Headache

Introduction

Headache is a common presenting complaint in both primary and secondary care. It is the seventh most common presenting complaint in primary care and is one of the top three neurological causes of acute presentations to hospital. A comprehensive and structured approach to assessment is vital to establishing the correct diagnosis. 

This article will cover primary and secondary headaches, as well as diagnostic features and investigations.

Aetiology

Headaches can be categorised into primary or secondary headaches.

Primary headaches are those with no identified pathology, such as migraine or tension-type headache. These are by far the most common types of headaches.

Secondary headaches are those which are secondary to organic pathology.

Most headaches seen in clinical practice are primary headache. However, a small minority of patients will have secondary headache. It is important to be able to identify red flags suggestive of organic pathology.

Primary headache

The commonest primary headaches are tension-type headache and migraine. Less common primary headaches are the trigeminal autonomic cephalalgias, a family of four disorders which includes cluster headache. 

Table 1. The features of migraine, tension-type headache, and cluster headache according to the international classification of headache disorders.¹

Medication-overuse headache

Medication-overuse headache is a common problem and causes a high level of morbidity in patients with primary headache conditions. This should be suspected in the history if a patient has headaches for more than 15 days per month (i.e. a frequency equal to or greater than every other day).²

The trigger (as is in the name) is medication overuse. Triptans, opioids, and combination analgesics (e.g. co-codamol) are likely to cause faster onset (they need to be taken on 10 or more days per month), in comparison to simple analgesics (e.g. paracetamol), which can trigger medication overuse headache if taken on 15 days or more per month.²

Secondary headache

Secondary headaches are those caused by organic pathology.

There are four evidence-based indicators for a secondary headache.

Thunderclap (sudden onset) headache

Headache with onset which reaches maximal intensity within a minute to five minutes of onset (depending on who has provided the definition). This is the most likely headache phenotype to have a secondary precipitant.

This presentation is an indicator of a potential acute vascular pathology, one of the most serious of which is a subarachnoid haemorrhage. Other potential differential diagnoses include meningitis and hypotensive pathology.

Associated focal neurological deficit

Neurological deficits may include unilateral limb weakness, cranial nerve abnormalities, or sensory deficits. Neuroanatomically, this suggests there may be a lesion that is altering the way that individual nerves, spinal, or intracerebral tracts are functioning.

Associated systemic features

Systemic features may include fever, weight loss, night sweats, in conjunction with recent-onset and progressive headache.

It is important to exclude temporal arteritis (a term used interchangeably with giant cell arteritis), a pathology that can cause permanent visual loss if untreated. Other differentials diagnoses include malignancy (e.g. central nervous system lymphoma) or chronic infections (e.g. cerebral toxoplasmosis).

Patients over the age over 50

Headaches in patients over the age of 50 can herald specific pathology such as temporal arteritis.^{3 4}

Assessment of headache

Acutely unwell patients with headache should undergo a rapid ABCDE assessment. Patients with secondary headache (e.g. subarachnoid headache) may deteriorate and become rapidly unresponsive. 

Assessment of headache should involve a comprehensive history. For more information, see the Geeky Medics guide to headache history taking.

Following the history, a neurological examination (including cranial nerves, upper limb, lower limb and fundoscopy) should be undertaken to elicit any abnormal neurological features suggestive of organic pathology.

Other important examination steps include:

• Basic observations (vital signs): including blood pressure
• Palpation of facial structures: palpation over the temporal arteries, TMJ, sites of trauma and sinuses may reveal an extracranial cause of headache
• Orbits: eye protrusion or periorbital swelling may suggest orbital/retro-orbital pathology

Investigations

Outside of an emergency setting, the chance of finding serious secondary pathology with imaging in an isolated headache with no abnormal neurology on examination is similar to people without a headache.^{5 6}

Therefore, imaging such patients provides no clinical benefit, only exposing them to unnecessary radiation, and risking uncovering incidental findings that lead to further harm due to over investigation.

However, if a patient does present with a headache in association with abnormal neurology, imaging is indicated. This is especially important if a patient has presented with a thunderclap headache, as this may be a symptom of a subarachnoid haemorrhage. A CT scan would be the imaging modality most appropriate first line.²

Key points

• Most headaches are primary headaches such as migraine or tension-type headache
• Tension-type headache is a non-disabling, bilateral headache that is pressing in nature and lasts 30 minutes to 7 days
• The key differentiator for migraine is the disabling nature of attacks (i.e. inability to perform activities of daily living), associated with nausea, vomiting, and photo or phonophobia
• Cluster headache is rare but recognisable due to the excruciating pain of the attacks
• Medication overuse headache can occur with the use of analgesia on as little as 10 days per month
• Secondary headache indicators are thunderclap headache, associated systemic features, focal neurology, and age over 50
• Patients presenting with secondary headache indicators should have a CT scan

Reviewer

Dr Stuart Weatherby

Consultant Neurologist

University Hospitals Plymouth NHS Trust

Editor

Dr Chris Jefferies

References

1. Headache Classification Committee of the International Headache Society (IHS) The International Classification of Headache Disorders, 3rd edition. Cephalalgia 2018;38(1):1-211. 
2. British Association for the Study of Headache. BASH Guidelines 2019. Available from: [LINK]
3. Locker TE, Thompson C, Rylance J, et al. The utility of clinical features in patients presenting with nontraumatic headache: an investigation of adult patients attending an emergency department. Headache 2006;46(6):954-61.
4. Ramirez-Lassepas M, Espinosa CE, Cicero JJ, et al. Predictors of intracranial pathologic findings in patients who seek emergency care because of headache. Arch Neurol 1997;54(12):1506-9.
5. Kurth T, Buring JE, Rist PM. Headache, migraine and risk of brain tumors in women: prospective cohort study. J Headache Pain 2015;16(1):501.
6. Morris Z, Whiteley WN, Longstreth WT, et al. Incidental findings on brain magnetic resonance imaging: systematic review and meta-analysis. BMJ 2009;339:b3016.