Brain Attack (Stroke) or cerebrovascular accident (CVA) is the clinical designation for a rapidly developing loss of brain function due to a disturbance in the blood vessels supplying blood to the brain. This phenomenon can be due to ischemia (lack of blood supply) caused by thrombosis or embolism, or due to a hemorrhage.

Stroke is a medical emergency and can cause permanent neurological damage, complications and death if not promptly diagnosed and treated. It is the third leading cause of death and the leading cause of adult disability in the United States and Europe. It is predicted that stroke will soon become the leading cause of death worldwide. Risk factors for stroke include advanced age, hypertension (high blood pressure), previous stroke or transient ischaemic attack (TIA, see below), diabetes, high cholesterol, cigarette smoking, atrial fibrillation, migraine with aura, and thrombophilia (a tendency to thrombosis). In clinical practice, blood pressure is the most important modifiable risk factor of stroke.

Stroke symptoms typically develop rapidly (seconds to minutes). The symptoms of a stroke are related to the anatomical location of the damage; nature and severity of the symptoms can therefore vary widely. On the basis of the history and neurological examination, as well as the presence of risk factors, a doctor can rapidly diagnose the anatomical nature of the stroke (i.e. which part of the brain is affected), even if the exact cause is not yet known.

The traditional definition of stroke, devised by the World Health Organisation in the 1970s, is of a "neurological deficit of cerebrovascular cause that persists beyond 24 hours or is interrupted by death within 24 hours". This definition was supposed to reflect the reversibility of tissue damage and was devised for the purpose, with the time frame of 24 hours being chosen arbitrarily. It divides stroke from TIA, which is a related syndrome of stroke symptoms that resolve completely within 24 hours. With the availability of treatments that, when given early, can reduce stroke severity, many now prefer alternative concepts, such as brain attack and acute ischemic cerebrovascular syndrome (modeled after heart attack and acute coronary syndrome respectively), that reflect the urgency of stroke symptoms and the need to act swiftly

Treatment of stroke is occasionally with thrombolysis ("clot buster"), but usually with supportive care (physiotherapy and occupational therapy) and secondary prevention with antiplatelet drugs (aspirin and often dipyridamole), blood pressure control, statins and anticoagulation (in selected patients).

Epidemiology

Stroke will soon be the most common cause of death worldwide. Stroke is the third leading cause of death in the  world, after heart disease and cancer, and causes 10% of world-wide deaths .

The incidence of stroke increases exponentially from 30 years of age, and etiology varies by age.

Classification

Strokes can be classified into two major categories: ischemic and hemorrhagic. Ischemia is due to interruption of the blood supply, while hemorrhage is due to rupture of a blood vessel or an abnormal vascular structure. 80% of strokes are due to ischemia; the remainder  are due to hemorrhage.

Ischemic stroke

In an ischemic stroke, blood supply to part of the brain is decreased, leading to dysfunction and necrosis of the brain tissue in that area. There are four reasons why this might happen: thrombosis (obstruction of a blood vessel by a blood clot forming locally), embolism (idem due to a blood clot from elsewhere in the body), systemic hypoperfusion (general decrease in blood supply, e.g. in shock) and venous thrombosis. Stroke without an obvious explanation is termed "cryptogenic" (of unknown origin).

Thrombotic stroke

In thrombotic stroke, a thrombus (blood clot) usually forms around atherosclerotic plaques. Since blockage of the artery is gradual, onset of symptomatic thrombotic strokes is slower. A thrombus itself (even if non-occluding) can lead to an embolic stroke (see below) if the thrombus breaks off, at which point it is called an "embolus". Thrombotic stroke can be divided into two types depending on the type of vessel the thrombus is formed on:

Large vessel disease involves the common and internal carotids, vertebral, and the Circle of Willis.

 

Small vessel disease involves the smaller arteries inside the brain: branches of the circle of Willis, middle cerebral artery, stem, and arteries arising from the distal vertebral and basilar artery. 

Embolic stroke

Embolic stroke refers to the blockage of an artery by an embolus, a traveling particle or debris in the arterial bloodstream originating from elsewhere. An embolus is most frequently a blood clot, but it can also be a number of other substances including fat (e.g. from bone marrow in a broken bone), air, cancer cells or clumps of bacteria (usually from infectious endocarditis).

Emboli most commonly arise from the heart (especially in atrial fibrillation) but may originate from elsewhere in the arterial tree. In paradoxical embolism, a deep vein thrombosis embolises through an atrial or ventricular septal defect in the heart into the brain.

