Definition
Migraine
A migraine is a recurrent neurobiological disorder characterised by moderate to severe head pain, autonomic dysfunction, and sensory hypersensitivity.
Episodic attacks may progress to chronic migraine through central sensitisation and neuroplasticity.
Origins
Where does it come from? Not from the brain tissue itself—the brain has no pain receptors. The pain originates in the meninges (the membranes surrounding the brain) and the large cranial blood vessels, which are densely supplied with trigeminal nerve endings.
Why is there pain? A neuronal event triggers the trigeminal nerve terminals to release CGRP and other neuropeptides. This causes inflammation and vasodilation in the meninges, which activates pain-sensing nerve endings there. The signal then travels to the brainstem and thalamus. The pain is essentially a protective alarm that has become pathologically amplified.
Diagnostic Thresholds
Episodic
Definition
Link to originalEpisodic Migraine
Episodic migraine is a form of migraine characterised by fewer than fifteen headache days per month.
It may progress to chronic migraine through central sensitisation, neuroplasticity, and medication overuse.
Chronic
Definition
Link to originalChronic Migraine
Chronic migraine is a form of migraine characterised by fifteen or more headache days per month, of which at least eight exhibit migrainous features, persisting for at least three months.
It often evolves from episodic migraine through central sensitisation and may be complicated by medication overuse.
Therapy
Acute Therapy
First-line options are triptans; alternatives for non-responders include gepants and ditans.
Preventive Therapy
Modern options include CGRP monoclonal antibodies and onabotulinumtoxinA.
Medication Overuse
Adaptation headache
Excessive use of acute medication lowers the pain threshold and can induce medication overuse headache (medication adaptation headache). Triptans should not exceed ten days per month; simple analgesics should not exceed fifteen days per month.