JPH04503462A - Control of FNS fluctuation of response EMG - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Control of FNS fluctuation of response EMG Technical field The present invention relates to functional neuromuscular stimulation (FNS), and in particular to improved control of FNS. Regarding.

Background technology Upper motor unit undergoes spinal cord injury and undergoes FNS (functional neuromuscular stimulation) anesthesia Patients with paralysis and other paralyzed patients usually experience muscle fatigue within a shorter period of time; I have no feeling of fatigue because I am paralyzed. Furthermore, when FNS is used functionally, Depending on the purpose, patients may use a walker, cane, crutches, etc. to help them stand and walk. manual adjustment of FNS level and pulse width to compensate for fatigue. It cannot be reduced. This is because the times when such adjustments are necessary are This is because the patient is unable to turn his attention to anything else and move his hand elsewhere. .

The present inventors have previously worked on electrical stimulation of anesthetized patients.

References include the following:

[l] Kralj, A., Electrical stimulation of the lower limbs of spinal cord injury, B. Roku, Nato Advanced Studies Instrument.

On Spinal Chord Injury (Proc, Nat.

Advance 5tudies In5t, On 5pinal Cord Inkuries), Stoke Mandeville, England, 1981.

[2] Electric stimulation that gives functional use of the muscles of anesthesia patients Intense, meth, prog, tingle, (Med, Prog.

Tech, ), vol. 7, pp3-9.1989; [3] Liberson, W. , T., (Liberson, W., T.) and other fluctuations in the gait of hemiplegic patients. Phase-synchronized functional electrical stimulation of human nerves, arc, and width. Metho, (Arch , Phys, Med, ), Volume 92, pp101-105.1961; [4 [Graupe D,] Other basic walking machines for anesthesia patients Patient-Controlled Electrical Stimulation with EMG Signature Identification for Improving Functionality, Journal Biomdo, 22.

(Journal Biomed, Any,), Volume 5, pp220-226 ．． 1983゜[5] Grope Day, and Cohn, K. H. (Grau pe.

D, and Kohn, K, H,) vs. EMG-controlled electrical Critical Test of Stimulus, CRCCrlt, Rev, in Biomed.

Eng, vol. 15, pp187-210, March 1987; [6] Glo Graupe, D., System Identification, 2nd Edition Kriegs Pa. Publishing Company, (Kr ieges Publishing C O,)? Malabar, FL, 1976゜ Additionally, the inventor has a pending US patent application Ser. No. 014.389.

In Reference [5], the present inventor describes how, in the vicinity of an electrical stimulation location, the stimulation applied to that location Surface (transcutaneous) response EMG taken in response to electrical stimulation during the application of electrical stimulation. It was shown that the fatigue of stimulated muscles changes with the progression of fatigue. Furthermore, references [5 ], the anesthetized patient is fatigued until his knee is bent from the extended (standing) position. It also explains that there is no sense of its progress and therefore the person collapses. Ta. When the patient begins to collapse, the patient must again try to overcome fatigue in order to increase the stimulation level. Do not have time or ability to use your hands or fingers to increase the location of the stimulation pulse width I can't do it either. The best he can do is use his arms to hold himself in the walker and fall. The best thing to do is to prevent this. Thus automatically monitor muscle fatigue and overcome it Therefore, it is essential to adjust the stimulation automatically (rather than manually). This adjustment proposal The proposal is the subject of the inventor's US patent application Ser. No. 014.389. The above US patent In this application, this adjustment involves measuring, storing, and comparing successive peaks of the response EMG. and the onset of a given stimulus and the occurrence of a corresponding peak in the response EMG signal. It is based on remembering and comparing time intervals from If the peak is It is higher after considerable muscle fatigue occurs than immediately after a severe level adjustment.

In other cases, no peak forms at all before the onset of fatigue. Therefore, the present invention A condition in which no peak is considered or the highest peak does not necessarily occur before the onset of fatigue. A state without or a low peak includes a state that does not represent the progression of muscle fatigue.

Disclosure of invention Muscles stimulated by FNS emit EMG (electrical muscle movement) signals in response to the stimulation. It occurs in areas that are stimulated, even in paralyzed parts of the body. This response- EMG patterns change as muscle fatigue progresses. The present invention is a response-E Utilizes MG pattern recognition. In that case the parameters of the pattern are identified and the time Its fluctuations over time are a function of muscle fatigue progression. Taking advantage of this temporal variation, automatically adjust the FNS pulse width and/or pulse level to require patient attention. To compensate for fatigue using an automatic method that does not require any physical effort. Another embodiment of the invention is this pulse Recognition is used as a diagnostic tool and for muscle contractions that are different from standing or walking. provide the means.

