A headache, a pain in the head or tissues surrounding the upper neck, has varied causes and consequences. The consequences range from uncomfortable to debilitating. Some of the latter can be a symptom of life-threatening abnormality or an illness.

While the symptoms and triggers of headaches are known the exact molecular basis of these ailments is as yet unclear. It has been suggested that the abnormal release in the brain of a chemical called seratonin shifts the flow of blood from the arteries to the veins. This causes changes in the nerves and nerve centers in the brain, which may induce a headache.

An excruciating type of headache is caused by an aneurysm, the swelling of a blood vessel in the brain. The headache appears suddenly and with great intensity. Prompt medical attention, including surgical repair, is usually necessary to avoid a stroke or death.

Another type of...