What is cortical spreading depression?

Cortical spreading depression (CSD) creates short-lasting waves that move across the brain; the waves create inflammation in the brain and cause pain. The blood flow increases and then decreases, causing the brain to experience excitation, followed by nerve cell depression. That change in pressure is what causes migraine pain.
Evidence shows that women are sensitive to the effects of CSD, which is one explanation for why women experience migraines at a higher rate than men