Causes And Effects Of Strokes Biology Essay

Causes And Effects Of Strokes Biology EssayStroke is defined as A neurological shortage of cerebrovascular crusade that persists beyond 24 hours or is interrupted by death within 24 hours. WHO (1970)A blow is the rapidly developing breathing out of sensation functions delinquent to a disturbance in the parenthood vessels supplying stock certificate to the brain. This place be due to ischemia caused by thrombosis or embolism or due to a hemorrhage. As a result, the change bea of the brain is unable to function, leading to inability to move one or more limbs on one side of the luggage compartment, inability to understand or formulate speech or inability to see one side of the visual argona (Donnan GA, Fisher M. May 2008).PREVALANCE AND INCIDENCEStroke could soon be the most common cause of death oecumenic (Murray CJ, Lopez AD 1997). Stroke is currently the secant leading cause of death in the Western world, ranking aft(prenominal) kindling disease and before cancer ( Donnan GA, Fisher M, May 2008)and it causes 10% of deaths worldwide (World Health Organization. 2004) .It has been noted that gibe incidence may vary considerably from country to country. The prevalence of stroke in India was estimated as 203 per 100,000 populations above 20 years, amounting to a total of about 1 million cases. Stroke represented 1.2% of total deaths in India (PK Sethi Neurosciences Today 2002).SEX DIFFERENCESMen are 1.25 times more in all likelihood to suffer strokes than women(PK Sethi Neurosciences Today 2002), yet 60% of deaths from stroke occur in women (Villarosa, Linda, Ed.1993).CLASSIFICATIONStrokes can be classified into two major categories ischaemic and hemorrhagic. ischaemia 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 remainders are due to hemorrhage (Donnan GA, Fisher M. May 2008).ISCHEMIC STROKEIn an ischemic stroke, blood su pply to a type of the brain is decreased, leading to dysfunction of the brain thread in that area. The four reasons responsible for ischemic stroke are thrombosis, embolism (Donnan GA, Fisher M. May 2008), general hypoperfusion (Shuaib A, Hachinski VC .September 1991) and venous thrombosis (Stam J. 2005).HAEMORRAGIC STROKEIntracranial hemorrhage is the accumulation of blood anywhere within the skull vault.Intracerebral hemorrhage (ICH) is bleeding directly into the brain tissue, forming a bit by bit enlarging haematoma.RISK FACTORSHigh blood pressure, High blood cholesterol levels, Diabetes, Cigarette smoking (Hankey GJ. August 1999), Heavy alcohol consumption (Reynolds K, Lewis B, Nolen JD, et al .2003) , drug use, (Sloan MA, 1991), pretermit of physical activity, obesity, unhealthy diet (American Heart Association.2007) and Atrial fibrillation.CAUSESWhen the flow of blood in an artery supplying the brain is interrupted for more than a fewer seconds, brain cells can die, caus ing permanent damage. An interruption can be caused by either blood curdles or bleeding in the brain. Most strokes are due to blood clots that blocks the blood flow to brain. Bleeding into the brain occurs if a blood vessel ruptures or if there is a significant injury (Ay H Furie KL. 2005).BLOOD CLOTSA common cause of stroke is atherosclerosis. Fatty deposits and blood platelets collect on the walls of the arteries, forming establishments. Over time, the plaques slowly begin to block the flow of blood. The plaque itself may block the artery enough to cause a stroke (Ay H Furie KL. 2005).The plaque causes the blood to flow abnormally, which leads to a blood clot. A clot can stay at the site of narrowing and prevent blood flow to all of the smaller arteries it supplies. In other cases, the clot can pilgrimage and wedge into a smaller vessel (Ay H Furie KL. 2005).Strokes caused by embolism are most unremarkably caused by heart disorders. An embolism may bulge in a major blood vess el as it branches off the heart. A clot can also form elsewhere in the body for any number of reasons, and then travel to the brain, causing a stroke (Ay H Furie KL. 2005).Arrhythmias of the heart, such as atrial fibrillation, can be associated with this type of stroke and may contribute to clot formation. Other causes of embolic stroke embroil endocarditis, or use of a mechanical heart valve. A clot can form on the artificial valve, break off, and travel to the brain (Ay H Furie KL. 2005).BLEEDING IN THE BRAINA second major cause of stroke is bleeding in the brain. This can occur when small blood vessels in the brain become weak and burst. Some people have shortcomings in the blood vessels of the brain that make this more likely. The flow of blood after the blood vessel ruptures damages brain cells (Ay H Furie KL. 2005).PATHOPHYSIOLOGYISCHAEMICIschemic stroke occurs due to a loss of blood supply to part of the brain, initiating the ischemic cascade. Brain tissue ceases to function if deprived of oxygen for more than 60 to 90 seconds and after a few hours will suffer irreversible injury possibly leading to death of the tissue. Atherosclerosis may disrupt the blood supply by narrowing the lumen of blood vessels leading to a reduction of blood flow, by causing the formation of blood clots within the vessel (National Institute of