Headaches are considered primary or secondary. In primary headache disorders, headache occurs in the absence of other clear nervous system pathology. Examples of primary headache disorders include tension headache, migraine and cluster headache. In secondary headache disorders, headache is a result of other pathology. Examples of disorders that can cause secondary headache include meningitis, raised intracranial pressure and carbon monoxide poisoning. The International Classification of Headache Disorders (ICDH) is a diagnostic manual for headache.
See headache on the Clinical Medicine Online database for more information.
When someone presents with a headache, a specific diagnosis should be sought. Features of the patient's history are often considered with respect to whether characteristics of a primary headache disorder are present and whether any concerning features (red or yellow flags) are present which might suggest the headache is secondary to another underlying pathology.
Before the history even starts, several pieces of information are available in our assessment of headache. In patients presenting to their GP with headache, around 5% will have a serious underlying pathology. By the time a patient has attended the emergency department, this number is closer to 50%. This pre-test probability should be taken into consideration during the assessment. The risk of a secondary disorder causing headache increases with age. A new progressive headache in a patient over 50 years old is considered a red flag in the NHS Scotland National Headache Pathway. Note that most new onset headaches even within this age group are benign, but the risk is increased.
It is important to establish the time taken from onset of pain to maximal intensity. When a severe headache reaches maximum intensity within less than five minutes is referred to as a 'thunderclap headache'. Thunderclap headaches can occur in primary headache disorders, but are also associated with a number of potentially fatal secondary headache disorders. Thunderclap headaches are urgently assessed.
| Disorder | Duration |
|---|---|
| Tension headache | 30m - 7d |
| Migraine | 4-72h |
| Paroxysma hemicrania | 2-15m |
| Cluster headache | 25-180m |
| Hemicrania continua | >4h |
The location of a headache is not particularly valuable in the diagnosis of the most common causes of headache. While migraine is often unilateral and this is used as a criteron to support the diagnosis in the ICHD-3, it is common to see patients with bilateral headache that fulfil the diagnostic criteria for migraine.
Nummular headache is a primary headache disorder characterised by (as you might expect from the name) a coin-shaped area of pain without any structural lesion.
A focal deficit associated with headache is a red flag that merits urgent assessment. When a patient has not presented with a focal deficit before, neuroimaging is clearly warrented to exclude secondary causes of headache such as intracerebral haemorrhage, cerebral venous sinus thrombosis or tumours.
The situation becomes more complicated if recurrent episodes of headache with a focal neurological deficit are occuring in patients who have previously been extensively investigated and an underlying secondary cause has not been investigated. In these cases, symptoms are often intermittent. Hemiplegic migraine is one such cause, but 'true' genetically defined hemiplegic migraine is rare and this is often overdiagnosed.
Visual deficits with headache can occur in migraine with aura, idiopathic intracranial hypotension, pituitary apoplexy, glaucoma and temporal arteritis.
Evidence of systemic upset such as fever, weight loss and night sweats is important to elicit as it can suggest infective, inflammatory or neoplastic pathology which may be causing headache.
Autonomic upset ipsilateral to the headache is characteristic of a group of primary headache disorders known as the trigeminal autonomic cephalalgias. These symptoms may not be volunteered and should be sought specifically:
Bear in mind that secondary headaches can also present with autonomic dysfunction. Carotid artery dissection may disrupt the sympathetic nervous system resulting in a Horner's sydnrome (ptosis and myosis) mimicking a TAC.
If it is possible the patient is pregnant, special considerations must be made. See headache in pregnancy for more details.
In patients presenting with a primary headache disorder a number of specific diagnoses are available. Two broad categories can be distinguished though - migraine and the trigeminal autonomic cephalalgias (TACs). Determining whether the headache is associated with agitation or avoidance can be helpful in these situations. Migraines tend to cause activity avoidance. In contrast, the TACs usually cause agitation. Determining if the patient likes to stay still or paces around during episodes can therefore be helpful.
A huge number of drugs list headache as a potential side effect. These include prescription drugs, recreational drugs like alcohol and over the counter medications which people may not think to mention such as nasal decongestants. Specifically enquiring about the use of such medications with examples is likely to elicit a more complete history.
While one strategy is to generate a comprehensive list of drugs that have been taken and identify any that are associated with headache this approach can be time consuming is often not particularly helpful. Identifying drugs with a temporal relationship to the headache can help identify potential culprits. The drug must of course have been started before the headache developed. It also seems likely that a drug that has been taken for 5 years is unlikely to be responsible for a headache that started in the last week. Where the lower end of this window for temporal relationship lies likely varies between drugs and is hard to establish. Dose changes and changes in body composition such as those with occur with aging which can equate to relative dose changes should be considered though.
Arguably the best evidence a headache is the result of a drug is improvement of the headache with cessation of the drug. Note that with drugs such as alcohol, headache occurs following exposure (rather than during). Of course, placebo effects can be at play - but either way the headache goes! The importance of the drug and possible alternatives needs to be considered - it is much more trivial changing an antihypertensive than stopping warfarin for a patient recently diagnoised with a massive pulmonary embolus.
Proximal muscle weakness and jaw claudication should prompt consideration of temporal arteritis.
Discharge from the nose, nasal congestion, hyponosmia and post nasal drip may raise suspicion of sinus pathology. Headache may result from acute or chronic rhinosinusitis or a more sinister ENT pathology.
Headache can be an early feature of acromegaly.
The neurological examination of a patient with headache can be considered to address the following objectives:
A screening neurological examination is often used to identify focal neurological deficits that may not have been reported. This examination usually involves the cranial nerves and examination of the limbs (inspection, tone, power, reflexes, coordination and sensation). Much less commonly done, though extremely helpful, is a cognitive examination. Those who have spend time in neurosurgical preassessment clinics will be aware that individuals with tumours may have an entirely normal neurological exam but a very abnormal cognitive assessment battery in some cases. The neurological exam is so often normal in headache, there may be a temptation to cut corners. Neurology registrars will recall cases of being called to review someone in the Emergency Department with a newly identified intracranial mass in whom the initial physician has documented a neurological exam - which inevitably turns out not to be accurate.
At the bedside, examination of the optic disc is used to seek evidence of raised intracranial pressure in the form of papilloedema.
It is sensible to check blood pressure in any patient presenting with a headache. Hypertension can cause headache in its own right but is also associated with other causes of headache including haemorrhagic stroke and posterior reversible encephalopathy syndrome (PRES).
Evidence of temporal arteritis can be sought by seeking proximal muscle weakness suggestive of coexistant polymyalgia rheumatica and palpation of the temporal artery.
Otoscopy...
Dental exam...
Inflammatory markers in the blood including white cell count, CRP and ESR have a role to play. Unfortunately, normal inflammatory markers do not exclude infection of the central nervous system. An elevated CRP or ESR may raise concern about the possibility of temporal arteritis.
Neuroimaging can be used to identify structural causes of headache or seek surrogate markers that suggest the intracranial pressure is abnormal.
| Imaging finding | Modality | Potential pathologies |
|---|---|---|
| Sinus obstruction | CT or MRI | Acute or chronic sinuitis, Neoplasia |
| Bony errosion around the sinuses | CT | Chronic infection |
| Empty stella (pituitary fossa) | CT or MRI | Raised intracranial pressure |
| Intracranial haemorrhage | Preferably CT | Intracranial haemorrhage |
| Space occupying lesion | Preferably MRI | Space occupying lesion |
CSF...
In some circumstances there are nuances to the way headache should be approaches that merit special consideration.
Headache in pregnancy