Stroke also called Cerebrovascular accident or CVA: Is a sudden impairment of cerebral circulation in one or more of the blood vessels supplying the brain. A CVA interrupts or diminishes oxygen supply and commonly causes serious damage or necrosis (death of an individual cell or group of cells) in brain tissues. The sooner circulation returns to normal after a CVA, the better the patients chance for recovery. There is different types of CVA and are classified according to their course of progression. (See * below)
* Transient ischemic attack or TIA , also called " little stroke", it is a result from a temporary interruption of blood flow. it is considered the least severe. It is usually a recurrent episode of neurologic deficit, it may last for just seconds or hours and clears within 12 - 24 hours. It is considered to be a warning sign of an impending thrombotic cerebrovascular accident (CVA ). Studies shows that TIA's have been reported in 50% to 80% of patients who have had a cerebral infarction from such thrombosis.. More common after the age of 50 and men are more prone to have TIA's. In TIA, microemboli released from a thrombus probably temporarily interrupt blood flow, especially in the small distal branches of the arterial tree in the brain. Small spasms in those arterioles may impair blood flow and also precede TIA. Predisposing factors are the same as for thrombotic CVAs. Distinctive characteristics of TIA's include the transient duration of neurologic deficits and complete return of normal function.
Symptoms of TIA's:
Double vision Speech deficits ( slurring ) Unilateral blindness Uncoordinated gait (staggering ) - May fall easily due to weakness of legs Unilateral weakness Numbness Dizziness
Treatment to prevent a complete CVA - Aspirin or anticoagulants to minimize the risk of thrombosis. After or between attacks; preventive treatment includes carotid endarterectomy or cerebral microvascular bypass
* Progressive CVA, or stroke - in - evolution ( thrombus - in - evolution ), begins with slight neurologic deficit and worsens in a day or two.
* Complete CVA, the patient experiences maximal neurologic deficits at onset.
Most common cause of CVA is a result from thrombosis. Other causes include embolism and hemorrhage. Risk factors increase the likelihood of CVA, such as atherosclerosis, hypertension, dysrhythmias, rheumatic heart disease, diabetes mellitus, gout, postural hypotension, and cardiac hypertrophy. Other risk factors include high serum triglyceride levels, and sedentary life - style ( inactive habit ), the use of contraceptives, cigarette smoking, and a family history of CVA.
Clinical features of CVA vary with the artery affected ( and , Consequently, the portion of the brain it supplies ), the severity of damage, and the extent of collateral circulation that develops to help the brain compensate for decreased blood supply. If CVA occurs in the left hemisphere, it produces symptoms on the right side; if in the right hemisphere, symptoms are on the left side. However, a CVA that causes cranial nerve damage produces signs of cranial nerve dysfunction on the same side as the hemorrhage. Usually the symptoms are classified according to the artery affected. It can also be classified as premonitory, generalized, and focal.
Middle cerebral artery: This type of CVA may cause aphasia ( loss of the power of expression of speech, writing, or signs or of comprehending spoken or written language) , dysphasia ( impairment of speech), visual field cuts, and hemiparesis on the affected side ( more severe in the face and arm than in the leg ).
Carotid artery: The patient may experience weakness, paralysis, numbness, sensory changes, visual disturbances on the affected side, altered level of consciousness, bruits, headaches, aphasia, and ptosis ( paralytic drooping of the upper eyelid ).
Vertebrobasilar artery: patients may experience weakness on the affected side, numbness around the lips and mouth, visual field cuts, diplopia ( the preception of two images of a single object ), poor coordination, dysphagia, slurred speech, dizziness, amnesia, and failure of muscular coordination (ataxia).
Anterior cerebral artery: This type of stroke can cause confusion, weakness and numbness on the affected side ( especially in the leg ), incontinence, loss of coordination, impaired motor and sensory functions, and may have personality changes.
Posterior cerebral arteries: Paralysis usually doesn't occur. Patient may experience visual field cuts, sensory impairment, dyslexia, coma, and cortical blindness.
Diagnostic tests: CT scan shows evidence of thrombotic or hemorrhagic stroke, tumor, or hydrocephalus. Brain scan show ischemic areas but may not be positive for up to 2 weeks after the CVA. Other tests includes; lumbar puncture, ophthalmoscopy, angiography, EEG, and lab studies.
Medication useful in CVA include: anticonvulsants to treat seizures, stool softeners, to avoid straining, which increases ICP ( intracranial - pressure ), corticosteroids, to minimize associated cerebral edema, analgesics to relieve headache that may follow hemorrhagic CVA. Usually aspirin is contraindicated in hemorrhagic CVA because it increases bleeding tendencies, but it may be useful in preventing TIAs.
Surgery to improve cerebral circulation for patients with thrombotic or embolic CVA includes; endarterectomy ( removal of atherosclerotic plaques from inner arterial wall), or microvascular bypass ( extracranial vessel is surgically anastomosed to an intracranial vessel ).
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