Enlargement of the cochlear aqueduct: does it exist?

Abstract

Our intention was to evaluate whether enlargement of the cochlear aqueduct could play a role in dysfunctions of the inner ear. There is little literature dealing with the question of cochlear aqueduct (CA) enlargement and results of reported radiological examinations are contradictory. Therefore, we decided to analyse 400 high-resolution CT-scans of the temporal bone to examine the diameter of the CA. We used scan-data from a 64-line multislice spiral-CT-scanner stored in our PACS-System. CA-enlargement was defined as a diameter of more than 1 mm in the whole otic capsule portion. A classification with four types of CA's proposed by Migirov and Kronenberg in 2005 was applied. Statistical analysis of diameters, different CA-types and side asymmetry was performed. We did not find any CA exceeding 1 mm in diameter in the otic capsule portion, there is no evidence of CA-enlargement, not even in patients with inner ear malformation. A new aspect compared with published literature to date is that nearly in all cases CA was identified, but in different degrees. According to our findings, it seems to be very unlikely that CA-enlargement is a reason for pathologic inner ear condition as it is in case of large vestibular aqueduct.

Metal Casts Showing the Three-Dimensional Structure of the Human Inner Ear Were Converted Into Jewelry

“…Young (21) also referred to a ''membrane barrier'' at the end of the perilymphatic duct and claimed that this prevented contact between perilymph and cerebrospinal fluid: ''This membrane barrier precludes any communication between the ear and the subarachnoid space'' (p. 306). Although this latter statement is contrary to the current view that perilymph is in contact with the cerebrospinal fluid (25), there is a possible explanation for Young's findings. Mercury is much more viscous than perilymph and so the presence of a membrane barrier or connective tissue could have halted the flow of mercury in Young's experiments with living rhesus monkeys.…”

“…Young's results, however, are not currently believed to be correct: the perilymphatic duct is thought to be in continuity with the subarachnoid space (15,25). Unfortunately, it is not possible to evaluate Young's evidence for the perilymphatic sac because he never published articles showing representations of the metal casts (Fig.…”

Accessible and Informative Sectioned Images, Color‐Coded Images, and Surface Models of the Ear

“…Therefore, users can acquire literal anatomical knowledge of the ear using our applications. In clinics, an otologist has to interpret the computed tomographs of head to identify the ear components (Stimmer, ; Phillips et al, ). The browsing software and PDF file could be utilized as the reference images.…”

Cerebrospinal Fluid Leak in Cochlear Implantation: Enlarged Cochlear versus Enlarged Vestibular Aqueduct (Common Cavity Excluded)

“…The contents of the PF and CSF are similar, except for some difference in electrolyte concentration; the perilymph possibly originates from the CSF [26]. …”

“…The narrow diameter of the CA is thought to buffer the inner ear from the wide pressure variations present within the posterior fossa subarachnoid spaces [15, 26, 30]. …”