What is the most likely cause of acute right-side weakness and aphasia in a 24-year-old after a car accident?

Acute right-side weakness and aphasia in a young individual following a car accident are likely due to a carotid dissection. This condition can occur when there is a tear in the inner lining of the carotid artery, which can disrupt blood flow to the brain and potentially lead to a stroke. Since the symptoms involve weakness on one side and problems with language, this suggests that the left hemisphere of the brain may be affected, as it is typically responsible for language abilities, and the opposite side of the body is impacted due to the way the brain processes motor control.

In the context of a car accident, the forces involved could lead to trauma that results in a dissection of the carotid artery, significantly increasing the risk of ischemic stroke and associated neurological deficits. This mechanism aligns well with the acute onset of neurological symptoms following the event, which is crucial in determining the cause of the clinical picture presented. Other options, while potentially problematic in the context of a car accident, are less directly connected to the specific combination of acute weakness and aphasia observed in this scenario.