ECAP Feedback Windows for High-Frequency Neurostimulation
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Solution Overview
Problem
High frequency electrical stimulation pulses mask evoked compound action potential (ECAP) signals, preventing effective control of stimulation parameters in medical devices, and existing ECAP feedback techniques are ineffective for high frequency systems.
Innovation Solution
A medical device pauses high frequency stimulation to sense ECAP signals, allowing for adaptive adjustment of stimulation parameters, and optionally delivers low frequency stimulation during pauses to elicit ECAP responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high frequency electrical stimulation is delivered continuously to provide therapeutic effect, then therapy delivery is maintained, but ECAP signals are masked and cannot be detected for parameter control
Solution Approach 1:
The system implements periodic interruption of high frequency stimulation trains to create detection windows. Each stimulation train is followed by an inter-train interval during which ECAP signals can be detected without masking from stimulation artifacts. This periodic action allows both continuous therapy delivery and periodic ECAP-based parameter optimization.
Solution Approach 2:
The system delivers a preliminary low frequency stimulation pulse before the high frequency train to elicit an ECAP signal that can be detected during the inter-train interval. This preliminary action provides the basis for parameter adjustment before the next high frequency train begins.
2Measurement precision
If ECAP feedback control is implemented to optimize stimulation parameters, then therapy precision is improved, but system complexity increases due to additional sensing and processing requirements
Solution Approach 1:
The sensing circuitry used for ECAP detection is integrated with the existing stimulation generator components. The same electrodes used for stimulation also serve as sensing electrodes, and the signal processing infrastructure is leveraged for both stimulation control and ECAP analysis, reducing overall system complexity.
Solution Approach 2:
The system implements closed-loop feedback by detecting ECAP signals during inter-train intervals and using this information to adjust stimulation parameters for subsequent trains. The feedback processing is integrated into the existing control architecture, allowing parameter optimization without proportionally increasing system complexity.
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
Enables effective closed-loop control of high frequency stimulation by using ECAP feedback for more targeted and efficient therapy delivery with reduced energy consumption.
Implementation Method 1
a characteristic value of a sensed ECAP can be employed to control titration of the amplitude of low frequency spinal cord neurostimulation (SCS) systems
Data Source
AI summary
Techniques are disclosed for implementing the use of electrically evoked compound action potentials (ECAPs) to adaptively adjust parameters of high frequency electrical stimulation. In one example, a medical device delivers electrical stimulation therapy comprising a train of electrical stimulation pulses to a patient, wherein the train of electrical stimulation pulses comprises a pulse frequency greater than or equal to 500 Hertz. After delivering the train of electrical stimulation pulses, the medical device ceases delivery of the high frequency electrical stimulation therapy for a predetermined period of time. During the predetermined period of time, the medical device senses an ECAP from the patient and determines, based on the sensed ECAP, a value of a parameter at least partially defining the train of electrical stimulation pulses. Responsive to the predetermined period of time elapsing, the medical device resumes delivery of the high frequency electrical stimulation according to the determined parameter.