migraine is a chronic neurological disorder that is mostly characterized by severe headaches and aura. Headache is called migraine if it meets four out of the following five criteria: Pulsating (the headache is pulsating or throbbing) One day (the headache lasts one day, actually between 4 and 72 hours) Unilateral (the headache is only on one side of the brain) Nauseating (the headache is accompanied by nausea or vomiting) Dibilitating (the headache precludes normal function/daily activities) There are many parallels between pain and migraine and therefore many of the literature discussion for pain also holds true for migraine. This section deals with the literature that is specific to migraine.
Cortical Spreading depression (CSD) is a transient wave of hyperexcitability, followed by a prolonged period of depressed activity that travels through the brain.
In humans, CSD is thought to manifest itself as an aura, which may precipitate the pain phase later on.
Pre-administered Anandamide significantly reduced nociceptive behavior in rats, suggesting that migraine may actually be a manifestation of a dysfunctional endocannabinoid system (Greco et al., 2011), which in turn offers interesting possibilities for endo- and plant cannabinoids in the treatment of migraine.
TRPV1 has also been implicated in the pathophysiology of migraine.
Interestingly, blocking TRPV1 function has no effect but stimulating these receptors offers pain relief; in fact transient activation is followed by prolonged de-sensitization and thus effective pain relief.
An important structure in pain processing is the ventrolateral periaqueductal grey (vlPAG).
Whether this opens more therapeutic avenues remains to be elucidated.
Akerman, S., Holland, P.R., Lasalandra, M.P., and Goadsby, P.J. (2013). endocannabinoids in the brainstem modulate dural trigeminovascular nociceptive traffic via CB1 and “triptan” receptors: implications in migraine. J. Neurosci. Off. J. Soc. Neurosci. 33, 14869–14877.
Greco, R., Mangione, A.S., Sandrini, G., Nappi, G., and Tassorelli, C. (2014). Activation of CB2 receptors as a potential therapeutic target for migraine: evaluation in an animal model. J. Headache pain 15, 14.
Hoffmann, J., Supronsinchai, W., Andreou, A.P., Summ, O., Akerman, S., and Goadsby, P.J. (2012). Olvanil acts on transient receptor potential vanilloid channel 1 and cannabinoid receptors to modulate neuronal transmission in the trigeminovascular system. pain 153, 2226–2232.
In one study, the effect of medical cannabis on migraine was tested. Without selecting for application route or dose, the use of medical cannabis highly significantly reduced the frequency of migraine headaches from 10.4 to 4.6 per month (p<0.0001)(Rhyne et al., 2016).
Rhyne, D.N., Anderson, S.L., Gedde, M., and Borgelt, L.M. (2016). Effects of Medical Marijuana on migraine Headache Frequency in an Adult Population. Pharmacotherapy.