Headache can be defined as discomfort or pain felt within or outside the skull, including the upper portion of the neck and behind the eyes. The most common and obvious cause of head pain is direct head trauma, which can lead to concussion symptoms, but headache usually infers pain perceived from within or around the head. The causes of headache pain are numerous and classified as either serious or benign, although the level of pain rarely correlates to the level of seriousness.
Infection
Infections of the central nervous system, bacterial or viral, are life threatening and frequently cause headache pain in addition to fever and neuralgias. The main types are meningitis, encephalitis and brain abscesses. Sinus infections cause facial pain as well as sharp headache pain, especially if the frontal sinuses are infected.
Increased Pressure
Pressure increase within the skull is also very serious and can cause severe headache pain. Hydrocephalus, which is water or fluid on the brain, brain tumors and bleeding types of strokes can all increase intracranial pressure.
Vascular Causes
Problems with blood vessel diameter or blood flow can create vascular-related headache pain often described as throbbing and severe. The most common type of vascular headache is migraine, although cluster headaches fall in this category also.
Stress
People who experience stress frequently manifest it physically within their muscles, usually the upper shoulders, jaw and base of the skull. Jaw muscle tension from clenching can irritate the temperomandibular joints, which can directly refer pain up to the sides of the head. Upper neck muscle tension and inflammation creates achy pain in that region and around the back of the skull, which is referred to as a tension headache.
Neck Trauma
The neck vertebrae, nerves, and muscles can be vulnerable to injury, ranging from whiplash to poor posture to a "kink" from a chill. When this happens, a cervicogenic headache often develops and creates pain in the occipital and sub-occipital regions of the neck, similar to a tension headache.
Toxicity
Toxins which cross the blood-brain barrier can cause direct inflammation and pain in the head, although the brain tissue does not generate pain or other damage, which can cause headaches. Drug toxicity, "hangovers" from excessive alcohol consumption, and food poisoning are examples. Food allergies can cause similar headache pains, with common triggers being red wine, chocolate, aged cheese, and MSG.
Withdrawal
Removal of addictive substances from the body temporarily disrupts various functions, which leads to headaches. Recreational drugs, certain pharmaceuticals, and caffeine all cause headaches within 24 hours if abruptly discontinued after long-periods of use.
Diseases Which Cause Headaches
Diseases can cause headache pain because of inflammation, tissue damage, change in blood pressure, increased toxins or complications from drug treatment. Such diseases include diabetes, glaucoma, hypertension, temporal arteritis, Lupus, and Paget's disease.
Other Causes
Dehydration; low blood sugar, also known as hypoglycemia; chronic coughing; sex; eye strain; toothaches; and even "brain freeze" from drinking cold liquids can all cause headache pain.
References
- "Comprehensive Review of Headache Medicine"; Morris Levin, et al; 2008
- "Harrison's Principles of Internal Medicine"; Anthony Fauci, et al; 2008
- National Institute of Health: Headache Causes
