What physiological changes are involved in a migraine headache?

The selection of a change in the size of blood vessels at the base of the brain as the correct answer highlights a critical physiological aspect of migraine headaches. During a migraine, there is often a complex interplay of neurovascular factors. Initially, the blood vessels in the brain dilate, leading to increased blood flow, which is associated with the onset of headache pain. This dilation occurs due to the release of various inflammatory mediators and neurotransmitters, such as calcitonin gene-related peptide (CGRP) and substance P, that promote vasodilation and inflammation.

Following the initial phase, there may be a vessel constriction phase but the significant point here is that the changes in blood vessel diameter are central to the pathophysiology of migraines. This neurovascular theory of migraine emphasizes how vascular changes contribute not only to headache pain but also to associated symptoms such as nausea, sensitivity to light, and sound.

In contrast, dilation and contraction of face muscles and constriction of neck muscles do not specifically pertain to the physiological alterations associated with the migraine process. Inflammation of the ear canals is unrelated to the pathophysiology of migraines and would not directly affect the headache experience related to migraines.