Introduction to Stroke
Stroke, which is also known as cerebrovascular accident, is a sudden loss of neurological function which is caused by interruption of the flow of blood to the brain. The most common type of stroke is an ischemic stroke which affects the 80% of the individuals with the stroke. It occurs when a brain does not get an adequate amount of blood and oxygen. Another type is a hemorrhagic stroke which occurs when blood vessels rupture, causing leakage of blood in or around the brain. It may cause changes in the consciousness level, impairments of sensory, motor, cognitive, perceptual and speech functions. For classifying stroke, neurological symptoms must persist for at least 24 hours. Motor deficits are characterized by paralysis called ‘hemiplegia’ or weakness called ‘hemiparesis’, usually on the side of the body which is opposite to the side of the lesion. The severity of the disease can be identified by the location, extension of brain injury and the amount of collateral blood flow.
Epidemiology and Etiology
Stroke is the fourth leading cause of death and long-term disability among adults. Every year, approximately 795,000 individuals experience a stroke. The disease is reversible in older ages and women over the age of 85 years have greater risk as compared to men. Incidence of stroke increases with the age. Very few per cents who survive an initial stroke will experience another within one year. According to current data, stroke has been declining in recent years in a largely white adult group.
Hemorrhagic stroke patients account for the largest number of deaths with a greater mortality rate as compared to ischemic stroke. Rate of survival decreases with increasing age, hypertension, heart disease, and diabetes mellitus. Loss of consciousness, size of the lesion, severe hemiplegia, multiple neurological deficits, and previous stroke history are important predictors of mortality. Atherosclerosis is a major contributing factor that leads to cerebrovascular disease. It is the hardening of the vessels and disease of elastic, large and medium-sized arteries. Effect of risk factors is multiplicative rather than additive. This led to progressive narrowing of blood vessels and generally includes bifurcations, constrictions, and dilations of arteries. Most common sites are common carotid artery and middle cerebral artery.
Major risk factors of stroke include cardio disease, diabetes mellitus and hypertension. The comorbidities increase significantly with age. While individuals with hypertension have twice the lifetime risk of stroke. The risk may increase with elevated total blood cholesterol ‘hypercholesterolemia’. On other hand, the lipid profile is also important. Elevated low-density lipoprotein (LDL) and marked elevation of hematocrit increase the possibility for stroke. Other probability factors include cardiac diseases such as endocarditis, heart valvular disease that increases the risk of embolic stroke. The most powerful factor for stroke includes atrial fibrillation with a fivefold increased risk. The end-stage of renal disease also increases the chance of stroke. Therefore, control of such conditions is essential to reduce stroke risk. Women with early menopause have twice the risk of ischemic stroke as compared to women with later menopause.
To prevent stroke, public awareness is important and concerning the early warning signs of a stroke. American heart association and National Stroke Association identify the early warning signs that include:
- Numbness and weakness of the facial muscles, arms, legs especially on one side of the body
- Confusion, language problem and understanding
- Eyesight issues
- Severe headache with unknown cause
Patients and families should be encouraged to immediately call emergency number even if the symptoms go away or are not painful. CT scan is used to differentiate between atherothrombotic and hemorrhagic strokes.
It may occur with extensive brain damage. The Glasgow coma scale is a gold standard method to document the conscious level. Three functions are examined such as eye-opening, best motor response and verbal response.
Disorders of Speech and Language
Patients with cortex involvement demonstrate speech and language impairments. This acquired communication disorder is termed as ‘aphasia’. It occurs in 30% of all patients of the stroke. It could be fluent, non-fluent and global. Whereas,40%-50% of patients of stroke are present with ‘dysarthria’. This term refers to a motor speech disorder. Respiration, articulation, phonation, and sensory response may be affected.
An inability to swallow or difficulty in swallowing is termed as ‘dysphagia’ which occurs with 50% patients of stroke. It is also common in patients with multiple strokes. Alteration in mental status, impaired sensation, impairment of jaw and head control, and poor sitting posture also contributes to swallowing difficulties.
It includes impairment in alertness, attention, orientation, and memory functions. Patient with acute stroke is usually unaware of what is going on in their surroundings. The patient would be unable to provide information about self, time, and location. Attention disorders include impairments in sustained attention, divided attention. Memory loss is another impairment commonly found in stroke patients. Short term loss is more common whereas long term memory is usually intact. Executive functions are also impaired. Dementia and delirium are also commonly found in 30% of patients.
Bladder and Bowel Dysfunction
Disturbance of bladder function is common during the acute phase of the stroke. Urinary incontinence may occur due to bladder hyperreflexia or hyporeflexia. This could cope up quickly or within the early period of stroke and early treatment is desirable to prevent further complications such as urinary tract infection and skin breakdown. Bowel dysfunction can include incontinence, diarrhoea, or constipation. Stool softeners, modified diet and other medications are required to resolve this problem.
Cerebrovascular imaging is important to rule out the diagnosis of ischemic stroke and other lesions. Computed tomography (CT) scan is the most used and readily available neuroimaging technique. It identifies the large arteries and veins sinuses. Bleeding and hemorrhagic transformation are visible on CT scan. Magnetic resonance imaging (MRI) has become the first-line imaging in some stroke centres, and it is used when a CT scan has not provided a clear location of the lesion.
Improving the cerebral perfusion assist in stopping the extension of the lesion. Oxygen should be given through a mask or cannula. Maintenance of blood pressure, sufficient cardiac output, blood glucose level and integrity of the skin is necessary. Infections, seizures, oedema, and intracranial pressure should be controlled.
Medication that is commonly used to treat stroke patients includes thrombolytics, anticoagulants, antiplatelets, antihypertensive, angiotensin, anticonvulsants, antidepressants and antispastics. In some cases, surgical intervention is necessary.