MRI surveillance following concurrent cochlear implantation in cases of vestibular schwannoma resection.

Objective: Cochlear nerve preserving translabyrinthine vestibular schwannoma (VS) resection enables concurrent cochlear implantation. Implantation in patients with VS raises important concerns including the ability to undergo postoperative magnetic resonance imaging (MRI) monitoring of residual tumor growth or tumor recurrence, specifically with a retained magnet. We aim to assess the feasibility of MRI monitoring and the impact on image quality with retained cochlear implant (CI) magnets.

Methods: Retrospective review of post-operative head MRI scans in CI recipients with a retained CI magnet, after cochlear nerve preserving translabyrinthine excision of VS. The ability to visualize the ipsilateral and contralateral internal auditory canal (IAC) and cerebellopontine angle (CPA) were assessed.

Results: A total of eight surveillance head MRI were performed in six patients. In one case, in which the receiver was positioned lower, the view of the ipsilateral IAC and CPA was distorted. In all other cases, the views of both the ipsilateral and contralateral IAC and CPA were overall unimpaired.

Discussion: Imaging artifact only very rarely impedes adequate visualization of the ipsilateral IAC or CPA in CI recipients. In anticipation of the need for further IAC and CPA imaging, it would be advisable to place the receiver in an exaggerated superior-posterior position to further decrease obscuring artifact. Thus, serial monitoring of VS tumors can be performed safely with preservation of image quality with a retained receiver magnet.

Conclusions: When placing the CI receiver-stimulator farther posterior-superiorly, excellent visualization of the IAC and CPA can be accomplished without significantly impairing the image quality.