Clinical relevance of magnetic resonance imaging and computed tomography in Cogan's syndrome.

The Pathologic changes in the inner ears of 5 patients with Cogan's syndrome were studied by a combined application of MR imaging and CT scanning. We used T1- and T2-weighted MR imaging sequences and a special three-dimensional MR imaging technique which allows a very detailed imaging of the inner ear structures. By the use of a CT scan simultaneously, calcified and noncalcified obliterations could be differentiated. The aim of the study was to visualize membranous labyrinth pathology in Cogan's syndrome and correlate them with the clinical findings. In one patient who recovered completely without hearing loss, the MR and CT investigations revealed no pathology. In the remaining 4 cases, narrowing or obliteration of parts of the vestibular labyrinth was seen. In 3 patients, we found aberrations in the cochlea consistent with the audiological data. The gadolinium-enhanced T1-images showed enhancement of the cochlea and vestibular labyrinth in one case, probably indicating an active process with interruption of the "blood-labyrinth barrier". The results are consistent with the hypothesis that the inner ear pathology in Cogan's syndrome is probably caused by obstructive vasculitis.