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The retrosigmoid approach for auditory brainstem implantation.
V Colletti1, F G Fiorino, M Carner
1Ear, Nose, and Throat Department, University of Verona, Italy.
The American Journal of Otology
|November 15, 2000
Summary
The retrosigmoid-transmeatal approach is effective for auditory brainstem implantation (ABI) in neurofibromatosis type 2 patients, enabling auditory sensation and potential hearing preservation.
Area of Science:
- Neurosurgery
- Otolaryngology
- Audiology
Background:
- Vestibular schwannomas (VS) often necessitate surgical intervention, potentially impacting hearing.
- Auditory brainstem implantation (ABI) offers a solution for hearing restoration in select cases.
Observation:
- The retrosigmoid-transmeatal (RS-TM) approach was utilized for ABI in five neurofibromatosis type 2 patients with VS.
- Detailed anatomosurgical guidelines were followed, identifying key cranial nerves and structures for electrode placement.
- Intraoperative electrically evoked auditory brainstem responses (EABRs) guided electrode positioning.
Findings:
- All patients achieved auditory sensations through ABI, with varying electrode numbers and discernible pitch variations.
- The RS-TM approach facilitated tumor removal while preserving anatomical structures for potential future cochlear implantation.
Implications:
- The RS-TM approach is a preferred surgical route for ABI, especially when hearing preservation is a possibility.
- Intraoperative monitoring of cochlear nerve action potentials (CNAPs) and round window stimulation are crucial for assessing hearing function.
- This approach allows for decompression and partial resection of VS, potentially preserving hearing function.