Systemic hypoperfusion

Systemic hypoperfusion is the reduction of blood flow to all parts of the body. It is most commonly due to cardiac pump failure from cardiac arrest or arrhythmias, or from reduced cardiac output as a result of myocardial infarction, pulmonary embolism, pericardial effusion, or bleeding. Hypoxemia (low blood oxygen content) may precipitate the hypoperfusion.

Venous thrombosis

Cerebral venous sinus thrombosis leads to stroke due to locally increased venous pressure, which exceeds the pressure generated by the arteries. Infarcts are more likely to undergo hemorrhagic transformation (leaking of blood into the damaged area) than other types of ischemic stroke.

Hemorrhagic stroke

Intracranial hemorrhage is the accumulation of blood anywhere within the skull vault. A distinction is made between intra-axial hemorrhage (blood inside the brain) and extra-axial hemorrhage (blood inside the skull but outside the brain). Intra-axial hemorrhage is due to intraparenchymal hemorrhage or intraventricular hemorrhage (blood in the ventricular system). The main types of extra-axial hemorrhage are epidural hematoma (bleeding between the dura mater and the skull), subdural hematoma (in the subdural space) and subarachnoid hemorrhage (between the arachnoid mater and pia mater). Most of the hemorrhagic stroke syndromes have specific symptoms (e.g. headache, previous head injury).

Intracerebral hemorrhage (ICH) is bleeding directly into the brain tissue, forming a gradually enlarging hematoma (pooling of blood). It generally occurs in small arteries or arterioles and is commonly due to hypertension, trauma, bleeding disorders, amyloid angiopathy, illicit drug use (e.g. amphetamines or cocaine), and vascular malformations. The hematoma enlarges until pressure from surrounding tissue limits its growth.

Signs and symptoms

The symptoms of stroke depend on the type of stroke and the area of the brain affected.

Ischemic strokes usually only affect regional areas of the brain perfused by the blocked artery.

Hemorrhagic strokes can affect local areas, but often can also cause more global symptoms due to bleeding and increased intracranial pressure.

Although the number of people affected by stroke is large, the public's awareness of stroke symptoms and the need for immediate treatment evaluation is poor . The five most common warning signs of stroke are (a) sudden numbness or weakness of the face, arm, or leg (especially on one side of the body); (b) sudden confusion, trouble speaking, or understanding speech; (c) sudden difficulty seeing in one or both eyes; (d) sudden difficulty walking, dizziness, or loss of balance or coordination; and (e) sudden severe headache with no known cause. In most cases, the symptoms affect only one side of the body. The defect in the brain is usually on the opposite side of the body (depending on which part of the brain is affected). Loss of consciousness, headache, and vomiting usually occurs more often in hemorrhagic stroke than in thrombosis because of the increased intracranial pressure from the leaking blood compressing on the brain. If symptoms are maximal at onset, the cause is more likely to be a subarachnoid hemorrhage or an embolic stroke.

Lack of public awareness about the emergent nature of stroke warning signs can delay stroke patients seeking medical attention. The availability of thrombolytic therapy has brought with it a need to shorten the length of time it takes a person to reach the hospital after experiencing one or more warning signs of a stroke. The time window for intravenous administration of tissue plasminogen activator (tPA) is 3 hours from the time of onset of the first warning signs until drug infusion . This period includes time for recognition of warning signs, getting to the hospital, preliminary diagnosis of stroke by the emergency department physician, completion of a head computed tomography (CT) scan, reading of the CT scan by a neurologist or radiologist, and administration of tPA if appropriate.

Diagnosis

Stroke is diagnosed through several techniques: a neurological examination, CT scans (most often without contrast enhancements) or MRI scans, Doppler ultrasound, and arteriography. The diagnosis of stroke itself is clinical, with assistance from the imaging techniques. Imaging techniques also assist in determining the subtypes and cause of stroke. There is yet no commonly used blood test for the stroke diagnosis itself, though blood tests may be of help in finding out the likely cause of stroke.

Physical examination

A systematic review found that acute facial paresis, arm drift, or abnormal speech are the best findings.

