Stroke - Symptoms And Stroke Treatment
A stroke, also known as a cerebrovascular accident or a brain attack, is a sudden impairment or disruption of cerebral circulation in one or more blood vessels. A stroke interrupts or diminishes blood supply and, therefore, the oxygen supply to or within the brain and commonly causes serious damage or necrosis in brain tissues. Chances for a complete recovery depend on how soon circulation returns to nonnal after a stroke. However, about one-half of the patients who survive a stroke remain permanently disabled and experience a recurrence within weeks, months, or years after the initial stroke. It's the leading serious neurologic disorder in the United States and the major cause of long-term disabilities in Americans.
Stroke is the third most common cause of death in the United States. It strikes over 500,000 persons per year and is fatal in approximately one-half of these persons. Although strokes may occur in younger persons, most patients experiencing strokes are over age 65. in fact, the risk of stroke doubles with each passing decade after age 55. Strokes are more common in men; however, more women die from strokes.
What causes Stroke?
Stroke typically results from one of three causes:
- thrombosis of the cerebral arteries supplying the brain or the intracranial vessels occluding blood flow (see types of stroke)
- embolism from thrombus outside the brain, such as in the heart, aorta, or common carotid artery
- hemorrhage from an intracranial artery or vein, such as from hypertension, ruptured aneurysm, arteriovenous malfonnations, trauma, hemorrhagic disorder, or septic embolism.
Risk factors that have been identified as predisposing a patient to stroke include:
- heredity (family history of stroke)
- prior history of stroke
- advancing age(60%t075% of all strokes occur in persons over age 65)
- history of transient ischemic attacks (TIAs)
- cardiac disease, including arrhythmias, coronary artery disease, acute myocardial infarction, dilated cardiomyopathy, and valvular disease
- diabetes mellitus
- race (blacks more than whites)
- familial hyperlipidemia
- cigarette smoking
- increased alcohol intake
- obesity, sedentary lifestyle
- use of hormonal contraceptives, especially in women over age 35 and in women who smoke cigarettes
- premenopausal women with migraines.
Regardless of the cause of stroke, the underlying event is deprivation of oxygen and nutrients to the brain. Normally, if the arteries become blocked, auto regulatory mechanisms help maintain cerebral circulation until collateral circulation develops to deliver blood to the affected area. If the compensatory mechanisms become overworked or cerebral blood flow remains impaired for more than a few minutes, oxygen deprivation leads to infarction of brain tissue. The brain cells cease to function because they can neither store glucose or glycogen for use nor engage in anaerobic metabolism.
A thrombotic or embolic stroke causes ischemia. Some of the neurons served by the occluded vessel die from lack of oxygen and nutrients. This results in cerebral infarction, in which tissue injury triggers an inflammatory response that in turn increases intra cranial pressure (ICP). Injury to the surrounding cells disrupts metabolism and leads to changes in ionic transport, localized addosis, and free radical formation. Calcium, sodium, and water accumulate in the injured cells, and excitatory neurotransmitters are released. Consequently, continued cellular injury and swelling set up a vicious cycle of further damage.
When hemorrhage is the cause, impaired cerebral perfusion causes infarction, and the blood itself acts as a space-occupying mass, exerting pressure on the brain tissues. The brain's regulatory mechanisms attempt to maintain equilibrium by increasing blood pressure to maintain cerebral perfusion pressure. The increased ICP forces cerebrospinal fluid (CSF) out, thus restoring balance. If the hemorrhage is small, this correction may be enough to keep the patient alive with only minimal neurologic deficits. However, if bleeding is heavy, ICP increases rapidly and perfusion stops. Even if the pressure returns to normal, many brain cells die. .
Initially, the ruptured cerebral blood vessels may constrict to limit blood loss. This vasospasm further compromises blood flow, leading to more ischemia and cellular damage. If a clot forms in the vessel, decreased blood flow also promotes ischemia. If the blood enters the subaraclmoid space, meningeal irritation occurs. The blood cells that pass through the vessel wall into the surrounding tissue may also break down and block the arachnoid villi, causing hydrocephalus.
Signs and symptoms of Stroke
The clinical features of stroke vary according to the affected artery and the region of the brain it supplies, the severity of the damage, and the extent of collateral circulation developed. A stroke in one hemisphere causes signs and symptoms on the opposite side of the body; a stroke that damages cranial nerves affects Structures on the same side as the infarction. In addition, symptoms of stroke in women may differ from those in men.
General symptoms of a stroke include:
- unilateral limb weakness
- speech difficulties
- numbness on one side
- vision disturbances (diplopia, hemianopsia, ptosis)
- altered level of consdousness (LOC).
