[Abnormal trajectory of the internal carotid artery in the middle ear. Report of a case].

The authors report a case with an aberrant course of the internal carotid artery within the middle ear--a rare abnormality with only about fifty cases so far reported in the literature. The combination of pulsatile tinnitus and a retro-tympanic mass calls for a precise anatomical investigation of the temporal bone before any surgery is undertaken. The role of the various complementary investigations is discussed. A high resolution CT scan is the key investigation, and is sufficient to give the diagnosis in the majority of cases. Angio-MRI currently affords the possibility of confirming this vascular malpositioning in a non-invasive way. Arteriography should be used only when there is remaining doubt about the possibility of a glomus tumour, or before treatment by clamping. The most logical course to adopt would seem to us to be to abstain from treatment once this diagnosis has been made, given the risk of major haemorrhage and the potential neurological complications.