neurologic disorders
Overview of Stroke
Evaluation of Stroke
Evaluation aims to establish the following: Whether stroke has occurred Whether stroke is Ischemic Stroke or Whether emergency treatment is required What the best strategies for preventing subsequent strokes are Whether and how to pursue rehabilitation Stroke is suspected in patients with any of the following: Sudden neurologic deficits compatible with brain damage in an arterial territory A particularly sudden, severe headache Sudden, unexplained Overview of Coma and Impaired Consciousness None Sudden impairment of consciousness When stroke is suspected, clinicians may use standardized criteria to grade severity and follow changes over time. This approach can be particularly useful as an outcome measure in efficacy studies. TheNational Institutes of Health Stroke Scale (NIHSS)is often used. It is a 15-item scale to evaluate the patient's level of consciousness and language function and to identify motor and sensory deficits by asking the patient to answer questions and to perform physical and mental tasks. It is also useful for choosing appropriate treatment and predicting outcome. Glucose is measured at bedside to rule out hypoglycemia. Measurement of blood glucose is the only laboratory test needed for all patients before thrombolytics are given. However, if the patient is receiving an anticoagulant, platelet count, international normalized ratio (INR), and partial thromboplastin time are measured. If stroke is still suspected, immediate Diagnosis is required to differentiate hemorrhagic from ischemic stroke and to detect signs of increased intracranial pressure. CT is sensitive for intracranial blood but may be normal or show only subtle changes during the first hours of symptoms after anterior circulation ischemic stroke. CT also misses some small posterior circulation strokes. MRI is sensitive for intracranial blood and may detect signs of ischemic stroke missed by CT, but CT can usually be done more rapidly. If CT does not confirm clinically suspected stroke, diffusion-weighted MRI can usually detect ischemic stroke. This image shows low attenuation in the distribution of the right middle cerebral artery consistent with a subacute ischemic stroke with hemorrhage developing in areas of ischemia. © 2017 Elliot K. Fishman, MD. This MRI scan shows an area of restricted diffusion consistent with an acute ischemic stroke in the left insular and frontal lobes. Image courtesy of Ji Y. Chong, MD. This noncontrast head CT scan shows a hyperdense left middle cerebral artery. This finding indicates a focal clot in the left middle cerebral artery (arrow). Image courtesy of Ji Y. Chong, MD. If consciousness is impaired and lateralizing signs are absent or equivocal, Testing is done to check for causes other than stroke(eg, postictal state, metabolic encephalopathies): Blood tests: Comprehensive metabolic panel (including at least serum electrolytes, bloodureanitrogen [BUN], creatinine, and calcium levels), complete blood count (CBC) with differential and platelets, liver tests, and ammonia level Arterial blood gases (ABGs) Blood and urine culture and routine toxicology Electrocardiography (ECG) to check for myocardial infarction and new arrhythmias Chest x-ray to check for new lung disease that may affect brain oxygenation. Imaging tests to check for masses, hemorrhage, edema, evidence of bone trauma, and hydrocephalus (first, noncontrast head CT, followed by MRI or contrast CT if needed for diagnosis) Echocardiography to check the heart for blood clots, pumping or structural abnormalities, and valve disorders Electroencephalography After the stroke is identified as ischemic or hemorrhagic, tests are done to determine the cause. Patients are also evaluated for coexisting acute general disorders (eg, infection, dehydration, hypoxia, hyperglycemia, hypertension). Patients are asked about depression, which commonly occurs after stroke. A dysphagia team evaluates swallowing; sometimes a barium swallow study is necessary. 