Additionally, the artery affected usually classifies symptoms. Signs and symptoms associated with middle cerebral artery involvement include:
- visual field deficits
- hemiparesis of affected side (more severe in the face and arm than in the leg).
Symptoms associated with carotid artery involvement include:
- sensory changes
- vision disturbances on the affected side
- altered LOC
Symptoms associated with vertebrobasilar artery involvement include:
- weakness on the affected side
- numbness around lips and mouth
- visual field deficits
- poor coordination
- slurred speech
Signs and symptoms associated with anterior cerebral artery involvement include:
- numbness, especially in the legs on the affected side
- loss of coordination
- impaired motor and sensory functions
- personality changes.
Signs and symptoms associated with posterior cerebral artery involvement include:
- visual field deficits (homonymous hemianopsia)
- sensory impairment
- perseveration (abnormally persistent replies to questions)
- cortical blindness
- absence of paralysis (usually).
Complications vary with the severity and type of stroke but may include unstable blood pressure (from loss of vasomotor control), cerebral edema, fluid imbalances, sensory impairment, infections such as pneumonia, altered LOC, aspiration, contractures, pulmonary embolism and death.
- Stroke is the sudden death of brain cells due to lack of oxygen.
- Stroke is caused by the blockage of blood flow or rupture of an artery to the brain.
Computed tomography scan identifies an ischemic stroke within the first 72 hours of symptom onset and evidence of a hemorrhagic stroke (lesions larger than 1 cm) immediately.
- Magnetic resonance imaging assists in identifying areas of ischemia or infarction and cerebral swelling.
- Cerebral angiography reveals disruption or displacement of the cerebral circulation by occlusion, as in stenosis and acute thrombus. or hemorrhage.
- Digital subtraction angiography shows evidence of occlusion of cerebral vessels, lesions or vascular abnormalities.
- Carotid duplex scan identifies the degree of stenosis.
- Brain scan shows is chemic areas but may not be conclusive for up to 2 weeks after a stroke.
- Single photon emission computed tomography and positron emission tomography scans identify areas of altered metabolism surrounding lesions not yet distinguishable with other diagnostic tests.
- Transesophageal echo cardiogram reveals cardiac disorders, such as atrial thrombi, atrial septal defect. or patent
foramen ovale, as causes of thrombotic stroke.
- Lumbar puncture (performed if there are no signs of increased ICP) reveals bloody CSF when stroke is hemorrhagic.
- Ophthalmoscopy may identify signs of hypertension and atherosclerotic changes in retinal arteries.
- EEG helps identify damaged areas of the brain.
Treatment of Stroke
Treatment is supportive to minimize and prevent further cerebral damage. Measures include:
- ICP management with monitoring, hyperventilation to decrease partial pressure of arterial carbon dioxide (Paco2) to lower ICP, osmotic diuretics (mannitol) to reduce cerebral edema. and corticosteroids (dexamethasone) to reduce inflammation and cerebral edema.
- stool softeners to prevent straining. which increases ICP
- anticonvulsants to treat or prevent seizures
- surgery for large cerebellar infarction to remove infracted tissue and decompress remaining live tissue
- aneurysm repair to prevent further hemorrhage
- percutaneous transluminal angioplasty or stent insertion to open occluded vessels.
For ischemic stroke:
- thrombolytic therapy (tPA. alterplase [Activase]) within the first 3 hours after the onset of symptoms to dissolve the clot. remove occlusion. and restore blood flow. thus minimizing cerebral damage.
- anticoagulant therapy (heparin, warfarin) to maintain vessel patency and prevent further clot formation in cases of high-grade carotid stenosis or newly diagnosed cardiovascular disease.
- antiplatelet agents (aspirin, ticlopidine, clopidogrel, Aggrenox) to reduce the risk of platelet aggregation and subsequent clot formation
- carotid endarterectomy to open partially occluded (greater than 70%) carotid arteries.
For hemorrhagic stroke:
- analgesics such as acetaminophen to relieve headache associated with hemorrhagic stroke.
Special considerations and Prevention
During the acute phase. efforts focus on survival needs and the prevention of further complications. Effective care emphasizes continuing neurologic assessment, respiratory support, continuous monitoring of vital signs, careful positioning to prevent aspiration and contractures, management of GI problems and careful monitoring of fluid. electrolyte and nutritional status. Patient care must also include measures to prevent complications, such as infection:
- Maintain patent airway and oxygenation. Loosen constrictive clothing. Watch for ballooning of the cheek with respiration. The side that balloons is the side affected by the stroke. If the patient is unconscious, she could aspirate saliva, so keep her in a lateral position to allow secretions to drain naturally or suction secretions,as needed. Insert an artificial airway, and start mechanical ventilation or supplemental oxygen, if necessary.
