A patient presents with sudden onset of right-sided weakness and dysarthria. What is the most likely cause of these symptoms?

The correct answer is a lacunar infarct of the internal capsule, which is a common cause of sudden onset of weakness and dysarthria, particularly when the weakness is unilateral, as seen in this patient. Lacunar infarcts occur due to small vessel disease, typically associated with chronic hypertension or diabetes, and affect deep structures of the brain such as the internal capsule.

The internal capsule contains important pathways for motor control and speech. An infarct in this area can disrupt the corticospinal fibers, which mediate voluntary movement, leading to motor deficits such as weakness. Additionally, because the internal capsule carries fibers related to speech production, damage in this area can also result in dysarthria, which is a slurred or slowed speech due to muscle control issues.

In contrast, other potential causes listed have characteristics that do not align as closely with the symptoms presented in this case. For example, embolism of the anterior cerebral artery typically causes weakness in the lower extremities and may not present with dysarthria as a prominent symptom. Border zone hypoperfusion tends to cause more diffuse weakness and other cognitive issues rather than isolated dysarthria and weakness. Intracerebral hemorrhage can indeed lead to weakness and language difficulties, but it often presents