The present invention relates to an upper motor neuron unit paired with anesthesia, consisting of certain quadraplegics (qu). adraplegics), especially for stake patients and cerebral palsy patients. It is effective for

According to the present invention, an improved functional neuromuscular stimulation (FNS) automatic control system and The method is based on the response produced by muscles in response to FNS - EMG (electrical muscle). motion) uses an action that responds to pattern variations in the signal.

Brief description of the drawing The invention will now be described with reference to illustrated embodiments.

Figure 1 shows a response-EMG controlled EFNS system coupled to a patient. This is a diagram.

Figures 2(a) and 2(b) are representative responses of the FNS-stimulated rotator femoral muscle, respectively. FIG. 2 is a diagram showing two patterns of PONSE-EMG signals.

Figures 3(a) and 3(b) show the response-EMG waveforms before and after fatigue, respectively. It is a diagram.

Embodiment of the invention Referring to Figure 1, a paraplegic patient IO has electrodes 21, 22, 23, 24 and a sensor. -31, 32, 33, 34, and these are (female) leg 12. Electrodes 21, 22, 23, 24 are electrical leads, respectively. 41.42.43.44 to the FNS stimulator 40. sensor 3I, 32, 33, 34 are attached to the patient's leg I2, for example by electrode gel, and each EMG pattern recognition subsystem 60 via leads 61.62.63.64 is combined with

Sensors 31-34 are connected to the EMG pattern recognition subsystem 60. Sponsor - Provides an EMG signal. The EMG pattern recognition subsystem 60 will be described later. Analyzes the response-EMG signal as shown in FIG. outputting a first control signal 66 coupled to the first control signal 66; The FNS level/pulse width controller 50 is a second control signal coupled to the FNS stimulator subsystem 40 in response. Outputs 55. FNS stimulator subsystem 40 outputs from FNS controller 50. FNS signal output automatically in response to second control signal 55 as 41.42.43 ．． 44 level and/or pulse width.

FIG. 1 shows a functional neuromuscular stimulation system. FNS electrodes 21-24 should be stimulated Attach to the skin near the muscles. FNS stimulation subsystem includes FNS electrodes 21 to 24 selectively output FNS stimulation signals 41-44 coupled via leads 41-44 to Output to. EMG electrodes 31-34 are responsive to the FNS stimulation subsystem. - coupled near the muscle to be stimulated to sense EMG signals. E.M. The G-pattern recognition subsystem recognizes multiple responses - EMG signals over the entire period. Selectively analyze and respond to predefined steps of changes in the pattern of the EMG signal FNS control signals 61-6 in response to recognized deflection exceeding a threshold level. 4 is selectively supplied via electrical leads 61-64. In this case, for the entire period The pattern changes after the initial application of FNS stimulation and with each successive readjustment of FNS stimulation. change to the EMG pattern within a specified small time interval after each change.

The FNS regulatory subsystem may, for example, adjust the EMG pattern to prevent fatigue. FN in response to changes over time in the EMG pattern recognized by the recognition means. Adjust the S stimulation signal.

FNS and EMG electrodes are preferably attached to the surface of the skin using, for example, an electrode gel. . However, FNS and EMG electrodes can alternatively be implanted below the skin surface. Ru. Pattern recognition shows stimulation levels versus arbitrary times after fatigue begins to take effect. The response between those voltage values at the discontinuous time immediately after the adjustment of the corresponding value − The response obtained at the EMG electrode - over a predetermined number of points of the EMG voltage vs. time signal. This can be done by measuring the spatial differences in All time scales are a series of The time instant t of the onset of each stimulus during the FNS stimulation. 2 compared in this case Each possible point in a pattern is the same distance from the time instant of the starting point of each pattern. It's in a remote area. As an alternative method to the above, it is possible to consider the difference in location (rather, the difference in area is the EMG pattern). It can be considered as a selected pattern to be analyzed as well.

Many other systems can be constructed with the techniques of the present invention. Implementation of the invention The method is as follows.

