Chapter: Medicine and surgery: Nervous system

Migraine - CNS causes of headache

Episodic headache which may be associated with visual and gastrointestinal disturbance. - Definition, Incidence, Age, Sex, Aetiology, Pathophysiology, Clinical features, Complications, Investigations, Management, Prognosis.





Episodic headache which may be associated with visual and gastrointestinal disturbance.




10% of the population.




Usually starts around puberty.




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The cause is unknown although there is a familial tendency. Precipitating factors include:


Emotion: anxiety, depression, shock, excitement.


Alcohol, chocolate, coffee are reported as potential triggers.


Migraine is common premenstrually and around the menopause.




The exact pathophysiology is unclear:


It has been suggested that migrainous headaches are due to vasodilatation, with auras due to preceding vasoconstriction.


A second theory suggests that there is a primary neurological dysfunction, probably originating in the brainstem, which then causes secondary neurovascular changes. The primary event appears to cause a wave of cortical hypoperfusion and hence neurological dysfunction (associated with the aura phase) which then precipitates the headache by activating the trigeminal nerve which leads to pain by neuroinflammatory changes (release of paincausing peptides and vasodilatation) at the meninges.


Serotonin (5-hydroxytryptamine (5-HT)) plays an important role probably via effects on the vasculature and on neurological function. Serum levels of hydrox-ytryptamine rise at the onset of the prodromal symptoms and fall during the headache.


Ischaemia and/or depression of cortical function may cause focal neurological symptoms, e.g. hemiplegic migraine.


Clinical features


Can be divided into prodromal symptoms, aura and headache.


Prodromal symptoms may last a few days and include mood and appetite changes.


The aura is usually visual, e.g. visual obscurations, flashing lights, distortion, but may involve other senses, motor or speech dysfunction. Each symptom lasts up to an hour.


The headache begins as the aura fades. It is unilateral in two-thirds of cases, bifrontal or generalised in others. It may be unilateral, then become generalised. The pain may be dull or pulsating and is usually exacerbated by movement, coughing or sneezing. Associated symptoms include photophobia, nausea and vomiting. The headache typically lasts several hours and may last up to several days.


Migraine without aura occurs in 80% of migraine sufferers.





In most cases, none are necessary. If there are neurological abnormalities on examination CT or MRI brain may be performed.





General measures include reassurance and avoidance of precipitating factors.


Treatment of the headache involves the use of simple analgesics especially NSAIDs which are most effective if taken early. The 5-hydroxytryptamine agonists (triptans) may be very effective. Antiemetics may be of value.


Prophylactic agents are used in patients with frequent headaches. They include pizotifen (a 5-hydro-xytryptamine antagonists), propranalol, tricyclic antidepressants such as amitryptiline and anticonvulsants such as sodium valproate.

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Medicine and surgery: Nervous system : Migraine - CNS causes of headache |

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