Indications and contraindications of auditory brainstem implants: systematic review and illustrative cases

Abstract

The number of non-neurofibromatosis type 2 (NF2) indications for auditory brainstem implant (ABI) in the literature is increasing. The objective of this study was to analyze and discuss the indications for ABI. Retrospective chart review and systematic review were conducted at Quaternary referral skull base center and referring centers. Analysis of ABI cases with non-NF2 indications and systematic review presenting non-NF2 ABI cases were performed. Fourteen referred cases with ABI were identified. All cases had unsatisfactory results of ABI and all could have been rehabilitated with a cochlear implant (CI). Of these 14 cases, 9 improved with a cochlear implant, and 2 with a hearing aid, two are still planned for CI, one received bilateral CI, no ABI. In literature, we found 31 articles presenting 144 non-NF2 ABI cases with at least 7 different indications other than NF2. ABI should be restricted to those patients who have no other rehabilitation options. Patency of the cochlea and evidence of an intact cochlear nerve should be examined with imaging and electrophysiologic testing. Sometimes a CI trial should be planned prior to proceeding with ABI. We have shown that in many cases a CI is still possible and CI provided better results than ABI. In vestibular schwannoma in the only hearing ear, cochlear otosclerosis, temporal bone fractures, (presumed) bilateral traumatic cochlear nerve disruption, auto-immune inner ear disease and auditory neuropathy primarily CI are indicated. Traumatic bilateral cochlear nerve disruption is exceptionally unlikely. In cochlear nerve aplasia, testing should be performed prior to meeting indications for ABI. In malformations, ABI is indicated only in severe cochlear hypoplasia or cochlear aplasia.

Recent Rehabilitation Experience with Pediatric ABI Users

“…However, young ABI users' language development improves more rapidly, but older children's language development decreases with time. We assumed that in the later years, language development tasks will become harder, and catching up with these tasks would be difficult [20] . Language tests were performed in the auditory-verbal mode; in further studies, their scores could possibly be better with sign language.…”

Cochlear implantation improves hearing and vertigo in patients after removal of vestibular schwannoma

“…Considering the large number of the affected patients, early diagnosis and treatment of the disease is mandatory in order to achieve favourable results. However, the chances to preserve hearing decrease with increasing tumour size despite advanced surgical techniques and a high percentage of the patients experience severe to profound hearing loss [10][11][12][13] . Therefore, the demand for a sufficient hearing supply after surgical removal is rising.…”

“…The quantity and quality of hearing rehabilitation is increasing from normal hearing aids, cross-and bicross-hearing-systems, bone conducted hearing aids, middle ear implants (MOI), cochlear implantation (CI), auditory brainstem implant (ABI) and auditory midbrain implant (AMI). After surgical removal of VSs, especially in neurofibromatosis type 2 patients, the supply with ABI is in most cases an option, but several studies showed an unsatisfactory outcome 8,11,13,14 . Especially the speech perception with an ABI in adults 15 , compared to the supply in young children 16 , is a huge breakdown.…”

Progress of hearing loss in neurofibromatosis type 2: implications for future management

“…Outcomes of cochlear implantation following growth stabilization with radiosurgery are poorer, however [34,35]. Finally, ABI is an option if a tumour requires removal and cochlear nerve preservation is not possible [36][37][38].…”