FNS electrodes are attached to the patient's legs and coupled to the FNS stimulator subsystem. The above service The system periodically outputs electrical stimulation. Attach the EMG electrode to the patient's leg, Coupled to EMG pattern recognition subsystem. This subsystem responds to − Analyzing the EMG signal and selectively outputting FNS application control signals in response.

The FNS stimulator subsystem outputs stimulation signals to the FNS electrodes. This FNS electrode is altered in response to the control signal to prevent patient fatigue.

The EMG signal is sensed from the stimulated muscle as a response-EMG signal. Re Sponsor - the dynamic pattern of the EMG signal is monitored repeatedly over the entire period; be analyzed. A finite set of patterns that can be related to patterns and exhibit fatigue properties. Parameters are analyzed. at least one of said parameters is expected to represent fatigue. When the control signal has a large change above the minimum value, the FNS stimulator subsystem Modify the FNS stimulation coupled to the FNS electrodes to prevent fatigue. Do it like this. A finite set of parameters is the minimum that matches the response-EMG signal. It can be determined according to a squared polynomial. This formula is described in the background section of the invention. It is stipulated in Chapter 5 of Reference [6].

A finite set of parameters is determined by a transfer function that fits response-EMG. be done. In this case, the response-EMG is considered an impulse response.

The transfer function becomes the inverse Laplace transform calculated for the impulse response. Before The impulse response is the EMG voltage vs. time response - EMG pattern. This starts at the moment of time when the stimulation impulse is applied by the stimulator.

As another example, a finite set of parameters may be used to determine the response over the entire period - EM can be determined by analyzing the deviation of the G pattern from its average . Alternatively, a finite set of parameters may analyzing the response-EMG signal by analyzing the difference between the two ends; It can be determined by

In accordance with the present invention, an improved system and method provides a cane, walker or elbow crutch support. FNS response of anesthetized patients standing up or walking with support - EMG control By doing this, you can overcome the loss of balance that accompanies muscle fatigue.

The importance of such control in paraplegic patients is clear. This is because paraplegic patients have muscular This is because there is no feeling of physical fatigue. Muscle fatigue has already caused loss of balance regarding original bending. Adjust FNS level or pulse width to enhance stimulation when lost It is too late for the patient. Furthermore, during loss of balance, the patient Removing hands from walker or crutches to adjust FNS level or pulse width and cannot divert his attention to make such adjustments.

The use of EMG control of FNS has also been previously proposed. stimulated in that way The EMG signals emanating from the muscles (or "response-EMG") are used. in this case , the first or second peak of the EMG signal is used. However, the value of this peak is The shape of EMG varies from patient to patient. However, in the present invention, in all cases Sponsor - EMG dynamic patterns change. Therefore, in the present invention, this EMG Pattern identification is performed using a finite set of patterns, Pl...Pn, and fatigue The progression is made by repeatedly motoring these parameters over the entire period. Determined by At least one important parameter is the minimum percentage of the appointment. When FNS levels and/or pulse widths change beyond the This is considered to be at a level that requires an increase.

For example, pattern recognition is based on the parameters of a least squares polynomial that fits the EMG pattern. or by an adapted transfer function. Recognition is between patterns (i.e. (between patterns before or during muscle fatigue), and the recognition of differences is based on comparison. For consecutive points starting at the time of each stimulus application to give a time reference for Responses as shown in Figures 2(a) or 2(b) obtained before and during muscle fatigue. - Directly by measuring the local differences between the front and middle of the EMG curve be able to.

■ In the example, this relates to the deviation of the pattern from its average.

In the simplest case, the response before and during fatigue - the area under the EMG pattern. You can think of the difference between them in this way.

According to the invention, specific parameters of the response EMG area rather than the peak is used.

If we use the response EMG area, its integral value over the entire period will be (it always decreases, so the change is unidirectional) ). These results are shown in the example shown in Figure 2 and have been experimentally measured over several years. It's been coming.

Therefore, peaks in the EMG signal may lead to completely incorrect conclusions regarding fatigue. Although there are many cases, the response ~ EMG area (integral over the entire period) is always the correct conclusion. give rise to an argument.

Response-Since both the EMG area and peak are between 1=0 and t=t0, It is worth noting that the measurement is not from time 1 = 0, but from t”’t o. That is. We have nothing more than an artificial configuration of stimuli and a response - EMG. It's not a thing.

In Figure 3(a), the highest value of response-EMG after E = t is no peak at all. The local maximum value (local peak) in Figure 3(a) is not the same as the peak in Figure 3(b). It is below the ku.

