, MD

Contributor

Doesn’t it seem like Botox is showing up everywhere as a medical treatment? Botox is a brand of botulinum neurotoxin (BoNT), a protein substance originally derived from the bacterium Clostridium botulinum. In its original form it was the toxin responsible for botulism, the paralyzing illness often caused by eating contaminated food.

BoNT is now used to treat a number of medical conditions including muscle spasms, excessive sweating, overactive bladder, and some eye muscle conditions. However, one of its most common uses is in the preventive treatment of chronic migraine. Chronic migraine, defined as headache occurring more than 15 days a month for more than three months, is rare, affecting only about 3% of the migraine population. Nonetheless, since migraine itself is so common, this condition ends up affecting a large number of people and can be extremely debilitating.

A recent meta-analysis pooled the results of multiple prior studies to investigate the usefulness of Botox, a brand of BoNT, in reducing the frequency of chronic migraine. The results suggested that there was benefit from this treatment; it not only improved quality of life and significantly reduced the frequency of chronic migraine headaches, but did so with few and mild side effects.

How might BoNT work to prevent chronic migraine?

Botox was introduced for treatment of chronic migraine in 2000, after some people receiving injections for cosmetic treatment of facial lines reported improvement of headaches. Initial studies after that observation produced conflicting results. Then in 2010, two large studies showed enough benefit (reduction in headache days and improved quality of life) that the FDA approved this treatment for chronic migraine.

Botulinum neurotoxin is taken up into nerves, where it may modify the release of neurotransmitters, chemicals that carry signals between brain cells. This is the original mechanism responsible for the paralysis in BoNT poisoning.

However, this same process in other nerves may interrupt pain production by blocking the release of pain-producing chemicals such as substance P and calcitonin gene-related peptide (CGRP). Although not yet proven, this process could lead to a turning-down of pain processes inside the brain that may be responsible for chronic migraine. Although this mechanism can reduce headache frequency and severity, it does not seem to change the underlying migraine condition.

What are the risks of this treatment?

Theoretically, the spread of BoNT from the site of injection to other areas could result in muscle weakness or paralysis, and doctors usually avoid using BoNT in people with muscle weakness conditions. In practice, however, body-wide reactions or side effects are rare.

Mild injection-related irritation is sometimes reported. At times, temporary eyelid drooping or a change in facial expression resulting from the loss of forehead lines can be seen. These complications can be avoided by moving subsequent injections to a different location. People typically have no restrictions after their injections, and they may return to work or normal activities.

Who would be a candidate for Botox and who wouldn’t?

Since its introduction Botox has become an accepted treatment for chronic migraine when other standard treatments have failed. Botox can help people feel and function better with fewer missed days of work, and the treatments are often covered by health insurance plans.

Botox is not typically used in people who have 14 or fewer migraine headaches per month. However, it is sometimes used “off label” (outside FDA approval) for other forms of chronic headache, such as chronic tension headache.

Where does Botox fit relative to other treatments to prevent migraine?

A comprehensive migraine management plan consists of maintaining a healthy lifestyle, avoiding migraine triggers as much as possible, and using over-the-counter and prescription abortive medications (to stop a migraine already in progress), as needed.

In chronic migraine, standard treatments, including daily prescription preventive medications alone or in combination, are usually tried before Botox. A disadvantage of Botox is that it must be administered through injection by a medical provider every three months in order to maintain the effect. In addition, those on Botox may need to continue taking their previous prescription migraine medications for optimal results.

Nonetheless, Botox has become a common treatment in headache centers in the US. Botox injections are well-tolerated, beneficial, and appear to be safe for long-term management of chronic migraine.

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