Imaging

For diagnosing ischemic / hemorrhagic  stroke  in the emergency setting

 Underlying etiology

  When a stroke has been diagnosed, various other studies may be performed to determine the  underlying etiology. Test selection may vary, since the cause of stroke varies with age, comorbidity and the clinical presentation. Commonly used techniques include:

Ultrasound / doppler study of the carotid arteries (to detect carotid stenosis) or dissection of the precerebral artieries

Electrocardiogram (ECG) and Echocardiogram (to identify arrhythmias and resultant clots in the heart which may spread to the brain vessels through the bloodstream)

Holter monitor study to identify intermittent arrhythmias

Angiogram of the cerebral vasculature (if a bleed is thought to have originated from an aneurysm or arteriovenous malformation)

Blood tests to determine hypercholesterolemia, bleeding diathesis and some rarer causes such as homocysteinuria

Treatment :

 Early assessment

Early recognition of the signs of stroke is generally regarded as important. Only detailed physical examination and medical imaging provide information on the presence, type, and extent of stroke, and hence hospital attendance — even if the symptoms were brief — is advised.

 Ischemic stroke

An ischemic stroke is due to a thrombus (blood clot) occluding a cerebral artery, a patient is given antiplatelet medication (aspirin, clopidogrel, dipyridamole), or anticoagulant medication (warfarin), dependent on the cause, when this type of stroke has been found. Hemorrhagic stroke must be ruled out with medical imaging, since this therapy would be harmful to patients with that type of stroke.

Whether thrombolysis is performed or not, the following investigations are required:

Stroke symptoms are documented, often using scoring systems such as the National Institutes of Health Stroke Scale, the Cincinnati Stroke Scale, and the Los Angeles Prehospital Stroke Screen.

A   CT scan is performed to rule out hemorrhagic stroke

Blood tests, such as a full blood count, coagulation studies (PT/INR and APTT), and tests of electrolytes, renal function, liver function tests and glucose levels are carried out.

Other immediate strategies to protect the brain during stroke include ensuring that blood sugar is as normal as possible (such as commencement of an insulin sliding scale in known diabetics), and that the stroke patient is receiving adequate oxygen and intravenous fluids. The patient may be positioned so that his or her head is flat on the stretcher, rather than sitting up, since studies have shown that this increases blood flow to the brain. Additional therapies for ischemic stroke include aspirin (50 to 325 mg daily), clopidogrel (75 mg daily), and combined aspirin and dipyridamole extended release (25/200 mg twice daily).

It is common for the blood pressure to be elevated immediately following a stroke. Studies indicated that while high blood pressure causes stroke, it is actually beneficial in the emergency period to allow better blood flow to the brain.

If studies show carotid stenosis, and the patient has residual function in the affected side, carotid endarterectomy (surgical removal of the stenosis) may decrease the risk of recurrence if performed rapidly after stroke.

If the stroke has been the result of cardiac arrhythmia with cardiogenic emboli, treatment of the arrhythmia and anticoagulation with warfarin or high-dose aspirin may decrease the risk of recurrence.

Thrombolysis

In increasing numbers of primary stroke centers, pharmacologic thrombolysis ("clot busting") with the drug tissue plasminogen activator ( tPA) , is used to dissolve the clot and unblock the artery. The time window for intravenous administration of tissue plasminogen activator (tPA) is 3 hours from the time of onset of the first warning signs until drug infusion This period includes time for recognition of warning signs, getting to the hospital, preliminary diagnosis of stroke by the emergency department physician, completion of a head computed tomography (CT) scan, reading of the CT scan by a neurologist or radiologist, and administration of tPA if appropriate.

Thrombectomy

Another intervention for acute ischemic stroke is removal of the offending thrombus directly. This is accomplished by inserting a catheter into the femoral artery, directing it up into the cerebral circulation, and deploying a corkscrew-like device to ensnare the clot, which is then withdrawn from the body.

Embolic stroke

Anticoagulation can prevent recurrent stroke. Among patients with nonvalvular atrial fibrillation, anticoagulation can reduce stroke by 60% while antiplatelet agents can reduce stroke by 20%. However, a recent meta-analysis suggests harm from anti-coagulation started early after an embolic stroke.

Hemorrhagic stroke

Patients with bleeding into (intracerebral hemorrhage) or around the brain (subarachnoid hemorrhage), require neurosurgical evaluation to detect and treat the cause of the bleeding. Anticoagulants and antithrombotics, key in treating ischemic stroke, can make bleeding worse and cannot be used in intracerebral hemorrhage. Patients are monitored and their blood pressure, blood sugar, and oxygenation are kept at optimum levels.

