MR Imaging of the Cochlear Modiolus: Area Measurement in Healthy Subjects and in Patients with a Large Endolymphatic Duct and Sac

Abstract

Findings in this study confirm that a large endolymphatic duct and sac is frequently associated with modiolar deficiency, but the modiolar area is normal in some cases. This result does not support the recently proposed hypothesis that hearing loss with a large endolymphatic duct and sac is caused by the transmission of subarachnoid pressure forces into the labyrinth through a deficient modiolus.

Endolymphatic Hydrops of the Labyrinth Visualized on Noncontrast MR Imaging: A Case Report

“…8 Proteinous or hemorrhagic ‰uid have been reported in the enlarged endolymphatic duct and sac on MR images. 10 Recent literature supports the latter theory, [9][10][11] especially a case report of a re‰ux of proteinous or hemorrhagic ‰uid from the duct and sac into the labyrinth visualized in 3D-FLAIR images. 11 However, no separate visualization between endo-and perilymph ‰uid was possible, probably as a result of contamination of the ‰uid by rupture of the Reissner's membrane.…”

“…[9][10][11][12] Theˆrst is that cerebrospinal ‰uid (CSF) pressure in the internal auditory canal is transmitted through an insu‹ciently developed cochlear modiolus to inner-ear hair cells, but reports of normal-sized cochlear modioli in some cases of this syndrome 9 seem to refute this theory. The other theory is that the hyperosmolar ‰uid in the endolymphatic duct and sac re‰uxes into the labyrinth and damages hair cells.…”

MR Imaging of the Cochlear Modiolus after Intratympanic Administration of Gd-DTPA

“…Various reports have investigated the shape and structure of the cochlear modiolus in patients with enlarged endolymphatic duct and sac syndrome, [9][10][11] agenesis of the cochlear nerve, 6 and X-linked sensorineural hearing loss 12 and in those who are candidates for a cochlear implant. 13 The cochear modiolus is also a target structure for future cell replacement therapy of the inner ear.…”

When Is the Vestibular Aqueduct Enlarged? A Statistical Analysis of the Normative Distribution of Vestibular Aqueduct Size

“…Reports in the literature describe the features of modiolar hypoplasia, VA and endolymph duct enlargements, and endolymph sac enlargement in the large endolymphatic duct and sac syndrome. 5,14,[21][22][23][24] We believe that the statistical approach set forth in this paper will prove useful for evaluation of the size of all these labyrinthine structures.…”