**2.2 Rapid acquisition of medical and surgical history**

Pertinent history and neurological exam are essential to establish a stroke diagnosis and guide subsequent treatment. History not only provide clues for potential stroke etiologies, but also detects contraindications for thrombolysis (discussed in detail later) and guide stroke prevention. Of particular importance in medical history are vascular risk factors, including modifiable conditions such as obesity, diabetes, hypertension, dyslipidemia, metabolic syndrome, chronic obstructive pulmonary disease, previous ischemic or hemorrhagic strokes, ischemic heart disease, congestive heart failure, atrial fibrillation, smoking, and excessive alcohol use [14]. The presence of some or many of these factors increase the likelihood of AIS.

### **2.3 Focused neurological exam and use of NIHSS score**

After history is obtained, the clinician should perform a focused neurological exam, calculating National Institutes of Health Stroke Scale (NIHSS) score, originally used for the NINDS Trial [15]. The NIHSS is a standardized scale ranging from 0 to 42 that grades patient's level of consciousness, language, visual fields, facial weakness, limb weakness, sensation, and incoordination [16]. Each category has a different score and a higher score for a component would indicate a worse deficit (for example, when testing left arm weakness, a score of 0 would mean no weakness, and 4 would indicate flaccid paralysis of the arm).

The NIHSS score strongly correlates with post-stroke modified Rankin scale (mRS) score1 at discharge from stroke stay [17, 18]. An NIHSS <5 is predictive of better outcomes with an mRS generally less than 3, and an NIHSS >22 predictive for poorer outcomes with an mRS greater than 3 or death. NIHSS scores between 5 and 22 inclusive on the other hand had a weaker correlation with mRS scores [19]. However, on the NIHSS, left hemispheric deficits are more heavily rated than those of the right [20]. Further the scores do not reliably detect posterior circulation findings, for example, vertigo and dizziness [21]. Nevertheless, the NIHSS is known as a reliable predictor for stroke severity, informing treatment decisions and post-thrombolysis prognosis. Of note, neurological exams should not be entirely limited to the items of the NIHSS, as the signs outside of those of NIHSS may inform alternate explanations. For example, a new vertical gaze palsy points to a midbrain localization and an acute onset dysphagia with saliva pooling may be caused by posterior circulation infarct. These are examples of signs separate from the NIHSS, and a rapid and focused neurological exam should not miss.
