Introduction:

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. The pain, instead, 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.
• Neurovascular headaches are the second most frequently occurring primary headaches and include migraines (the more common) and cluster headaches. Such headaches are caused by an interaction between blood vessel and nerve abnormalities. [See In-Depth Report #97: Migraine headaches and In-DepthReport #99: Cluster headaches.]

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. Over-the-counter pain medications can relieve most headaches.

Symptoms of migraine and tension-type headaches often overlap, and a diagnosis is sometimes difficult.

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's classification system 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 last fewer than 4 hours. The most common short-acting chronic headaches are cluster headaches.
• Long-duration headaches 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.

Tension-Type Headaches

General Description. Tension-type headaches, also called muscle contraction headaches or simply tension headaches, are the most common of all headaches. Tension-type headaches tend to have the following characteristics:

• The pain is commonly described as a tight feeling, as if the head were in a vise. It usually occurs on both sides of the head and is often experienced in the forehead, in the back of the head and neck, or in both regions. Soreness in the shoulders or neck is common.
• The pain is of mild-to-moderate intensity and is steady, not throbbing or pulsating
• The headache is not accompanied by nausea or vomiting
• The pain is not worsened by routine physical activity (climbing stairs, walking)
• Some patients may have either sensitivity to light or sensitivity to noise, but not both

Types of Tension Headache. In 2004, the International Headache Society updated its original 1988 classification criteria. Tension-type headaches are now divided into the following four classifications:

• Frequent episodic tension-type headache. Headaches occur at least once but not more than 15 days per month for at least 3 months (a minimum of 12 days but not more than 180 days per year). Headaches last from at least 30 minutes to 7 days.
• Infrequent episodic tension-type headache. At least 10 episodes of headache that occur less than 1 day per month (12 days per year). Because these headaches occur infrequently, they do not impact a patient's quality of life as severely as frequent episodic headaches and may not require attention from a medical professional.
• Chronic tension-type headache. Headaches occur at least 15 days per month for at least 3 months (180 days per year). The headache persists for hours at a time and may be continuous.
• Probable tension-type headache. Probable tension headaches may be classified as probable frequent episodic, probable infrequent episodic, or probable chronic. They have most, but not all, of the symptoms of tension-type headaches and are not attributed to migraine without aura or other neurological disorders. Probable chronic tension-type headache may be related to medication overuse.