Although extracranial ICA dissection is recognized as a cause of cerebral infarction, 1-3 the pathogenesis of ischemic symptoms in an individual patient with the condition is not always understood, making treatment decisions difficult. We describe a patient with traumatic cervical ICA dissection diagnosed on the basis of noninvasive tests, in whom TCD ultrasonography was used to detect ipsilateral distal microembolization associated with clinical deterioration.