Care and rehabilitation

Stroke rehabilitation is the process by which patients with disabling strokes undergo treatment to help them return to normal life as much as possible by regaining and relearning the skills of everyday living. It also aims to help the survivor understand and adapt to difficulties, prevent secondary complications and educate family members to play a supporting role.

A rehabilitation team is usually multidisciplinary as it involves staff with different skills working together to help the patient.

Good nursing care is fundamental in maintaining skin care, feeding, hydration, positioning, and monitoring vital signs such as temperature, pulse, and blood pressure. Stroke rehabilitation begins almost immediately.

For most stroke patients, physical therapy (PT) and occupational therapy (OT) are the cornerstones of the rehabilitation process. PT involves re-learning functions as transferring, walking and other gross motor functions. OT focusses on exercises and training to help relearn everyday activities known as the Activities of daily living (ADLs) such as eating, drinking, dressing, bathing, cooking, reading and writing, and toileting. Speech and language therapy is appropriate for patients with problems understanding speech or written words, problems forming speech and problems with eating (swallowing).

Patients may have particular problems, such as complete or partial inability to swallow, which can cause swallowed material to pass into the lungs and cause aspiration pneumonia. The condition may improve with time, but in the interim, a nasogastric tube may be inserted, enabling liquid food to be given directly into the stomach. If swallowing is still unsafe after a week, then a percutaneous endoscopic gastrostomy (PEG) tube is passed and this can remain indefinitely.

Stroke rehabilitation should be started as immediately as possible and can last anywhere from a few days to several months. Most return of function is seen in the first few days .  Daily rehabilitation exercises should continue to be part of the stroke patient's routine. Complete recovery is unusual but not impossible and most patients will improve to some extent : a correct diet and exercise are known to help the brain to self-recover.

Prognosis

Disability affects 75% of stroke survivors enough to decrease their employability. Stroke can affect patients physically, mentally, emotionally, or a combination of the three. The results of stroke vary widely depending on size and location of the lesion. Dysfunctions correspond to areas in the brain that have been damaged.

Some of the physical disabilities that can result from stroke include paralysis, numbness, pressure sores, pneumonia, incontinence, apraxia (inability to perform learned movements), difficulties carrying out daily activities, appetite loss, vision loss, and pain. If the stroke is severe enough, or in a certain location such as parts of the brainstem, coma or death can result.

Emotional problems resulting from stroke can result from direct damage to emotional centers in the brain or from frustration and difficulty adapting to new limitations. Post-stroke emotional difficulties include anxiety, panic attacks, flat affect (failure to express emotions), mania, apathy, and psychosis.

30 to 50% of stroke survivors suffer post stroke depression, which is characterized by lethargy, irritability, sleep disturbances, lowered self esteem, and withdrawal. Depression can reduce motivation and worsen outcome, but can be treated with antidepressants.

Up to 10% of all stroke patients develop seizures, most commonly in the week subsequent to the event; the severity of the stroke increases the likelihood of a seizure.

Prevention

Prevention of stroke can work at various levels including:

Primary prevention - the reduction of risk factors across the board, by public health measures such as reducing smoking and the other behaviours that increase risk;

Secondary prevention - actions taken to reduce the risk in those who already have disease or risk factors that may have been identified through screening; and

Tertiary prevention - actions taken to reduce the risk of complications (including further strokes) in people who have already had a stroke.

Prevention is an important public health concern  . Identification of patients with treatable risk factors for stroke is paramount .The most important modifiable risk factors for stroke are hypertension, heart disease, diabetes, and cigarette smoking. Other risks include heavy alcohol consumption, high blood cholesterol levels, illicit drug use, and genetic or congenital conditions. Family members may have a genetic tendency for stroke or share a lifestyle that contributes to stroke. Higher levels of Von Willebrand factor are more common amongst people who have had ischemic stroke for the first time.

One of the most significant stroke risk factors is advanced age. A person's risk of dying if he or she does have a stroke also increases with age.

Sickle cell anemia, which can cause blood cells to clump up and block blood vessels, also increases stroke risk. Stroke is the second leading killer of people under 20 who suffer from sickle-cell anemia.

Men are 1.25 times more likely to suffer strokes than women, yet 60% of deaths from stroke occur in women. Since women live longer, they are older on average when they have their strokes and thus more often killed. Some risk factors for stroke apply only to women. Primary among these are pregnancy, childbirth, menopause and the treatment thereof (HRT).