Cluster headaches are not common but cause a very characteristic pattern of headache, usually associated with excess sweating of one or both sides of head. They occur in episodes once or twice a year to cause severe pain around or behind one eye which spreads to a temple, the jaw, teeth or chin. They often begin during sleep. Other effects may include a red, watery eye, drooping eyelid, altered pupil in the eye, stuffy nose and flushed face. Cluster headaches may be triggered by alcohol, temperature changes, wind blowing on the face or excitement. They usually last for 15 minutes to three hours and are named because of their tendency to occur in clusters for several weeks.
Many people fear that their headache may be due to a brain tumour but this is actually very rare. Most brain tumours cause other symptoms that lead to their diagnosis well before a headache develops. Cancerous and benign tumours may develop not only in the brain tissue itself, but also in the other structures within the skull such as the pituitary gland, membranes around the brain (meninges), sinuses and eyes. Most brain tumours are benign and can be cured by surgery.
Anything that puts abnormal pressure on the brain may cause headaches. An abscess caused by an untreated infection in the brain or an injury that penetrates the skull is one possibility. Bleeding inside the skull caused by an injury or rupture to a blood vessel is another. An aneurysm is the ballooning out of one side of an artery. The aneurysm may put pressure on the brain to cause a headache, or rupture to cause very severe effects on the brain function.
Inflammation of nerves in the scalp and face may appear to be a headache, when really it is the tissue outside the skull that is affected. Trigeminal neuralgia is one relatively common example, as is the pain of neuralgias associated with pinched nerves in the neck that spread from the base of the skull up the back of the head and as far forward as the hairline.
Psychiatric disorders as varied as phobias (abnormal fears), depression, post-traumatic stress disorder and excessive anxiety may cause headaches.
Other common causes of headache include:
- eye disorders that vary from increased pressure within the eye (glaucoma) to poor vision (resulting in eye muscle strain) and inflammation of the eye (iritis);
- menstrual periods (premenstrual tension),
- contraceptive pills,
- pregnancy and other fluctuations in the level of the sex hormone oestrogen;
- sexual intercourse may result in a headache, either with arousal or orgasm/ejaculation;
- inflammation or infection of the teeth (e.g. abscess or dental decay), jaw joint (.eg. arthritis), neck (e.g. arthritis or ligamentous strain), nose (e.g. large polyp) or sinuses (e.g. polyp or infection);
- cancer of any tissue in the body may cause headaches due to the release of toxins into the blood (e.g. leukaemia);
- an under active and over active thyroid gland (hypothyroidism and hyperthyroidism);
- diseases of other glands (e.g. adrenal glands, testes, parathyroids);
- extreme high blood pressure (e.g. phaeochromocytoma);
- anaemia (a lack of haemoglobin and/or red blood cells).
A wide range of medications (e.g. for control of high blood pressure, epilepsy and cancer) may cause headache as a side effect.
Uncommon causes of headache may include:
- SUNCT syndrome (variant of cluster headache),
- poorly controlled diabetes (either high sugar levels from lack of treatment, or low blood sugar from excess medication),
- severe allergy reactions (anaphylaxis),
- acromegaly (thickening and enlargement of the bones in the skull and legs),
- cyclic vomiting syndrome (episodes of vomiting associated with severe headache),
- Cushing syndrome (over production or over dosage of steroids),
- low blood pressure (e.g. from excessive medication, sudden change in position, shock or fright),
- failure or inflammation of any of the body’s major organs (e.g. kidneys, spleen or liver),
- pre-eclampsia (severe complication of pregnancy that is associated with a rise in blood pressure),
- autoimmune diseases (e.g. systemic lupus erythematosus, rheumatoid arthritis, scleroderma),
- inflammation of arteries in the neck (carotidynia) or temples (giant cell or temporal arteritis),
- chronic paroxysmal hemicrania (episodes of headache on one side only),
- Paget’s disease (softening of bone throughout the body),
- toxic shock syndrome.
Many other causes that have not been included may cause a headache. Almost any abnormality in the body may result in some kind of headache as our brain, or its surrounding structures, perceives the disorder in body function.