Patients who present with headache invariably think that they need glasses, have high BP or have a tumour. Headache presenting as an uncorrected refractive error is rare, a relationship with BP is unlikely unless significantly raised, but a tumour is always a concern for patient and practitioner alike.
Fortunately, brain tumours are rare. The annual population incidence is 0.006-0.01 per cent, of which 72 per cent will present above the age of 50. Although a brain tumour can present with a number of signs or symptoms, headache is a common symptom at some stage of a tumour's history.
However, in a population of 100,000 adults, less than two people a year will present with isolated headache, i.e. no other signs or symptoms.
If a head-ache is bad enough to present to a GP, the likelihood of brain tumour is one in 1,000 or one in 2,000 if a diagnosis of migraine or tension-type headache can be made.
Deciding to investigate
The decision to investigate headache is based upon a number of complex factors.
These include therapeutic value, the clinical confidence of the doctor, time constraints within the consultation, availability of imaging, GP's and patient's approach to risk and uncertainty, reassurance of an anxious patient and medico-legal concerns.
The context in which the decision is made also plays an important part.
In primary care GPs experience difficulty in diagnosing headaches but have the benefit of frequent follow up, while in secondary care, patients will often anticipate the exclusion of secondary pathology and consultants will be under pressure to make a diagnosis at the first appointment.
Due to the paucity of rigorous evidence in this area, expert opinion is an important input. Like all other investigations, there will be a balance between advantages and disadvantages.
The main advantage of investigation is reassurance that there is no serious underlying problem causing a headache.
If there is a tumour, early diagnosis may improve outcome, but in many cases a short delay in diagnosis will not make a great difference to long-term outcome.
Some tumour risks to bear in mind
Disadvantages of investigation
Headaches are very common, occurring in over 70 per cent of the population in any one year. Investigating even a small number of these would consume significant healthcare resources.
The identification of incidental pathology, its clinical relevance and the unnecessary anxiety it incurs is a well recognised problem and can be very significant.
Imaging studies in asymptomatic populations yield abnormalities ranging from 0.6 per cent to 2.8 per cent and in older populations up to 10 per cent. These findings may also have implications for future life insurance applications.
MRI can be distressing for patients, while the radiation exposure from CT should not be overlooked. As current investigative techniques become more accurate, this is likely to be an increasing problem.
Although MRI is a more accurate modality, cost and availability will dictate the use of CT in many areas. However, CT can miss up to 10 per cent of tumours, particularly in the posterior fossa.
It is important to emphasise that there are some important secondary causes of headache where imaging can be normal and a normal investigation does not eliminate the need for appropriate management of a primary headache.
Recommended guidance for investigating for tumour in primary care
Red flags Presentations where the probability of an underlying tumour is likely to be greater than 1%. These warrant urgent investigation.
Orange flags Presentations where the probability of an underlying tumour is likely to be between 0.1 and 1%. These need careful monitoring and a low threshold for investigation.
Yellow flags Presentations where the probability of an underlying tumour is likely to be less than 0.1% but above the population rate of 0.01%. These need appropriate management and the need for follow up is not excluded.
Who to investigate?
Current guidance suggests that imaging should take place where there is a risk of a tumour of greater than 1 per cent.
The box (above) outlines three types of clinical flags, their clinical presentations and action required.
The box (below) gives guidance for GPs when patients present with an isolated headache where a diagnostic threshold is not reached.
- Dr Kernick is a GP with a special interest in headache in Exeter, RCGP headache lead and chair of the primary care group of the International Headache Society (IHS)
- Further information and patient handouts can be found at www.exeterheadacheclinic.org.uk
Guidance for new presentations of non-urgent headache
Around 15 per cent of isolated headaches will be undiagnosable at first presentation. The emphasis is on monitoring and allowing a diagnostic pattern to emerge.
Extra vigilance is advisable in patients over 50, where the incidence of underlying pathology is higher.
At presentation (approximately 0.06 per cent risk)
At one month
Exclude urgent features as above. If diagnosis still uncertain and headache persists:
At two months (approximately 0.8 per cent overall risk)