Migraine is due to -

Ans. is 'c' i.e., Cortical spreading dissociation Pathophysiology of migraineTraditional theories of mieraine# The once popular vascular theory of migraine, which suggested that migraine headache was caused by the dilatation of blood vessels, while the aura of migraine resulted from vasoconstriction, is no longer considered viable in its original form.# Vasodilatation itself is probably an epiphenomenon, resulting from instability in the central neurovascular control mechanism.Cortical spreading depressiono A causal association between migraine aura and headache is supported by evidence that both are linked to the phenomenon known as cortical spreading depression of Leao.o Cortical spreading depression is a self propagating wave of neuronal and glial depolarization that spreads across the cerebral cortex.o Cortical spreading depression is hypothesized to :# Cause the aura of migraine# Activate trigeminal nerve afferents# Alter blood-brain barrier permeability by matrix metalloproteinase activation and upregulationo The activation of trigeminal afferents by cortical spreading depression in turn causes inflammatory chanties in the pain-sensitive meninues that generate the headache of mieraine through central and peripheral reflex mechanisms,o It has been suggested that migraine without aura may be caused by the occurrence of cortical spreading depression in areas of the brain (eg, cerebellum) where depolarization is not consciously perceived.