Usefulness of cervical magnetic resonance imaging for detecting type A acute aortic dissection with acute stroke symptoms

Type A acute aortic dissection (TAAAD) sometimes presents with acute stroke-like symptoms. When intravenous tissue plasminogen activator (IV-tPA) therapy is considered for acute ischemic stroke, TAAAD must be excluded. Painless TAAAD presenting with acute stroke may be easily missed. Two cases of painless TAAAD presenting with acute stroke in which IV-tPA therapy was considered are reported. In these cases, cervical magnetic resonance angiography (MRA) was useful for detecting TAAAD, and IV-tPA therapy was canceled. The mottled high signal (“snowstorm”) in the common carotid artery on cervical MRA is specific for TAAAD. We have thus named this phenomenon the “snowstorm sign” and believe it can help diagnose TAAAD.