Headaches are classified by the International Headache Society as primary or secondary headaches (http://www.ichd-3.org).
The majority of headache is primary (such as migraine). Primary headache is the best validated within this classification system.
Secondary headaches are precipitated by another condition or disorder, local or systemic . Serious causes of secondary headache are uncommon.
Using the temporal pattern of headache to help differentiate primary from secondary headache
While we acknowledge that not all the following descriptors have tight definitions, we have tried to consider different temporal clinical patterns that the ‘jobbing’ clinician might frequently encounter and recognise.
Sudden onset headache
Sudden onset headache reaching maximum intensity within 5 minutes is called thunderclap headache. Thunderclap headache has the greatest probability of a secondary precipitant.
Recent onset and progressive headache
Evolution of headache over days to weeks. If associated systemic features and/or focal neurological signs there is an increased probability of secondary precipitant.
Recurrent episodic headache
Recurrent episodic headache in isolation is most likely due to a primary headache disorder.
Headache which occurs on the majority of days in a month
Headache present for at least 15 days per month for over 3 months in isolation is most likely due to a primary headache disorder.
Laterality and site of headache
Strictly unilateral (right or left but never bilateral) headache most consistently occurs in the Trigeminal Autonomic Cephalalgias (TACS) (http://www.ichd-3.org). 11.5- 20% of migraine sufferers experience unilateral headache.
Bilateral headache more commonly occurs in migraine, and is a more consistent defining feature of tension-type headache.
In most primary headache disorders the pain is experienced in the distribution of the first division of the trigeminal nerve and second cervical root. Neck pain can therefore be a feature of a migraine attack.
Prominent features in migraine include nausea, vomiting, photophobia, phonophobia and motion sensitivity (a tendency for the headache to be exacerbated by head movement or mild exertion).
Cranial autonomic features, such as lacrimation, conjunctival injection, rhinorrhoea, and nasal blockage, are characteristic of the TACs, but can occur in up to 25% of migraine sufferers.
Unlike migraine sufferers who are frequently motion sensitive and generally prefer to remain still during an attack, patients with cluster headache and to a lesser extent TACs tend to be restless during an attack.
Aura can be experienced in all headache disorders, but is by far most common in migraine.
The presence of abnormal neurological signs significantly increases the chance of an intracranial abnormality. Therefore, an appropriate neurological examination including fundoscopy is required when assessing the patient presenting with headache.
Useful and brief ways to perform the neurological examination:
Common Primary Headaches
(although often bilateral)
Pressing, tightening, non-pulsating
Moderate or severe
Mild or moderate but not disabling
Aggravated by, or causing avoidance of, routine physical activity
No aggravation by, or avoidance of, routine physical activity
No aggravation by physical activity
Nausea and/or vomiting
No nausea, vomiting, photophobia, or phonophobia
Ipsilateral to pain, there may be:
Attacks last hours to days
Attacks last hours to days
Attacks last from 15 mins to 3 hours
Frequency 1-2 attacks per month
Frequency 1-3 attacks per day (up to 8) and usually occur daily for 2-3 months at a time
Chronic migraine or chronic tension-type headache: At least 15 headache days per month for >3 months with the above clinical description, in the absence of medication overuse
Chronic cluster headache: Attacks occurring for more than 1 year without remission, or remission periods lasting <3 months
|Effect of Medication Overuse
Ergotamine, triptans, or opioids taken on 10 or more days per month, or 15 days for simple analgesics, for >3 months. Chronic migraine is fulfilled 2 months after medication has been withdrawn without improvement
No medication overuse headache
Medication-overuse headache only reported in patients with a predisposition to migraine and/or tension-type headache; clinical syndrome of the headache exacerbated by the acute-relief medication overuse is of the migraine and/or tension-type headache 50
Identifying Secondary Headaches
The most consistent indicators for serious secondary headache are:
- Thunderclap (sudden onset) headache
- Associated focal neurological deficit
- Associated systemic features
- Patients over the age over 50 years
The history is the key to diagnosis in headache. The neurological examination is also helpful in differentiating primary from secondary headache For example, patients with migraine (with or without typical aura) or tension-type headache and a normal neurological examination do not have an increased likelihood of a secondary precipitant relative to the background population.
For other isolated headache syndromes with normal neurological examination there is insufficient data to enable a definitive conclusion.
Role of Neuro-Imaging
People suffering from headache can be anxious about the possibility of a brain tumour. Outside of an emergency setting, current data indicates that the risk of finding serious secondary pathology in patients with isolated headache and a normal neurological examination is similar to that in people who do not have headache.
Normal imaging can reduce subsequent health care utilisation in the short term (less than one year) presumably because of reassurance. The effect however does not appear to be sustained in patients with anxiety and depression.
Moreover, there is a significant potential for uncovering incidental findings in 6-15% patients, which may not necessarily require further management but can themselves increase anxiety, and even potentially affect insurance coverage/premiums for that individual.
An information sheet can be useful to act as an ‘aide memoire’ when discussing these issues.