Anode Guard Electrode Placement for Spinal Cord Stimulation
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Solution Overview
Problem
Implantable electrical stimulation systems face challenges in effectively stimulating the spinal cord due to cerebrospinal fluid shunting electrical current to dorsal roots, leading to uncomfortable sensations and reduced therapeutic efficacy, especially when the fluid thickness varies along the spinal cord.
Innovation Solution
The method involves identifying and calculating the placement of anode guard electrodes relative to cathode electrodes, taking into account the estimated thickness of cerebrospinal fluid at the vertebral level to steer the stimulation current away from dorsal roots, thereby increasing the range of therapeutic current delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical stimulation is delivered through the spinal cord, then therapeutic effect is achieved, but cerebrospinal fluid shunts current to dorsal roots causing uncomfortable sensations
Solution Approach 1:
The patent applies local quality by varying the electrical stimulation parameters (current amplitude, pulse width, frequency) across different electrode contacts at different vertebral levels. The system adjusts stimulation characteristics locally at each segment of the spinal cord to account for varying cerebrospinal fluid thickness and anatomical differences, thereby delivering effective therapy while minimizing unwanted dorsal root stimulation in specific regions.
Solution Approach 2:
The patent implements dynamics by making the stimulation system adjustable and adaptable in real-time. The programmable pulse generator allows dynamic modification of stimulation parameters, electrode configurations, and active contacts based on patient response and therapeutic needs. This dynamic adjustment enables the system to optimize therapeutic effect while reducing uncomfortable sensations as conditions change.
2Reliability
If higher current is used to overcome shunting and achieve therapeutic stimulation, then spinal cord stimulation effectiveness improves, but unwanted dorsal root stimulation increases
Solution Approach 1:
Rather than uniformly increasing current across all electrodes, the system applies local quality by adjusting current amplitude and distribution specifically at electrodes positioned near regions with thinner cerebrospinal fluid. This targeted approach allows sufficient current to reach the spinal cord in problematic areas without excessively increasing overall current that would amplify dorsal root stimulation throughout the entire implant.
Solution Approach 2:
The patent uses intermediary approaches by employing multiple electrode contacts and configurable stimulation patterns that act as mediators between the current source and the spinal cord. The system can selectively activate specific electrode combinations to create optimized current paths that favor spinal cord stimulation while diverting or reducing current flow toward dorsal roots, effectively mediating the conflicting stimulation goals.
3Reliability
If electrode placement is optimized for spinal cord stimulation, then therapeutic benefit increases, but system complexity increases due to need for precise vertebral level identification and CSF thickness measurement
Solution Approach 1:
The patent applies preliminary action by pre-programming the pulse generator with multiple electrode configurations and stimulation patterns before implantation. The system includes pre-established parameter sets that can be selectively activated based on the implantation site and patient needs, reducing the complexity of real-time programming and optimization during and after the surgical procedure.
Solution Approach 2:
The system implements self-service through its programmable architecture that allows for autonomous adjustment and optimization of stimulation parameters. The pulse generator can be programmed to automatically select appropriate electrode contacts and parameters based on stored configuration data, reducing the need for continuous manual intervention and complex real-time adjustments by clinicians.
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 therapeutic efficacy of spinal cord stimulation by reducing unwanted stimulation of dorsal roots and expanding the range of effective stimulation current, improving patient comfort and treatment outcomes.
Implementation Method 1
cerebrospinal fluid shunting electrical current to dorsal roots
Implementation Method 2
estimated thickness of cerebrospinal fluid at the vertebral level
Data Source
AI summary
A method of stimulating a portion of a spinal cord of a patient includes identifying an arrangement of electrodes including a relative placement of each electrode within the arrangement; identifying a vertebral level for implantation of the arrangement and a position of the arrangement with respect to the spinal cord; determining by calculation, for a selection of at least one cathode from the electrodes, at least two anode guard electrodes from the electrodes including in the calculation an estimated thickness of cerebrospinal fluid at the vertebral level; and stimulating the portion of the spinal cord of the patient at the vertebral level using the at least one cathode and the at least two anode guard electrodes.