Primary Headache

Context

The presentation of a patient with a severe headache to the emergency department (ED) is a common one. Whilst most are benign in nature, a small percentage represent potentially devastating aetiologies.

The task of the ED doctor is to differentiate between the two.

The doctor must be guided by the knowledge that:

• Extensive investigation of all cases will result in many false positives
• Failure to identify headaches due to serious aetiologies can result in fatal, or irreversible, outcomes

Definition

The International Headache Society classifies headaches into primary and secondary groupings. Primary headaches are those where the specific aetiology is not fully understood e.g. migraine. Secondary headaches have a clear and understandable origin e.g. ruptured aneurysm.

Primary causes are sometimes referred to as benign. However, this term is misleading as they are associated with considerable morbidity and indirect mortality.

This session will cover primary headaches.

Headache is the most common neurological condition in the world, with more than 90% of people experiencing headaches at some point in their lives.

90% of headache presentations to the ED are due to primary headaches, usually tension headaches or migraine.

Most patients will be discharged, and many require no investigation beyond a focussed clinical history and examination.

Clinical history

The clinical history is the single most important assessment tool when determining the cause of a headache.

Following clinical assessment of a patient with headache, most patients will have features that are consistent with one of the primary headache syndromes. However, approximately 10% of patients will have signs or symptoms of headache due to a secondary cause. More information on this topic can be found in the session specifically dealing with secondary headache.

Certain features of the presentation may be regarded as ‘red flags’.

These significantly increase the risk that there is a secondary cause for the headache and, therefore, further investigation is warranted.

These are:

• Headache in someone >50 years
• Thunderclap headache (headache reaching maximum intensity within 60 seconds of onset)
• Headaches increasing in severity and frequency
• Headache with fever, neck stiffness, or reduced level of consciousness
• Focal neurological symptoms or signs
• Papilloedema
• Headache after trauma
• Loos of vision/ amaurosis fugax
• Immunocompromised, Malignancy

Learning bite

The presence of any ‘red flag’ feature mandates further investigation of a patient presenting with headache.

Tension Headaches

Tension headaches are the most common type of primary headaches, and are responsible for the vast majority of all headache presentations. Approximately 3% of people are chronic sufferers.

They were renamed tension-type headaches by the International Headache Society in 1988.

Usually, the pain is band like across the forehead, but can radiate from the neck, back or eyes.

Typically, they last four to six hours.

There are often identifiable triggers e.g. stress, hunger, sleep deprivation or eye strain.

Learning bite

Frequent use of analgesic medications (paracetamol, codeine and NSAID’s) in patients with tension-type headache may lead to the development of ‘medication overuse headache’ or ‘rebound headache’.

Introduction to Migraine

It is important to appreciate that patients, and doctors in general, use the term migraine rather loosely.

Migraine usually begins in people under the age of 40, and is more common in women.

Classic migraine headache is unilateral and associated with an aura but these features are only seen in 60% and 20% of migraine patients respectively.

The image on the right is a representation of the type of aura experienced by migraine sufferers. The commonest auras are visual, for example rings, flashes and blurring. Paresthesia is also a relatively common aura.

Pathophysiology

The exact pathophysiology is undetermined.

Until recently, it was thought to be caused by altered blood flow. However, it is now thought that these vascular changes are the result of the headache, not the cause.

Currently, the most probable hypothesis is that migraine is not a disorder of blood vessels, but one of brain function.

Establishing a diagnosis of migraine

To establish a diagnosis of migraine, the physician should use five screening criteria:

• Pulsating
• Duration 4-72 hours
• Unilateral
• Nausea
• Disabling

If three of these features are present, the likelihood ratio (LR) for migraine is 3.5. If four are present, the LR is 24.

The best predictors for migraine can be summarised as follows: POUNDing (Pulsating, Duration of 4-72 hOurs, Unilateral, Nausea, Disabling.

Migraine Sub-types

The table below shows migraine sub-types with their symptoms.

Migraine with aura	Visual disturbance develops over 5-20 minutes and resolves within an hour
Migraine without aura	Also known as common migraine
Hemiplegic migraine	A juvenile form. May last hours to days
Ophthalmoplegic migraine	Acute III nerve palsy, dilated pupil and unilateral eye pain
Basilar migraine	Severe headache preceded by e.g. ataxia, vertigo, nystagmus, diplopia and reduced level of consciousness

Cluster Headaches

In contrast to migraine, cluster headaches are much more common in men (6:1).

The onset is usually in the mid 20s.

Typical symptoms are a sharp, stabbing unilateral pain around the orbit, or temporal area. It is often associated with lacrimation (tearing of the eye)

The onset is acute and the pain escalates rapidly and may last
from a few minutes to several hours. Each cluster lasts a few weeks.

