Classification and causes of cerebrovascular disorders
In medical practice, two main categories of cerebral vascular pathology are distinguished:
- Acute disorders — include ischemic stroke (develops when blood flow stops due to vasospasm, thrombosis, or embolism against the background of atherosclerosis of major arteries, leading to necrosis) and hemorrhagic stroke (bleeding into brain tissue due to arterial hypertension or aneurysm rupture).
- Chronic disorders — dyscirculatory encephalopathies. They develop gradually due to age-related changes in the vascular wall, atherosclerosis, arterial hypertension, and metabolic disturbances in neurons. Clinically, they manifest as memory impairments, cognitive decline, psychiatric changes, and motor deficits.
Principles of pharmacotherapy for ischemic disorders
Therapy and prevention of chronic ischemia, as well as rehabilitation after acute ischemic states, rely on the following principles:
- Main goal: Dilation of cerebral blood vessels, i.e., cerebral vasodilation.
- Drug requirement: High selectivity of action. Medications must increase cerebral blood flow without disrupting overall hemodynamics. Excessive drops in systemic blood pressure are unacceptable, as they worsen perfusion of brain tissue.
- Indications for prescribing: Prevention and management of chronic disorders, as well as elimination of residual effects after ischemic strokes.
Classification of vasodilators used
Pharmacological agents that improve cerebral circulation are divided into the following pharmaceutical groups:
- Calcium channel blockers: nimodipine, cinnarizine.
- Periwinkle alkaloid derivatives: vinpocetine.
- GABA derivatives: nicotinoyl-gamma-aminobutyric acid.
- Ergot alkaloid derivatives: nicergoline.
- Nicotinic acid derivatives: xanthinol nicotinate.
Briefly: answers to topical questions
What is the mechanism of the vasodilating action of vinpocetine?
Vinpocetine is a derivative of periwinkle alkaloids; sources indicate it is used to improve cerebral circulation and possesses neuroprotective properties, but the mechanism of its vasodilating action is not specified.
What is the mechanism of action of cinnarizine on vascular smooth muscle cells?
Cinnarizine is a calcium channel blocker with selective action on cerebral arterioles. The drug reduces the reactivity and sensitivity of vascular smooth muscle cells in response to endogenous vasoconstrictors such as catecholamines, angiotensin, bradykinin, and vasopressin.
The classification of vasodilators is easy to remember by key chemical and herbal sources: CCBs (Nitsi), Periwinkle (Vin), GABA, Ergot (Nits), and Nicotinic acid (Xantinol).
Class and exam questions
What are the two main clinical forms of cerebrovascular disorders?
Acute disorders (strokes) and chronic disorders (dyscirculatory encephalopathies) are distinguished.
What is the difference between the mechanisms of ischemic and hemorrhagic strokes?
Ischemic stroke occurs due to the cessation of blood flow (spasm, thrombosis, embolism) resulting in necrosis, whereas hemorrhagic stroke represents hemorrhage into brain tissue.
What is the main requirement for vasodilators in cerebral blood flow?
Drugs must exhibit selectivity of action: increase cerebral blood flow and exert minimal influence on systemic hemodynamics to avoid hypotension.
What else to study on this topic
- Pathogenetic differences between thrombosis and embolism in ischemic stroke
- The effect of arterial hypertension on the development of hemorrhagic strokes
- Metabolic disorders in neurons during chronic ischemia
- Pharmacodynamics of calcium channel blockers in cerebral vessels
- Features of the pharmacological action of periwinkle and ergot derivatives
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