[Spontaneous dissecting aneurysm of the internal carotid artery]. / Dissection spontanée de l'artère carotide interne.

INTRODUCTION: Dissecting aneurysms of the internal carotid artery are due to arterial wall dissection caused by hematoma. We report a case of spontaneous dissection. EXEGESIS: A 65-year-old man presented with painful Horner's syndrome and hypoglossal palsy, without a history of arterial traumatism. Magnetic resonance imaging showed carotid artery dissection. CONCLUSION: Distal and subadventicial dissection can induce compression of adjacent nerves without modifications of the arterial lumen. This type of wall hematoma may not be detected by ultrasonography and angiography. Magnetic resonance imaging proves to be the best method of investigation and should be primarily advocated. Anticoagulation treatment is necessary.