Cochlear implantation for vestibular schwannoma

Cochlear implantation for vestibular schwannoma (VS) may be a viable option to improve hearing. There is strong evidence in the literature that VS patients benefit and use their implants. Results compare well with other patients who have been implanted for single sided deafness (SSD).

Cochlear implantation for vestibular schwannoma
Cochlear implantation with vestibular schwannoma removal.

The cochlear implant (CI) can be inserted during the primary surgical removal of the VS or at a later stage. In patients where it is decided not to operate on a small VS, a CI can be placed for hearing loss. A large number of smaller vestibular schwannomas may not grow and the presence of tumour is not necessarily a contraindication for CI. Some patients who received radiotherapy for a VS may also benefit from a CI, although it seems that the outcome is more variable and unpredictable after radiation.

In patients with neurofibromatosis type 2 (NF2), CI may be formed before Auditory brainstem implant (ABI) becomes necessary. It may also be used with an ABI on the other side in a patient with NF2. A CI does not disqualify patient for the later placement of an ABI should it become necessary.

Cochlear implantation for vestibular schwannoma can only be performed in those patients who retain functional cochlear nerve fibers. This is often not possible in larger tumours. The same factors which determine functional outcome after CI in the rest of the population are also applicable in a patient with a VS. The duration of hearing loss is an important factor and the longer the deafness the poorer the outcome after CI. It is sometimes better to implant the only hearing ear with a VS than the other side with longstanding hearing loss.

A concern that is often raised is the effect that a CI may have on future magnetic resonance imaging (MRI). MRI is required to follow up patients with VS. Certain precautions will then have to be taken to insure that the CI is not damaged and does not influence the result of the MRI. By placing the CI in a certain position adequate information can still be obtained from MRI. Always inform the radiologist before a MRI if you have a CI.