ECAP-Servoed Neuromodulation Control Policy
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Solution Overview
Problem
The distance between implanted electrodes and target nerves changes due to patient movements, affecting neural recruitment and the efficacy of electrical stimulation therapy.
Innovation Solution
A system that determines the type of movement-based aggressor and uses evoked compound action potential (ECAP) signals as feedback to adjust stimulation parameters, such as frequency, amplitude, pulse width, and pulse shape, to maintain effective therapy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical stimulation is delivered via implanted electrodes, then therapeutic effect is achieved, but the distance between electrodes and target nerves changes due to patient movements, affecting neural recruitment and therapy efficacy
Solution Approach 1:
The system measures ECAP signals in real-time to detect changes in electrode-nerve distance caused by patient movements. Based on these measurements, the control system automatically adjusts stimulation parameters (amplitude, pulse width, frequency) to compensate for distance changes and maintain consistent therapeutic effect. This closed-loop feedback mechanism resolves the contradiction by making the system adaptive to positional variations.
Solution Approach 2:
The patent implements dynamic adjustment of stimulation parameters based on real-time ECAP measurements. Instead of using fixed stimulation settings, the system continuously adapts the electrical stimulation characteristics in response to detected changes in electrode-nerve distance, thereby maintaining reliable therapy efficacy despite mechanical instability.
2Measurement precision
If control stimulation pulses with shorter pulse width or lower frequency are delivered to detect ECAP signals, then ECAP detection is enabled, but these pulses may not contribute to therapeutic effect
Solution Approach 1:
The system alternates between delivering control stimulation pulses (optimized for ECAP detection) and informed stimulation pulses (optimized for therapeutic effect). By periodically switching between these two pulse types, the system enables accurate ECAP measurement while maintaining overall therapeutic benefit through the informed pulses that occur during other time periods.
Solution Approach 2:
The patent delivers control pulses with parameters specifically optimized for ECAP detection, even though these pulses provide minimal therapeutic effect individually. This partial action on therapy is acceptable because the primary purpose of these pulses is measurement, and the overall therapeutic effect is maintained through the combination of multiple control and informed pulses delivered over time.
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
The system ensures consistent therapeutic effects by dynamically adjusting stimulation parameters in response to changes in electrode-nerve distance caused by patient movements, thereby minimizing discomfort and maintaining treatment efficacy.
Implementation Method 1
receive, from a sensing electrode located at a target region of a patient, a plurality of evoked compound action potential (ECAP) signals elicited from respective electrical stimuli delivered to the patient
Data Source
AI summary
Systems, devices, and techniques for adjusting electrical stimulation are described. For example, processing circuitry is configured to receive, via a sensing electrode located at a target region of a patient, a plurality of evoked compound action potential (ECAP) signals elicited from respective electrical stimuli delivered to the patient; determine, based on the plurality of ECAP signals, an aggressor category for at least some ECAP signals of the plurality of ECAP signals, the aggressor category determined from a plurality of aggressor categories; determine, based on the aggressor category, a set of control policy parameters that at least partially define closed-loop control of stimulation therapy; and controlling delivery of the stimulation therapy according to at least the set of control policy parameters and one or more subsequent ECAP signals.