Headaches - Cluster In-Depth

Most people are familiar with headaches, the all too common affliction marked by throbbing, piercing, or vise-like pain around much or a part of the head. There are many different kinds of headaches, and they range from being an infrequent annoyance to a persistent, severe, and disabling medical condition.

The brain itself is insensitive to pain, so that is not what hurts when a headache arises. Rather, the pain occurs in the following locations:

• The tissues covering the brain
• The attaching structures at the base of the brain
• Muscles and blood vessels around the scalp, face, and neck

Doctors categorize headaches as either primary or secondary, which helps to distinguish the many different kinds of headaches and to determine appropriate treatments for each.

Primary Headaches

A headache is considered primary when a disease or other medical condition does not cause it. Most primary headaches fall into three main types: tension-type, migraine, and cluster headaches.

• Tension headache is the most common primary headache and accounts for 90% of all headaches.
• Migraines are the second most frequently occurring primary headaches. Migraine is referred to as a neurovascular headache because it is most likely caused by an interaction between blood vessel and nerve abnormalities.
• Cluster headache is a less common type of primary headache. Although it is sometimes referred to as a neurovascular headache, evidence now suggests that its cause lies in the hypothalamus, a region deep in the brain that regulates, among other functions, the biologic rhythms of the body.

Headaches are usually caused by muscle tension, vascular problems, or both. Migraines are vascular in origin, and may be preceded by visual disturbances, loss of peripheral vision, and fatigue. Most headaches can be relieved by over-the-counter pain medications.

Secondary Headaches

Secondary headaches are caused by other medical conditions, such as sinus infections, neck injuries, and strokes. About 2% of headaches are secondary to abnormalities or infections in the nasal or sinus passages, and they are commonly referred to as sinus headaches.

Chronic Daily Headaches

The International Headache Society has developed a classification system that includes a category called chronic daily headaches. They may originate as tension headaches, migraines, or a combination of these or other headache types. Chronic daily headaches affect 4 - 5% of the population.

Chronic daily headaches are defined as any benign headache that occurs at least 15 days a month and is not associated with a serious neurologic abnormality. Most people with these headaches have them daily or almost daily and they can be quite debilitating.

Chronic daily headaches are, in turn, subdivided into two categories:

• Short-duration headaches, or those lasting less than 4 hours. The most common short-acting chronic headaches are cluster headaches.
• Long-duration headaches, which last more than 4 hours. Tension-type headaches are the most common type of long-duration chronic (recurring) headaches and, in fact, the most common type of chronic headaches in general.