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Headache

life science Maturity 11-13 Next article →

A headache, known scientifically as cephalalgia, is a symptom involving pain in the face, head, or neck. It is one of the most common physical discomforts experienced by humans. Statistics show that about half of all adults suffer from a headache in any given year. There are more than 200 different types of headaches recognized by experts. These range from harmless sensations to life-threatening medical emergencies.

Cruikshank - The Head Ache
Cruikshank - The Head Ache

Medical professionals use various classification systems to organize these pains. The International Headache Society is the most well-recognized system. It classifies headaches into more than 150 different types. These are broadly divided into two main categories: primary and secondary headaches. Understanding this distinction is vital for determining the correct medical response.

Primary headaches are considered benign, meaning they are not caused by an underlying disease or structural problem. They do not pose a physiological danger, though they can cause significant daily disability. Approximately ninety percent of all headaches are primary. These typically first appear in people between the ages of 20 and 40. Tension-type headaches are the most common, affecting about 1.6 billion people, or 21.8% of the population. Migraines follow as the second most common, affecting about 848 million people, which is 11.7% of the population.

Primary headaches have very different characteristics. Migraines often involve pulsing pain, nausea, and photophobia, which is sensitivity to light. They may also cause phonophobia, or sensitivity to sound. Tension-type headaches usually feel like a non-pulsing, "bandlike" pressure on both sides of the head. Other rare primary types include cluster headaches, which cause severe pain around one eye. These episodes last between 15 and 180 minutes and occur at the same time every day. There are also primary stabbing headaches, which feel like "ice pick" pains lasting from one second to several minutes.

Secondary headaches are different because they are caused by an underlying condition. These can be caused by infections, head injuries, or vascular disorders. Some secondary headaches are very dangerous and require immediate attention. For example, meningitis is an inflammation of the meninges that presents with fever and a stiff neck. A brain tumor may cause a dull headache that worsens with exertion or changes in position. Other serious causes include an ischemic stroke or a subarachnoid hemorrhage. Doctors look for specific "red flags" to identify these dangerous secondary types.

To understand how a headache happens, we must look at the biology of pain. Interestingly, the brain itself is not sensitive to pain because it lacks pain receptors. Instead, pain is sensed by other structures in the head and neck. These include the meninges, which are the membranes covering the brain, and various blood vessels. Other sensitive areas include the eyes, ears, teeth, and head and neck muscles. When these areas are irritated, a specialized nerve cell called a nociceptor sends a signal. This message travels up the nerve fiber to the brain to indicate pain.

Scientists have different theories about the exact mechanisms of certain headaches. For many years, the vascular theory suggested that migraines were caused by blood vessel problems. It was thought that vessels inside the brain constricted and then dilated. However, most specialists now believe migraines are actually caused by a primary problem with the nerves in the brain. They believe an "aura" is caused by a wave of increased activity in the cerebral cortex. This is known as cortical spreading depression, followed by a period of decreased activity. Other theories suggest that the release of chemicals like serotonin may cause inflammation in the arteries and meninges.

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