Migraine

Migraine is recurrent headache associated with visual and GI disturbance. Approximately 12% of the population world-wide suffers from the condition.

Pathology:

Precise mechanisms are still unknown. Although some factors are as follows:

1) Genetic factors play some part;
2) Also, release of neuropeptide, calcitonin-gene-related peptide (CGRP) is implicated as it is a potent dilator of cerebral and dural vessels.
The headache of migraine is usually caused by dilation or edema of cranial vessels and subsequent stimulation of nearby nerve endings. Nitric oxide, a vasoactive substance, also has a role. Magnesium deficiency, nueral excitation by glutamate and asparate as well as alterations in hypothalamic-pituitary axis is also suggested.

Some precipitating factors:
1) Weekend migraine (time of relaxation)
2) Chocolate (phenyl ethylamine)
3) Cheese (high in tyramine)
4) Noise and irritating lights
5) Premenstrual symptoms
6) Also common around puberty and menopause


Clinical Presentation:

1) Migraine with aura - prodromal symptoms are usually visual mostly related to visual cortex depression or retinal problems. Other neurological symptoms like tingling, nausea, numbness and vague weakness of one side may occur. It can last for few minutes to an hour followed by the headache. It is usually hemi cranial but often begins locally. Patient is irritable and prefers dark environment. Diuresis follows resolution after several hours and deep sleep often ensues.

2) Migraine without aura (common migraine) - the usual variety. Prodromal symptoms are vague and headache is recurrent accompanied by nausea and malaise.

3) Basilar migraine - prodrome includes vertigo, diplopia, transient visual disturbance, syncope and dysarthria. They can occur alone or progress to typical migraine

4) Hemi paretic migraine - classical migraine with hemi paretic features, but resolves within 24 hours differentiating from stroke.

5) Ophthalmoplegic migraine - associated with third nerve, or sometimes sixth nerve palsy.

6) Facioplegic migraine - associated with unilateral facial palsy.


Differential Diagnosis:

The sudden headache may resemble meningitis or Sub-Arachnoid Hemorrhage. Prodromal symptoms must be distinguished from Transient Ischemic Attacks - TIAs usually deficit immediate and without headache.
Sensory abnormalities may resemble sensory epilepsy.


MANAGEMENT:

General measures include:
1) Reassurance and relief of anxiety
2) Avoidance of dietary factors - rarely helpful. Also patients taking oral contraceptives may benefit from change of brand or trying without. Severe symptoms are indication for stopping hormonal medications.

During an attack:
After ruling out serious pathology for headache, paracetamol or other simple analgesics should be given, with an antiemetic (e.g. Metaclopromide) if necessary. Repeated use may lead to further headaches.
Also, Triptans (5-HT1 agonists) can be used as well. In 30% cases of severe recurrent migraine, sumatriptan, zolmitriptan and naratriptan are of value by either subcutaneous injection or orally by inhaler. They should be avoided when there is vascular disease. Recently, some CGRP antagonist was effective in treating attacks.

Prophylaxis:
The following are used when attacks are frequent:

1) Pizotifen (antihistamine and 5-HT antagonist) - 0.5mg at night for several days, increasing to 1.5mg (common side-effects: weight gain and drowsiness)
2) Propanolol (beta-blocker) - 10mg three times daily, increasing to 40-80mg thrice daily
3) Amitriptyline - 10mg (or more if required) at night

Sodium valproate, methysergide, SSRIs, verapamil, topiramate and nifedipine are also used.

Hopefully the article would help my fellow medical students understand migraine better for it is a common problem encountered by most GPs and even by us students during daily life.

(Sources: Kumar and Clark, Davidson)