stroke

Definition and Overview

Stroke is a disease in which acute neurological dysfunction occurs when a cerebral blood vessel is blocked or ruptured and blood flow to brain tissue is interrupted. In Oriental medicine, it is traditionally referred to as stroke, and in English medical terminology, it is also called cerebrovascular accident (CVA).

Worldwide, stroke is the second leading cause of death and third leading cause of disability. As of 2019, approximately 12.2 million new cases of stroke and approximately 6.55 million deaths due to stroke were reported worldwide. In Korea, cerebrovascular disease ranks fourth as the cause of death, and as a single disease, it has a high mortality rate. The social burden of stroke continues to grow as the population ages and the prevalence of metabolic syndrome increases.

Stroke is an emergency disease in which brain cell damage progresses by the minute. In an ischemic stroke, it is estimated that approximately 1.9 million nerve cells die every minute after blood flow is blocked. For this reason, the expression “Time is Brain” has become a core principle of acute stroke treatment.

Classification

Stroke is largely classified into ischemic stroke and hemorrhagic stroke.

Ischemic stroke (cerebral infarction)

It accounts for approximately 80% of all strokes. This is a condition in which the supply of oxygen and nutrients to the brain tissue in that area is interrupted when a cerebral blood vessel is blocked by a thrombus or embolus. Depending on the mechanism of occurrence, it is subdivided as follows.

• Large artery atherosclerosis: A type of atherosclerosis that forms on the inner walls of large arteries that supply blood to the brain, narrowing or blocking the blood vessels.
• Small vessel occlusion (lacunar cerebral infarction): A type of blockage of small penetrating arteries deep in the brain, the main cause of which is high blood pressure. Forms small infarcts less than 15 mm in diameter.
• Cardioembolism: A type of blood clot formed in the heart that travels through the bloodstream and blocks a cerebral blood vessel. Atrial fibrillation is the most common cause, and the risk of stroke in patients with atrial fibrillation is approximately five times that of the general population.
• Other causes: Vascular dissection, blood clotting disorders, vasculitis, etc.
• Cryptogenic: A case in which the cause cannot be identified even after sufficient testing, accounting for approximately 25% of all ischemic strokes.

hemorrhagic stroke

It accounts for approximately 20% of all strokes, but the mortality rate is higher than that of ischemic stroke. This is a condition in which a blood vessel in the brain ruptures and bleeding occurs inside the brain tissue or in the space surrounding the brain.

• Intracerebral hemorrhage: A blood vessel within the brain parenchyma ruptures and a hematoma forms. Arteriolar degeneration due to chronic hypertension is the most common cause and accounts for approximately two-thirds of all hemorrhagic strokes.
• Subarachnoid hemorrhage: Bleeding occurs in the space under the arachnoid membrane that surrounds the brain. The main cause is a ruptured cerebral aneurysm, and is characterized by sudden, severe headaches (“thunderclap headaches”).

Transient ischemic attack (TIA)

Transient ischemic attack (TIA) is a condition in which cerebral blood flow is temporarily reduced, causing symptoms similar to stroke, and usually fully recovers within minutes to tens of minutes. The difference from a stroke is that there is no finding of cerebral infarction on imaging tests. The risk of developing a stroke within 90 days after TIA is reported to be approximately 10-15%, and TIA is considered a strong warning sign of stroke.

risk factors

Stroke risk factors are divided into correctable factors and non-correctable factors. According to the 2019 Global Burden of Disease Study (GBD 2019), approximately 90.3% of stroke occurrence is due to modifiable risk factors.

Modifiable Risk Factors

• Hypertension: The strongest risk factor for stroke. For every 20 mmHg increase in systolic blood pressure, the risk of stroke approximately doubles. It increases the risk of both ischemic and hemorrhagic stroke.
• Atrial fibrillation: The annual incidence of stroke in patients with non-valvular atrial fibrillation is approximately 5%, and the risk increases significantly without anticoagulant treatment.
• Diabetes mellitus: Increases the risk of stroke by approximately 1.5 to 3 times, and the prognosis for strokes occurring in diabetic patients is worse.
• Dyslipidemia: Elevated LDL cholesterol contributes to increased risk of carotid atherosclerosis and ischemic stroke.
• Smoking: The risk of stroke in smokers is approximately twice that of non-smokers, and five years after quitting smoking, the risk decreases to the level of non-smokers.
• Obesity and physical inactivity: Abdominal obesity and lack of exercise are independent risk factors for stroke.
• Heavy drinking: Daily alcohol intake exceeding 60 grams increases the risk of hemorrhagic stroke.
• Migraine with aura: The risk of ischemic stroke in patients with migraine with aura is reported to be approximately two times higher, and the risk increases further when taking oral contraceptives.

non-correctable risk factors

• Age: The risk of stroke approximately doubles every 10 years after age 55.
• Gender: Men have a higher incidence of stroke than women, but women have a higher incidence and mortality rate in older age.
• Family history: If an immediate family member has had a stroke, the risk increases approximately 1.3 times.
• Race: The incidence is relatively high in African and Hispanic people.

