System Design And Experiment Research Of Nerve Signal Blocking Method Based On Antimissile Principle For Restraining Spasticity

Muscle spasm is a movement disorder that is caused by abnormal nerve discharge and has the characteristics of speed dependence,increased muscle tone,and spinal hyperreflexia.There are millions of patients with spasticity all over the world.How to treat spasticity safely and effectively has become a major medical problem that needs to be solved urgently.The current clinical treatment has shortcomings,such as the traditional Chinese medicine treatment has two-stage differentiation,the side effects of western medicine treatment,and the irreversible surgical treatment.Electrical stimulation blocking technology can quickly and reversibly block the conduction of nerve signals,thereby realizing the regulation of abnormal nerve activity.However,long-term direct current stimulation causes the nerve damage,and high-frequency electrical stimulation causes nerve excitement at the beginning of the block.The aim of the thesis is to find a novel technology for treating spasticity based on the anti-missile principle(anti-missile blocking can safely and reversibly block the conduction of nerve signals without causing nerve excitement).The thesis demonstrates the feasibility of inhibiting spasm from two routes of anti-missile block and body surface block,with a realrization of neural blocking system.The main research achievements are as follows:1)Different shapes of blocking waveforms are evalueated.According to the experimental results,the inverted triangular blocking waveforms with a sharp drop and a slow rise is chosen.By comparing the sciatic nerve signal blocking results of the toads and bullfrogs,bullfrogs were selected as experimental animals.Using two electrode configurations,the blocking threshold and minimum pulse width were measured on the bullfrog sciatic nerve and gastrocnemius muscle specimens.The results show that the blocking threshold and minimum pulse width measured when the anode of the blocking electrode is located at the distal end of the nerve are both smaller than the cathode of the electrode.The value measured at the distal end of the nerve,the blocking threshold and the diameter of the bullfrog sciatic nerve are highly negatively correlated,with a correlation coefficient of-0.95.Blocking the signal will not affect the signal conduction function of the nerve itself.The results of the blocking effectiveness show that the average maximum advance time of the stimulus signal relative to the blocking signal is 0.86 ms.For a signal with a fixed blocking pulse width,the blocking effective time is increased with blocking threshold.The blocking effect of the bidirectional symmetrical charge balance blocking waveform is unstable.Although the blocking effect of the asymmetric charge balance waveform is stable,the waveform is complicated.On the basis of the single-phase inverted triangle waveform,the related parameters of the biphasic asymmetric charge-balanced sawtooth wave and the biphasic asymmetrical charge-balanced ladder wave are studied.2)A blocking system is implemented and tected based on the anti-missile principle.The blocking system is composed of the detection and blocking electrodes,a nerve signal detection module,a nerve signal processing module,and a blocking signal generation module.The detection electrode adopts a three-point Cuff electrode.According to the diameter of the sciatic nerve for the toads and bullfrogs,the inner diameter of the electrode is set to 1 mm,which can effectively wrap the nerve to form a good contact surface.The blocking electrode is a needle-shaped double electrode made of platinum wire.The neural signal detection module has an adaptive amplifier,which effectively reduces the interference caused by the imbalance of the electrode input impedance.The neural signal processing module and the blocking signal generation module are controlled by the microcontroller STM32F103.The neural signal detection module records the detected signal to identify and judust the bloking signal.When an abnormal nerve signal is detected,the blocking signal generating circuit is triggered,which is adjusted and amplified by the driving circuit to output.The results show that the system can generate a blocking signal after detecting abnormal nerve signals at the proximal end of the bullfrog sciatic nerve and apply it to the distal end of the nerve to block the conduction of nerve signals.3)The influence of the diameter,spacing and placement method of the electrode is studied.The results show that in practical applications,the diameter of the electrode should be increased as much as possible,and the contact area between the electrode and the nerve should be increased,to obtain a smaller blocking threshold and ensure the efficiency and safety of nerve blocking.It is necessary to ensure that the electrode spacing is above3 mm,so that the entire nerve bundle is in the electric field,and the signal conduction on all nerve fibers is blocked more effectively.In addition,we innovatively discovered that when a dual electrode structure is used and placed laterally on both sides of the nerve bundle,it can also block the conduction of nerve signals.However,the contact area between the anode and the nerve of the electrode must be greater than the contact area between the cathode and the nerve,and the optimal width is 5mm.4)A rat spasticity model was prepared,and muscle spasm was inhibited by blocking the conduction of pathological nerve signals.In the experiment,9 thoracic spinal cords were completely transected in the rat,and the changes in the ratio of muscle excitation waveform caused by direct motor activation and Hoffman reflection wave(H/M ratio).Frequency-dependent characteristics before and after the modelingis measured.The muscle spastic EMG signal after modeling were quantified for the reliability of the rat spasticity model.After applying different parameters of blocking signals to the sciatic nerve of spastic rats,it was found that as the amplitude of the blocking signal increased,the effective blocking time and the blocking efficiency of the spasticity increased.Although the highest blocking efficiency in all experiments is 73%,it cannot completely inhibit muscle spasm,but the feasibility of inhibiting the corresponding muscle spasm by blocking pathological nerve signals has been verified.This study provieds a new technique for clinical treatment of spasm.5)Improved the dual-channel microelectronic myoelectric bridge system,increased the function of inhibiting spasm,and conducted experiments by stimulating the antagonizing muscles to inhibit spasm in healthy people.Based on the dual-channel limb movement device previously studied by our research group,the programing is modifiedby adding the function of suppressing spasm.When the system is in the anti-spasm mode,the system will first detect and identify the EMG signal at the upper limb flexor spasm via the ECG electrodes.When the spasm signal is found,the system will output a series of stimulation pulse sequences up to 4 s.The hydrogel electrode is applied to the spasm antagonist the muscle to activate the antagonist muscle and inhibit the spasm through the contraction of the antagonist muscle.Experiments were carried out on healthy humans simulating patients with spasticity.The results show that when the stimulation current intensity is higher than 7 m A,the human body will feel uncomfortable.When the stimulation current is less than 3 m A,the effect of suppressing spasticity is not obvious.Hence,the suitbale current intensity is between 5 to 6 m A to suppress the spasm with no discomfort.