Triphasic Pulses Reduce Somatic Side-Effects in Cochlear Implants

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Solution Overview

Problem

Cochlear implant systems experience undesired somatic effects such as facial nerve stimulation due to collateral stimulation, limiting the intensity of auditory sensation and potentially rendering the implant unusable, as existing solutions focus on extra-cochlear electrodes and do not effectively mitigate these effects using triphasic pulses.

Innovation Solution

Adopting charge-balanced triphasic electrical stimulation pulses with inter-phase gaps or forming triphasic pulses from consecutive biphasic pulses of opposite polarity to reduce unwanted somatic responses, applied sequentially or in parallel to stimulation electrodes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If biphasic stimulation pulses are used to provide auditory sensation, then hearing function is restored, but unwanted somatic effects such as facial nerve stimulation occur due to collateral stimulation

Engineering Contradiction:

Improvehearing functionVSAvoidsomatic effects

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The stimulation pulse is divided into three phases instead of two: a first phase with first polarity, a second phase with second polarity (opposite to first), and a third phase with first polarity. This segmentation allows the first and third phases to stimulate the auditory nerve while the second phase counteracts unwanted somatic effects, effectively separating the useful auditory stimulation from harmful collateral stimulation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention changes the temporal parameters of the stimulation pulse by introducing a specific pulse width ratio between phases. The first and third phases have a combined pulse width that is greater than the second phase, creating a charge-balanced triphasic waveform where the area under the curve for phases of the same polarity exceeds the opposing phase, thereby reducing somatic effects while maintaining auditory sensation.

Inventive Principle:

Principle #35Parameter changes

2Illumination intensity

If stimulation intensity is increased to improve hearing sensation, then auditory perception improves, but unwanted side-effects increase in intensity

Engineering Contradiction:

Improveauditory sensation intensityVSAvoidside-effects intensity

Core Design Contradiction:

Illumination intensityVSObject-affected harmful factors

Solution Approach 1:

By segmenting the stimulation into three phases with the middle phase having opposite polarity, the invention allows intensity increase for better hearing while the second phase actively counteracts the somatic effects that would otherwise intensify proportionally with the overall stimulation level.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The second phase with opposite polarity converts the harmful somatic effects into a beneficial counteracting force. The unwanted somatic stimulation caused by the first and third phases is neutralized by the second phase, allowing higher overall intensities to be used for improved hearing without proportional increase in side effects.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Object-affected harmful factors

If stimulation electrodes are deactivated to eliminate side-effects, then unwanted somatic responses are reduced, but hearing quality deteriorates due to loss of stimulation coverage

Engineering Contradiction:

Improvesomatic responsesVSAvoidhearing quality

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The triphasic pulse structure allows all electrodes to remain active while the segmented pulse phases selectively target auditory nerve stimulation over somatic nerve stimulation, maintaining hearing quality without requiring electrode deactivation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

By changing the pulse waveform parameters to triphasic with specific width ratios, the invention maintains activation of all stimulation electrodes while the altered pulse characteristics selectively reduce somatic effects, preserving both hearing quality and reducing side effects simultaneously.

Inventive Principle:

Principle #35Parameter changes

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

Significantly reduces unwanted side-effects while maintaining desired loudness perception, making the cochlear implant more usable by minimizing collateral stimulation.

Implementation Method 1

charge-balanced triphasic electrical stimulation pulses to apply stimulation signals to one or more of the stimulation electrodes

Methodology Applied

Scientific EffectElectrical stimulation: Electric Field

Data Source

PatentEP3777963B1Triphasic pulses to reduce undesirable side-effects in cochlear implants

Publication Date: 2023.08.30 MED EL ELEKTROMEDIZINISCHE GERAETE GMBH

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AI summary

An arrangement for operating a cochlear implant system is described. Stimulation signals are applied to stimulation electrodes in a cochlear implant electrode with an initial signal format using biphasic electrical stimulation pulses. One or more undesired somatic responses to the stimulation pulses are identified. The one or more undesired somatic responses are reduced by selecting an adapted signal format using charge-balanced triphasic electrical stimulation pulses to apply stimulation signals to one or more of the stimulation electrodes.