Headache affects virtually everyone at some point in their lifetime. It is one of the commonest symptoms for consultation in both primary and secondary care (Bone and Fuller, 2002; Royal College of Physicians and Association of British Neurologists, 2011). Headaches account for 55% of neurology referrals from acute assessment units (AAU) (Craig et al, 1997; Weatherall, 2006). Around 30% of a neurologist's caseload involves dealing with various kinds of headache disorders (Sender et al, 2004).
Fortunately, the vast majority of headaches are benign. In patients with new-onset headache presenting to their general practitioner, the one-year risk of a malignant brain tumour is only 0.045% (Kernick et al, 2008). Serious headaches, including those related to brain tumours, account for only 1% of all headaches, with the vast majority presenting acutely through accident and emergency departments (A&E) and AAUs. It is therefore extremely important for paramedics to be able to recognize common headache subtypes and identify those that require urgent attention by the relevant specialty.
The International Headache Society (IHS) revolutionalized the understanding of headache through the classification of headache disorders; this was revised in 2004 (IHS, 2004). Broadly speaking, headaches are divided into primary and secondary types. The clinical features of primary headaches are not associated with an underlying pathology. Migraines, tension-type headache and cluster headache are the common primary headache disorders. Secondary headaches have an underlying cause that may range from a trivial upper respiratory tract infection to a life-threatening subarachnoid haemorrhage. Prevalence of common headache disorders is given in Table 1 (Olesen et al, 2005).
| Type of headache | Prevalence (%) |
|---|---|
| Primary | |
| Migraine | 16 |
| Tension type | 69 |
| Cluster headache | 0.1 |
| Idiopathic stabbing | 2 |
| Exertional | 1 |
| Secondary | |
| Systemic infection | 63 |
| Head injury | 4 |
| Subarachnoid haemorrhage | <1 |
| Vascular disorders | 1 |
| Brain tumour | 0.1 |
Source: adapted from Olesen et al, 2005
History
The history is the most important aspect in evaluating headache patients (Blau and McGregor, 1995). The longer the duration of a headache, the less likely the possibility of a serious underlying cause.
It is important to rule out a secondary cause in those with new-onset headache without previous history (Goadsby and Boes, 2002). Features in the history usually point to the possible underlying cause.
For example headaches that a patient describes as the worst ever, building up within a minute or so—called thunderclap headache—may be due to subarachnoid haemorrhage (SAH) requiring an urgent computerized tomography (CT) scan of brain and lumbar puncture (LP) (Dodick, 2002).
Systemic features such as fever may indicate underlying infection such as meningitis or encephalitis, which requires urgent antibiotic therapy.
It is rare for a headache to be the only symptom of a space-occupying lesion presenting in the acute setting; such patients often have seizure or rapidly developing focal neurological signs (Hopkins, 1988; Levy et al, 2004). Early-morning headaches and those worse on straining or postural change merit urgent medical attention as this may indicate raised intracranial pressure.
Because patients known to have a primary headache disorder such as migraine are not immune to secondary causes, a change in the characteristic of existing headaches require further investigation (Kernick et al, 2008).
Table 2 gives a summary of the ‘red fags’ that are generally accepted as helpful to increase the index of suspicion (Ahmed et al, 2010; British Association for the Study of Headache (BASH), 2010).
| New onset of headache over the age of 50 |
| Sudden onset (thunderclap headache) |
| Early-morning onset |
| Orthostatic headaches |
| Cluster headache |
| Orthostatic headaches |
| Headaches worsen on straining such as coughing, sneezing, lifting or Valsalva's manoevre |
| Change in the pattern of existing headaches |
| Systemic features such as fever or weight loss |
| Loss of consciousness |
| Focal neurological symptoms or signs such as weakness, swollen optic discs (pappilloedema) |
Serious headache disorders
Infections, inflammation, haemorrhage and space-occupying lesions of the central nervous system (CNS) are uncommon but potentially life-threatening conditions; recognizing them requires vigilance.
Glaucoma and idiopathic intracranial hypertension, if not treated urgently, may compromise vision as a result of pressure on the optic nerves.
Patients with intracranial venous sinus or cerebral vein thrombosis may present with non-specifc diffuse headaches similar to other headache disorders and a high index of suspicion is needed to avoid misdiagnosis.
