FI130570B - Selective method for multi-channel measurement, and equipment for electromyographic analysis - Google Patents

Abstract

The invention is related to medical diagnostics and especially electromyographic measurement of muscle-nerve diseases. In electromyographic measurement, muscle cell membranes simultaneously produce signals that promote diagnostics and disturb them (21, 30, 130). In the measurement, the analysis of the voltage difference between the tip (11) and the stem part (12) of the measuring needle (10) is routinely used. In the method according to the invention, the voltage differences between the tip part (11), the stem part (12) and the skin surface (40) are separated by two channels (13, 41). By processing and analyzing these, the selectivity of the measurement can be improved and the share of disturbing transients (130) in the analysis results can be reduced.

Description

Method and equipment of selective multichannel measurement in electromyography research

FIELD OF THE INVENTION

The invention is related to medical diagnostic measurement, especially to measurements of the electrical properties of the muscle membrane needed for diagnostics in muscle-nerve diseases. —BACKGROUND OF THE INVENTION

The electrical properties of muscle cells are studied in medical diagnostics in electromyography (EMG, also electroneuromyography ENMG, in English electromyography). The electrical voltage fluctuations of the cell membranes are a few tens of microvolts or at most a few millivolts in the voltage of the muscle — inside the cell outside the needle electrode measurement. The interesting frequency range of voltage fluctuations is e.g. 5 — 3000 Hz and the duration of voltage transients is 10 microseconds — 20 milliseconds. The activity is monitored with a specially made medical device, called an electromyography device or EMG device. The EMG device consists of the so-called from the differential amplifier, — which can be one or more for one or more simultaneous measurement channels.

The signal is filtered in order to look at the interesting frequency range, a bandpass filter, e.g. 5-10,000 Hz. The device has a display unit with which the signal can be monitored visually. The display can be continuous or consist of selected periods.

Often, the signal is also converted to an audio signal, so that the frequency characteristics of the signal — can be monitored from the audio channel through the loudspeaker. When the device is used for clinical

For the ENMG study, an electric stimulator is also included, which is used to stimulate the peripheral nerves. With the help of the nerve and muscle responses produced by the stimulation, delays and action speeds can be determined. — Typically, in an EMG study, the electrical activity of muscle cells is monitored using a thin needle electrode. The electrode is then passed through the skin close to the muscle cells, inside the muscle. Muscle responses can also be measured using measuring electrodes attached to the surface of the skin. Needle measurement can be used to measure the function of a single or a few muscle fibers. Plate measurement is used to measure the activity of larger groups of cells and — especially electrical stimulation responses.

The measurement is performed both when the muscle is relaxed and during varying degrees of muscle tension.

A healthy, relaxed muscle does not produce electrical activity. As muscle tension increases, the amount of muscle electrical activity increases. In neuromuscular diseases, there are qualitative and quantitative abnormalities in these — functions.

One of the key points of the EMG study is to assess whether spontaneous electrical voltage fluctuations can be detected in muscle cell membranes, the so-called spontaneous activity, when the muscle is relaxed. This occurs as short transients lasting e.g. 20-100 msec, which — are called e.g. fibrillation and positive sharp wave. These phenomena arise after nerve or muscle tissue damage, when the cell membrane of a single muscle cell becomes electrically unstable. These are objective evidence that there is damage, disease or dysfunction in the neuromuscular system. The investigation of these functional disorders is central to the investigation of neurological neuromuscular diseases, i.e. neuromuscular diseases,

in diagnostics. The distribution of the occurrence of these transients also shows the distribution and nature of the aforementioned diseases.

In a routine EMG patient examination, the measurement often takes place in the so-called with a concentric needle electrode by placing the measuring needle between the muscle cells inside the muscle. Inside the needle is an insulated wire, the tip of which is not insulated and works as a so-called as an active measurement point. In the measurement, the insulated stem part of a needle that is about 0.3 - 0.5 mm thick and e.g. 20-50 mm long works as a so-called as a reference electrode, as a reference. The needle is therefore used to measure the voltage difference between the active and the reference contact surface. The needle material — (steel, platinum, plastic) and shape (thickness, sharpness) is suitable for observing electrical phenomena in tissues. Needles are disposable and cheap. The voltage variation measured through the needle is fed to the EMG amplifier described above, amplified and band-pass filtered from it to an interesting e.g. 5-10,000 Hz frequency range, which is monitored on a digital or analog display. The signal is listened to simultaneously — with the help of an audio amplifier. The differential amplifier also needs a ground signal, e.g. from a surface electrode glued to the surface of the skin, which has a suitable measuring surface (silver, silver chloride). Such a differential measurement system is therefore routinely used in all clinical EMG equipment and ENMG studies. — In EMG measurement, the muscle cell acts as a medium that dampens voltage fluctuations. In addition, the shape of the measuring areas of the measuring electrodes (the tip of the needle and the stem of the needle) is causing the voltage fluctuation to be measured to be dampened quickly, as the distance of the tip of the needle from the target active voltage source (muscle cell membrane) to the tip of the measuring electrode (active electrode) mentioned above increases. In the literature of the field, the measuring range of the EMG needle electrode and the distance from the muscle cell membranes and the voltage source are described and estimated as 0-5 mm. The voltage value measured by the active electrode (needle tip) decays exponentially as the distance to the muscle cell membrane increases.

