What is a headache?
Headache is defined as pain in the head or upper neck. It is one of the most common locations of pain in the body and has many causes.
How are headaches classified?
Headaches have numerous causes, and in 2007 the International Headache Society agreed upon an updated classification system for headache. Because so many people suffer from headaches, and because treatment is sometimes difficult, the new classification system allows health care practitioners to understand a specific diagnosis more completely to provide better and more effective treatment regimens.
There are three major categories of headaches:
- primary headaches,
- secondary headaches, and
- 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; as many as 90% of adults have had or will have tension headaches. Tension headaches are more common among women than men.
Migraine headaches are the second most common type of primary headache. An estimated 28 million people in the United States (about 12% of the population) will experience migraine headaches. 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. An estimated 6% of men and up to 18% of women will experience a migraine headache.
Cluster headaches are a rare type of primary headache, affecting 0.1% of the population. An estimated 85% of cluster headache sufferers are men. The average age of cluster headache sufferers is 28-30 years of age, although headaches may begin in childhood.
Primary headaches affect quality of life. Some people have occasional headaches that resolve quickly, while others are debilitated. Tension, migraine, and cluster headaches are not life-threatening.
What are secondary headaches?
Secondary headaches are those that are due to an underlying structural problem in the head or neck. There are numerous causes of this type of headache ranging from bleeding in the brain, tumor, or meningitis and encephalitis.
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 spasm and cause pain. Common sites include the base of the skull where the trapezius muscles of the neck inserts, the temple where muscles that assist the jaw to move are located, and the forehead.
There is little research to confirm the exact cause of tension headaches. Tension headaches occur because of physical or emotional stress placed on the body. Physical stress that may cause tension headaches include difficult and prolonged manual labor, or sitting at a desk or computer for long periods of time Emotional stress may also cause tension headaches by causing the muscles surrounding the skull to contract.
What are the symptoms of tension headaches?
The symptoms of tension headache are:
- A pain that begins in the back of the head and upper neck as a band-like tightness or pressure.
- Described as a band of pressure encircling the head with the most intense pain over the eyebrows.
- The pain is usually mild (not disabling) and bilateral (affecting both sides of the head).
- Not associated with an aura (see below) and are not associated with nausea,vomiting, or sensitivity to light and sound.
- Usually occur sporadically (infrequently and without a pattern) but can occur frequently and even daily in some people.
- Most people are able to function despite their tension headaches.
What diseases cause secondary headaches?
Headache is a symptom associated with many illnesses. While head pain itself is the issue with primary headaches, secondary headaches are due to an underlying disease or injury that needs to be diagnosed and treated. Controlling the headache symptom will need to occur at the same time diagnostic tests are being considered. Some of the causes of secondary headache may be potentially life-threatening and deadly. Early diagnosis and treatment is essential, if damage is to be limited.
The International Headache Society lists eight categories of secondary headache. A few examples in each category are noted (this is not a complete list):
Head and neck trauma
- Injuries to the head may cause bleeding in the spaces between the layers of tissue that surround the brain (subdural, epidural and subarachnoid bleeding) or within the brain tissue itself.
- Concussions, where head injury occurs without bleeding
- A symptom of whiplash and neck injury
- Blood vessel problems in the head and neck
- Stroke or transient ischemic attack (TIA)
- Arteriovenous malformations (AVM) may cause headache before they leak.
- The carotid artery in the neck can become inflamed and cause pain.
- Temporal arteritis (inflammation of the temporal artery)
Non-blood vessel problems of the brain
- Brain tumors, either primary, originating in the brain or metastatic from a cancerthat began in another organ
- Idiopathic intracranial hypertension, once named pseudotumor cerebri, where there is too much cerebrospinal fluid pressure within the spinal canal.
Medications and drugs (including withdrawal from those drugs)
- Systemic infections (for example, pneumonia or influenza)
- Changes in the body’s environment
- High blood pressure (hypertension)
- Renal dialysis
Problems with the eyes, ears, nose throat, teeth and neck
What are the exams and tests for secondary headaches?
The patient history and physical examination provide the best means for determining the cause of secondary headaches. Therefore, it is extremely important that patients with severe headaches seek medical care and give their health care practitioner an opportunity to assess their condition. Tests that may be useful in making the diagnosis of the underlying disease causing headaches include:
- blood tests,
- computerized tomography (CT Scan),
- magnetic resonance imaging (MRI) scans of the head, and
- lumbar puncture.
Specific tests will depend upon what potential issues the health care practitioner and patient want to address.
Blood tests provide helpful information in association with the history and physical examination in pursuing a diagnosis. For example, an infection or inflammation in the body may cause a rise in the white blood cell count, the erythrocyte sedimentation rate(ESR) or C-reactive protein (CRP). Blood tests can also assess electrolyte disturbances, and a variety of organ functions like liver, kidney, and thyroid.
Computerized tomography of the head
Computerized tomography is able to detect bleeding, swelling, and tumor. It can also show evidence of previous stroke. With intravenous contrast injection, it can also be used to look at the arteries of the brain.
Magnetic resonance imaging (MRI) of the head or Electroencephalography (EEG)
MRI is able to better look at the anatomy of the brain, meninges (the layers that cover the brain and the spinal cord). While it is more precise, the time to perform the scan is significantly longer than for computerized tomography. This type of scan is not available at all hospitals. EEG is also helping to rule out seizures, tumours or any focal abnormalities.
Cerebro-spinal fluid, the fluid that surrounds the brain and spinal cord, can be obtained with a needle that is inserted into the spine in the lower back. Examination of the fluid can reveal infection (such as meningitis due to bacteria, a virus, or tuberculosis) or blood from hemorrhage. In almost all cases, computerized tomography is done prior to lumbar puncture to make certain there is no bleeding, swelling, or tumor in the brain.