Symptoms and FAST identification method

Stroke symptoms appear in various ways depending on the area covered by the blocked or bleeding cerebral blood vessel. Most symptoms occur suddenly, which is the most important characteristic of stroke.

main symptoms

• Hemiparesis: Sudden loss of strength or numbness in one side of the face, arm, or leg. It is the most common symptom of stroke.
• Speech disorder: Speech becomes slurred (dysarthria), or aphasia occurs, in which words cannot be understood or expressed.
• Vision impairment: Sudden loss of vision in part of the field of vision in one or both eyes.
• Dizziness and balance problems: Sudden onset of severe dizziness, gait instability, and coordination problems. Posterior circulation is common in stroke.
• Sudden severe headache: Especially with subarachnoid hemorrhage, a severe headache described as “the worst headache of your life” can occur suddenly.

FAST identification method

This is a detection method developed to help the general public quickly recognize stroke.

• F (Face): Check whether one side of the face droops when asked to smile.
• A (Arms): When asked to raise both arms, check whether one arm falls down.
• S (Speech): When asked to repeat simple sentences, check if the pronunciation is slurred or the content is strange.
• T (Time, time): If you have any of the above symptoms, immediately call 119. Be sure to record the time of symptom onset.

The FAST method has been reported to have a stroke recognition sensitivity of approximately 85%, and is widely used in the prehospital setting.

diagnosis

If a stroke is suspected, a neuroimaging test is performed along with a neurological examination to distinguish between ischemic and hemorrhagic types and to evaluate the location of the occluded blood vessel and the extent of brain damage.

Brain computed tomography (Brain CT)

This is the first test performed after arriving at the emergency room. The imaging time is only a few minutes, making it suitable for acute patients. Hemorrhagic strokes are immediately identified as high-density lesions on CT, but hyperacute ischemic strokes may appear normal on CT. By adding CT angiography (CTA), large vessel occlusion can be quickly confirmed.

Brain MRI

Diffusion-weighted imaging (DWI) can detect acute cerebral infarction within minutes of occurrence, and is more accurate than CT in diagnosing ischemic stroke. When combined with perfusion imaging, the extent of brain tissue (ischemic penumbra) that can still be saved can be evaluated to help determine treatment policy.

Angiography

CT angiography (CTA), MR angiography (MRA), and digital subtraction angiography (DSA) are used to evaluate cerebral blood vessels for stenosis, occlusion, aneurysm, and vascular malformation. DSA is the standard for diagnosing microvascular lesions because it is invasive but has the highest resolution.

Other tests

• Electrocardiogram, echocardiogram: Evaluate causes of cardiogenic emboli (atrial fibrillation, valvular disease, intracardiac thrombosis).
• Blood tests: Check blood sugar, clotting function, lipid levels, infection markers, etc.
• Carotid artery ultrasound: Noninvasively evaluates the degree of carotid artery stenosis.

acute care

The key to acute stroke treatment is to minimize brain damage by reopening blocked blood vessels as quickly as possible.

Intravenous thrombolysis (IV tPA)

This is a treatment that dissolves blood clots by administering tissue plasminogen activator (tPA, alteplase) intravenously. Administration within 3 hours of symptom onset is standard, and ECASS III study (2008), the treatment time period was extended to 4.5 hours. In this study, the proportion of patients who showed a good functional outcome (mRS 0 to 1) in the group administered alteplase within 4.5 hours was significantly higher than the placebo group (52.4% vs. 45.2%). The sooner treatment is started, the greater the effect, and the greatest benefit is reported when administered within 90 minutes.

Mechanical Thrombectomy

In patients with occlusion of large vessels of the anterior circulation (internal carotid artery, middle cerebral artery M1 segment), this is a procedure in which a catheter is inserted into the blood vessel and the blood clot is physically removed using an instrument such as a stent retriever. In a meta-analysis of five randomized controlled trials published in 2015, the thrombectomy group had a significantly higher rate of achieving functional independence (mRS 0-2) compared to the control group, at 46% vs. 26.5%. The standard treatment time period is within 6 hours after onset, but in some cases, it can be expanded to up to 24 hours depending on the results of perfusion imaging.

Acute treatment of hemorrhagic stroke

Thrombolysis or thrombectomy is not indicated in hemorrhagic stroke. Prevent further bleeding by actively controlling blood pressure, and provide medical treatment for increased intracranial pressure. Surgical hematoma removal is considered depending on the size and location of the hematoma. For subarachnoid hemorrhage caused by ruptured cerebral aneurysm, aneurysm ligation (clipping) or coil embolization (coiling) is performed early to prevent rebleeding.

prevention

primary prevention

It is a strategy to prevent the first stroke in people who have never had a stroke.

