MIGRAINE: 

• Pathology:

Migraine is caused by the trigeminal nerve distribution into the intracranial and perhaps the extracranial arteries. These nerves cause the release of peptide neurotransmitters particularly calcitonin gene-related peptide- it is a very strong vasodilator. There is also extravasation of plasma and plasma proteins into the perivascular space . Mechanical stretching is then caused by this perivascular edema and it may be the cause of activation of pain nerve endings in the dura. 

• Treatment: 

The mechanisms of action of drugs used are poorly understood, because of the wide variety of the drug groups and action. 

Drugs that can be used: 

• Triptans

These drugs are the first line therapy for acute severe migraine attacks. An example is Sumatriptan. They should not be used in patients with risk of coronary artery disease. They activate the 5-HT 1D/1B receptors on the presynaptic trigeminal nerve endings and inhibit the release of the vasodilating peptides. It is also 5-HT antagonist, which may prevent vasodilatation and stretching of the pain endings. 

• Anti- inflammatory analgesics like aspirin and ibuprofen are also often useful in controlling the pain of migraines. 

• Ergot alkaloids: 

They have mixed effects at 5HT 2 receptors and alpha receptors. They cause marked smooth muscle to contract but block the alpha 1 vasoconstriction. It then prevents pain by preventing vasodilatation. Example: Ergotamine.