The present invention utilizes changes in pattern recognition parameters rather than maxima or peaks. It is something. In the case of the present invention, changes in specific pattern recognition parameters or changes in area is the factor that determined fatigue. In the present invention, the area or pattern recognition parameter data does not require a non-fatiguing response EMG peak (reaching a maximum). death However, when considering areas, they are always at their maximum in the non-fatigued state (only There is no need to do so). Other pattern recognition parameters are not necessarily optimal in the non-fatigue state. Although it is not very large, it can be used in the present invention.

In all cases, the controller detects that the pre-fatigue pattern is either immediately after the first switch of stimulation or Response-EMG pattern obtained immediately after increase in stimulation level (Second (a) , 2 (solid line in Figure 2(b)), but the EMG pattern during fatigue (the solid line in Figure 2(b)) 2 (a), 2 (b) (dashed line) is the arbitrary record at the same electrode location after an arbitrary time. It is considered to be a sponse-EMG pattern. All patterns are EMG voltage It is compared as a pattern over time. Here the time is the stimulation pulse produced by the stimulator. Measured starting from j''t o which is started or restarted.These Stimuli were applied at consecutive time intervals varying from 20 to 50 msec It will be opened.

Figures 2(a) and 2(b) show the sensor 31 in the rotator femoral muscle stimulated by FNS. Two typical response-EMG signal waveforms sensed by ~34 are shown. Many Many other waveforms may also occur. The first peak of each waveform represents the artifactual configuration of the FNS stimulus. vinegar. The solid waveform represents the response-EMG pattern under non-fatigue conditions. dashed wave The shape represents the progression of muscle fatigue state measured at later times.

These are sensed and utilized by the present invention as described above.

Although various embodiments have been described, the present invention is not limited to the above embodiments. Various modifications can be made within the scope of the invention.

Copy and translation of written amendment) Submission (Article 184-7, Paragraph 1 of the Patent Act) May 2, 1991 8th day

Claims (21)