neurological Disorders and Stroke.1999).Embolic infarction occurs when emboli formed elsewhere in the circulatory system, typically in the heart as a consequence of atrial fibrillation, or in the carotid arteries. These break off, enter the cerebral circulation, then lodge in and occlude brain blood vessels (National Institute of Neurological Disorders and Stroke.1999).HAEMORRAGICHemorrhagic strokes results in tissue injurys by causing compression of tissues from an expanding hematomas. This can distort and injure the tissues. In addition, the pressure may lead to a loss of blood supply to affected tissue with resulting infarction, and the blood released by brain hemorrhage appears to have direct toxic effects on brain tissue and vasculature (National Institute of Neurological Disorders and Stroke.1999).SIGNS AND SYMPTOMSA stroke symptom typically starts suddenly, over seconds to minutes, and in most cases dont progress further. The symptoms depend on the area of the brain affected. The more extensive the area of brain affected, more the functions that are likely to be lost (National Institute of Neurological Disorders and Stroke.1999).A sudden development of one or more of the following indicates a strokeParesis or paralysis of any part of the body, Numbness, tingling, or decreased sensation, Changed or diminished vision, Language difficulties, including slurred speech, inability to speak, inability to understand speech, impediment in reading or writing, Swallowing difficulties or drooling, Loss of memory, Vertigo, Loss of counterbalance or coordination, Personality changes, Mood/emotion changes, Drowsiness, le thargy, or loss of consciousness, Uncontrollable spirit movements or eyelid drooping.SUB TYPESIf the area of the brain affected contains one of the three prominent Central nervous system pathways-the spinothalamic tract, corticospinal tract, and dorsal column, symptoms may include hemiplegia and muscle weakness of the face, numbness, reduction in sensory or vibratory sensation.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. In addition to the above CNS pathways, the brain stem also consists of the 12 cranial nerves. Hence a stroke affecting the brain stem can produce symptoms relating to deficits in the cranial nerves. The symptoms are alter smell, taste, hearing, or vision, drooping of eyelid and weakness of ocular muscles, decreased reflexes like gag, swallow and pupil reactivity to light, decreased sensation and muscle weakness of the face, balance problems and nystagmus,altered breathing and heart rate,weakness in sternocleidomastoid muscle with inability to turn head to one side,weakness in tongue.If the cerebral cortex is involved, the CNS pathways can again be affected, but also can produce the symptoms like aphasia, apraxia, visual field defect, memory deficits, hemineglect, disorganized thinking, confusion, hypersexual gestures ,anosognosia (Bamford JM 2000).When the cerebellum is involved, the patient may have the symptoms like stretch out walking, altered movement, coordination, Vertigo and disequilibrium (Bamford JM 2000).ASSOCIATED SYMPTOMSLoss 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.DIAGNOSISThe techniques which were used to diagnose the stroke are neurological examination, CT scans or MRI scans, Doppler ultrasound, and arteriography. The diagnosing of stroke itself is clinical, with assistance from the resourcefulness 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 (Hill M 2005).PREVENTIONScreening for risque blood pressure at least every two years, regular cholesterol check up, treat high blood pressure, diabetes, high cholesterol and heart disease, follow a low-fat diet, quit smoking, exercise regularly, lose weight if you are over weight, avoid excessive alcohol use (Goldstein LB, Adams R, Alberts MJ et al. 2006).TREATMENTTreatment of ischemic strokePharmacologic thrombolysis with the drug tissue plasminogen activator (tPA), Mechanical thrombectomy and anticoagulants.Treatment of hemorrhagic strokePatients with intracerebral hemorrhage require neurosurgical evaluation to detect and treat the cause of the bleeding, although many may no t need surgery. Patients are monitored and their blood pressure, blood sugar, and oxygenation are kept at optimum levels.PHYSIOTHERAPY TREATMENTThe rehabilitation techniques commonly used were Roods Sensorimotor Approach, Knotts and Voss Proprioceptive Neuromuscular Facilitation, Brunnstroms move Therapy, Bobaths Neuro Developmental Therapy, Motor Relearning Programme, Bimanual Rapid Alternating Movement, Motor Imagery Therapy, Robot Assisted Movement Therapy, Functional Electrical Stimulation, Bilateral Isokinetic Training, Cyclic Electrical Neuromuscular Stimulation, Biofeedback etc.PROGNOSISThe results of stroke vary widely depending on size and location of the lesion (Stanford infirmary Clinics.2005). Dysfunctions correspond to areas in the brain that have been damaged. Disability affects 75% of stroke survivors enough to decrease their employability (Coffey C. Edward.2000). Stroke can affect patients physically, mentally, emotionally, or a compounding of the three. 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 exasperate outcome (Senelick Richard C.1994).