Headache*

The following article has been written by a neurosurgeon for the General Practice/Family Physician community, and for nursing and paramedical staff and medical students.

Introduction

Headache is a symptom frequently reported to general practitioners (GP or family physician). The purpose of this brief editorial is to review its pathogenesis (mechanism), clinical presentation (how headache may present to a doctor), and the “red flags” (more concerning features) suggesting a possible neurosurgical problem. Recommendations regarding investigation and patient referral in the setting of worrisome types of headache are also mentioned.

Pathogenesis of Headache

Headache can arise from structures within the cranial vault (skull; intracranial) or from tissues surrounding the cranial vault (extracranial). Extracranial causes are by far the more common, and include strained eye muscles, congested air sinuses, decaying teeth and inflamed gums, arthritic joints, and tense head and neck muscles. Intracranial processes generating a headache tend to somehow inflame, infiltrate and/or stretch the leathery covering of the brain known as the dura. This pain-sensing layer is innervated by all three divisions of the fifth cranial nerve (trigeminal nerve), and posteriorly also by the second cervical nerve. The “cervico-trigemino-vascular” theory of headache pathobiology is one that is currently being touted as explaining the mechanism of headache generation, but this remains unresolved. Interestingly, many medications relieving migraine headaches (e.g., triptans, ergots) rely upon the activation of 5-hydroxytryptamine (5-HT; serotonin) receptors. From a neurosurgical perspective, more worrisome causes of headache include brain tumour, aneurysm, arteriovenous malformation, cavernous malformation (cavernoma), meningoencephalitis, hydrocephalus, and “benign” intracranial hypertension (Figure 1). Note that headaches from raised intracranial pressure can worsen in the morning hours owing to normal respiratory patterns overnight that lead to brain venodilatation and therefore more cerebral congestion.

Clinical Presentation of Headache

Often, the key to sorting out the nature of the headache is the medical history. Some important questions to ask include:

• For how long has it been going on?
• Is it different to any other previous headache(s)?
• What time of the day is it worse?
• Is it the worst headache ever?
• Does it come on slowly or was it very sudden in its onset?
• Is it associated with nausea, vomiting, or some kind of aura?
• Is there fever or neck stiffness, or any double vision, blurred vision, or loss of vision?
• Are there any spells such as seizures, slurred speech or aphasia?
• Is there any weakness, gait imbalance or vertigo, or a change in personality or level of consciousness?

Red Flags of Headache

Several red flags suggest that the headache may be a neurosurgical problem (Table 1). For example, the patient is not usually a headache sufferer, but now presents with a new-onset and worsening headache, or a sudden-onset severe headache, or a headache that is worse in the morning hours and occurs over more than a few days. Red flags also include new-onset headache with unexplained nausea and vomiting or fever and neck stiffness, or additional worrisome neurological symptoms or signs such as those mentioned in the previous paragraph.

Investigation of Headache

If the headache appears one of the more worrisome types, then a “head CT scan with and without contrast” should be ordered. The intravenous contrast picks up neurosurgically relevant lesions better than a standard “noncontrast” study. Other investigations such as MRI/MR-angiography, CT-angiography and so forth may be ordered by the physician to whom the patient is referred, or by the admitting physician if the patient happens to be so unwell that the GP refers him or her directly to the Emergency Room.

Referral to a Neurosurgeon

In the setting of a patient presenting with headache, a neurosurgeon can be contacted following a CT scan with a positive radiological finding, or if there are worrisome features of the clinical assessment that a GP wishes to discuss. Note that in a subset of “migraine” sufferers, the migraine itself can be accompanied by worrisome features that can make the “migraine-headache” difficult to distinguish from a “neurosurgical-type” headache. However, such headaches in migraine sufferers tend to be recurrent rather than new-onset or sudden-onset or persistent. Headache alone, in the absence of a radiological finding, is much less likely to warrant any neurosurgical intervention. If in doubt, consider discussing with a neurosurgeon or neurologist.

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“Morning”, “worsening”, “new-onset”, “sudden-onset”, “severest”, and/or “persistent” headache…

+/- Unexplained nausea, vomiting

+/- Fever, neck stiffness

+/- New double vision, blurred vision, loss of vision

+/- Weakness or paralysis

+/- Motor or sensory seizures

+/- Speech changes

+/- Gait imbalance, vertigo

+/- Personality, mental status change

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Figure 1. Common “neurosurgical” causes of headache

A. MRI of synchronous high-grade primary brain tumours in a patient who presented with headache. B. Cerebral angiogram showing a leaking arteriovenous malformation. C. Head CT showing subarachnoid haemorrhage (arrow heads) from a ruptured brain aneurysm. D. Head CT showing a collection of pus compressing the brain (arrows) secondary to fulminant frontal sinusitis (arrow heads). E. MRI showing multiple cavernous malformations. F. Head CT showing hydrocephalus.

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