Headaches can be caused by a large variety of reasons. Those suffering from regular headaches are often aware of the cause of their headache, however in many cases, the cause of a headache may go unknown.
There are two basic categories of headaches, namely primary and secondary. Primary headaches are those headaches that are caused for no specific underlying reason. They are not the result of any specific disease or process and are commonly thought of as being a result of a problem in brain function rather than a problem with the brain’s basic structure itself. Primary headaches include migraine & cluster headaches as well as tension-type headaches. Being that there is no underlying brain structural problem with primary headaches, it is important to note that there are no investigative tests such as magnetic resonance imaging tests (MRIs) or computed tomography (CT) scans that can be done to determine an exact reason for the headache. If you suffer from primary headaches, however, some investigative tests may still be used to rule out other causes of your headaches.
Secondary headaches result from another problem, which has a headache as a symptom of the underlying initial problem. Secondary headaches can result from a huge variety of problems including head and neck injuries, inflammatory processes within the body, hormonal issues, as well as more serious causes such as brain tumors or aneurysms.
The main types of primary headaches and some common secondary types of headaches are described in detail below:
Migraines are often described as a severe (and often unbearable) throbbing or pulsating pain in one or both sides of the head, often around the temples, front of the head or behind an eye. Approximately 15-20% of migraine headaches are accompanied by a sensory aura, which is a particular sensation that, in adults, precedes the actual headache pain (children sometimes get the aura at the same time as the headache). An aura can present in the form of a variety of sensations such as suddenly smelling a certain smell, seeing spots or zigzags, feeling a twitch, excessive yawning, numbness or tingling in the face or one part of the body, or even weakness on one side of the body. Some migraine sufferers even crave certain foods, such as chocolate, as their aura.
Nausea, vomiting, double vision and an extreme sensitivity to light, sound or smells often accompany migraines. Migraines can also be accompanied by a loss in memory, altered thinking capacity, and altered speech. Migraines can last anywhere from an hour to, in extreme cases, several days. Most migraines are severe enough that they cannot be ‘worked through’ and once the headache has passed a ‘headache hangover’ is often felt, which is a feeling of extreme fatigue, dizziness and difficulty concentrating. Neck pain may or may not be present during or after a migraine headache.
Migraine headaches are often familial, meaning that they run in one’s family. Being depressed can also increase your likelihood of suffering a migraine headache, as can lack of restorative sleep or having chronic sinus problems. Migraines are more common in women than in men.
Migraine headache triggers are not always known but some common food and drinks that may trigger migraines include certain red wines, cheeses, chocolate, excessive caffeine, pickled foods, foods containing monosodium glutatmate (MSG), citrus fruits and sourdough bread. Other common non-food related triggers include flickering lights, intense exercise, intense smells (such as perfume), weather changes (barometric changes), and menstruation cycles. Stress is an extremely common trigger of migraine headaches in many sufferers.
The physiology of migraines is still being studied however it is accepted that there is an increased sensitivity in the brain to certain environmental triggers which then sets off a chemical chain of events in the brain. The migraine trigger causes a chemical release in the brain, which in turn affects the blood vessels of the brain, causing them to swell and release further chemicals. The chemicals released act as an irritant to the pain structures in the head and face including the trigeminal nerve and the area that it supplies, hence causing the headache. Altered levels of serotonin, which is an important brain chemical that regulates pain and mood, have also been associated with migraines. It has also been shown that during a migraine headache there is an altered blood flow to certain parts of the brain’s cortex such as the occipital (visual) cortex.
Cluster headaches are an extremely painful type of headache, which comes on rapidly and occurs in a cyclic time frame, hence the name. Headaches occur over a specific time frame, usually a two to twelve week period and this is often related to a particular season of the year. During the cluster period, headaches generally occur every day (often more than once in a day) and often occur at the same time during the day. Time between headaches is pain-free.
Cluster headaches often occur at night, generally within a couple of hours of going to sleep. Most cluster headaches are 30-90 minutes in duration but can be shorter or longer. Sufferers often describe the pain as burning and sharp like a red-hot stick poking through the eye. Cluster headaches occur on one side (and do not switch sides within a cluster period) and they are usually located around an eye but may extend to other areas of the head and neck. Other symptoms can include redness, swelling or tearing of the affected eye, droopiness of the affected eye, sweating of the face, and stuffy or runny nasal passages on the affected side. Sufferers of cluster headaches often also describe restlessness as a symptom of the headache; due to pain, the headache sufferer just can’t sit still. Fortunately in most cases, cluster headaches usually dissipate as quickly as they began.
Although the exact cause of cluster headaches are unknown, the cause appears to be related to activation of the trigeminal nerve which supplies sensation to side of the face, jaw and eye. Triggering of the trigeminal nerve appears to occur for an unknown reason by a deep part in the brain called the hypothalamus. The hypothalamus is related to our ‘circadian rhythm’ which regulates our sleep and wake cycles. Activation of the trigeminal nerve appears to then trigger other cranial nerves in the area, which can lead to the symptoms such as tearing, nasal congestion, and eye redness. Triggers for cluster headaches can be strong smells, high altitudes, bright lights, heavy exercising or becoming overheated. Alcohol is also a well-known cluster headache trigger. An aura may occur with a cluster headache but it is uncommon.
Cluster headaches are more common in men and are also more common in heavy smokers. Having a family member who also suffers from cluster headaches increases one’s chance of also suffering from cluster headaches.
Cluster headaches can be described as episodic cluster headaches or chronic cluster headaches. An episodic cluster headache is a period of headaches then a significant period without headaches. Chronic cluster headache sufferers have very little remission time (less than approximately 14 days a year) that are headache free.
