Cochlear Implant Fitting via Efferent Nerve Masking
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Solution Overview
Problem
Current cochlear implant fitting methods rely heavily on subjective measures, which are inadequate for uncooperative patients or those with limited expressive language skills, and lack precise objective physiological measures for determining patient-specific operating parameters, leading to potential loud perception issues.
Innovation Solution
A frequency matching system that objectively measures patient-specific operating parameters by using contralateral stimulation to mask efferent nerve fibers, allowing for the determination of the optimal stimulation location on the cochlear implant, which is then verified by switching roles and repeating the stimulation process, thereby adjusting processing parameters for improved fitting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If subjective response measures are used for cochlear implant fitting, then the fitting process can be performed with simple measurement methods, but the measurement precision is insufficient for uncooperative patients or those with limited expressive language skills
Solution Approach 1:
The patent replaces subjective behavioral measurement methods with objective electrophysiological measurement methods. Specifically, it uses electrically evoked compound action potentials (eCAP) and electrically evoked stapedial reflex (ESR) to objectively assess auditory nerve response, eliminating the need for patient subjective responses while achieving precise measurement of fitting parameters
Solution Approach 2:
The patent introduces intermediate physiological responses (eCAP and ESR) as mediators between the electrical stimulation and the final fitting parameters. These intermediate measures serve as objective proxies that bridge the gap between stimulation delivery and parameter determination, allowing precise measurement without direct patient participation
2Device complexity
If conventional eCAP measurement methods are used without contralateral masking, then the measurement process is simple, but the eCAP signal voltage is too high leading to loud perception issues
Solution Approach 1:
The patent converts the harmful effect of efferent nerve fiber activation (which causes loud perception) into a beneficial masking mechanism. By applying contralateral stimulation to activate efferent fibers, the system creates a masking effect that reduces the perceived loudness of the test stimulation, transforming a harmful side effect into a useful tool for accurate threshold determination
3Measurement precision
If contralateral stimulation is applied to mask efferent nerve fibers, then the eCAP signal voltage is reduced improving measurement accuracy, but the device complexity increases
Solution Approach 1:
The patent makes the cochlear implant system multi-functional by enabling it to deliver both test stimulation and contralateral masking stimulation. The same implant device performs multiple functions: delivering the primary electrical stimulus to the cochlea, recording the eCAP response, and delivering contralateral stimulation to activate efferent masking pathways, thereby reducing the need for separate specialized equipment
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 method enables more accurate and objective fitting of cochlear implants by reducing eCAP signal voltage through contralateral masking, resulting in a more precise adjustment of stimulation parameters, reducing loud perception and improving auditory perception for patients.
Implementation Method 1
the fluid-filled cochlea 104 functions as a transducer to convert mechanical motion and energy and, in response, to generate electric pulses which are transmitted to the auditory nerve 113
Implementation Method 2
auditory prostheses that have been developed, such as cochlear implants, brainstem-implants, midbrain-implants or cortical implants, that electrically stimulate auditory nerve tissue with small currents delivered by multiple electrode contacts
Implementation Method 3
using contralateral stimulation to mask efferent nerve fibers, allowing for the determination of the optimal stimulation location on the cochlear implant
Data Source
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AI summary
A system for frequency matching a cochlear implant during fitting includes a tissue stimulation device configured to generate a tonal stimulus to mask efferent nerve fibers in a subject, one or more response measurement contacts configured to measure CAP signals during and outside of a refractory period, a frequency matching module in communication with the response measurement contacts and configured to receive the CAP signals during and outside of the refractory period to determine a stimulation location on the cochlear implant based on a comparison of the received CAP signals both during and outside of the refractory period, and a parameter adjusting module in communication with the frequency matching module and configured to interface with the cochlear implant and to adjust its processing parameters based on the stimulation location. Methods for frequency matching a cochlear implant during fitting are also disclosed.