How the dichotomy emerged (1980s–1990s)
In the mid-1980s, when the drug group later known as triptans entered research, it became clear that there were no internationally agreed-upon precise definitions for migraines or other headaches. Therefore, the International Headache Society developed definitions for migraines and tension-type headaches, among others. Because a new and promising group of drugs for migraines was on the horizon, the criteria were designed to ensure that the new medications would be effective. This led to a stark contrast between migraine and tension-type headache, forcibly making them opposites:
Criteria in a nutshell
Migraine vs. Tension-Type Headache – Symptom Comparison
How to interpret the criteria
The first four criteria relate to the pain, and at least two of these should be met. The last two are associated symptoms, of which at least one must be present for migraine. For tension-type headache, only photo- or phonophobia is possible.
Why the understanding changed (research evidence)
When the first triptan, sumatriptan, became available in pharmacies in the early 90s, medical training focused on the differential diagnosis of migraine and tension-type headache, and unfortunately, this still echoes in headache diagnostics today. Well, since then, it has been understood that there are a few more aspects to the matter. Already in 1992, chronic tension-type headache was found to improve with sumatriptan (1). When the International Headache Society published the third version of its headache classification (2), chronic migraine was included, defined as having headache on 15 or more days per month for at least three months, with at least 8 headache days meeting migraine criteria or successfully treated with triptans, and the remaining at least 7 headache days meeting tension-type headache criteria. This divided headache researchers for a while, but gradually even the last stubborn ones, mainly from Southern Europe, understood that the scientific evidence was very convincing. The most convincing evidence for the sliding connection between tension-type headache and migraine is Finnish. A working group led by Docent Mikko Kallela showed that individuals completely free of headaches do not have a genetic burden caused by migraine genes (3). Surprisingly, those suffering from tension-type headache did have such a burden, and this burden increased when progressing to clinically more severe forms of migraine.
Conclusion
Are tension-type headache and migraine different stages of the same disease?
Yes, they are.
Markku Nissilä, specialist in neurology
Sources
Brennum J, Kjeldsen M, Olesen J. The 5-HT1-like agonist sumatriptan has a significant effect in chronic tension-type headache. Cephalalgia. 1992 Dec;12(6):375–9. doi: 10.1111/j.1468-2982.1992.00375.x. PMID: 1335361.
https://ichd-3.org/1-migraine/1-3-chronic-migraine/
1.3 Chronic migraine - ICHD-3
Description: Headache occurring on 15 or more days/month for more than 3 months, which, on at least 8 days/month, has the features of migraine headache. Diagnostic criteria: Headache (migraine-like or tension-type-like1) on ≥15 days/month for >3 months, and fulfilling criteria B and C Occurring in a patient who has had at least five attacks fulfilling criteria B-D for 1.1 Migraine without ...
ichd-3.org
Häppölä P, Gormley P, Nuottamo ME, Artto V, Sumelahti ML, Nissilä M, Keski-Säntti P, Ilmavirta M, Kaunisto MA, Hämäläinen EI, Ripatti S, Pirinen M, Wessman M, Palotie A, Kallela M; International Headache Genetics Consortium (IHGC). Polygenic risk provides biological validity for the ICHD-3 criteria among Finnish migraine families. Cephalalgia. 2022 Apr;42(4–5):345–356. doi: 10.1177/03331024211045651. Epub 2021 Oct 14. PMID: 34648375; PMCID: PMC8988286.