Often referred to as hormonal migraine or hormonal headache it might at first seem unusual that this could be related to the neck.
Clearly it is hormonal. The timing of it dictates that there must be a direct link to the hormones, and there is.
However, as Dr Elizabeth Loder (2001) noted, “Patients with menstrual migraine do not generally have hormonal abnormalities.”
So what is happening?
Put simply the underlying problem is an overactive brainstem. The drop in oestrogen affects this underlying activity making it uncontrollable, and the result is severe headpain. The upper cervical spine is in the box seat to cause or at least significantly contribute to this over activity.
In the remainder of part 1 I will expand on the role of the brainstem and the evidence for it’s over activity in menstrual migraine. Part 2 will look more at the interaction between the brainstem and hormones, particularly oestrogen.
A small area in the brainstem of chronic headache and migraine sufferers is overactive. This is also true for menstrual migraine sufferers. This small area is called the trigemino-cervical nucleus or TCN. The TCN receives all the input (other than special senses – sight, smell, hearing, taste) from the head and face and also receives information from the upper three cervical nerves. So any information, from a scratch on the head, to the sensation of muscles in the scalp contracting, and even the pulsing of blood vessels on the lining of the brain all send their information back to the TCN where it must be relayed onto central nerves to be sent to the brain. Once this information arrives at the brain you become aware of whatever the sensation is.
If this area is overactive it means that your brain can receive information, for example “throbbing” from the blood vessels on the lining of the brain, without the nerves on those blood vessels being active. In effect your brain feels something that really isn’t there. This is called referred pain. The same is true for a vast majority of headaches. There isn’t a problem where you actually feel the pain, but it is referred from somewhere else. That somewhere else is the TCN.
Inside the TCN we have all the nerves arriving from the face and head, and they intermingle and interconnect with the upper three cervical nerves and this area is overactive. How do we know?
Two important studies confirm that the same process that is occurring in other chroninc headache and migraine types, is also occurring in Menstrual Migraine.
In 2005 Mannix and Files published a study regarding the use of triptans in menstrual migraine. Triptans are a drug that “turn down” the activity of the TCN, and by doing so turn down or switch off headaches and migraines by stopping the referral process. For these to be effective in menstrual migraine there must be over activity in the TCN.
In 2009 Varlibas and Erdemoglu studied a reflex that goes through the TCN. Reflex activity, whether they are dulled, normal or excited inform doctors and researchers about how active the central nervous system is. They found that menstrual migraine sufferers had “excited reflexes” compared to non-migraine controls, during their attack and outside of an attack. This supports research in non-menstrual migraine, Tension Type Headache, cervicogenic headache and cluster headache, indicating the TCN is always over active, and not just during a migraine attack.
These studies confirm that the underlying process in menstrual migraine IS an overactive TCN. So where is this overactivity coming from?
In a vast majority (over 80%) of cases it is a problem in the upper cervical spine that is causing constant input into the TCN and making it overactive. Using dedicated “headache specific” techniques this problem is assessable, treatable and self manageable in most people.
So how do the hormones relate then?
In Menstrual Migraine part 2 we will look at the role of oestrogen and its effect on this over activity.
To recap on the anatomy of the TCN, and the role of the trigemino-cervical nucleus in headache and migraine you may wish to read some earlier posts on this blog.
Loder, E (2001) Menstural Migraine. Current Treatment Options in Neurology, Vol 3 (2), pp 189-200.
Mannix and Files (2005) The use of triptans in the management of menstrual migraine. CNS Drugs 19 (11), pp 951-972.
Varlibas and Erdemoglu (2009) Altered trigeminal system excitability in menstrual migraine patients. Journal of Headache Pain, 10 (4), pp 277-282.
Roger O'Toole is the Director and Senior Clinician of the Melbourne Headache Clinic and has over 10 years experience as a physiotherapist.