Computed tomographic findings in Ménière's disease

Symptoms in Ménière's disease are explained by hydrops of the endolymphatic system with recurrent ruptures of the membranous labyrinth. The primary cause of the increased endolymphatic volume appears to be an imbalance between secretion and resorption of endolymph which may be due to an obstruction of the endolymphatic duct and sac, located in the vestibular aqueduct (VA). Non-visualization or narrowing of the latter have been demonstrated by conventional tomography. Also, sclerosis and hypoplasia of the retrolabyrinthine portions of the temporal bone have been documented. By high resolution computed tomography (CT) we prospectively tried to demonstrate morphological alterations in 10 patients with Ménière's disease. These were compared with a group of 14 non-Ménière patients. Visualization of the VA as well as perilabyrinthine pneumatization were assessed and the width of the retrolabyrinthine part of the temporal bone was measured. Whereas there was a slight difference in the average retrolabyrinthine width (3.8 mm in Ménière versus 5.8 in non-Ménière cases) and degree of pneumatization, there was a distinctly decreased visualization of the VA in the Ménière group. As findings were always bilateral and only 3 of 20 temporal bones showed peripheral hypopneumatization, possibly due to chronic otitis media, the theory of a predisposing constitutional abnormality must be taken into consideration. However, we were not able to confirm a statistically proven usefulness of the CT technique in identifying an anatomical abnormality which is directly in correlation with the side of the lesion in cases of unilateral Ménière's disease.