In particular, medically interesting weak, short and fast voltage fluctuations and transients can only be measured very close to the voltage source and therefore require the placement of a needle electrode inside the muscle near the interesting damage area.

The above-mentioned transient describing instability, fibrillation, is a short transient of 1-5 ms duration, a voltage swing, a potential whose voltage amplitude is mostly of the order of 40-150 uV. The form of fibrillation is characteristic and either two- or — one-phase (so-called positive sharp wave). Fibrillation occurs somewhat rhythmically, e.g. with a frequency of 2-10 Hz and its occurrence often stops gradually within a few seconds and the occurrence becomes more lively as a result of the movement of the measuring needle electrode, insertion.

The amount of fibrillation correlates with the number of damaged muscle cells and the proportion of all muscle cells. The damage can be related to a disease of the muscle cell or related to damage to the nerve innervating the muscle. Fibrillation thus reflects the electrical activity of the muscle cell membrane of one damaged muscle cell or part of a muscle cell and occurs locally in the area of the above muscle cell and can only be measured from the measuring electrode placed right next to the cell.

If the muscle is completely relaxed, no nerve action potentials brought by motor nerves from the central nervous system come to it. If there is voluntary muscle tension, the action potentials of the motor nerves cause the muscle to so-called motor unit (MU) activation. The motor nerve divides into numerous branches within the muscle in an area of several millimeters. The branches activate one muscle fiber each. In this case tens to hundreds of muscle fibers are activated synchronously when one MU is activated. Activation — takes place, for example, at a frequency of 5-30 Hz. The activated numerous fibers form the EMG in the measurement as a sum potential, the so-called of a motor unit potential (MUP), which is tens of times higher (ad 1-2 mV), longer lasting (ad 20 ms) and in a wider area in the muscle (1-20 mm) than fibrillation, which therefore consists of the spontaneous release of an unstable muscle cell membrane of a single muscle cell or part of it and locally occurring activity.

In a routine needle EMG measurement, signals that reflect the voltage difference between the active measuring point of the concentric needle electrode, the tip, and the stem part isolated from it, the reference, are amplified, filtered and brought to the display of the measuring device and to the loudspeaker. This enables the observation of both local and wider transient signals occurring in the muscle. Typically, observation of spontaneous small fibrillation transients is done with high gain and large amplitudes

Observation of MUP transients with lower gain so that the shape of the transients can be observed on the display device as a whole.

MUP transients therefore occur during voluntary and reflex muscle tension. If, when monitoring fibrillation, the muscle is not completely relaxed with the high amplification level of the EMG device, repeated large MUP transients occurring widely in the muscle may occur, which in the EMG measurement add up to a weaker signal and thus significantly interfere with both the visual and auditory detection of fibrillation of small-sized interesting transients. Most of the time, the muscle to be examined can of course be sufficiently relaxed and the MUPIs stop or become rarer and the measurement succeeds well enough. Sometimes this is not possible, e.g. when the perceived pain, etc. causes muscle tension or when measuring muscles that have automatic muscle tension, etc. activity (respiratory muscles, muscles of the mouth area, muscles that maintain the back position, etc.). The accuracy of the measurement then deteriorates unfavorably and neurological diagnostics becomes more difficult.

As the measurement takes longer, it also becomes more painful for the subject.

The EMG measurement also aims to evaluate the distribution of the muscle fibers that make up the MUP and the similar repeatability that occurs when the activity is repeated, i.e. reliability. This assessment of the distribution of muscle fibers is particularly important in such neuromuscular diseases that have caused typical changes in the distribution of nerve fibers and muscle cells as the disease continues and possibly progresses and recovers. Such changes occur especially in connection with repair (regeneration, reinnervation, nerve sprouting), when

The distribution of the muscle fibers forming the MUP transient changes from a uniform distribution — to a patchy one, or when the muscle fibers atrophy, they are located closer to each other. Other properties of nerve and muscle signals can also change very locally in such situations. The muscle cell can produce repeated transient series (series, discharges) or the signals can be of variable shape when repeated, reflecting the unreliable electrical transmission of the signal on the membranes of nerves and muscle cells or — in the area of the neuromuscular junction (tremor, jitter).

