Headache. Migraine
Headache is one of the most common complaints. It can be primary or secondary in case of various organic or mental illnesses. 60-80% of the population world-wide suffers from sporadic chronic headache. As it’s not a homogenous illness, often its diagnosis is difficult and is classified predominantly by subjective complaints of the patients.
Migraine
- Chronic illness characterized by recurrent attacks of pulsating headaches accompanied by nausea, vomiting, photo and phono phobia.
- It is more common in females.
Etiology
It has a multifactorial genesis, including genetic predisposition, with a typical unilateral pulsating headache, provoked by a variety of exogenic and endogenic factors.
Endogenic factors
- Associated with CNS structures:
- Cerebral cortex, limbic system- triggered by stress, emotions, mood changes
- Hypothalamus - through biologic circadian rhythm, hormonal changes, related to the menstrual cycle in women and fluctuations in autonomic nervous functions
- Locus caerulus, nucleus raphe dorsalis and other brainstem pain control structures, which change the neuronal activity and lead to reduced pain threshold of the afferent neurons of the trigeminal nerve.
Exogenic factors
- Excessive sensory stimuli e.g. strong noise, cold, heat, foods, exhaustion, stress
- Meteorological factors - change of weather and seasons, fluctuations of barometric pressure
- Food stuffs - hunger, chocolate, nuts, alcohol, red wine, smoking.
- Vasodilators, drugs, chemical substances.
Pathogenesis is not completely understood. Hereditary predisposition existing in about 55-70%. Mutation of chromosome 19 with impairment of the function of the voltage dependent calcium channels. This causes susceptibility to migraine attacks by various neuronal cellular mechanisms of impaired afferent control;
- Low pain threshold of the nociceptors due to lowered threshold of excitation, enhanced afferentiation and pain supersensitivity.
- Disbalance of homeostasis with low level of magnesium in the neurons, which serves as key modulator of the neuronal excitation
- Abnormal release of excitatory neurotransmitters like glutamate
- Disturbed energy metabolism in dysfunction of the mitochondria in the nervous cell, which causes deviation in the cellular ion homeostasis, membrane lability and readiness for easy depolarisation of the neurons
- Vegetative vascular lability, instability of the trigeminovascular reflex and generally reduced neuromuscular tone
- Impaired function of the brainstem descending system and lowered pain control threshold
Therefore migraine is a consequence of a genetically predetermined dysfunction of calcium ion channels and it appears to be a disorder, associated with the so called channelopathies.
The Aura is the first representative of the migraine seizure.