Individual Optimization of the Insertion of a Preformed Cochlear Implant Electrode Array

Abstract

Purpose. The aim of this study was to show that individual adjustment of the curling behaviour of a preformed cochlear implant (CI) electrode array to the patient-specific shape of the cochlea can improve the insertion process in terms of reduced risk of insertion trauma. Methods. Geometry and curling behaviour of preformed, commercially available electrode arrays were modelled. Additionally, the anatomy of each small, medium-sized, and large human cochlea was modelled to consider anatomical variations. Finally, using a custom-made simulation tool, three different insertion strategies (conventional Advanced Off-Stylet (AOS) insertion technique, an automated implementation of the AOS technique, and a manually optimized insertion process) were simulated and compared with respect to the risk of insertion-related trauma. The risk of trauma was evaluated using a newly developed “trauma risk” rating scale. Results. Using this simulation-based approach, it was shown that an individually optimized insertion procedure is advantageous compared with the AOS insertion technique. Conclusion. This finding leads to the conclusion that, in general, consideration of the specific curling behaviour of a CI electrode array is beneficial in terms of less traumatic insertion. Therefore, these results highlight an entirely novel aspect of clinical application of preformed perimodiolar electrode arrays in general.

Atraumatic Insertion of a Cochlear Implant Pre-Curved Electrode Array by a Robot-Automated Alignment with the Coiling Direction of the Scala Tympani

“…Even though all instructions were written and insertions were manually performed, there was a reduction to the intracochlear trauma. Other study considered the geometry of the array and the size of the cochlea, and the insertion was performed automatically by a mini-invasive access to the cochlea, the intracochlear trauma being significantly diminished [Rau et al, 2015]. Although the benefits of a personalization of the array insertion are obvious, the use of a surgical robot coupled with navigation and the automatization of the procedure could be a requirement to perform a personalized surgery.…”

Towards All-Polymeric Cochlear Implant Micro-Electrode Arrays

“…Firstly, pre-curved arrays are usually larger in volume and create a higher intracochlear pressure [65]. Secondly, pre-curved arrays are straightened and inserted in the inner ear via a stylet (advanced off-stylet technique (AOS)) [67]. The AOS technique is described in Figure 3.8.…”

Toward steerable electrodes. An overview of concepts and current research.

“…So far, fabrication of the intracochlear devices includes a large amount of handmade production techniques. These cause remarkable variability in the mechanical properties of the electrode arrays, especially regarding the curling behaviour [23,2] making it less predictable. This is contradictorily to an accurate precursory planning and may be overcome by a higher degree of automated fabrication methods like batch-processing using thin-film techniques.…”

“…In contrast, there is the vision of atraumatic electrode arrays which hug the inner wall of the cochlea (called perimodiolar EA) in order to place the stimulating contacts in close proximity to the auditory nerve, enable deeper insertion due to the perimodiolar course inside the cochlea and allow for a controllable end position [2]. The shape of such an "active" or "steerable" electrode array could be adapted to the individual geometry of the spiral inner ear in order to avoid any contact between the EA and the surrounding tissue-resulting in a contactless, and therefore, truly atraumatic insertion.…”