How common is stroke, and what is its public health burden?
Acute ischemic stroke is in most areas of the world the most prevalent neurological emergency; one American has a stroke every 40 seconds. In the United States alone there are more than 780,000 strokes per year, with the majority being new events.1 The number of hospitalizations in the United States continues to increase. The cost associated with the care of stroke patients in 2008 was $65.5 billion; the cost of care per patient is almost double for severe strokes. Stroke is the third leading cause of death in the United States, and among adults the leading cause of long-term disability. Stroke is disproportionately a disease of individuals of lower socioeconomic status, African Americans, elderly persons, and women in the older age groups. Ischemic stroke accounts for the majority of stroke subtypes in case series from the United States.1 The majority of stroke survivors have some form of a residual disability, though 50% to 70% will nonetheless regain functional independence.1 These patients remain at high risk for subsequent morbidity and mortality. A small proportion of acute ischemic stroke patients will be eligible for reperfusion therapy, and an even smaller proportion will actually receive it. In series from various locations in the United States the rates of thrombolysis varies when considering all stroke patients but remains low at 2% to 8.5%2 ; however, analysis of data from the Nationwide Inpatient Service reveals this rate to be less than 2%.3 The primary reason for not receiving reperfusion therapy is arrival outside of the appropriate time window.4 Those who arrive by the appropriate window still have several reasons within the national guidelines for not being treated, and in some hospital series there are sizeable numbers of patients who do not meet any exclusion criteria but still are not treated.5 Prevention and treatment of the complications related to stroke remain the cornerstone of treatment for ischemic stroke. Risk factors for ischemic stroke are somewhat similar to that of ischemic heart disease, with some notable exceptions. Hypertension remains the most important risk factors for ischemic stroke.6 Dyslipidemia, although prominent for ischemic heart disease, is a less potent risk factor for ischemic stroke.7 Large population-based cohort studies have failed to find a consistent association between dyslipidemia and ischemic stroke, though for the atherosclerotic stroke subtype this may still be the case.8 Atherosclerotic disease of the extra- or intracranial vessels is an important cause of ischemic stroke, most likely due to artery-to-artery emboli or in a smaller proportion of cases due to flowfailure.9 Atrial fibrillation is a unique risk factor for ischemic stroke risk and is particularly important because of the severity of the strokes from cardiac embolism and the response to acute treatment. Atrial fibrillation is more likely to be associated with large infarctions that could lead to malignant cerebral edema, as well as hemorrhagic infarcts and transformation.
What are the steps required for the diagnosis of acute stroke in the ED before treatment can be initiated?
Stroke remains a clinical diagnosis, and in the acute setting a history and physical examination remain an integral component of evaluation. In the triage area the staff can activate the stroke team, if they have not already been activated based on a notification from the EMTs, and will start the initial evaluation. This includes checking a finger stick glucose, vital signs, and a screening examination such as the Cincinnati Stroke Scale.10 The latter can be used with excellent reproducibility and sensitivity by nonphysician personnel and involves checking for facial droop, arm drift, and dysarthria. In patients with suspected stroke, two large-bore intravenous (IV) lines (at least 20 gauge) should be placed, and the following serum tests should be sent to the laboratory immediately: complete blood count, coagulation panel, basic metabolic panel, troponin level, and type-and-hold. Our acute stroke pathway involves completing the history, carrying out an examination, and obtaining neuroimaging
The history must be focused, and the initial goal should be to establish the exact time of onset. Frequently patients such as the man described above will not be able to provide an exact time of onset, and in any way possible, it is prudent to confirm the time of onset with friends or family. It is important to establish if there were minor symptoms present before the ones that caused the current symptoms, as well as whether the patient woke up with the deficits. The time of onset is assumed to be the moment the patient fell asleep for wake-up strokes, and otherwise the last time the patient was seen at the baseline
A complete neurological examination is often not necessary in the initial evaluation in the ED; the National Institutes of Health Stroke Scale (NIHSS) is the initial examination of choice. It has excellent interexaminer reliability and sensitivity for most strokes11 and can be performed quickly; also, training is available free of charge through the American Heart Association. Depending on the clinical scenario, a more detailed examination may be required for suspected nondominant hemisphere injury, subtle aphasia, or cerebellar syndromes with a predominant astasia-abasia picture. Neuroimaging is obtained before or after the examination, but should be completed within 20 minutes of arrival to the ED. Streamlining the process of acute stroke evaluation, termed the “Helsinki model,”12 which includes ambulance prenotification and ability to obtain a history before the patient arrives, early ordering of thrombolytics, and administration of thrombolytics immediately after the imaging is obtained, can reduce door-to-needle times to as low as 20 minutes without safety concerns. This process, as well as other streamlining protocols, have been successfully implemented in other stroke centers with improved treatment times.