Management of Ischemic Stroke in Geriatric Patients: PATIENT RISK ASSESSMENT
Age, sex, race, and family history are nonmodifiable risk factors for cerebrovascular events. Therefore, older patients (i.e., 65 years and above) are at higher risk for stroke-associated mortality and morbidity. Other factors associated with increased risk of stroke include hypertension, blood pressure differences in each arm, heart disease, carotid bruits, diabetes, dyslipidemia, elevated fibrinogen levels, migraine headaches, sickle cell disease, retinal em-boli, and TIAs. The 10-year stroke risk relative to the average risk for a given age and sex can be assessed by means of Framingham data. This estimation of risk is limited to assessment based on sex, age, systolic blood pressure, antihypertensive treatment, cardiovascular disease, atrial fibrillation, and left ventricular hypertrophy. Furthermore, it is unclear how accurately these predictors estimate the risk of cerebrovascular events in patients of advanced age.
CLINICAL PRESENTATION AND DIAGNOSIS
Individuals may experience signs of cerebral ischemia as brief, intermittent events known as TIAs. There is a 4% to 8% risk of an ischemic stroke in each year following the initial TIA. Stroke symptoms (Table 1), including aphasia, ataxia, blindness, confusion, and paralysis, vary according to the location of diminished cerebral blood flow. Confirmative diagnosis requires imaging technology such as computed tomography (CT scan) to exclude hemorrhagic strokes. The evaluation of stroke in geriatric patients is challenging. For example, symptoms such as confusion may be difficult to evaluate in individuals with dementia or in patients who cannot communicate with health care providers. In addition, symptoms such as muscle weakness and gait changes may be attributed to advanced age instead of cerebrovascular ischemia.
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Table 1 Stroke Symptoms
Sudden onset of any of the following:
• Difficulty understanding what others are saying
• Vision changes in one or both eyes
• Difficulty walking, dizziness, loss of balance or coordination
• Numbness, tingling, or weakness of the face, arm, or leg, particularly unilateral involvement
The primary goal in patients during an acute stroke is immediate reperfusion of ischemic areas. Once patients are stabilized, long-range goals become the prevention of reocclusion and risk reduction of future cerebrovascular episodes. Individuals with multiple risk factors should be advised to consider lifestyle modifications and optimization of treatment for diabetes, hypertension, and dyslipidemia to reduce the risk of strokes.
For patients who experience symptoms consistent with a cerebrovascular event, time is of the essence. Thrombolytics have emerged as an option for acute treatment when they are administered within three to six hours of symptom onset. Their value beyond six hours is unknown. The goal is timely restoration of cerebral perfusion to limit irreversible brain injury.
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The agent most widely studied (Table 2) for acute treatment is recombinant tissue plasminogen activator (tPA); however, its routine use remains controversial. Optimal administration demands the implementation of institutional protocols and criteria for patient selection to foster appropriate use. Streptokinase has been studied in three trials but is not currently recommended for treatment because of an association with increased mortality and disability.
Table 2 Use of Thrombolytic Agents in Acute Ischemic Stroke
|Study||Significant Bleeding||Mortality Rates|
The National Institute of Neurological Disorders and Stroke (NINDS) tPA Stroke Study was the first trial to demonstrate that patients given 0.9 mg/kg tPA within three hours of stroke onset had a 30% higher probability of recovery with few or no deficits at three months. Benefits observed were independent of age, stroke subtype, stroke severity, or previous aspirin use. Results indicated that for every 25 patients treated with tPA, one life would be saved at three months after a stroke. However, patients with severe initial neurological deficits or signs of brain edema were at higher risk for intracranial hemorrhage (ICH). Overall, 6.4% of patients in the tPA group developed ICH in contrast to 0.6% in the placebo group. Therefore, for every 17 patients treated with tPA, one patient would go on to experience a significant hemorrhage.
The European Cooperative Acute Stroke Study (ECASS) evaluated tPA at a higher dose (1.1 mg/kg) in patients whose stroke onset was within six hours. No statistical difference in efficacy was found between treatment and control groups; however, more patients in the tPA group developed parenchymal hemorrhages. In the ECASS II trial, patients with mild strokes presenting within six hours of symptoms received tPA 0.9 mg/kg. No statistical differences occurred in death rates or clinical improvement. The results illustrated that 500 patients would need to be treated with tPA to prevent one stroke-related death. Of these 500 patients, approximately 26 would develop significant hemorrhages.
Most recently, the Alteplase Thrombolytic for Acute Noninterventional Therapy in Ischemic Stroke (ATLANTIS-B) study evaluated tPA 0.9 mg/kg in patients with stroke onset within three to five hours. However, the study was stopped early because patients who received tPA experienced increased hemorrhage and mortality rates compared with placebo-treated patients.
Meta-analyses indicated that tPA significantly reduced mortality rates from 71.6% to 57.7% in patients treated within three hours of symptom onset. This translated to one additional life saved for every seven patients treated with tPA. When the treatment window was extended to six hours, the number needed to treat to prevent one death increased to 25 individuals. Alternatively, the risk of death from ICH in the first 10 days following thrombolytic treatment increased dramatically. Rates of significant bleeding reported in clinical studies ranged from 6.5% to 19.8%. Therefore, strict adherence to treatment protocols and patient selection criteria are strongly recommended to achieve a favorable risk-benefit profile. In addition, patients should not be excluded from treatment simply because of advanced age (i.e., 65 years and older). These studies documented treatment advantages in patient populations whose average age ranged from 65 to 68 years.