Migraine Headache or Neurovascular Headache- Description, Types, Causes
Headache is classified as primary and secondary headache. Primary headaches are chronic (last more than 6 months) and benign (not caused by life threatening disease). Headache is considered primary when a disease or other medical conditions does not cause the headache. Most primary headaches fall into three main types described as tension, migraine, and cluster headaches. Tension headache is the most common primary headache and accounts for 90% of all headaches. Migraines are the second most frequently occurring primary headaches. Migraine headache is also known as a Neurovascular Headache.
Description of Migranous Headache
- Intense throbbing or a pulsating headache
- Headache may last for hours to days
- Patient prefers to lie in a dark, quiet place.
- Headache is triggered by exercise and strenuous activities.
- Headache follows- nausea, vomiting
- Headache preceded by aura
- During headache- increased sensitivity to light and sound.
Description of Classic Migranous Aura
Visual Aura: It is the most common form.
- Hemianoptic: Shape of a crescent, bright and sparkling ragged edge. Less common visual aura- Scotoma photopsia or phosphenes.
- Visual Distortions: Metamorphopsia, Micropsia or macropsia are more common in children.
Sensory Symptoms: Second most common aura, occurs in about one-third of patients with migraine.
- Numbness, tingling or paresthesia
- Distribution - Often face and hand.
- Brain Stem Dysfunction - Rare, presented with hemi motor weakness dysphasia, and incoordination
- Ranges in level of consciousness- Rare
Types Of Migraine Headache Or Neurovascular Headache
Migraine is either migraine headache or migraine with aura and no headache. Characteristics of Migraine Headache includes unilateral headache and aura. Unilateral Headache described as migraine headache may or may not be associated with aura or aura described as Migraine may or may not be associated with unilateral headache.
Following Are The Three Major Types Of Migraine-
- Migraine Headache with Aura
- Migraine Headache without Aura
- Migrainous Aura Without Headache
A. Migraine Headache With Aura
Subtype of Migraine Headache with Aura-
a. Classic Migraine Headache-
- Presented as Unilateral Headache
- Symptoms of Aura Precedes Headache
- Headache is triggered by exercise and strenuous work
b. Familial or Hereditary Hemiplegic Migraine-
- A rare form of migraine with aura, familial hemiplegic migraine, is an autosomal dominant disease.
- This is the first migraine syndrome to be linked to a specific genetic set of polymorphisms.
- Migrainous headache with aura- Mild to severe hemiparesis of short or long duration.
- Familial: At least one first-degree relative has identical attacks.
- History of cerebellar ataxia in family members. 20% of familial hemiplegic migraine sufferers have another member of family with history of cerebellar ataxia.
c. Irregular Hemiplegic Migraines-
- Patients with sporadic hemiplegic migraine have migraine with aura including motor weakness but do not have an affected first- or second-degree relative
d. Basilar Form of Migraine
- Basilar migraine is seen mostly in young adults.
- Basilar symptoms in 60% patients: Two or more fully reversible aura
- Dysarthria, vertigo, tinnitus, decreased hearing, double vision, ataxia, decreased level of consciousness, simultaneous bilateral visual symptoms in both the temporal and the nasal field of both eyes, and simultaneous bilateral paresthesias.
- No motor weakness is present.
- Symptoms are bilateral.
- Posterior fossa involvement seen.
B. Migraines Headache Without Aura
- Patient complaints of unilateral headache
- Symptoms of aura are absent
- Headche is triggered by exercise and strenuous work.
C. Aura Without Headache
- Aura is predominant symptom and headache is of mild intensity.
- Headache does not follow aura, headache is not unilateral or pulsatile.
- Headache is not increased following exercise. Headache may be mild and discrete.
- Often occurs in middle-aged men.
- Aura lasts for short period of time and disappears without headache.
- In few cases aura may be prolonged and needs further investigations to rule out life threatening disease.
- Patient older than 40 years must be investigated further if aura is prolonged.
Causes Of Migraine Headache Or Neurovascular Headache
A. Vascular Origin
Migraine is the headache mostly expressed as unilateral headache with aura. Cerebral blood vessels carry blood supply to brain tissue in a compact space enclosed within bony skull. Expansion or change of diameter or volume of any of brain structure including blood vessels causes pressure symptoms such as headache. Migraine is the symptom that originates when blood vessels in the brain contract and expand inappropriately. Visual aura may occur when occipital lobe blood vessels are involved in initiation of migraine.
B. Serotonin Induced Migraine
Serotonin is a neurotransmitter, which contribute transmission of information between brain cells. Balance of level of serotonin is essential to maintain vascular tone in brain. Changes in arterial dilatation and constriction triggers migraine headache. Low serotonin level changes the vascular balance of constriction and dilatation of the blood vessels within brain tissue triggering throbbing migraine headache. There are other neurotransmitters such as dopamine also involved in maintaining normal vascular activities within brain tissue.
C. Cortical Depolarization- A Cause of Migraine
Migraine attack is associated with temporary wave of depolarization of surface of brain. The depolarization begins in occipital lobe thus starts a symptoms of aura. Occipital lobe is at the back of the brain. The spread from occipital lobe to front of brain is 3 to 5 mm per minute. The theory is being evaluated in animal studies in the lab. Depolarization of brain cells are followed by spreading silence of electrical brain activities. Silence phase initiate symptoms of aura. Silence phase is followed by release of inflammatory mediators causing symptoms of pain such as headache. Most of these theories are evaluated by neuroimaging techniques.
D. Migraine Induced by Aspartame and Tyramine
Tyramine and aspartame was thought to be the cause of migraine headache. Research of human studies has not concluded the possible relations between aspartame and tyramine as a cause of headache.
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