The term "migraine" refers to a syndrome of vascular spasms of the cranial blood vessels. Symptoms of a migraine attack may include heightened sensitivity to light and sound, nausea, auras (loss of vision in one eye or tunnel vision), difficulty of speech and intense pain predominating on one side of the head.

One theory of the cause of migraine is a central nervous system (CNS) disorder. The CNS consists of the brain and spinal cord. In migraine, various stimuli may cause a series of neurologic and biochemical events which affect the brain's vascular system.

A CT or CAT scan (computed tomography) is a much more sensitive imaging technique than x-ray, allowing high definition not only of the bony structures, but of the soft tissues. Clear images of organs such as the brain, muscles, joint structures, veins and arteries, as well as anomalies like tumors and hemorrhages may be obtained with or without the injection of contrasting dye.

The central nervous system is comprised of the brain and spinal cord. The peripheral nervous system includes all peripheral nerves.