Asymmetric Current Focusing in Cochlear Implants
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Solution Overview
Problem
Conventional auditory prostheses face challenges in controlling electro-acoustic interactions within the cochlea, where electrical stimulation can interfere with acoustic stimulation in lower frequency regions, potentially damaging remaining inner ear hair cells and affecting sound perception.
Innovation Solution
The use of asymmetric current focusing through multipolar channel configurations to create an electrical stimulation boundary within the cochlea, limiting the spread of current into apical regions and establishing a 'protected apical zone' with controlled voltage fields, thereby minimizing electro-acoustic interactions and preserving low-frequency hair cell function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrical stimulation is delivered to the cochlea via conventional monopolar channels, then high-frequency sound perception is achieved, but current spreads into apical regions causing electro-acoustic interactions that damage hair cells and degrade low-frequency acoustic hearing
Solution Approach 1:
The cochlea is segmented into distinct electrical and acoustic stimulation zones using a virtual boundary. The current weights are segmented such that apical electrodes receive negative current weights to cancel forward spread, while basal electrodes receive positive current weights for effective stimulation. This segmentation isolates the harmful electro-acoustic interactions to specific regions while preserving beneficial stimulation in other regions.
Solution Approach 2:
Asymmetric current weights are applied to electrodes based on their position relative to the virtual boundary. Apical electrodes receive negative current weights with different magnitudes than basal electrodes, creating an asymmetric current distribution that actively cancels forward spread into protected regions while maintaining effective stimulation at the target site. This asymmetry is key to controlling the spread of current in different directions.
2Reliability
If current weights are adjusted to limit current spread into apical regions, then hair cell protection is improved, but sound perception quality may deteriorate
Solution Approach 1:
Negative current weights are applied to apical electrodes in advance to preemptively counteract the forward spread of current from basal stimulation electrodes. This preliminary anti-action creates a protective effect that prevents harmful electro-acoustic interactions before they can damage hair cells, while the overall current distribution is optimized to maintain effective sound perception through the combined effect of all electrodes.
3Device complexity
If conventional current delivery methods are used, then device simplicity is maintained, but electro-acoustic interactions cause harmful effects in the cochlea
Solution Approach 1:
The current weights parameter is changed from conventional uniform or symmetric distribution to asymmetric distribution with negative values for apical electrodes and positive values for basal electrodes. This parameter change fundamentally alters the current spread pattern, creating a virtual boundary that confines current to desired regions while eliminating harmful electro-acoustic interactions, all within the existing cochlear implant device architecture.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances sound perception by reducing interference between electrical and acoustic stimulation, protecting residual hearing capabilities and improving sound localization and music appreciation by maintaining undisturbed acoustic temporal coding in apical regions.
Implementation Method 1
implantable auditory prostheses that stimulate nerve cells of the recipient's auditory system in other ways (e.g., electrical, optical and the like). Cochlear implants are often proposed when the sensorineural hearing loss is due to the absence or destruction of the cochlear hair cells
Implementation Method 2
determining current weights for at least one of the plurality of stimulation channels at a basal side of the electrical stimulation boundary, wherein the current weights are configured to for use in generating current signals for delivery to the cochlea via the at least one stimulation channel to evoke perception of one or more frequencies of a sound obtained at the auditory prosthesis while creating a protected apical zone at an apical side of the electrical stimulation boundary
Data Source
AI summary
Presented herein are techniques to control the spread of current beyond, in an apical direction, a predetermined location/point in the cochlea. As a result, the techniques presented herein create a protected apical zone at an apical side of the predetermined location for undisturbed acoustic temporal coding (i.e., an apical region of the cochlea in which the voltage fields from delivered current signals are nulled, minimized, or otherwise controlled in order to eliminate, reduce, or otherwise limit electro-acoustic interactions that could negatively affect remaining low-frequency hair cells).