What type of headache do you have?
The answer should be simple. The diagnostic criteria set out for each disorder are clear and distinct, however there are many sufferers who’s symptoms blur the boundary between headache types, and will shift from one definition to another as the headache progresses, and they just don’t fit the arbitrary boundaries that have been set by the International Classification of Headache Disorders.
What does this mean for the treatment of these people, and what does it mean for the medical approach to headaches?
In National Headache Awareness week 2018 I was fortunate enough to attend a talk given by Dr Michael Eller on ‘Migraine management and treatment options’. He began the talk with a little of the history of headache management through time and went on to talk about how migraines are classified – in other words how you can tell it’s a migraine compared to other forms of headache. I was a little shocked, but overwhelmingly in agreement with Dr Eller’s comment that the classification system is ‘a little bit silly really’.
In other words lots of people don’t fit the neat description we have for each headache type, and at different times of the day their classification would change depending on how the episode is behaving.
Anyone who has been to see more than 2 or 3 doctors for their condition will know exactly why a leading specialist in Melbourne would make such a comment. You will rarely end up with the same diagnosis from the same doctors, and despite the attestation of experts that ‘an accurate diagnosis is essential to good care’ the facts remain that this diagnosis is difficult to obtain.
The classification system is based on the differences in how each headache type looks, but many experts over the years have argued there are more similarities between headache types than there are differences, and that instead of ‘headaches being separated diagnostically by subtle clinical nuances of dubious reliability’ we should view headaches as slightly different manifestations of the same underlying process (Cady et al 2002).
So what does a migraine look like? Some people would say if they have aura then it’s a migraine, but aura only occurs in 20% of cases. Others would say if they feel nausea or the headache throbs then its migraine, but as we will see sometimes that’s not the case.
We have the following definitions according to the International Classification of Headache Disorders (ICHD) 3:
A.At least 5 attacks fulfilling criteria B-D
B.Headache attacks lasting 4-72 hours (untreated or unsuccessfully treated)
C.Headache has at least two of the following four characteristics
3.Moderate or severe pain intensity
4.Aggravation by or causing avoidance of routine physical activity (e.g. walking or climbing stairs)
D.During the headache at least one of the following:
1.Nausea and/or vomiting
2.Photophobia and phonophobia
E.Not better accounted for by another ICHD-3 diagnosis
So to satisfy the criteria for a migraine we could have moderate pain on one side of the head with nausea. Easy right?
So let’s compare to a frequent tension-type headache (TTH):
A patient reporting moderate throbbing/pulsing pain on one side of the head with sensitivity to light, but no nausea or sensitivity to sound will not meet the criteria for migraine. Those having a unilateral and pulsing headache will not meet the criteria for tension-type headache either. So what do they have? That depends on the doctor you see. Is it important to know? Probably not.
What about a client with bilateral headache of moderate intensity and no nausea or sensitivity to light and sound? That’s a TTH according to the rules. If we add nausea then it’s a migraine – simple. Unless it’s occurring more than 15 days per month. Chronic TTH can have nausea as part of the diagnosis – so which do you have?
If you think you’re confused, you’re not the only one. Dr Lawrence Newman at the recent Migraine World Summit gave a talk on the differences between tension-type headache and migraine. His first comment was tension-type headache ‘is not a headache that is disabling, or one that tends to drive people to see a doctor. There is no nausea, light or sound sensitivity. It’s just a mild to moderate headache that comes and goes’.
Very little of what he said reflects the diagnostic criteria. There is nothing mentioned of the level of disability of the headache in ICHD-3, most likely because that is a very subjective quality. In contrast, the presence of one of sensitivity to light or sound is permitted in the tension type headache classification, yet not by Dr Lawrence.
Migraines are defined as lasting 4-72 hours whereas a TTH may last 30 minutes to 7 days. If either of those two is ‘coming and going’ it is the migraine rather than a 7 day long TTH.
Later in the same talk he mentions nausea and says ‘by definition you can have mild nausea associated with tension-type headache’. For episodic TTH that is in fact the exact opposite of the diagnostic criteria – which specifically state no nausea or vomiting and no more than one of light and sound sensitivity.
Confusing, and to quote an expert ‘a bit silly’.
A majority of the clients we see at Melbourne Headache centre would be diagnosed with Chronic migraine. That is, more than 15 headache days per month with at least 8 being migraine. Typically many of the other days include headache that fits the TTH criteria.
Despite the fuss made over an accurate diagnosis, as Dr Lawrence points out, may of the same drugs are used to try and treat both cases, such as amitriptyline (Endep) or topiramate (topomax). In fact we regularly see people who have bilateral moderate headache with mild nausea but no sensitivity to light or sound (Chronic TTH) that have been treated with Botox - a drug only available under PBS to Chronic Migraine patients. Clearly in these cases the diagnosis is not reflecting the symptoms necessarily, but might be more reflective of what treatments your doctor wants to try with you. As Dr Newman puts it:
'it doesn't matter what you call it, it's the frequency of headache that's often going to guide the treatment'.
We treat a condition that is common to all headache types, which is a sensitized brainstem, so the diagnosis isn’t particularly important. What is critical is what the source of sensitization is.
Imagine each headache type is a different train, all sitting at the platform at a major centralized railway station (i.e. Southern Cross Station). Each train begins its journey in the same place, in the same way, and looks basically the same. Then as they move out of the station some trains will head north, some south, east and west, and others elevate or go underground. From that point the journey of each train looks quite different to each other.
When your job is to try and disrupt the journey of each train at different points along its journey, (i.e. drugs targeting specific pathways of different headaches) you need to try and understand which headache type you are dealing with.
When your treatment involves stopping the train from leaving the platform at the first station (i.e. decreasing brainstem sensitivity – Melbourne Headache Centre) then it really doesn’t make a huge difference which train you are referring to. We can potentially deal with all of them.
Cady R, Schreiber C, Farmer K, and Sheftell (2002) Primary Headaches: A Convergence Hypothesis. Headache 42 ; 204-216.
The American Headache Society: International https://www.ichd-3.org
Roger O'Toole is the Director and Senior Clinician of the Melbourne Headache Clinic and has over 10 years experience as a physiotherapist.