Spatiotemporal Spinal Cord Stimulation via Multi-Electrode Arrays
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Solution Overview
Problem
Current spinal cord neuromodulation therapies lack spatial selectivity and temporal specificity, restricting their ability to effectively activate specific motor circuits and mimic the natural dynamics of motoneuron activation, which is crucial for restoring motor functions in individuals with spinal cord injuries.
Innovation Solution
A system comprising a signal processing device, an Implantable Pulse Generator (IPG), and a multi-electrode array that delivers spatiotemporally specific electrical stimulation to the spinal dorsal roots, using real-time feedback from neural, kinematic, and electromyography signals to adjust stimulation parameters and target specific spinal segments and roots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-specific epidural stimulation of the lumbar spinal cord is applied, then muscle activity is produced through recruitment of dorsal root afferents, but the spatial selectivity and temporal specificity required for precise motor control are lost
Solution Approach 1:
The stimulation system is segmented into multiple independently controllable electrode contacts arranged in a multi-electrode array. Each electrode can be activated separately to target specific spinal cord segments or dorsal root regions, enabling spatial selectivity without requiring a completely new device architecture. This segmentation allows precise targeting of affected circuits while maintaining system manageability.
Solution Approach 2:
The stimulation protocol transitions from static, continuous non-specific stimulation to dynamic, time-varying patterns. The system delivers stimulation in phase-locked bursts synchronized with the subject's movement cycle, with amplitude and timing adjusted in real-time based on feedback from motion sensors and EMG signals. This dynamic adaptation enables temporal specificity that mirrors natural motor control patterns.
2Productivity
If continuous non-modulated stimulation patterns are used, then spinal circuit excitability is raised, but the precise temporal sequencing required for coordinated limb movement cannot be achieved
Solution Approach 1:
The stimulation system employs periodic, rhythmically modulated bursts delivered at frequencies matching the subject's natural movement cycle. Each stimulation burst is time-locked to specific phases of the movement cycle (e.g., swing phase, stance phase), creating a periodic pattern that reinforces natural motor rhythms. This periodic action enables precise temporal sequencing of motor outputs across different muscle groups.
Solution Approach 2:
The system incorporates real-time feedback from motion capture sensors and electromyography (EMG) electrodes to detect the subject's actual movement phase and timing. This feedback is processed to dynamically adjust stimulation onset and offset timing, ensuring that stimulation is delivered at the precise moment needed to facilitate the intended movement phase. The feedback loop maintains temporal precision even as movement characteristics vary.
3Ease of operation
If stimulation is confined to single spinal cord regions based on empirical mapping, then implantation is simplified, but the ability to target spatially distributed motor circuits involved in coordinated movement is limited
Solution Approach 1:
The multi-electrode array is designed with a configuration that can serve multiple functions: it can stimulate single spinal segments, multiple adjacent segments, broad dorsal root regions, or specific lateralized pathways depending on which electrodes are activated. This universal design allows the same implant to address various injury patterns and motor deficits without requiring multiple different devices or complex repositioning procedures.
Solution Approach 2:
The system enables local quality control by allowing different stimulation parameters (amplitude, frequency, pulse width) to be applied to different electrode contacts simultaneously. This means that specific local regions can be targeted with optimized parameters tailored to the particular circuit being stimulated, while other regions receive different parameter settings or remain inactive, achieving spatially differentiated stimulation quality.
4Ease of manufacture
If non-specific stimulation protocols are applied, then clinical implementation is simplified, but the precision required to activate specific motor pools during different gait phases cannot be achieved
Solution Approach 1:
The system achieves precise spatiotemporal control by dynamically changing multiple stimulation parameters: spatial parameters (which electrodes are active), temporal parameters (timing relative to movement phase), and intensity parameters (amplitude, frequency). These parameter changes are coordinated based on real-time detection of movement phase, enabling precise targeting of specific motor pools at specific times without requiring complex custom protocols for each patient.
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 approach enhances the specificity and efficacy of motor control by precisely activating desired motor circuits, improving the quality and vigor of lower-limb movements, and facilitating the restoration of locomotor functions in subjects with spinal cord injuries.
Implementation Method 1
electrical neuromodulation applied to the dorsal aspect of lumbar segments primarily engages proprioceptive feedback circuits recruited by the stimulation of dorsal roots fibers
Data Source
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AI summary
The present invention refers to systems for selective spatiotemporal electrical neurostimulation of the spinal cord. In particular, it is an object of the invention a system comprising: a signal processing device receiving signals from the subject and operating signal-processing algorithms to elaborate stimulation parameter settings, operatively connected with an Implantable Pulse Generator (IPG) receiving stimulation parameter settings from said signal processing device and able to simultaneously deliver independent current or voltage pulses to one or more multiple electrode arrays; operatively connected with one or more multi-electrode arrays suitable to cover at least a portion of the spinal cord of said subject for applying to said subject a selective spatiotemporal stimulation of the spinal circuits and/or dorsal roots, wherein said IPG is operatively connected with said one or more multi-electrode arrays to provide a multipolar stimulation. Such system advantageously allows achieving effective control of locomotor functions in a subject in need thereof by stimulating the spinal cord, in particular the dorsal roots, with spatiotemporal selectivity.