Migraine Flashcards
How common is it?
Prevalence: 18%, mean age of onset 18 years. Men 6% with mean age of onset 14 years.
What causes it?
Exact pathophysiology is not fully understood. Research has focused on neuroanatomical and genetic causes, such as the trigeminovascular system (Kumar and Clarkes says that changes in brainstem blood flow lead to an unstable trigeminal nerve nucleus and nuclei in the basal thalamus. This results in release of vasoconstrictive, neuropeptides including calcitonin-gene-related peptide and substance P which then results in neurogenic inflammation) and its relationship with pain pathways.
What risk factors are there?
Migraine has a significant genetic component, with about half of people with migraine having a first degree relative with the condition. Furthermore, the more serious it is the more likely there is to be a family connection. Diet rarely seems to play a part. Sex, age (peak about 30) and hormonal changes.
How does it present?
Migraine is classified into 3 types: with aura, without and migraine variants (unilateral motor or sensory symptoms resembling a stroke).
The headaches are classically unilateral, throbbing and builds up over minutes to hours. It may be associated with nausea, vomiting and photophobia. It may last for some days and is made worse by physical exertion.
The patient is irritable and prefers the dark.
Fatigue, nausea and changes in mood and appetite may occur hours or days before the migraine.
Auras are related to depression of visual cortical function or retinal function. Other aura include aphasia, tingling, numbness and weakness of one side of the body. Sleep is the best resolve.
Investigations
Head MRI
Various bloods to rule out other causes (pheochromocytoma)
Treatment
Mild attacks: Simple analgesia + antiemetic such as metoclopramide.
Moderate/severe attacks: triptans (e.g. Sumatriptan, almotriptan, eletriptan, or rizatriptan) are serotonin agonists. They inhibit the release of vasoconstrictive peptides. They are contraindicated when there is vascular disease and in migraine variants.
Prophylactically (say >2attacks per month and resistant to treatment when they start): Pizotifen (titrate dose up, take at night, causes weight gain and drowsiness). β blockers. Amitriptyline.
Conditions that would present similarly
A sudden migraine headache may resemble meningitis or subarachnoid haemorrhage.
The hemiplegic, visual and hemisensory symptoms must be distinguished from thrombotic TIAs. In TIAs the maximum deficit is present immediately and headache is unusual.
