Migraine is classified as vascular headache. Traditionally, intracranial vasoconstriction was considered responsible for the AURA and extra cranial vasodilatation for the headache. However, it now appears that vascular events are secondary to neurogenic changes. The liberation of vasoactive substances including serotonin (5HT), catecholamines, histamine, kinins, neuropeptides and prostaglandin playing an aetiological role. Migraine is classified as :
1. Migraine with aura or classical migraine
Migraine is a form of headache, which is severe, and usually one sided, frequently associated with nausea and vomiting. This is sometimes preceded by warning symptoms, which usually affect the eyesight and are known as an Aura. If the patient is among the 10% of the adults who have migraine with Aura, the warning signs about 20 minutes before the headache. These may include:
· Sparking flashes of light
· Dazzling zigzag lines in field of vision
· Slowly spreading blind spots in vision
· Weakness, numbers of tingling in face, hand or leg
· Difficulty in seeing or speaking
2. Migraine without aura or common migraine
When aura is absent that is called migraine without aura or common migraine . although a migraine without aura has no classic warning signs, the patient may have one or more symptoms of premonition several hours before headache actually strikes including
· Feeling of elation or intense energy
· Craving for sweets
· Irritability or depression
3. Retinal or ophthalmic migraine
Retinal migraine is repeated attacks of monocular scotoma or blindness lasting less than one hour and associated with headache. This condition may be broadly defined as transient or permanent monocular visual disturbances accompanying a migraine attack or occurring in an individual with a strong history of migrainous episodes. One may consider two forms of anterior visual pathway migraine. I) transient monocular blindness and ii) permanent unilateral visual loss, a much less common occurrence. The transient form has relatively stereotyped presentation, consistent with retinal or optic nerve hypo perfusion from spasm of central retinal or ophthalmic artery.
4. Basilar migraine
Basilar artery migraine (BAM) is a subtype of "Migraine with aura." The category now combines the term "basilar artery migraine" with " prosterior fossa migraine" under the term " basilar migraine" implying involvement of the basilar artery and its branches to the brainstem as well as the posterior cerebral arteries.
Basilar artery migraine has two or more of the following symptoms:
· Visual symptoms (bilateral temporal and nasal fields) double vision
· Dysarthria, Ataxia
· Vertigo, tinnitus
· Bilateral parenthesis, decreased hearing
· Decreased level of consciousness, bilateral paresis
5. Familial Hemiplegic Migraine
An autosomal dominant characterized by attacks of transient hemi paresis followed by a migraine headache, is divided into pure familial hemiplegic migraine (affecting 80% of families) and familial hemiplegic migraine with premature cerebellar signs(affecting 20% of families). Familial Hemiplegic Migraine (FHM) is a type of maigraine with aura.
6. Complicated Maigraine
Complicated maigraine is a type of migraine in which migraine attacks are accompanied by permanent neurological deficits, such as paralysis.
7. Menstrual Migraine
Migraine is thought to affect 15% to 20% of women and according to the American Academy of Neurotology, an estimated 50% of these women experience migraine due to hormonal changes experienced during their menstrual cycle. Menstrual migraine can be divided into two, firstly True Menstrual Migraine - with attacks that occur 2 days prior during and up to 3 days after the menstrual period and at no other times is triggered off by this rapid fall in levels of oestrogen. The fall of progesterone leads to the bleeding but does not contribute to headache. Falls in oestrogen likely influence chemicals in the brains such as serotonin, adrenalin, dopamine and endorphins. Changes in activity of these brain trigger the development of migraine headache and secondly, Menstrual Associated Migraine (sometimes referred to as Menstrual Related Migraine) with attacks that occur during midcycle or around three time of ovulation. Menstrual migraines are generally of longer duration, more in debilitating more likely to recur and more resistant to treatment than other migraine.
8. Abdominal Migraine
Abdominal migraine is an idiopathic disorder seen in mainly in children. It is also known as "periodic syndrome." The symptoms are of recurrent episodes of midline abdominal pain with attacks lasting 1 - 72 hours and complete normality between episodes. The pain is of moderate to severe intensity and is felt in the midline of the abdomen, usually around the umbilicus, or poorly localized. The attacks of pain are usually accompanied by anorexia and nausea and half of the patients will vomit with at least some attacks although some patient may appear flushed. Associated symptoms include photophobia, phonophobia and dizziness.
9. Post hypoglycaemic Migraine
Post hypoglycaemic migraine may occur exceptionally in patients with unstable diabetes as a rebound phenomenon caused by an unidentified mechanism. There is an increased prevalence of headache in persons with diabetes. Although hypoglycaemic may precipitate headache in some diabetic patients. Baseline electroencephalogram was normal but showed mild slowing of background in immediate posthypoglycaemic state. Computerized tomography of the head demonstrated mild atrophic changes. Severe bout of hypoglycaemic and migraine were ameliorated by hypoglycaemic treatment.