A 82-year-old female presented with history of loss of vision in right eye for about 15 minutes and it cleared up. She has a history of diabetes and hypertension. She had which showed old infarct on right side. Carotid duplex showed that patient had 99% carotid artery stenosis. Which one of the following statements is TRUE?

Neurological events are associated with extracranial carotid artery in about 60%. Forty percent may have extracranial/intracranial cause for neurological events, which includes cardiac emboli, arch of aorta as source of emboli; intracranial bleed may be more than just a TIA. It is not always that platelet emboli are the cause of TIA, it could be due to atheroma. It is not always attributed to thrombus.