Headaches: Cluster - Causes

Causes

Cluster headaches, like migraines, are likely due to an interaction of abnormalities in the blood vessels and nerves that affect regions in the face.

Abnormalities in the Hypothalamus

Evidence strongly suggests that abnormalities in the hypothalamus, a complex structure located deep in the brain, may play a major role in cluster headaches. Advanced imaging techniques have shown that a specific area in the hypothalamus is asymmetrical in these patients and is activated during a cluster headache attack.

The hypothalamus is involved in the regulation of many important chemicals and nerve pathways, including:

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Click the icon to see an image of the hypothalamus.

• Nerve clusters that regulate the body's biologic rhythms (its circadian rhythms)
• Serotonin and norepinephrine. These are neurotransmitters (chemical messengers in the brain) that are involved with well-being and appetite.
• Cortisol (stress hormones)
• Melatonin (a hormone related to the body's response to light and dark)
• Beta-endorphins (substances that modulate pain)

By some not completely understood mechanism, the trigeminal nerve is also involved. The trigeminal nerve carries sensations from the face to the brain.

Circadian Abnormalities. Cluster attacks often occur during specific sleep stages. They also often follow the seasonal increase in warmth and light, beginning in summer and ending in the fall. Researchers have therefore focused attention on circadian rhythms, and in particular small clusters of nerves in the hypothalamus that act like biologic clocks. The hormone melatonin is also involved in the body's biologic rhythms.

Dilation of Blood Vessels

Cluster headaches are associated with dilation (widening) of blood vessels and inflammation of nerves behind the eye.