Epidural recordings in cochlear implant users

Abstract

Objective. In the long term it is desirable for CI users to control their device via brain signals. A possible strategy is the use of auditory evoked potentials (AEPs). Several studies have shown the suitability of auditory paradigms for such an approach. However, these investigations are based on non-invasive recordings. When thinking about everyday life applications, it would be more convenient to use implanted electrodes for signal acquisition. Ideally, the electrodes would be directly integrated into the CI. Further it is to be expected that invasively recorded signals have higher signal quality and are less affected by artifacts. Approach. In this project we investigated the feasibility of implanting epidural electrodes temporarily during CI surgery and the possibility to record AEPs in the course of several days after implantation. Intraoperatively, auditory brainstem responses were recorded, whereas various kinds of AEPs were recorded postoperatively. After a few days the epidural electrodes were removed. Main results. Data sets of ten subjects were obtained. Invasively recorded potentials were compared subjectively and objectively to clinical standard recordings using surface electrodes. Especially the cortical evoked response audiometry depicted clearer N1 waves for the epidural electrodes which were also visible at lower stimulation intensities compared to scalp electrodes. Furthermore the signal was less disturbed by artifacts. The objective quality measure (based on data sets of six patients) showed a significant better signal quality for the epidural compared to the scalp recordings. Significance. Altogether the approach revealed to be feasible and well tolerated by the patients. The epidural recordings showed a clearly better signal quality than the scalp recordings with AEPs being clearer recognizable. The results of the present study suggest that including epidural recording electrodes in future CI systems will improve the everyday life applicability of auditory closed loop systems for CI subjects.

EEG-based diagnostics of the auditory system using cochlear implant electrodes as sensors

“…Early responses such as the EABR are useful as they reflect low-level neural processing of sound in the brain, but they do not correlate well with higher-level auditory functions such as speech understanding. Haumann et al 24 placed epidural electrodes over the auditory cortex during an otherwise conventional CI surgery. Three extra holes were drilled through the skull down to the dura.…”

“…Furthermore, the clinical software used in these studies is not designed for such recordings, requiring manual adjustment of recording parameters for every repetition, rendering this method impractical and time-consuming. Other studies have demonstrated the recording of neural responses to electrical stimulation using (non-cochlear) implanted electrodes, for instance with a few epidural electrodes 24 or an intracranial electrode grid 25 placed during surgery. These methods are highly invasive and only appropriate for temporary use.…”

EEG-based diagnostics of the auditory system using cochlear implant electrodes as sensors

“…Early responses such as the EABR are useful as they reflect low-level neural processing of sound in the brain, but they do not correlate well with higher-level auditory functions such as speech understanding. Haumann et al [2019] placed epidural electrodes over the auditory cortex during an otherwise conventional CI surgery. Three extra holes were drilled through the skull down to the dura.…”

“…This renders the method of stitching together multiple recordings impractical and time-consuming. Some studies have demonstrated the recording of neural responses to electrical stimulation using (non-cochlear) implanted electrodes, for instance with a few epidural electrodes [Haumann et al, 2019] or an intracranial grid [Nourski et al, 2013] placed during surgery. These methods are highly invasive and only appropriate for temporary use.…”

Design and Implementation of High Performance PPSK demodulator in Biomedical Implant

“…In general, implants are contrived from the skin, bone, tissues &materials-metal/plastic/ceramic, insertion of nanometer scaled (nm) implant and generation of ionic potential stimulus from injected electrode array inside the human body through these kinds of the implant is challenging task. The best HYPACUSIS treatment implant is COCHLEAR IMPLANT (CI) [2] helps to impetus the auditory nerve directly by stimulating hair cells of the EAR. However, VLSI advanced technologies like CNTFET, FINFET, TFET makes the scaling of channel width rather than CMOS, leading to certain parametric variations (Power, Delay & Area) accordingly.…”