Vestibular schwannomas (VSs) are the most common tumors located in the cerebellopontine
angle (CPA). While facial nerve function is often preserved, the cochlear nerve is frequently
affected. Magnetic resonance imaging (MRI) is the gold standard for diagnosis. Treatment
options include observation, microsurgical resection, fractionated radiotherapy, and
radiosurgery. The main goals of surgery are to preserve facial nerve function and, ideally,
cochlear nerve function. However, hearing loss is often unavoidable due to the vulnerability of
the cochlear nerve.
To restore hearing postoperatively, cochlear implants (CI) and auditory brainstem implants
(ABI) are available. CI is the preferred option when the cochlear nerve is preserved and the
cochlea remains patent. However, cochlear obliteration presents a challenge for CI
implantation. It is assumed that the surgical approach (retrosigmoid vs. translabyrinthine) may
influence the risk of cochlear obliteration.
This monocentric, retrospective study evaluated the frequency of cochlear obliteration after
retrosigmoid VS surgery using high-resolution, T2-weighted MRI scans. Cochlear obliteration
was observed in 32% of cases. Factors such as age, tumor size, operation duration, and
reoperation were not significantly associated with higher obliteration rates. However,
obliteration occurred more frequently in female patients and was significantly associated with
obliteration of the semicircular canals. The proximity of these canals to the posterior lip of the
internal auditory canal may contribute to inner ear susceptibility. Future studies should explore
surgical technique differences and the ideal timing for CI implantation before cochlear
obliteration develops