Meningitis
This is a serious infection of the CNS and an acute medical emergency. Even with optimal care, 15% mortality is reported (Weatherby, 2008). The causative agent may be bacterial, viral or fungal; the last is most often seen in immunocompromised patients. Most patients with viral meningitis have fairly mild symptoms and recover quickly and completely without any treatment or residual complication. Bacterial meningitis is the most common form of serious CNS infection.
Patients present with recent onset of progressive pulsating headache, neck pain and stifness with nausea, vomiting and intense sensitivity to light and sound. Systemic symptoms of fever with rigors, malaise and irritability are present in the vast majority, with confusion and altered levels of consciousness. On examination, patients are often restless with severe neck rigidity, although these symptoms may not become evident until further in the disease process; there may be a maculopapular rash that becomes petechial and seen mainly on the trunk and lower extremities. It is worth pointing out that a few patients with meningitis may not have the typical symptoms—one should therefore have a low threshold for treating suspected cases.
Clinical features should alert the clinician that the diagnosis could be meningitis. Intramuscular benzylpenicillin or other broad spectrum antibiotics such as ciprofloxacin or ceftriaxone should be given as soon as possible, even before any investigations, with the treatment changed as appropriate following brain imaging and LP.
Encephalitis
In encephalitis, infection and inflammation extends beyond the meninges to cause encephalomyelitis, which involves the brain parenchyma or even the spinal cord.
In addition to signs of meningeal irritation, patients may have altered conscious levels, hallucinations, agitation and changes in personality or behavioural disturbance. Some patients present with a focal or generalized seizure with or without focal neurological deficits such as loss of speech (aphasia), unsteadiness in walking (ataxia) or focal weakness.
Infection with herpes simplex virus I (HSVI) is treatable so treatment with acyclovir, an antiviral drug, is started immediately.
Imaging with CT or magnetic resonance imaging (MRI) often show oedema in temporal lobes and polymerase chain reaction (PCR), a technique for viral identification, is mostly positive for HSVI infection in the cerebrospinal fluid (CSF) (Lakeman and Whitely, 1995).
Intracranial haemorrhage
Sudden onset of headache is a common problem and the main concern is to exclude SAH. The diagnosis of SAH should be considered in all patients presenting with sudden onset of headache reaching its maximum intensity in less than one minute (Linn et al, 1994; Landtblom et al, 2002). Other symptoms are similar to meningitis but without fever.
Most SAHs are caused by a ruptured intracranial aneurysm which is potentially treatable with radiological intervention such as coiling, stenting and, in some cases, surgery (Locksley, 1966).
Making the diagnosis is crucial as 50% of patients will rebleed within a few weeks, which may be life threatening (Bonita and Thomson, 1985). CT and LP are mandatory to confidently exclude the diagnosis (Dodick, 2002). Missed diagnosis of SAH accounts for a significant amount of litigation in neurology and neurosurgery.
Other causes of intracranial haemorrhage include arteriovenous malformation (AVM) and parenchymal cerebral bleed secondary to hypertension that may present with acute headache (Fleetwood and Steinberg, 2002).
Temporal arteritis
The condition is rare in patients younger than 50 and the average age of onset is 70 years (Bengtsson and Malmvall, 1982). It is more common in women than men (Nordborg and Nordborg, 2003).
It is characterized by inflammation involving branches of the external carotid artery, commonly the temporal arteries. If untreated, half of the patients will develop blindness due to inflammation of the ophthalmic artery (Hayreh et al, 1998). Treatment with steroids is extremely efective in avoiding this complication so recognition of the condition is important.
Patients commonly present with recent onset of unilateral or bilateral temporal headache that is boring or aching in character. The majority of patients will have systemic features of anorexia, weight loss, insomnia, malaise, fever and night sweats (Healy and Wilske, 1978). Pain in the jaw on chewing (jaw claudication) and aches and pains in the shoulder and pelvic girdle muscles (polymyalgia rheumatica) may be an accompanying feature (Harrison and Bevan, 1967). Scalp tenderness may cause pain on brushing hair and resting the head on a pillow may be very painful. The majority of patients will have raised inflammatory markers in routine bloods such as erythrocyte sedimentation rate (ESR), plasma viscosity (PV) and C-reactive protein (CRP), although normal results do not exclude the diagnosis (Bengtsson and Malmvall, 1982). The role of temporal artery biopsy is controversial as the disease may afect other intracranial vessels without involving the temporal artery (Hall and Hunder, 1984).
Brain tumours
The brain itself is not a pain-producing structure. Relatively few structures in the cranium, such as meninges and blood vessels, produce pain.
