Headaches are one of the most common symptoms reported by patients. Virtually all headaches are caused by irritation of the nerves in the meningeal lining surrounding the brain. Unfortunately, these neurons are pretty sensitive and a lot of things can irritate them. Headaches can be caused by conditions ranging from the common cold to a malignant brain tumor. The mere presence of a headache, therefore, is not very useful diagnostically. However, if a headache is the main or only symptom being experienced, then the specific characteristics of the headache can be extremely useful for diagnosing the cause of the headache and determining the best course of treatment.
Several key features of a headache can be important for identifying its cause, including: the rate of development, duration, localization, quality of the pain, intensity, and whether it is a single event or recurring phenomenon. Other symptoms occurring around the same time or before the onset of the headache, however minor or apparently unconnected, can also provide important diagnostic clues.
The rate of a headache’s development can often give clues to its cause. On the extreme end of the spectrum, a headache from a leaking cerebral aneurism bursts into full intensity almost instantaneously (like a thunderclap), while a headache from a brain tumor often builds slowly over several weeks or months. Cluster headaches typically reach peak intensity over less than a minute or two, while migraines generally take a half hour or more to reach peak intensity. Headaches from food poisoning normally develop over an hour or two as the toxin is slowly absorbed and builds up in the blood stream, while headaches from encephalitis or meningitis are more likely to emerge over the course of one or two days. Headaches caused by epileptic seizures develop during the seizures themselves, when the sufferer is often unconscious, and appear full force when the individual comes out of the seizure.
The typical duration of the pain also tends to differ for headaches caused by different conditions. A headache caused by a brain tumor, by a disruption of cerebrospinal fluid flow in the brain, or by an underlying metabolic disorder is unlikely to go away or diminish unless the condition is corrected. Cluster headache pain typically ends 15 minutes to 3 hours after onset. Migraines can last anywhere from 4 hours to 3 days. The pain from encephalitis or meningitis often lingers on for several days and can last more than a week. The headache pain from a leaking cerebral aneurism may diminish slowly over a few days as the body slowly removes the excess fluid from the brain, but this pain may be the only warning signal for a much more catastrophic event.
The location where the pain is experienced and whether it is focused in one place or more broadly distributed, can also indicate what kind of headache it is. Most common headaches are experienced as having roughly the same intensity on both side of the head (bilateral), but they may feel stronger in some regions of the head than others. Headaches caused by dehydration, elevation sickness (and other sources of oxygen deprivation), concussions, fluid buildup in the brain, or an expanding cerebral aneurism are usually experienced through the entire head, as though your head were in a vice. Headache pain caused by a brain tumor usually feels like it is focused deep inside of the head. Migraines are most often experienced as being on one side of the head only. Cluster headaches are also usually felt on one side of the head, but they also are typically experienced as having a distinct focus, usually the eye. Headaches from food poisoning generally feel more intense in the back of the head, as do most muscle tension headaches. By contrast, headaches due to eyestrain or eye irritation tend to be focused around the eyes. Sinus headaches and headaches caused by dental problems are felt more in the front of the face.
The overall quality of the pain also differs for different types of headaches. Most headaches produce a more-or-less constant level of pain until they begin to go away, but headaches caused by problems involving the blood vessels, including migraines and the kinds of headaches that people with low blood pressure can experience when standing up suddenly, are usually described as throbbing or pulsing. The pain from a leaking cerebral aneurism is usually described as quite unique, like nothing the person has ever experienced before. Cluster headaches are more often described as a hot and or stabbing pain. Headaches caused by medication side effects tend to fluctuate in intensity over the course of the day, paralleling the dosing schedule, with the peak occurring an hour or two after taking the medication and the low occurring shortly before taking the next dose.
