A 60-year-old man presents to the emergency department with sudden-onset right-sided weakness and difficulty speaking. His symptoms began approximately 2 hours ago. On examination, you note right hemiparesis and expressive aphasia. His blood pressure is within normal limits, and there are no signs of trauma. A non-contrast CT scan of the head shows no acute abnormalities. What is the most likely diagnosis?

Correct answer is A) Ischemic Stroke Ischemic Stroke: Despite the normal CT image, this patient’s sudden-onset focal neurological deficits (right-sided weakness and expressive aphasia) are consistent with an ischemic stroke. Further evaluation with MRI or vascular imaging may be necessary to confirm the diagnosis. Traumatic Brain Injury (TBI): Although the CT scan is normal, mild TBI can cause diffuse axonal injury (DAI), which may not be visible on routine imaging. However, the absence of trauma in this case makes TBI less likely. Multiple Sclerosis (MS): MS can present with focal neurological symptoms, but initial imaging (such as CT) may not always reveal abnormalities. However, the acute onset and lack of typical MS features make this less likely. Brain Tumor: While a tumor could cause focal deficits, the acute onset and absence of mass effect on CT argue against this diagnosis. Remember, sometimes significant pathology can be missed on CT scans, and further investigations are crucial for accurate diagnosis .