• Blood pressure management: In patients with high blood pressure, lowering systolic blood pressure by 10 mmHg reduces the risk of stroke by about 30-40%.
• Smoking cessation: Smokers' risk of stroke decreases significantly 2 to 5 years after quitting smoking.
• Regular exercise: Moderate aerobic exercise of at least 30 minutes, 3 to 5 times a week, is recommended.
• Dietary management: Limiting sodium intake, increasing fruit and vegetable intake, and a Mediterranean diet are associated with a reduced risk of stroke.
• Atrial fibrillation management: Decide whether to initiate anticoagulation treatment according to the CHA₂DS₂-VASc score.
• Management of diabetes and dyslipidemia: Maintain blood sugar and LDL cholesterol below target levels.

secondary prevention

It is a strategy to prevent recurrence in patients who have experienced a stroke or TIA. In addition to primary prevention strategies, the following are added:

• Antiplatelet drugs: Antiplatelet drugs such as aspirin and clopidogrel are administered to patients with non-cardiogenic ischemic stroke.
• Anticoagulants: Direct oral anticoagulants (DOACs) or warfarin are administered to patients with atrial fibrillation-related stroke.
• Statins: High-dose statin treatment is recommended for patients with atherosclerosis-related stroke.
• Carotid intervention: If symptomatic carotid artery stenosis is greater than 70%, consider carotid endarterectomy (CEA) or carotid artery stenting (CAS).

Relationship between autonomic nervous system and stroke risk

Autonomic nervous system dysfunction is closely related to the occurrence and prognosis of stroke. Decreased heart rate variability (HRV) has been identified as an independent predictor of cardiovascular events, and sympathetic overactivation increases blood pressure variability, endothelial dysfunction, and promotes atherosclerosis progression. Even after a stroke, damage to the insular cortex can lead to autonomic dysregulation, leading to complications such as arrhythmia, blood pressure instability, and myocardial damage.

Autonomic imbalance also contributes to the occurrence of atrial fibrillation, and changes in the sympathetic-vagal balance are being studied as one of the mechanisms that trigger atrial fibrillation. Therefore, assessing autonomic function can be a useful tool for early detection and management of stroke risk factors.

rehabilitation

Post-stroke rehabilitation is a process to restore damaged neurological function as much as possible, minimize disability, and help return to daily life. The first 3 to 6 months after a stroke are when neuroplasticity is most active, so it is important to perform intensive rehabilitation treatment during this period.

Main rehabilitation areas

• Physical therapy: Restore motor function through muscle strengthening, balance training, and gait training.
• Occupational therapy: Restores the ability to perform activities of daily living (ADL) such as dressing, eating, and washing.
• Speech therapy: Improves language expression and comprehension in patients with aphasia and dysarthria.
• Swallow rehabilitation: Provide training for safe eating in patients with dysphagia. Approximately 37-78% of patients in the acute stage of stroke have swallowing disorders.
• Psychological support: Post-stroke depression occurs in approximately 30% of patients and requires active management as it has a negative impact on rehabilitation will and functional recovery.

rehabilitation principles

Early start, sufficient intensity, and task-oriented repetitive training are the three principles of rehabilitation. It is recommended that rehabilitation begin within 24 to 48 hours after stroke, as long as the patient's condition allows. Rehabilitation programs must be individualized according to the patient's functional level and goals, and are carried out collaboratively by a multidisciplinary team including doctors, physical therapists, occupational therapists, speech therapists, nurses, and social workers.

life guide

Daily life management rules to prevent stroke and recurrence are as follows.

• Self-measurement of blood pressure: Measure and record your blood pressure in the morning and evening at home. Target blood pressure is generally less than 130/80 mmHg.
• Regular exercise: Practice moderate aerobic exercise such as walking, swimming, or cycling for more than 30 minutes 3-5 times a week.
• Quit smoking and drinking alcohol: Stop smoking immediately and limit drinking to no more than two drinks a day for men and one drink a day for women.
• Balanced diet: Reduce sodium intake to less than 5g per day and maintain a diet centered on fruits, vegetables, whole grains, and fish.
• Maintain appropriate weight: Maintain body mass index (BMI) between 18.5 and 24.9, and keep waist circumference below 90cm for men and 85cm for women.
• Compliance with medication: Do not stop taking prescribed medications, such as antiplatelet agents, anticoagulants, blood pressure medications, diabetes medications, or statins.
• Regular check-ups: Check blood pressure, blood sugar, lipid levels, electrocardiogram, etc. regularly, and respond early if there are any abnormalities.
• Stress management: Chronic stress promotes increased blood pressure and blood vessel damage through overactivation of the sympathetic nervous system, so manage it with abdominal breathing, meditation, and sufficient sleep.

Knowing the pre-stroke symptoms (FAST), immediately reporting to 119 when symptoms occur, and receiving treatment within the golden time is the key to survival and preservation of function.