The Vestibular Implant: Hearing Preservation during Intralabyrinthine Electrode Insertion—A Case Report

Abstract

ObjectiveThe vestibular implant seems feasible as a clinically useful device in the near future. However, hearing preservation during intralabyrinthine implantation remains a challenge. It should be preserved to be able to treat patients with bilateral vestibulopathy and (partially) intact hearing. This case study investigated the feasibility of hearing preservation during the acute phase after electrode insertion in the semicircular canals.MethodsA 40-year-old woman with normal hearing underwent a translabyrinthine approach for a vestibular schwannoma Koos Grade IV. Hearing was monitored using auditory brainstem response audiometry (ABR). ABR signals were recorded synchronously to video recordings of the surgery. Following the principles of soft surgery, a conventional dummy electrode was inserted in the lateral semicircular canal for several minutes and subsequently removed. The same procedure was then applied for the posterior canal. Finally, the labyrinthectomy was completed, and the schwannoma was removed.ResultsSurgery was performed without complications. No leakage of endolymph and no significant reduction of ABR response were observed during insertion and after removal of the electrodes from the semicircular canals, indicting no damage to the peripheral auditory function. The ABR response significantly changed when the semicircular canals were completely opened during the labyrinthectomy. This was indicated by a change in the morphology and latency of peak V of the ABR signal.ConclusionElectrode insertion in the semicircular canals is possible without acutely damaging the peripheral auditory function measured with ABR, as shown in this proof-of-principle clinical investigation.

Analysis of Vestibular Labyrinthine Geometry and Variation in the Human Temporal Bone

“…This could result in designing ideally sized electrodes which fit in the confines of the bony labyrinth while preserving the membranous structures. Assuming the electrode lead diameter used (van de Berg et al, 2017 ) of 0.4–0.6 mm, which results in a cross-sectional area of 0.13–0.28 mm 2 , our data support the assumption that this diameter would possibly not disrupt the membranous labyrinth. Nevertheless, it has to be considered that the cross-sectional area of the perilymphatic spaces are not shaped circularly (Figure S4 ).…”

“…The electrochemical gradient present only in the cochlea may be more sensitive for potassium ion changes triggered in the vestibular system. Recently it was shown (van de Berg et al, 2017 ) that intra-operative electrode insertion in the human SCC is possible without acutely damaging the peripheral auditory function measured with acoustic brainstem response.…”

Model-based Vestibular Afferent Stimulation: Modular Workflow for Analyzing Stimulation Scenarios in Patient Specific and Statistical Vestibular Anatomy

“…Animal experiments were undertaken to prove the feasibility of vestibular implants (Della Santina et al, 2007 ; Fridman and Della Santina, 2012 ; Rubinstein et al, 2012 ; Nie et al, 2013 ; Lewis, 2016 ) and also to analyze the effects of different stimulation parameters on the stimulation of the vestibular nerve (Fridman et al, 2010 ; Davidovics et al, 2011 ). The feasibility of vestibular implants was also confirmed in humans (Guyot et al, 2011 ; Perez Fornos et al, 2014 ; Guinand et al, 2015 ; van de Berg et al, 2017 ). The close proximity of the vestibular nerve bundles, the N. facialis and the N. cochlearis poses a major challenge in targeted stimulation of the vestibular system.…”

“…Vestibular dysfunction can lead to blurred vision and impaired balance and spatial orientation, causing a significant decrease of quality of life (Guinand et al, 2012 ; Sun et al, 2014 ; van de Berg et al, 2017 ). While unilateral and mild to moderate bilateral vestibular dysfunction can be (partially) compensated by the remaining function of the vestibular system and other sensory input in most cases, insufficient compensation on severe bilateral vestibular dysfunction can be devastating (Sun et al, 2014 ).…”

The resilience of the inner ear—vestibular and audiometric impact of transmastoid semicircular canal plugging

“…The implanted electrodes are relatively big in diameter compared to the small semicircular canal, and may, therefore, act similar to a plugged semicircular canal. It has been shown that hearing may endure during the surgical procedure [ 34 ]. However, the effect of intralabyrinthine vestibular implantation on both hearing and residual vestibular function has not been sufficiently investigated.…”