When most patients enter the emergency room, in most cases the medical staff already knows whether or not the patient has had an acute stroke. The patient may already have knowledge and may have informed the staff when making a phone call to emergency system, or the emergency medical technicians in an ambulance may observe the patient and inform the emergency room medical staff before arrival, although this varies between countries based on their systems. Even if the information is not provided prior to the arrival, the emergency medical technicians should consider the patients that show sudden focal neurological deficits as stroke patients. In most cases, the suspected patient is indeed suffering from stroke, and even if misdiagnosed, it has little effect on the patient’s prognosis.

When treating a stroke patient, the emergency ABC (airway, breathing, and circulation) assessment should first be in order. After securing the airway, and checking the breathing and circulation of the patient, necessary treatment should be administered. If aspiration of vomit is present in the bronchus or the respiration is unstable, immediate endotracheal intubation may be necessary. In most cases, the patients have elevated blood pressure (BP), but intervention to reduce the BP is not immediately applied and the BP is monitored unless the systolic and diastolic blood pressures (SBP and DBP) are above 220 and 120, respectively. The need for oxygen supply and Levin tube insertion should be checked, and blood sampling as well as the establishment of an intravenous (IV) route with a large bore needle should be performed. Basic laboratory testing should be performed immediately with the obtained blood sample, while the blood glucose level should be confirmed using the fingertip to identify potential hypoglycemia. Normal saline should be infused intravenously through the obtained IV route, but the infusion should be just enough to maintain euvolemia before the diagnosis is confirmed. If needed, a Foley catheter should be inserted. Concurrently, the medical history should be obtained from the patient, guardians, or family members, and a basic physical examination with neurological examination should be performed to confirm the initial neurological status in an early stage. The National Institutes of Health Stroke Scale (NIHSS) scoring is the standard index that is widely used. The neurological physicians should try to perform all the above tasks within 10 min of the patient’s arrival.

As the neurological physicians perform the above procedures, they should also prepare to perform brain computed tomography (CT). The brain CT result should not be delayed due to the above procedures; therefore, they should ensure the fast completion of the above procedures. Brain CT is an extremely useful examination to distinguish whether or not the patient’s symptom presentation is due to hemorrhagic stroke. The sensitivity and specificity of brain CT in the diagnosis of hemorrhagic stroke are very high, and a majority of hemorrhagic stroke patients are identified from this examination. If the patient has a brain hemorrhage, the patient is treated accordingly. The treatment details are outlined in Sect. 3.3. If the brain CT results are normal or the patient shows initial ischemic change, there is a very high chance that the patient has suffered from an ischemic stroke. A detailed explanation is outlined in Chap. 5. In most cases, a non-contrast brain CT is sufficient, although some centers perform CT angiography or magnetic resonance imaging (MRI) for a more detailed initial diagnosis. While both approaches have their own advantages and disadvantages, a plain CT should be sufficient to distinguish hemorrhage in the centers with experienced physicians, since the time is the most important factor in the early stages of treating stroke. Both general and professional aspects of performing CT are outlined in Chap. 9.