Migraine Award funded by Gustof Ringstrom and Macquarie Bank
The cortex, brainstem and migraine.
Dr Geoffrey Lambert
University of New South Wales
Co-Investigator: Associate Professor A.S. Zagami
Migraine is the most prominent chronic pain suffered by Australians and chronic pain itself is in the top 3 medical conditions in terms of socio-economic cost. The top two are cancer and cardiovascular disease.
But migraine differs from cancer and heart disease in a very baffling way- there is no pathology. We can’t perform a brain scan or a blood test to determine if someone is suffering from a migraine. The only way we can be sure is to ask them. This has conditioned doctors to assume that migraine is not an organic disease, but a psychological one. Even patients often blame themselves. No way! Migraine is definitely an organic disease.
If we can’t find anything wrong inside the head of a migraine patient, what could be causing this excruciating pain? There are many trigger factors- bright light, wine, stress can all precipitate a migraine headache, but we don’t know why or how. The pain appears to arise from the dura mater which covers and protects the brain from injury. We know that pain is a “warning signal” which tells us all is not well. Pain tells us to withdraw our hand from the hotplate or to visit the dentist. What is migraine pain warning us of?
We have concluded that the pain warning received during a migraine is a false alarm caused by an overly sensitive warning system. Just as you would protect your expensive assets with a sensitive alarm, so our brain is protected with a warming system of very high sensitivity.
We believe that the circuitry which sets the sensitivity of the migraine pain alarm system is buried deep in the brain- the brainstem. But the controls for that circuitry are higher up- in the cerebral cortex, the conscious part of the brain. Migraine triggers cause neurons in the cortex to become over-active. These over-active neurons affect the controls of the alarm circuitry and cause normal sensations from the head to be perceived as painful sensations- as a headache.
We have recently shown that such an alarm system actually exists and that migraine triggers activate it by cranking up its sensitivity. We are now moving ahead to investigate the mechanisms by which this tweaking of the alarm system occurs. If we can discover this mechanism, we may be able to prevent migraine by preventing the false alarm. This would be the “magic bullet” that migraineurs have been seeking for 150 years.