Timothy C. Hain, MD •Page last modified: March 3, 2021
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As of July, 2020, there were more than 1100 papers with "chronic migraine" in their title in Pubmed. This is not an underreported topic.
Surprisingly, CM is rather common -- affecting about 2% of the entire population, and about 8% of the persons who are already diagnosed as having Migraine (see Epidemiology below)
There are several definitions of chronic migraine. The International Headache society defines it as headaches on at least 15 days per month over 3 months (i.e. a 50% duty cycle), and migraine attacks for at least 8 days per month (i.e. a 25% duty cycle) .
This number should be considered rather tenative -- Migraine is based on symptoms only, and of course, the number of people who choose to report these symptoms can vary immensely. Accordingly, the available studies results for the prevalence (number of people that have CM) are very variable (see following).
Overall, the estimate of Natoli (2010) of 2% appears to be a reasonable consensus estimate. (Manack et al, 2011).
CM in the population at large
Natoli et al (2010), reported in a metaanalysis of 12 studies that "The prevalence of CM was 0-5.1%, with estimates typically in the range of 1.4-2.2%. Seven studies used Silberstein-Lipton criteria (or equivalent), with prevalence ranging from 0.9% to 5.1%. Three estimates used migraine that occurred >/=15 days per month, with prevalence ranging from 0 to 0.7%. "
According to Buse et al (2012), which surveyed 120,000 US housholds, the prevalence of CM was "nearly 1%".
In Germany, there is less chronic migraine. Straube et al (2010) reported: "Using the IHS definition from 2004, chronic migraine was diagnosed in 0.2% of the population. "
Chronic migraine in persons who have migraine
According to Buse, among persons diagnosed with migraine, CM represented 7.68%. According to Lipton et al (2016), using a web survey methodology, compared two studies and reported that "The proportion of persons with migraine who had chronic migraine was similar (AMPP, 6.6%; CaMEO, 8.8%). "
CM in children:
Lipton et al (2011) reported that the prevalence of CM in adolescents (12-17) was 1.75%.
Ozge et al (2013) reported that "Totally, 10.4% of the children, predominantly the girls, received the diagnosis of migraine when they grew older (1.7% CM, 8.6% EM)." (EM is episodic migraine).
CM according to gender
Scher et al (2019) broke out men from women in the CaMEO (Chronic migraine epidemiology and outcomes) study. "Of the 16,789 migraine respondents, 4294 were men (25.6%). Compared to women, men were slightly older at onset of their headaches (mean 24.1 vs. 22.3 years) and had fewer headache days/month (4.3 vs. 5.3 days), slightly less severe attacks (Migraine Symptom Severity Score, 21.6 vs. 22.6), reduced frequencies of grade IV Migraine Disability Assessment scores (15.7% vs. 24.1%), allodynia (32.6% vs. 49.7%), chronic migraine (6.5% vs. 9.6%, each p < 0.001), and common comorbidities. "
Again from Lipton et al (2016), "Rates of moderate/severe disability (Grade III/IV) were substantially higher in both studies for chronic migraine (AMPP: men = 66.9%, women = 78.9%; CaMEO: men = 71.0%, women = 82.6%) than episodic migraine (AMPP: men = 23.0%, women = 31.8%; CaMEO: men = 26.7%, women = 37.9%). "
CM has a much higher economic cost than episodic migraine, because it lasts longer. Someone who has headaches all the time, is much more impaired than someone who has headaches once/month (Lanteri-Minet et al, 2011).
Chronic migraine is usually treated starting with the drugs used for prevention of episodic migraine. In addition, some treatments such as Botox are FDA approved only for Chronic Migraine. A new family of medications based on blocking CGRP are generally tried as well. It is currently felt that opiate drugs (e.g. oxycodone) are not appropriate treatments for chronic migraine.
Adapted from lecture handout given for the seminar "Recent advances in the treatment of Dizziness", American Academy of Neurology, 1997 and "Migraine Vs Meniere's", at the American Academy of Otolaryngology meeting, 1999-2001.