Migraine is recurrent headache associated with visual and gastrointestinal disturbance. The borderline between migraine and tension headaches is vague. Over 12% of any population world-wide report these symptoms.
Mechanisms of migraine
Precise mechanisms of migraine remain unknown. Genetic factors play some part . The headache of migraine, often throbbing, is due to vasodilatation or oedema of blood vessels, with stimulation of nearby nerve endings. Release of vasoactive substances such as nitric oxide has a role . Serum 5 – hydroxytryptamine (5HT) rises with initial symptoms and falls during the headache. Cerebral features, such as tingling limbs, aphasia and weakness, are caused by focal depression of cortical function.
Some patients recognize precipitating factors:
#Week-end migraine (a time of relaxation)
#Chocolate (high in phenylethylamine)
#Cheese (high in tyramine)
#Noise and irritating lights
#With premenstrual symptoms.
Migraine is common around puberty and at the menopause and sometimes increases in severity or frequency with hormonal contraceptives, in pregnancy and with the onset of hypertension. There is no reason to suppose that the development of migraine is suggestive of any serious intracranial lesion. However, since migraine is so common, an intracranial mass and migraine sometimes occur together by coincidence. Migraine sometimes follows a blow to the head - often minor.
Symptoms of Migraine
Migraine attacks vary from intermittent headaches indistinguishable from tension headaches to discrete episodes that mimic thromboembolic cerebral ischaemia.
Distinction between variants is somewhat artificial.
Migraine can be separated into phases:
# initial or, prodromal symptoms
# the main attack (headache, nausea, vomiting)
# sleep and feeling drained afterwards.
Types of Migraine
Migraine with aura (classical migraine)
Prodromal symptoms are usually visual and related to depression of visual cortical function or retinal function. Unilateral patchy scotomata (retina) (Patchy blindness), hemianopic symptoms (cortex), teichopsia (flashes) and fortification spectra (jagged lines resembling battlements) are common. Transient aphasia (Unable to speak) sometimes occurs, with tingling, numbness, vague weakness of one side and nausea. The prodrome persists for a few minutes to about an hour.
Headache then follows. This is occasionally hemicranial (i.e. splitting the head) but often begins locally and becomes generalized. Nausea increases and vomiting follows. The patient is irritable and prefers a darkened room. Superficial temporal arteries are engorged and pulsating. After several hours the migraine settles, sometimes with a diuresis. Deep sleep often ensues.
Migraine without aura (common migraine)
This is the usual variety. Prodromal visual symptoms are vague. There is recurrent headache accompanied by nausea and malaise.
Basilar migraine
Prodromal symptoms include circumoral and tongue tingling, vertigo, diplopia, transient visual disturbance (even blindness), syncope, dysarthria and ataxia. These occur alone or progress to a typical migraine.
Hemiparetic migraine
This rarity is classical migraine with hemiparetic features, i.e. resembling a stroke but with recovery within 24 hours. Exceptionally, cerebral infarction (stroke) occurs.
Ophthalmoplegic migraine
This rarity is a third nerve, or exceptionally a sixth nerve, palsy with a migraine - and difficult to diagnose without investigation to exclude other conditions.
Facioplegic migraine
This is unilateral facial weakness during a migraine.
The diseases, which should be differentiated from migraine
The sudden headache may resemble meningitis or SAH(Sub Arachnoid Haemorrhage). Hemiplegic, visual and hemi sensory symptoms must be distinguished from thromboembolic TIAs(Transient Ischaemic Attacks). In TIAs maximum deficit is present immediately and headache is unusual. Unilateral tingling or numbness may resemble sensory epilepsy (partial seizures). In epilepsy, distinct march (progression) of symptoms is usual.
Treatment of Migraine
#reassurance and relief of anxiety
#avoidance of dietary factors - rarely helpful.
Patients taking hormonal contraceptives may benefit from a brand change, or trying without. Premenstrual migraine may respond to diuretics. Depot oestrogens are sometimes used. Severe hemiplegic symptoms are an indication for stopping hormonal contraceptives.
During an attack. After ruling out any serious cause for a sudden headache, paracetamol or other simple analgesics should be given, with an antiemetic such as metoclopramide if necessary. Repeated use of analgesics leads to further headaches.
Triptans (5-HT, agonists) are also helpful. In some 30% of cases, where there is
recurrent severe migraine, sumatriptan, zolmitriptan, naratriptan and rizatriptan are of value either by prompt self-administered subcutaneous injection, or orally by wafer or inhaler. Triptans should be avoided when there is vascular disease, and not overused.
Prophylaxis of Migraine attack
It is difficult to discern placebo effects of prophylactic drugs. The following are used when attacks are frequent:
#pizotifen (antihistamine and 5-HT antagonist) 0.5 mg at night for several days, increasing to 1.5 mg (common side-effects: weight gain and drowsiness)
#propranolol 10 mg three times daily, increasing to 40-80 mgthree times daily
#amitriptyline: 10 mg(or more) at night.
#Sodium valproate, methysergide, SSRIs, verapamil, topiramate, nifedipine and naproxen are also used.
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