Why do migraines happen?
There are many theories as to why migraines happen and researchers are still trying to figure out the exact details. One of the current leading theories is that there is an area of the brain called the ‘trigeminovascular complex’ that becomes overly active. The trigeminovascular complex includes multiple areas of the brain. In the trigeminovascular complex, there is the trigeminal nucleus, as well are the vasculature in between the brain's protective layers, as well as the protective layers. The trigeminal nucleus is an area of the brain stem (which connects the brain to the spinal cord). The theory is that this area sends out a signal after the individual encounters a trigger. The signal goes out to the blood vessels below the protective layers that surround the brain. The blood vessels become dilated and inflammation happens below the protective layers of the brain, called the meninges. The meninges become irritated by the inflammation and this irritation is why people with migraines feel pain when they have a migraine. 1
The trigeminal nucleus, in the brain stem, sends out signals that act on the blood vessels, or vasculature, in between the brain's protective layers.
The blood vessels are in between the protective layers or meninges of the brain. The blood vessels dilate which leads to inflammation in the meninges and that inflammation is experienced as pain.
Here the blood vessels are dilating. The dilation of blood vessels leads to inflammation. Researchers believe pain is experienced because of this inflammation. The dilation of the blood vessels and then later their constriction also contributes to the aura and post-drome symptoms of a migraine.
Other current theories as to why migraines happen mostly focus on the different signals that the brain sends out. Too much or too little of different signals can change how the brain reacts and can lead to migraine pain.
One different current explanation of migraine is a theory about mitochondrial dysfunction. Mitochondria are the powerhouses of the cell and are where energy is transformed from the building blocks of what people eat into the type of energy that is the cell’s power source, called ATP (short for adenosine triphosphate). When there is dysfunction, the mitochondria in the body and specifically the brain are not working properly and the brain is not getting enough ATP energy to do its daily tasks. When the brain does not get enough energy the individual experiences pain in the form of a migraine. 2 Some supplements that individuals take to improve prevent migraines are also naturally found in the inner membrane of the mitochondria. These compounds (such as magnesium, coenzyme Q10 and Riboflavin) help stabilize the inner mitochondrial matrix where ATP energy is formed making the process that creates the ATP energy happen more easily.
Images modified from original art courtesy of Servier Medical Art by Servier https://smart.servier.com/
1. Noseda, R. & Burstein, R. Migraine pathophysiology: anatomy of the trigeminovascular pathway and associated neurological symptoms, CSD, sensitization and modulation of pain. Pain 154 Suppl 1, (2013).
2. Younis, S., Hougaard, A., Vestergaard, M. B., Larsson, H. B. W. & Ashina, M. Migraine and magnetic resonance spectroscopy: a systematic review. Curr. Opin. Neurol. 30, 246–262 (2017).