Migraine is a common and disabling condition reported in approximately 12% of the population. In the Global Burden of Disease Study by the World Health Organization, updated in 2013, migraine was found to be the sixth highest cause worldwide of years lost due to disability. Migraine attacks sometimes increase in frequency over time. Headache experts divide this process of transition into four distinct states:
- No migraine
- Low-frequency episodic migraine (less than 10 headache days per month)
- High-frequency episodic migraine (10-14 headache days per month)
- Chronic migraine (15 or more headache days per month; meaning that people with chronic migraine have a migraine or headache more often than not)
As per the International Headache Society, chronic migraine is defined as headache occurring on 15 or more days per month for more than three months, which, on at least 8 days per month, has the features of migraine headache. Chronic migraine occurs in approximately 1% of the population. Studies estimate that about 2.5% of people with episodic migraine will transition to chronic migraine each year.
To make a diagnosis of chronic migraine, it is very important to know the exact number of days per month that a person experiences a headache of any kind. This is best done my maintaining a daily headache diary. Often when people are asked how many headaches they have, they may report only their most severe headaches (like the ones that keep them from work/school or the ones that they take medications for). By reporting only their most severe headaches, they may give the doctor a false impression of their true headache burden and consequently a diagnosis of chronic migraine may be missed.
People suspected of having chronic migraine should be carefully assessed by their doctor to exclude other potential causes of frequent headaches such as secondary headaches (meaning headaches caused by an underlying condition or disease) or other forms of chronic daily headache including chronic tension-type headache, hemicrania continua, or new daily persistent headache.
Please refer to the International Classification of Headache Disorders 3rd edition (beta version) website for more information on the criteria used to diagnosis chronic migraine: https://www.ichd-3.org/1-migraine/1-3-chronic-migraine/
Risk Factors for Chronic Migraine
Transition to chronic migraine is associated with well-recognized, potentially treatable risk factors. Some examples of risk factors include:
- Other pain disorders
- Stressful life events
- Head/Neck injury
- Acute medication overuse
- Persistent, frequent nausea
Treatment of chronic migraine is similar to that of episodic migraine with a few notable exceptions. Treatment should consist of:
- Acute medications for use at onset of a headache attack to try to break it. Limitation on number of uses of acute medications is important to try to avoid medication overuse and risk of medication overuse headache
- Preventive medications to help reduce the frequency and severity of headache attacks. Currently, Onabotulinumtoxin A (Botox) is the only FDA approved preventive treatment for chronic migraine. Preventive treatments used for episodic migraine such as anti-seizure medications (Example: depakote, topiramate), anti-depressants (Example: amitriptyline, venlafaxine) and blood pressure medications (Example: propranolol) may also be used for chronic migraine prevention.
- Non-medication preventive treatments including biofeedback, cognitive behavioral therapy
- Addressing risk factors such as depression, anxiety, snoring, obesity, etc.
Migraine is considered chronic when people have 15 or more headache days per month, with at least 8 of those days meeting criteria for migraine. Chronic migraine can be a very disabling condition. Development of chronic migraine has been associated with a number of potentially treatable risk factors. Chronic migraine treatment should primarily focus on prevention through use of medication and non-medication preventive strategies as well as addressing identified risk factors.
The International Headache Society. https://www.ichd-3.org/1-migraine/1-3-chronic-migraine/
Lipton RB. Tracing transformation: Chronic migraine classification, progression, and epidemiology. Neurology 2009;72:S3-7.
Schwedt TJ. Chronic migraine. BMJ 2014; 348:g1416
Bigal ME, Lipton RB. Modifiable risk factors for migraine progression. Headache 2006; 46:1334.