Most sufferers have two or three clusters per year.

Exertional Headaches

Exertional headaches are a group of headache syndromes associated with physical activity. Typically, these headaches become very severe quite quickly.

The following strenuous activities contribute to exertional headaches:

• Weight lifting
• Running
• During sexual intercourse

Exertional headaches may also become severe as a result of:

• Coughing
• Sneezing
• Straining with bowel movements

Most exertional headaches are benign, but some are related to important intra-cranial pathologies e.g. SAH or a brain tumour.

Patients who present with recent onset headache related to exertion, require urgent MRI scanning to exclude structural brain lesions.

Trigeminal Neuralgia

Trigeminal neuralgia is also referred to as tic douloureux.

It is most common in patients between the age of 50 and 70 years of age and most cases are idiopathic.

The patient experiences brief electric shock-like pains in the distribution of one, or more, branches of the trigeminal nerve. The episodes are often triggered by minimal stimuli. There are no neurological signs on examination.

Learning Bite

Patients with neurological signs do not have trigeminal neuralgia.  

Investigations

Of necessity, the investigations required for any patient with an acute headache will depend upon the:

• Characteristics of the headache
• Age and co-morbidities of the patient
• Presence, or absence, of focal neurological signs

The most important investigation is the neurological examination itself. This must include:

• Alertness and cognitive function
• Limb power, tone, reflexes and sensation
• Pronator drift
• Cranial nerves
• Visual fields to confrontation
• Fundoscopy
• Cerebellar function

Most patients with a normal neurological examination and a ‘non-thunderclap’ headache will require no further investigation.

In about 10% of ED headache patients, the history and/or the examination will suggest the possibility of a secondary cause. Such patients will need to undergo a brain computerised tomography (CT) scan.

The management of headache patients depends entirely upon the diagnosis:

Migraine

Analgesics

Analgesics are the first-line treatment for migraine. Aspirin 1000 mg is an effective treatment for acute migraine headaches, similar to sumatriptan 50 mg or 100 mg. [5] Most NSAID’s and paracetamol to be significantly more effective than placebo.

Anti-emetics
Metoclopramide and domperidone relieve the sensation of nausea, overcome gastric stasis and, consequently, enhance the bio-availability of other oral medication.

Non-specific Therapies

Both chlorpromazine (25–50 mg IM) and prochlorperazine (10mg IV or IM) have been used successfully as single agent therapies.

Specific Therapies: Triptans

Many placebo-controlled trials have shown these to be effective in relieving headache at 1 hour. The triptans are most effective if taken when the headache is mild. They are ineffective if taken before the onset of symptoms.

Patients whose migraine does not respond to triptans should be considered for treatment with ergotamine tartrate 1-2 mg.

Tension headaches

In patients with a tension headache, ascertain that the patient is not:

• Over-using analgesic medication
• Showing evidence of drug dependency
• Showing signs of depression

Episodic tension-type headaches generally respond well to over-the-counter analgesics, and in controlled studies, ibuprofen has been found to be more effective than paracetamol.

Other prophylactic medications for chronic tension-type headaches include amitriptyline and sodium valproate.

Regular exercise, stretching, balanced meals, and adequate sleep may be part of a headache treatment program.

Cluster headaches

High flow O₂ therapy i.e. 10 L/minute for 15 minutes is usually effective.

The triptans (e.g. sumatriptan, 6 mg, sub-cut) can also be used.

Exertional headaches

After excluding a structural lesio,n management is aimed at advising the patient of the benign nature of this condition. Some patients benefit from beta-blocker therapy.

Trigeminal neuralgia

A number of drugs have been shown to be effective:

• Carbamazepine
• Phenytoin
• Valproate
• Lamotrigine
• Gabapentin

Approximately 30% of patients do not respond to drug therapy, and these patients may need surgical intervention.

The pitfalls when assessing and treating headache in the ED are:

• Failing to appreciate that any patient with a ‘red flag’ requires further assessment and investigation
• Failing to appreciate that most headache patients presenting to the ED require only a careful history and neurological examination
• Failing to appreciate that migraine sufferers with a change in the pattern of their headache require thorough re-evaluation

1. Detsky ME, McDonald DR, Baerlocher MO, Tomlinson GA, McCrory DC, Booth CM. Does this patient with headache have a migraine or need neuroimaging? JAMA. 2006 Sep 13;296(10):1274-83.
2. Steiner TJS, MacGregor E, Davies PT. A proposed hierarchy of treatment with Triptans. Guidelines for all doctors in the management and diagnosis of Migraine and tension type headache. 2nd Ed. 2004.
3. Matchar D, Young W, et al. Evidence based guidelines for migraine headache in the primary care setting; pharmacological management of acute attacks. Neurology. 55. 2000.