BACKGROUND- Internal carotid artery (ICA) dissections are among the common causes of ischemic strokes in young and middle-aged adults. Most patients with ICA dissections, however, present with a variety of other manifestations and never develop strokes. The disease is much more common than was initially thought.REVIEW SUMMARY- In this article, the following features of spontaneous ICA dissections are reviewed: incidence, pathology and pathogenesis, terminology, etiologic factors, clinical manifestations, angiographic and imaging findings, treatment options, outcome, and rate of recurrence. Multiple diagrammatic, angiographic, magnetic resonance imaging, and pathologic figures are assembled to demonstrate correlation between pathologic observations and the angiographic as well as imaging findings.CONCLUSIONS- Spontaneous ICA dissections are diagnosed with increasing frequency as a result of the increased familiarity of clinicians and radiologists with clinical, angiographic, and imaging features of the disease. A wider spectrum of clinical presentation is recognized. Death from massive cerebral infarct and edema can occur, but this is quite uncommon. Marked neurologic residuals are infrequent. The outcome is quite good in the majority of the patients, and the rate of recurrence is low.