What is a headache?
Headache is defined as a pain arising from the head or upper neck of the body. The pain originates from the tissues and structures that surround the skull or the brain because the brain itself has no nerves that give rise to the sensation of pain (pain fibers). The thin layer of tissue (periosteum) that surrounds bones, muscles that encase the skull, sinuses, eyes, and ears, as well as thin tissues that cover the surface of the brain and spinal cord (meninges), arteries, veins, and nerves, all can become inflamed or irritated and cause headache. The pain may be a dull ache, sharp, throbbing, constant, intermittent, mild, or intense.
How are headaches classified?
In 2013, the International Headache Society released its latest classification system for headache. Because so many people suffer from headaches, and because treatment is difficult sometimes, it was hoped that the new classification system would help health-care professionals make a more specific diagnosis as to the type of headache a patient has, and allow better and more effective options for treatment.
The guidelines are extensive and the Headache Society recommends that health-care professionals consult the guidelines frequently to make certain of the diagnosis.
There are three major categories of headache based upon the source of the pain.
Cranial neuralgias, facial pain, and other headaches
What are primary headaches?
Primary headaches include migraine, tension, and cluster headaches, as well as a variety of other less common types of headache.
Tension headaches are the most common type of primary headache. Tension headaches occur more commonly among women than men. According to the World Health Organization, 1 in 20 people in the developed world suffer with a daily tension headache.
Migraine headaches are the second most common type of primary headache. Migraine headaches affect children as well as adults. Before puberty, boys and girls are affected equally by migraine headaches, but after puberty, more women than men are affected.
Cluster headaches are a rare type of primary headache. It more commonly affects men in their late 20s though women and children can also suffer from this type of headache.
Primary headaches can affect the quality of life. Some people have occasional headaches that resolve quickly while others are debilitating. While these headaches are not life threatening, they may be associated with symptoms that can mimic strokes.
Many patients equate severe headache with migraine, but the amount of pain does not determine the diagnosis of migraine. Read our Migraine Headachearticle for more information about the symptoms, causes, and treatment of migraines.
What causes headaches?
Migraine headache is caused by inflammation or irritation of structures that surround the brain or affect its function. While the brain itself has no pain nerve fibers, everything else above the shoulders, from the neck, skull, and face, can cause a person to have of head pain. Systemic illnesses, including infection or dehydration, can have associated headache. These are known as toxic headache. Changes in circulation and blood flow or trauma can also cause headache.
Changes in brain chemistry may also be associated with headache: medication reactions, drug abuse and drug withdrawal can all cause pain.
Every person is different so the history of the headache is important. Recognizing patterns or precipitating (foods eaten, stress, etc.) factors, in combination with the physical examination and associated symptoms, can help identify the cause for each individual's specific headache.
What causes tension headaches?
While tension headaches are the most frequently occurring type of headache, their cause is not known. The most likely cause is contraction of the muscles that cover the skull. When the muscles covering the skull are stressed, they may become inflamed, go into spasm, and cause pain. Common sites include the base of the skull where the trapezius muscles of the neck insert, the temples where muscles that move the jaw are located, and the forehead.
There is little research to confirm the exact cause of tension headaches. It is believed that tension headaches occur because of physical stress on the muscles of the head. For example, these stressors can cause the muscles surrounding the skull to clench the teeth and go into spasm. Physical stressors include difficult and prolonged manual labor, or sitting at a desk or computer concentrating for long periods. Emotional stress also might cause tension headaches by causing the muscles surrounding the skull to contract.
What are the signs and symptoms of tension headaches?
Common signs of tension headaches include:
Pain that begins in the back of the head and upper neck and is often described as a band-like tightness or pressure. It may spread to encircle the head.
The most intense pressure may be felt at the temples or over the eyebrows where the temporalis and frontal muscles are located.
The pain may vary in intensity but usually is not disabling, meaning that the sufferer may continue with daily activities. The pain usually is bilateral (affecting both sides of the head).
The pain is not associated with an aura (see below), nausea, vomiting, or sensitivity to light and sound.
The pain occurs sporadically (infrequently and without a pattern) but can occur frequently and even daily in some people.
The pain allows most people to function normally, despite the headache.