- Check vital signs and neurologic status, record observations, and report any significant changes to the physician. Monitor blood pressure, LOC, pupillary changes, motor function (voluntary and involuntary movements), sensory function, speech, skin color, temperature, signs of increased ICP and nuchal rigidity or flaccidity. Remember, if a stroke is impending, blood pressure rises suddenly, the pulse is rapid and bounding, and the patient may complain of a headache. Also, watch for signs of pulmonary , emboli, such as chest pains, shortness of breath, dusky color, tachycardia, fever, and changed sensorium. If the patient is unresponsive, monitor her blood gases often and alert the physician to increased Paco2 or decreased partial pressure of arterial oxygen.
- Maintain fluid and electrolyte balance. If the patient can take liquids orally, offer them as often as fluid limitations permit. Administer I. V. fluids, as ordered; never give too much too fast because this can increase ICP. Offer the urinal or bedpan every 2 hours. If the patient is incontinent, she may need an indwelling urinary catheter; however, this should be avoided. if possible, because of the risk of infection.
- Ensure adequate nutrition. Check for gag reflex before offering small oral feedings of semisolid foods. Place the food tray within the patient's visual field because loss of peripheral vision is common. If oral feedings aren't possible, insert a nasogastric tube.
- Manage GI problems. Be alert for signs that the patient is straining at elimination because this increases ICP. Modify diet, administer stool softeners as ordered, and give laxatives, if necessary. If the patient vomits (usually during the first few days), keep her positioned on her side to prevent aspiration.
- Provide careful mouth care. Clean and irrigate the patient's mouth to remove food particles. Care for her dentures, if needed.
- Provide meticulous eye care. Remove secretions with a cotton ball and sterile normal saline solution. Instill eye drops, as ordered. Patch the patient's affected eye if she can't close
- Position the patient and align her extremities correctly. Use high-topped sneakers to prevent foot drop and contracture and convoluted foam. flotation, or pulsating mattress or sheepskin to prevent pressure ulcers. To prevent pneumonia, turn the patient at least every 2 hours. Elevate the affected hand to control dependent edema, and place it in a functional position.
- Assist the patient with exercise. Perform range-of-motion exercises for both the affected and unaffected sides. Teach and encourage the patient to use her unaffected side to exercise her affected side.
- Give medications, as ordered, and monitor for and report adverse effects.
- Establish and maintain communication with the patient. If she's aphasic, set up a simple method of communicating basic needs, such as asking simple "yes" or "no" questions. Remember to phrase your questions so she'll be able to answer using this system. If you have to repeat yourself, do so quietly and calmly. (Remember, she doesn't have hearing difficulty.) Also use gestures if necessary to help her understand. Even the unresponsive patient can hear, so don't say anything in her presence that you wouldn't want her to hear and remember.
- Physical activities like brisk walking, cycling, swimming, and yard work lower the risk of both stroke and heart disease.
- Provide psychological support. Set realistic short-term goals. Involve the patient's family in her care whenever possible, and explain her deficits and strengths.
- Begin your rehabilitation of the patient with a stroke on admission. The amount of teaching you'll have to do depends on the extent of neurologic deficit.
- Establish rapport with the patient. Spend time with her, and provide a means of communication. Simplify your language, asking "yes-or-no" questions whenever possible. Don't correct her speech or treat her like a child. Remember that building rap- , port may be difficult because of the mood changes that may result from brain damage or as a reaction to being
- If necessary, re-teach the patient to comb her hair, dress, and wash. With the aid of a physical therapist and an occupational therapist, obtain appliances, such as walking frames, hand bars by the toilet, and ramps, as needed. The patient may fail to recognize that she has a paralyzed side (called unilateral neglect) and must be taught to inspect that side of her body for injury and to protect it from harm. If speech therapy is indicated. encourage the patient to begin as soon as possible and follow through with the speech pathologist's suggestions. To reinforce teaching, involve the patient's family in all aspects of rehabilitation. With their cooperation and support, devise a realistic discharge plan. and let them help decide when the patient can return home.
- Before discharge, warn the patient or her family to report any premonitory signs of a stroke. such as severe headache, drowsiness, confusion. and dizziness. Emphasize the importance of regular follow-up visits.
- Stop smoking.
- If aspirin has been prescribed to minimize the risk of embolic stroke, tell the patient to watch for signs of possible GI bleeding. Make sure the patient and her family realize that acetaminophen isn't a substitute for aspirin.
- Emphasize to the patient that, if symptoms develop, she should go to the emergency department immediately.