A 72-year-old man is brought to the emergency department by his family after suddenly developing left-sided weakness and facial droop 1 hour ago. His medical history includes hypertension and hyperlipidemia. On examination, he has a left hemiparesis and left facial palsy. What is the most critical immediate diagnostic study to perform?
✓ Correct Answer: Option C
A non-contrast head CT scan is the most critical immediate diagnostic study in suspected acute stroke to rapidly differentiate between ischemic and hemorrhagic stroke, which guides subsequent management, especially regarding thrombolytic therapy.