Today we post our response to a question that gets asked frequently by patients in our clinic.
Injection therapy has shown efficacy in chronic migraine, though the way it works to achieve this effect remains unknown. Recent studies have however provided some intriguing insights as to the potential mechanism of action of the drug.
Migraine is presumed to commence with a cortical spreading depression (CSD) phenomenon, which then activates the trigeminovascular system (TVS). The release of neuropeptides, mainly Calcitonin gene-related peptide (CGRP), is then thought to occur from nerve terminals of blood vessels around the brain. The local release of these neuropeptides causes these vessels to widen and for inflammation to occur, resulting in the typical, throbbing, migraine pain.
Supporting this concept the researchers found that CGRP levels are elevated in most patients with chronic migraine, as opposed to subjects either with less frequent migraine, or those without any migraine history.
These researchers have previously shown that increased CGRP levels significantly correlate with a beneficial response to injection therapy
In their most recent study they wanted to analyse whether treatment with injection therapy is able to induce changes in blood CGRP concentrations.
CGRP levels were determined from blood samples of 83 patients with chronic migraine, before, and after, treatment with injection therapy. All patients were outside of a migraine attack.
Importantly they discovered 2 things:
1/Pre-treatment CGRP levels in responders were significantly higher than those seen in non responders;
2/One month after treatment, the CGRP levels did not change in non responders, but significantly decreased in responders
The researchers concluded that CGRP levels can be of help in predicting the response to injection therapy, and suggest that the mechanism of action of injection therapy in chronic migraine, is as a result of the inhibition of CGRP release.
Other than in the research environment we are currently not able to test CGRP levels in our patients. Studies like these however contribute greatly to our understanding of migraine, and have provided further support to new, targeted therapies, currently in development for this debilitating condition.
If you want to hear more on migraines and their management come along to the free headache Australia seminar. Register at https://www.headacheweek.org.au/brisbane-migraine-management/
Note: Information on this site is not a substitute for professional medical advice. Also as per TGA guidelines we are not permitted to name the drug referred to as ‘injection therapy’.
References:CGRP and VIP levels as predictors of efficacy of injection therapy in chronic migraine. Cernuda-Morollon E, et al. Headache 2014; 54: 987-95
Injection therapy decreases interictal CGRP plasma levels in patients with chronic migraine. Cernuda-Morollon E, et al. Pain 2015 May;156 (5):820-4