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Updated: Oct 24, 2026

Extracting the Cochlea from a Human Temporal Bone: A Cadaveric Protocol
Published on: August 18, 2023
The cochlear modiolus as a functional gateway for fluid exchange between cerebrospinal flow and perilymph
Yu-Fen Wang1, Yi-Ho Young2, Mei-Chi Chen1
1Department of Medical Imaging, National Taiwan University Hospital, No. 7, Zhong-Shan S. Road, Taipei, 100, Taiwan.
Background:
Long considered as the primary conduit to connect the inner ear and the subarachnoid space, the cochlear aqueduct has been shown obstructed in a paradoxically high percentage of population. This study aimed to elucidate the role of modiolus in perilymph-cerebrospinal fluid (CSF) communication.
Methods:
A cohort of patients diagnosed with unilateral vestibular schwannoma (VS) were prospectively enrolled in this single-center observational study. On inner ear-specific magnetic resonance images, delayed enhancement (4 h after intravenous contrast administration) was quantitatively evaluated and compared among the tumor, the fundus of the internal auditory canal (IAC), and the cochlear modiolus, followed by bivariate correlation and multivariable regression analyses with respect to tumor-modiolus distance and spatial extent of inner ear enhancement.
Results:
Twenty-one patients (mean age, 63.6 ± 13.6 years, 13 men) were evaluated. Significant positive enhancement was found in the tumor and the ipsilateral fundal fluid cap (Wilcoxon signed-rank test, p < 10-4), but not in the contralateral IAC (p = 0.167). The patient group with a high-grade spatial extent of enhancement (n = 10) had a shorter tumor-modiolus distance (Mann-Whitney test, p = 0.004), as compared with the low-grade group (n = 11). Ordinal logistic regression identified tumor-modiolus distance as an independent predictor of the cochlear enhancement grade (adjusted odds ratio = 0.366 per 0.1 cm increase, p = 0.001) after controlling for tumor volume, age, and sex.
Conclusion:
We have demonstrated a tumor-modiolus-distance-dependent pattern of inner ear enhancement, quantitatively supporting the hypothesis that the modiolus serves as a functional gateway for CSF-perilymph communication.
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