When brain images are taken of people who experience primary headaches, they’re normal. This has led scientists to believe that headaches come from dysfunction rather than an abnormality in the structure of the brain. However, researchers from the National Hospital for Neurology and Neurosurgery in London are suggesting that this conclusion may have been made in error.
Headaches not directly due to injury or disease are called primary headaches. Included in this category are tension, migraine, and cluster headaches. Magnetic resonance imaging (MRI) or computed tomography (CT) scans have consistently shown no structural abnormality in these people—until now.
With a new type of imaging called voxel-based morphometry, British researchers have conducted a study that shows that people with cluster headaches have an abnormality in the part of the brain called the hypothalamus. The hypothalamus lies deep in the brain and is responsible for maintaining a constant internal environment, including temperature and wakefulness, and carrying out certain behavior patterns—sexual behavior, physical expression of emotions, and pain and pleasure. It affects the nervous system directly and through hormones.
Researchers compared the brain images of 25 people with cluster headaches to the brain images of 29 people in the control group. Fourteen of the headache sufferers had a headache during the test.
The tests showed that all the people with cluster headaches had a greater density of grey matter in their hypothalamus. Researchers then compared the two groups using positron emission tomography (PET). The PET scans showed both structural and functional abnormalities in this same area of the hypothalamus.
Now that an exact area of the brain has been identified with cluster headaches, researchers are hoping to develop more effective treatments for these and other types of primary headaches.
However, they can’t say that the extra grey matter actually causes the headache, just that all the participants with cluster headaches had this hypothalamic density. Perhaps the increased density is the result of the headaches, not the cause. Further testing will be needed to explore the exact association between primary headaches and hypothalamic abnormality.