[Claims] 1. FNS electrodes (21, 22, 2) for coupling to the skin near the muscles to be stimulated 3, 24) and selectively outputting an FNS stimulation signal coupled to the FNS electrode. an FNS stimulation means (40) and a response-EMG in response to said FNS stimulation means; a stimulus-response for coupling near said muscle to be stimulated in order to sense the signal; S-EMG electrodes (31, 32, 33, 34) and multiple response EMG signals. In order to analyze and the response - predefined changes in the pattern of the EMG signal. the FNS control signal in response to a recognized deflection that exceeds a set threshold level. EMG pattern recognition hand to recognize fatigue patterns for selective delivery step (60), said variation of said pattern over a period of time being an EMG reference pattern. The EMG reference pattern changes after the initial application of FNS stimulation and after the FNS stimulation. EMG patterns within a specified small time interval after each successive readjustment of NS stimulation. and further by said EMG pattern recognition means to prevent fatigue. said pattern recognition hand responsive to changes in the recognized EMG pattern over time; FNS adjustment means (10) for automatically adjusting the FNS stimulation signal in response to a step; A system characterized by: 2. 2. The FNS electrode according to claim 1, wherein the FNS electrode is for coupling to the surface of the skin. system. 3. the FNS and EMG electrodes are for implantation below the surface of the skin; The system of claim 1. 4. 2. The EMG electrode according to claim 1, wherein the EMG electrode is for coupling to the surface of the skin. system. 5. 2. The EMG electrode according to claim 1, wherein the EMG electrode is for implantation below the surface of the skin. The system described. 6. The adjusting means adjusts the FNS signal by adjusting the FNS stimulation pulse width. 2. The system of claim 1, wherein the system is configured to: 7. The adjusting means adjusts the FNS signal by adjusting the FNS stimulation amplitude. 2. The system of claim 1, wherein the system is configured to: 8. Pattern recognition measures stimulation level vs. that after any time fatigue begins to take effect. The response between those voltage values at discrete points in time immediately after the adjustment of the value corresponding to −EM Response obtained at the G electrode - field at a given number of points of the EMG voltage versus time signal This is done by measuring local differences, all on a time scale, for each individual within a series of FNS stimuli. At the moment of stimulus onset time, there is also no thought during the two patterns being compared. 2. Each point in the pattern is at the same distance from the instant in time of the starting point of each pattern. system. 9. Pattern recognition measures stimulation level vs. that at any time after fatigue begins to take effect. The response between those voltage values at discrete points in time immediately after the adjustment of the corresponding values - EMG Response obtained at the electrode - area difference at a given number of points of the EMG voltage versus time signal All time scales are for each stimulus within a series of FNS stimuli. associated with the moment of time of onset and each possible during the two patterns being compared. A system according to claim 1, wherein the points are at the same distance from the instant in time of the starting point of each pattern. stem. 10. Electrically stimulates the selected muscle and produces a response from the stimulated muscle. Senses EMG signals and responds - dynamic patterns of EMG signals over the entire period Iteratively monitors and analyzes a finite set of parameters associated with the pattern. If at least one of the above parameters exceeds the expected minimum value, detecting when there is a change and adjusting the electrical stimulation in response to the detection. Features a functional neuromuscular stimulation method. 11. The finite set of parameters is the minimum two that fit the response-EMG signal. 11. The method according to claim 10, wherein the method is determined according to a multiplicative polynomial. 12. The finite set of parameters is a transfer function that fits the response-EMG. In this case the response-EMG is considered as a pulse response and the previous The transfer function starts at the instant of time when the stimulation impulse is applied by the stimulator, EMG voltage vs. time response - EMG pattern impulse response 11. The method of claim 10, resulting in an inverse Laplace transform calculated for . 13. The finite set of parameters determines the response-EMG pattern over the entire period. as claimed in claim 10, wherein the Method. 14. means for selectively and controllably electrically stimulating selected muscles; Means for sensing response-EMG signals from stimulated muscles and response-E means for repeatedly monitoring and analyzing the dynamic pattern of the MG signal over its entire duration; , means for identifying a finite set of parameters associated with said pattern; Detect when one of the parameters changes significantly beyond a predetermined minimum value. means for preventing fatigue of the stimulated muscle in response to the detecting means; uni, a functional device characterized by comprising means for automatically changing the electrical stimulation; Transmuscular stimulation system. 15. The finite set of parameters is a minimum of two that fit the response-EMG signal. 15. The system of claim 14, wherein the system is determined according to a multiplicative polynomial. 16. The finite set of parameters is a transfer function that fits the response-EMG. In this case, the response-EMG is considered to be an impulse response. , the transfer function starts at the instant of time when the stimulation impulse is applied by the stimulator. EMG voltage vs. time response - Impulse response, which is an EMG pattern 15. The method of claim 14, resulting in an inverse Laplace transform calculated for the 17. The electrical stimulation has a definable electrical characteristic of voltage level, duration and time interval. the means for changing further comprises a plurality of pulses having a Claim 1 comprising means for responsively changing at least one said electrical characteristic. 4. The system described in 4. 18. The means for identifying further comprises identifying selected parameters of the response-EMG signal. means for selecting a signal characteristic that varies voltage versus time as a meter, said characteristic being change in a detectable manner to indicate the nature of the muscle fatigue state of the stimulated muscle; 15. Further, the means for detecting is responsive to the selected parameter. The system described. 19. response-EMG signal for coupling close to and from said muscle; EMG electrodes for sensing and multiple response - selectively analyzing EMG signals. and the response--a predefined pattern of changes in the pattern of the EMG signal. selectively providing a control signal in response to perceived deflection that exceeds a threshold level; EMG pattern recognition means for supplying the is the response-EMG pattern within a specified small time interval after the initial time. Diagnostic neuromuscular system characterized by changes to the tone. 20. Pattern recognition shows the initial time reference versus an arbitrary time after fatigue begins to take effect. The response between those voltage values at a discontinuous point immediately after the value corresponding to that of The field at a predetermined number of points of the response-EMG voltage vs. time signal obtained at the G electrode. This is done by measuring local differences, where all time scales are relative to the moment of time of onset. , and each possible point in the two patterns being compared is the starting point of each pattern. 20. The system of claim 19, being at the same distance from an instant in time. 21. Pattern recognition shows the initial time reference versus an arbitrary time after fatigue begins to take effect. The response between those voltage values at discrete points in time immediately after the adjustment of the corresponding value of - the response obtained at the EMG electrode - at a predetermined number of points of the EMG voltage vs. time signal; This is done by measuring the area difference between the each possible point in the two patterns being compared is the start of each pattern. 20. The system of claim 19, wherein the points are at the same distance from the instant of time.