Spontaneous dissecting aneurysm of the internal carotid artery.

Introduction.-Dissecting aneurysms of th internal carotid artery are due to arterial wall dissection caused by hematoma. We report a case of spontaneo us dissection. Exegesis. - A 65-year-old man presented with painful Horner's syndrome and hypoglossal palsy, without a history of arterial traumatism. Magnetic reson ance imaging showed carotid artery dissection. Conclusion. - distal and subadventicial dissection can induce compression o f adjacent nerves without modifications of the arterial lumen. This type of wall hematoma may not be detected by ultrasonography and angiography. Magn etic resonance imaging proves to be the best method of investigation and sh ould be primarily advocated. Anticoagulation treatment is necessary. (C) 19 99 Elsevier, Paris.