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?
60%chance that extra cranial carotid artery stenosis is the cause of transient ischemic attack (TIA) It is always due to platelet emboli. 25% may be intracranial bleed. 0.5 to 10% may have cardiac and other causes of TIA.