Headache is one of the most common medical complaints and something that everybody will experience at some stage in their lifetime. The vast majority of headaches are unpleasant but harmless however on some occasions headaches can be the first symptom of a serious and life-threatening condition. This has been recognised throughout human history and Hippocrates (400 B.C.) classified headache into Primary and Secondary.
Primary headaches are painful but do not represent a sinister disease.
Secondary headaches are manifestations of an underlying condition that is often serious and life threatening.
Therefore the first thing to consider about headache is whether it is likely to be Primary, and therefore uncomfortable but harmless, or whether the headache is the presentation of a sinister underlying condition, a Secondary headache. The obvious priority is not to miss a Secondary headache and therefore if any of the features below are present one should suspect a Secondary headache and medical advice should be sort.
Systemic features. This means involvement of other parts of the body such as a raised body temperature (normal is 37oC), neck stiffness, rash, which indicate meningitis for which the individual needs to seek urgent medical advice. Swelling of glands such as in the neck may indicate an infective or neoplastic process.
Predisposing Risk factors. Unfortunately some individuals have an increased risk of having a Secondary headache. This may be due to a known underlying condition such as cancer, medication such a warfarin, or a family history of brain haemorrhages (subarachnoid haemorrhage, see below). However the most common risk factor is age and the older the person is the higher the risk of a Secondary headache.
Sudden Onset. As a general rule if a headache develops suddenly and dramatically then it should be considered serious. This is because leakage of blood from a blood vessel in the brain will present with a sudden headache, often severe. Leakage of blood from a ruptured blood vessel is one of the most serious Secondary headache conditions. It is known as subarachnoid haemorrhage. It is important that this condition is recognised immediately and the patient admitted to hospital because even if the patient survives the first leakage of blood they are at risk of another and this is very likely to be fatal.
Physical signs. The development of physical signs such as weakness or altered sensation in one half of the body, visual disturbance, poor balance may indicate an underlying problem in the brain that is causing the headache. Often these physical signs may be subtle and that is why an examination by a Neurologist is required if a Secondary headache is suspected.
New Headache. Headache is common and many people have regular headaches however if they experience a new and different type of headache all the features discussed in this list should be considered.
Continuing Headache. Most Primary headaches are self-limiting and so if a headache is persistent for more than a few days, or worsening before this then medical advice should be sort to exclude an underlying cause.
All the above may be used as a guideline for whether a headache is Primary or Secondary and if there is any doubt then medical advice should be sort. The two most important diagnoses not to be missed are meningitis, which presents with fever, headache, neck stiffness, photophobia, and occasional rash, and subarachnoid haemorrhage, which presents with sudden onset headache often severe and associated on occasions with alteration in consciousness, collapse, nausea and vomiting.
Primary headache is the predominate headache type. This group includes tension headache and migraine headache along with rarer forms of Primary headache.
Tension headache accounts for 80 % of Primary headache. It is defined as mild to moderate headache with no nausea, which is not worsened by physical activity. It usually responds to simple analgesia such as aspirin, paracetamol or ibuprofen.
Migraine headache occurs in about 10% of the population and is often not diagnosed by doctors. Typically the headache is mild to moderate with a pulsating quality. The headache may last 4 to 72 hours. To be certain that a headache is migraine it should have occurred at least five times with 2 of the following features;
• moderate to severe quality
• aggravation with physical activity
During the headache the patient must have one of the symptoms of nausea, photophobia, an intolerance of light, or phonophobia, an intolerance of noise.
In around a fifth of people with migraine they will have an aura preceding the headache. An aura is due to an alteration in the messages in the brain. This can result in visual phenomenon, such as bright lights or zig-zag lines, or sensory disturbances, numbness in the face, arm, leg or difficulty with speech. Migraine auras develop over minutes and should not last over an hour. Obviously when a migraine aura first occurs it is suggestive of a Secondary headache and should be suspected as such. Secondary headache should be considered if the aura is sudden onset, lasts over an hour or occurs in someone over 40 years of age.