Neurostimulator Refractory Period Control for Side Effect Reduction
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Solution Overview
Problem
Implantable neurostimulators often cause unwanted side effects due to energy wastage and stimulation of non-target tissues, such as muscle contractions and hoarseness, as current electrical signals can propagate to nearby tissues during refractory periods, leading to inefficient therapy and discomfort.
Innovation Solution
An implantable medical device that applies a first electrical signal to induce action potentials in target nerves and a second signal during refractory periods to alter the refractory state of non-target tissues, either extending or shortening it to minimize side effects and enhance therapeutic efficacy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a first electrical signal is applied to induce action potentials in target axons, then therapeutic efficacy is improved, but non-target tissues are stimulated causing side effects and energy wastage
Solution Approach 1:
The patent applies a preliminary electrical signal during the absolute refractory period of non-target tissues before they can be stimulated by the main therapeutic signal. This preliminary action puts non-target tissues into a refractory state, preventing them from responding to subsequent therapeutic signals, thereby eliminating side effects while preserving therapeutic efficacy on target axons.
Solution Approach 2:
The patent converts the harmful effect of current propagation to non-target tissues into a beneficial mechanism by utilizing the refractory period phenomenon. By intentionally inducing a refractory state in non-target tissues through a preliminary signal, the patent transforms what would normally be unwanted stimulation into a protective mechanism that prevents side effects.
2Reliability
If electrical signals are provided continuously to maintain therapy, then therapeutic effect is maintained, but energy consumption increases and non-target tissues remain susceptible to stimulation
Solution Approach 1:
The patent employs periodic electrical signals synchronized with the refractory periods of non-target tissues. By delivering therapeutic signals during specific time windows when non-target tissues are refractory, the system maintains continuous therapeutic effect while minimizing energy consumption and avoiding unnecessary stimulation of non-target tissues.
Solution Approach 2:
The patent ensures continuous therapeutic action on target axons by carefully timing signal delivery to coincide with periods when non-target tissues are refractory. This continuous useful action is achieved without interruption while preventing energy wastage on non-productive stimulation of non-target tissues.
3Object-generated harmful factors
If the refractory period of non-target tissue is extended to prevent side effects, then side effects are reduced, but the relative refractory period extension may interfere with additional therapies
Solution Approach 1:
The patent applies different signal characteristics to different tissue types: a preliminary signal is applied specifically to non-target tissues to extend their refractory period and prevent side effects, while the main therapeutic signal is applied to target axons at appropriate times. This local differentiation allows side effect reduction without interfering with additional therapies on target tissues.
Solution Approach 2:
The patent dynamically adjusts the timing and characteristics of electrical signals based on the refractory states of different tissues. By making the stimulation protocol adaptive and time-dependent, the system can extend refractory periods in non-target tissues to reduce side effects while maintaining the ability to deliver additional therapies to target tissues when appropriate.
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 solution effectively reduces unwanted side effects by maintaining non-target tissues in a refractory state, preventing further stimulation and improving the overall efficacy of neurostimulation therapy while minimizing energy wastage.
Implementation Method 1
The electrical signal generator applies a first electrical signal to a nerve to evoke an action potential. As a result, the nerve enters a refractory period in which the nerve is in a refractory state.
Implementation Method 2
During the refractory period, the electrical signal generator provides a second electrical signal to the nerve thereby altering the refractory period of the nerve.
Data Source
AI summary
In some embodiments, a method comprises providing an electrical signal to a nerve to evoke an action potential. The nerve thereby enters a refractory period in which the nerve is in a refractory state. The method further comprises, during the refractory period, providing an electrical signal to the nerve thereby altering the refractory period of the nerve or non-target tissues.