Tension-type headaches are the most common type of headache and many people experience them regularly, particularly when under stress. For this reason, these headaches are also sometimes referred to as ‘stress headaches’. Aside from stress, tension-type headaches are reported to be commonly triggered by a number of other factors including hunger, fatigue, poor posture and eye strain.
Tension-type headaches can last anywhere from 30 minutes up to even a week! The pain of a tension-type headache is generally described as a mild to moderate dull but constant and diffuse pain, and usually occurs on both sides of your head. Tension-type headaches are often described as a tight band around the head near the temples, or tightness and pressure at the head and around the lower neck and trapezius muscle. Tension-type headaches are not associated with any visual disturbances or auras and often the pain of a tension-type headache can be tolerated such that sufferers are able to ‘work through them’. For some people, however, the pain is more severe, can last a long time, and is unable to be ‘worked through’. Women are more than twice as likely to suffer from tension-type headaches than men.
The underlying cause of tension-type headaches used to be thought of as increased tension in the muscles of the neck and face which then causes the headache pain. More recently, however, tension-type headaches have been thought to be linked to sufferers being hypersensitive to pain and stress, which then causes the headache. The neck pain and muscle soreness that results is thus a symptom of the headache rather than a cause of it, which was thought in the past. For this reason, along with migraines and cluster headaches, tension-type headaches are included in the category of primary headaches, which occur for no specific reason and are not the symptom of another underlying problem but rather thought to be as the result of altered brain function.
Tension-type headaches can also be described as episodic or chronic. Episodic tension-type headaches occur once to twice a month whereas chronic tension-type headaches occur more than 15 days in a month.
Cervical is the medical term meaning ‘relating to the neck’ and ‘genic’ means originating or coming from. Cervicogenic headaches are headaches that are associated with neck pain and stiffness; the cause of the headache comes from structures in the neck. As noted in the anatomy section above, the nerves that supply the joints of the upper three cervical vertebrae also supply the skin overlying the scalp, forehead, ears and eyes. Injury to structures in the upper neck such as ligaments, nerves, joints, muscles or other structures can refer pain and cause a headache.
Cervicogenic headaches are most commonly felt on one side of the head but occasionally a cervicogenic headache can cause pain on both sides. These types of headaches typically occur due to excessive strain on the structures of the upper neck, which can occur from a traumatic event such as whiplash. More often than a traumatic event, however, cervicogenic headaches occur as the result of prolonged stress on the upper neck structures such as when sitting at a computer for prolonged periods, especially when sitting with poor posture. Sufferers of cervicogenic headaches often feel the headache come on right as they are in the aggravating neck position or as they move their neck, but a cervicogenic headache can also be felt hours after aggravating the neck structures. For instance, a cervicogenic headache may come on in the evening following or the next morning after driving for a long period or sitting in a plane. Pain is felt when the suboccipital structures of the neck or the neck itself is palpated or touched. Secondary pain may be felt down the neck and into the trapezius muscle area. Nerves in the neck that become entrapped or ‘pinched’ may also cause cervicogenic-type headaches.
The sinuses of the face lie in the cheeks, behind the bridge of your nose, as well as in the forehead/brow area. The sinuses help to humidify air and secrete mucus to assist air filtration. Those suffering from a sinus headache often complain of the area ‘feeling full’. Pressure and fullness felt may even extend into the upper teeth area.
Sinus headaches most often occur after an upper respiratory infection or cold. The upper respiratory infection or cold causes inflammation of the lining of the sinuses (sinusitis), which prevents draining of the mucus in the sinuses and then causes the build-up of pressure in the area. Inflammation may also occur as a result of an allergy. Sinus headaches are not associated with nausea or vomiting nor do they have a related aura. Often the pain of a sinus headache worsens when the sufferer bends forward, lies down, makes sudden movements, or when they first get out of bed due to the added pressure that the change in position causes. Sudden temperature changes, such as going from a warm house into the cold outdoors, can also increase the pain of a sinus headache. The face overlying the inflamed sinus may be tender to touch.
Frequent colds, climbing or flying to high altitudes, frequent diving or swimming, or having a history of allergies such as hay fever increases your risk of suffering from a sinus headache. In addition, having any type of issue with your nasal passages such as polyps or a deviated septum, or can also put you at a higher risk of developing this type of headache.
Sinus headaches are often confused with migraines or tension-type headaches. Many people who seek medical attention due to what they believe are sinus headaches are actually diagnosed as having migraines or tension-type headaches.
Temporomandibular Joint (TMJ)-Related Headaches
TMJ disorders can commonly cause headaches. As mentioned above, the TMJ joint is a complicated joint and because of this easily becomes injured. In many cases it is obvious that one has a TMJ disorder because there will be pain around the jaw or ear as well as clicking in the joint or problems opening or closing the jaw itself. Headaches may develop related to these symptoms. In some TMJ cases, however, local TMJ pain may not be present and headaches may be the only symptom one feels so the TMJ joint gets overlooked as the culprit.
TMJ-related headaches can also closely mimic tension-type headaches, cervicogenic headaches, migraines, and sinus-related headaches therefore a thorough examination of the TMJ should be included in any physical examination for headaches to either rule the TMJ joint in or out.
See a Patient’s Guide to Temporomandibular Joint Disorders
Related Document: Momentum Health's Guide to Guide to Temporomandibular Joint Disorders
Other secondary type headaches can come on as a result of a number of other causes including:
- poor posture or work biomechanics
- skipped meals
- food sensitivities
- lack of sleep
- head injury/concussion
- inner-ear problems
- excessive noise
- hormones (menstrual-related, pregnancy-related, or other),
- glare from sunlight, computer screens or other screens
- alcohol, particularly from red wine or excessive drinking
- ice cream or eating/drinking extremely cold items (brain freeze)
- excessive exercise
- brain aneurysm
- brain tumour