Headache due to a brain tumour is often a late feature and caused by irritation or distension of the pain-sensitive structures raising the intracranial pressure. A headache is the main symptom in only 30% of patients with brain tumour (Lowry et al, 1998). Seizures and focal neurological deficits are more common presenting features. The headaches are non-specific, moderate and dull— they may worsen on straining or changing posture, particularly when a person lies fat, and may be more noticeable on waking up in the morning (Foresyth and Posner, 1992).
Cerebral vein/venous sinus thrombosis
Cerebral vein/venous sinus thrombosis (CVT) can occur at any age. Women of childbearing age are at a high risk and it is increased further if they are taking the combined oral contraceptive pill and even higher if they smoke. The risk is considerably higher in the few months after childbirth because of hypercoagulability (Bousser and Kittner, 2000).
Clinical presentation of CVT is variable. Some patients present with thunderclap headache (De Bruijn et al, 1996); others may have non-specific diffuse headache with postural exacerbation and/ or features of raised intracranial pressure (Ameri and Bousser, 1992). Focal neurological symptoms and signs develop rapidly and seizure may be the presenting feature. Optic discs may be swollen (papilloedema), indicating raised intracranial pressure, so imaging is required to confirm whether a LP can be performed safely.
CT scans have a very low sensitivity and a CT venogram or MRI and MR venogram is required to confirm the diagnosis (Lövblad et al, 2002). Anticoagulation therapy for six months remains the best practice in the absence of robust evidence in the literature (Ameri and Bousser, 1992).
Idiopathic intracranial hypertension (IIH)
The condition is more common in women who are obese, smoke and take oral contraceptives (Digre and Corbett, 2001).
Headaches caused by idiopathic intracranial hypertension (IIH) have features of raised intracranial pressure with swollen optic discs (papilloedema) but with normal imaging. Urgent intervention with LP is indicated because there is a risk of visual loss (Wall and George, 1991). CSF pressure is high and LP is both diagnostic and therapeutic.
Patients are referred to a dietitian to lose weight. They are given diuretics such as acetazolamide and bendrofumethiazide to maintain low pressure. They need regular follow up with the ophthalmologist and neurologist.
Primary headache disorders
To exclude a serious headache disorder, it is important to be able to identify the primary headache disorders. This will also prevent unnecessary hospital admission and expensive investigation.
Migraine, tension-type headache and cluster headache account for the vast majority of primary headache disorders. Medication-overuse headache, although secondary, complicates a significant number of primary headaches.
Migraine
Migraine is the second most common cause of headache, affecting 15% of the population (18% of women and 6% of men) (Steiner et al, 2003; 2011). The vast majority are episodic, characterized by recurrent attacks of moderate to severe headaches lasting 4–72 hours that are unilateral or bilateral, throbbing and may worsen on physical activity. The attack may have one or more features of nausea, vomiting, sensitivity to light sound and smell (IHS, 2004).
Chronic migraine (CM) is the most disabling of all headache disorders and has a major impact on quality of life. Of those who experience migraine, 1–5% have chronic migraine, which is characterized by headaches on >15 days of the month of which eight days are with migrainous features (Natoli et al, 2009).
Some 50–80% of patients with CM overuse painkillers. Their daily headaches are refractory to conventional treatment and they often present through emergency services hoping to find a remedy (Goadsby et al, 2010).
Of those affected by migraine, 20–25% report focal neurological symptoms (aura) preceding the attacks, typically lasting 5–20 minutes and developing gradually. Visual aura is by far the most common focal symptom with fashing lights or zigzag lines moving across the visual field; disturbance of sensorimotor function or speech is less common (Russell and Olesen, 1996). Aura symptoms without headache may occur in 20–44% of people who experience migraine, mainly those aged over 50 and in some with no previous history of headache.
Aura without headache must be differentiated from transient ischaemic attacks (TIA), particularly if vascular risk factors are present (Fisher, 1986). The development of symptoms in TIA are rapid, within seconds to a minute, compared to migrainous aura where there is gradual spread of neurological symptoms taking a few minutes to reach their maximum (Blau, 1986).
Tension-type headaches
This is a syndrome of head pain without features of migraine, and is also known as featureless headache (IHS, 2004). The condition is frequently diagnosed but poorly understood (Bendtsen and Jensen, 2006).
Typically, the pain is bilateral and feels like a tight band that builds up slowly, fluctuating in severity and persisting for many days. The patient may often describe the pain as if the ‘head were in a vice’, with pressure building in the head. Tension-type headaches (TTHs) are described as episodic or chronic (present >15 days/month). Episodic TTH is never severe and rarely affects physical activity, although chronic TTH can be disabling, with a significant number of patients overusing painkillers (Bahra et al, 2003).