The severity of headache pain can also provide an indication of the cause or source of the pain. The mild dehydration experienced by many coffee, tea, or soda drinkers, due to the diuretic properties of caffeine, tends to produce low level headaches that are annoying, but not something that you cannot live with. The pain from a cluster headache, in contrast, is often so intense that sufferers contemplate suicide during their attacks. Migraine headache pain is usually not as great as that caused by a cluster headache but can also be quite debilitating, with sufferers being unable to tolerate almost any stimulation during an attack. The pain from a growing tumor or build-up of cerebrospinal fluid may start out low, but can build to an intolerable level.
Recurring headaches suggest different underlying causes than headaches which occur as rare single events. A headache which occurs as an isolated event is more likely to result from something like food poisoning, meningitis, or encephalitis. Even though the pain from such a condition may be quite severe, it usually does not call for any ongoing medical treatment after the pain has passed. Headaches recurring several times a month suggest a possible migraine pathology and may warrant prescribing preventative medication. Headaches which recur at predictable times of day, particularly in the middle of the night, suggest a cluster headache pathology and are likely to respond to different treatments than either common headaches or migraine headaches.
Although the pain of the headache may be the most prominent feature for the sufferer, other symptoms occurring at the same time as, or before, the headache can often give clues to the source of the problem, as well as the treatment which is most likely to be effective. Migraines headaches are often preceded or accompanied by an aura consisting of visual disturbances such as seeing flashing lights or zig-zag lines; migraines that are accompanied by an aura tend to respond better to different preventative medications than migraines that do not have an aura. Cluster headaches typically are accompanied by symptoms like a runny nose, eye watering, or facial puffiness. Since cluster headaches are most effectively treated with medications that target this specific condition, and can even be made worse by some pain medications, it important to distinguish this type of headache from other kinds of headache. The symptoms associated with other types of headaches can also help diagnose their cause. A person with encephalitis typically experiences mental confusion and a fever as well as a severe headache, while someone with meningitis usually experiences an extremely stiff and painful neck along with a fever and headache. Furthermore, both encephalitis and meningitis usually arise as a secondary manifestation of infections which begin elsewhere. Since many infections which have an affinity for the skin also have an affinity for the brain, any rash appearing on the body prior to the onset of meningitis or encephalitis, likely was caused by the same agent that produced the encephalitis or meningitis, and the appearance of the rash can often help in identifying and treating the infection. Headaches caused by epileptic seizures are typically accompanied by memory loss (retrograde amnesia), covering a period of thirty to forty minutes before the seizure. If no one is around to notice that the affected individual had frozen in place for a minute or two, an individual who had an absence seizure would only know that he or she woke up in an unfamiliar room, feeling very tired and having a bad headache.
A single headache can sometimes have complex causes and may exhibit symptoms of more than one condition. For example, the vomiting induced by food poisoning often causes dehydration, which can be a migraine trigger for someone who is susceptible to migraines. Furthermore, not all individuals exhibit all the standard symptoms typical of that headache type. Most migraines are experienced on only one side of the head, but some people experience migraines on both sides. Even when the source of the headaches has been identified, recurring headaches can be difficult to treat. Considerable trial and error is often necessary to find a medication which can effectively prevent or quickly relieve migraines or cluster headaches, without causing unacceptable side effects.
Although the task of diagnosing and treating headaches can be challenging, providing your doctor with as precise and complete a description of your headache experience as possible, as well as any co-occurring symptoms, can significantly increase your chances of quickly getting a correct diagnosis and effective treatment. Every piece of information can help your doctor narrow down the potential range of headache causes. If you can take your temperature and blood pressure while experiencing a long-lasting headache, that information may help your doctor focus on, or rule out, an infection. If you have to wait for an appointment, you may also consider trying a few simple experiments to assess whether, for example, dehydration or medication side effects may play a role. If drinking a couple of glasses of water and eating a salty snack does not help, then dehydration is not likely to be a significant contributor. If shifting the time that you take your medications does not change the time of day when a recurring headache typically recurs, then the headaches are not likely to be a medication side effect. Every piece of information that you can provide your medical professional can bring you one step closer to relief.