Sub-perception Calibration via Time Domain Scaling
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Solution Overview
Problem
Current neuromodulation systems face challenges in accurately programming sub-perception fields for spinal cord stimulation due to patient-specific differences in electrode-tissue coupling and neural excitability, as patients do not provide real-time feedback for adjustments.
Innovation Solution
The use of space domain scaling and time domain scaling to compensate for patient-specific displacements and account for neural target and waveform properties, allowing for improved energy allocation to electrodes by determining time and space scaling factors based on properties like pulse width, frequency, and waveform shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sub-perception modulation energy is delivered to provide therapeutically effective modulation, then therapeutic effect is improved, but patient feedback availability deteriorates (patient does not perceive the delivery)
Solution Approach 1:
The system uses objective feedback metrics (ECAP thresholds, impedance measurements) to replace subjective patient feedback. By measuring the threshold at which evoked compound action potentials are perceived and using this as a scaling reference, the system achieves closed-loop control without requiring continuous patient subjective input, thus resolving the contradiction between delivering sub-perception therapy and maintaining feedback availability for programming.
2Device complexity
If energy allocation is standardized across patients, then device complexity is reduced, but patient-specific neural excitability differences cause deterioration in treatment precision
Solution Approach 1:
The system changes the scaling parameter from fixed standardized values to dynamic patient-specific values based on measured ECAP thresholds. The pulse amplitude is scaled as a function of the ratio between target ECAP threshold and baseline ECAP threshold, allowing customization to each patient's neural excitability while maintaining a straightforward programming interface that automatically applies these personalized parameters.
3Device complexity
If electrode-tissue coupling variations are ignored, then calibration complexity is reduced, but energy delivery accuracy deteriorates due to patient-specific displacements
Solution Approach 1:
The system performs preliminary calibration measurements during implantation or initial programming to establish baseline ECAP thresholds and impedance values for each electrode. These pre-measured parameters are stored and used as reference points for subsequent automatic scaling, eliminating the need for complex real-time adjustments while ensuring accurate energy delivery tailored to each patient's anatomical variations.
Data Source
AI summary
An example of a system to program a neuromodulator to deliver neuromodulation to a neural target using a plurality of electrodes may comprise a programming control circuit configured to determine target energy allocations for the plurality of electrodes based on at least one target pole to provide a target sub-perception modulation field, and normalize the target sub-perception modulation field, including determine a time domain scaling factor to account for at least one property of a neural target or of a neuromodulation waveform, and apply the time domain scaling factor to the target energy allocations.