Trigeminal autonomic cephalalgias
Migraine and TTH are generally mild, moderate or severe; they have a long duration (>4 hours) and present to primary or secondary care via routine consultation.
Trigeminal autonomic cephalalgias (TAC) are distinct primary headache disorders characterized by strictly unilateral and excruciating pain in the first division of the trigeminal nerve (in the periorbital area); they are short lasting (<4 hours), with prominent cranial autonomic dysfunction such as lacrimation (excessive watering of the eyes), conjunctival injection (red or bloodshot eyes) and rhinorrhea (runny nose), pupillary constriction on the same side (Horner's syndrome). Cluster headache is the commonest TAC (May et al, 2006).
Cluster headaches
Cluster headache (CH) affects around 0.2% of the population (Katsarava et al, 2007) and is probably one of the most painful conditions known, with affected women describing it as worse than childbirth. It is more common in men (4:1) and 90% patients are heavy smokers (Bahra et al, 2002). The pain of CH is strictly unilateral, commonly affecting the periorbital or temporal region—areas innervated by the fist division of the trigeminal cranial nerve—in association with cranial autonomic features. Attacks occur 1–8 times each day and last from 15 minutes to three hours.
The striking feature its circadian rhythm, with patients reporting attacks occurring at the same time each day. Alcohol triggers an attack in almost all CH patients (Bahra et al, 2002). Some 90% of CHs are episodic, with attacks occurring on a daily basis for weeks to months, followed by a gap of months to years. Those without remission for a year or remission of less than a month are regarded as chronic (Kudrow, 1987).
Patients with episodic CH often improve before the outpatient consultation with a specialist. Those with chronic CH are often refractory to preventive treatment and present to the emergency care with excruciating pain that prompts the acute physician to repeatedly investigate with intracranial imaging. Conventional oral painkillers or specific acute migraine medications such as sumatriptan may not work due to the brief duration of headache. Inhalation of 100% oxygen at 7–12 litres/minute is rapidly effective in relieving pain in the majority of patients (Cohen et al, 2009). Intranasal or injectable triptans are excellent in treating acute attack (Ekbom et al, 1995).
Other TAC
Paroxysmal hemicrania (PH) is rare and slightly more common in women than men. The attacks are more frequent than in cluster headaches, with 1–40 occurring a day, each lasting 2–30 minutes. The condition responds remarkably well to indometacin (Cittadini et al, 2008).
Short-lasting unilateral neuralgiform headache with conjunctival tearing (SUNCT) is a very rare condition where the attacks are even shorter, lasting 5–240 seconds, and occur with a frequency of 3–200 per day. The attacks are triggered by touching areas innervated by the trigeminal nerve (Cohen, 2007).
Medication overuse headaches
Patients who regularly take painkillers on more than 10 days a month are at risk of developing medication overuse headaches (MOHs) (IHS, 2004). The condition, which affects 1–2% of the population, is more common in patients with primary headache disorders, especially migraine and tension-type headaches.
All acute medications are implicated although opioids, triptans and ergotamine are more likely to cause MOH (Bahra et al, 2003). The time to develop MOH after frequent intake is shortest for triptans, longer for ergots, and longest for other analgesics (Bigal and Lipton, 2008). Some 50–80% of patients with daily or near daily headache (chronic daily headaches) overuse medications (Scher et al, 2008).
The presence of MOH makes it difficult to identify the primary headache disorder and attempts should be made to address analgesic overuse before embarking on prophylactic therapy, although some headache experts would tackle both issues at the same time (Hagen et al, 2009; Rossi et al, 2009).
Patients are encouraged to stop medications in an outpatient clinic where they are advised. They then stop medications at home with the warning that headaches may get worse initially. Those who fail to stop may benefit from a brief inpatient admission. Withdrawal of medication is successful in 50–80% of cases, although one third of patients relapse over time.
Conclusion
Headache is the most prevalent neurological condition that those working in healthcare come across, irrespective of their field of work. The majority are harmless and potentially treatable so are rewarding to manage.
Headaches caused by intracranial haemorrhage, infection and raised intracranial pressure are uncommon but potentially life threatening. Recognizing them among the more common benign conditions such as migraine, tension and medication overuse headache can be like finding a needle in a haystack and impossible without an in-depth knowledge of these conditions.