During dental treatment, a patient suddenly develops slurred speech, blurred vision, facial droop, and unilateral weakness, with a blood pressure measurement of 200/90 mmHg. What is the most likely diagnosis?

The combination of sudden neurological deficits — slurred speech (dysarthria), blurred vision, and unilateral weakness — along with severely elevated blood pressure (200/90 mmHg) is classic for a cerebrovascular accident (stroke). The FAST acronym (Face drooping, Arm weakness, Speech difficulty, Time to call 911) captures the key signs. In the dental setting, the immediate management is to stop treatment, call EMS (911), maintain the airway, and place the patient in a comfortable position (semi-reclined if unconscious). Do NOT give nitroglycerin or aspirin without medical direction. Anaphylaxis presents with urticaria, bronchospasm, and hypotension. Vasovagal syncope causes pallor, diaphoresis, and hypotension, not neurological deficits.