Measuring even these phenomena describing abnormal muscle and nerve activity is advantageous using various modifications of measurement systems, which typically aim to increase the selectivity or sensitivity of the measurement. Such are e.g. of the signal — strong filtering (e.g. raising the lower limit frequency) and the use of small-sized measuring electrodes (so-called Single Fiber EMG, SFEMG technology), increasing the surface area of the measuring electrode (so-called MacroEMG) or gradually moving the measuring electrode (so-called

Scanning EMG). These measurement modifications are aimed at e.g. increasing the targeting of the measurement to specifically desired cells or cell groups.

The characteristics of the signals to be measured can be described with conventional signal statistical graphs, e.g. frequency, amplitude, duration, area, rise rate, etc. — undercutting part) or the number of separate parts of complex signals and the number of Turn Points of the signal. Statistical analysis of these requires careful standardization of the measurement and targeting of the measurement to the muscle and nerve cell area of interest. However, when signals are generated widely within the muscle in a healthy muscle and from a particularly wide area in disease-related situations, it is not always easy to assess which part — of the measurement transients originates from local signal sources and which part comes from more distant sources. Similarly, when the interest is focused on the reliability of the local operation, the measurement should also be aimed at the local voltage source for the evaluation of the cause vibration. — In clinical patient measurement, the professional performing the ENMG measurement, e.g. a doctor, therefore has to choose the measuring electrode, measurement amplification, filtering and possible further statistical analysis of the signal in such a way that the measurement would be sensitive to show the above-described normal (physiological) and potentially disease-related abnormal (pathological) changes in the electrical properties of muscle cell membranes . In particular — in situations where the measurement situation is not optimal, problems arise from the simultaneous operation of different groups of cells producing signals and overlapping in the signal.

This electrical activity may be of such a nature that it is not easy to distinguish, determine and quantify the nature of the signals reliably with statistical analysis. — Real-time patient measurement is described above. It should be noted that the recorded signals can be recorded in digital or analog form and a corresponding analysis can also be made of the characteristics of the recorded signals.

SUMMARY OF THE INVENTION

The advantageous solution provided by the invention to these problems described above in the separation of voltage sources for needle EMG measurement is based on the fact that the generator of the interesting signal transient (e.g. fibrillation, MUP) and the summable true signal transient (MUP) is, as described above, composed of different biological - cell membrane functions and is distributed differently in the muscle indoors. These transients can therefore be detected and separated selectively and advantageously using the measurement and analysis system of several simultaneous measurement channels described in this invention, however, using the same needle and measurement electrode system as in routine measurement and by applying statistical analysis simultaneously to both measurement channels.

As described above, the fibrillation transient arises in the EMG measurement from the instantaneous activity of the membrane of a single muscle fiber and is only visible very locally as measured by the tip of the needle. The MUP transient arises as a sum potential of several (ad hundreds) causes — in the area of a muscle area several millimeters in diameter. It is measurable as well

Through the tip of the EMG needle and the stem part of the needle. In this invention, this phenomenon is utilized by removing, processing or suppressing the points of interest from the signal of interest (the signal measured from the tip of the needle) as containing disturbances, where other transients and action potentials, which are often widespread and undesired and hinder statistical evaluation, can be detected in the signal measured through the needle shaft. Using the statistical analysis and processing of the signal coming through the needle shaft, the aim is to process, filter and suppress the tip signal of a diagnostically interesting needle when there are transients disturbing the signal of the needle tip, so that what remains on the screen and for the audio amplifier and for further analysis are primarily those 5 — interesting transients that are selectively generated by the needle measured by the tip and have not spread so much to the area of the needle shaft and are therefore diagnostically important, e.g. fibrillation transients or MUP transients. If there are no disturbing transients (e.g. MUP) in the needle cannula measurement, the needle tip signal does not need to be processed and attenuated, and the measurement proceeds like a conventional single-channel measurement. — With the help of the invention, the aim is therefore to increase the diagnostic accuracy, sensitivity, specificity and selectivity of the study and to improve the technical performance.

With the help of the invention, the analysis of an interesting signal can also be directed selectively to the transients generated near the tip of the needle. The invention is implemented in such a way that the meter can, with the help of a switch, e.g. a push button, or automatically programmatically — choose what kind of signal or what kinds of signals he wants for analysis.

With the help of the invention, for further analysis of the signals, after statistical analysis, for example, transients whose electric generator is located near the tip of the needle can be selected. This is important when aiming to improve the reproducibility of measurements and — quantitative analysis properties. The invention enables the automatic damping of transients that are unfavorable in terms of their distribution and the selection of favorable transients for further analysis.

The measurement and analysis system according to the invention is characterized by what is — specified in the distinguishing parts of the patent claims.

PRESENTATION OF PATTERNS

In the following, the invention is described in more detail with reference to the attached figures

Figures 1-3 show the current level of EMG measurement technology by describing — patient measurements that monitor normal or abnormal muscle electrical activity.

Figure 4 shows one embodiment of the invention, in which a measurement is performed to detect fibrillation transients occurring in muscle or nerve diseases.

Figure 5 shows the second embodiment of the invention, where with the measurement according to the invention, the measurement is preferably selectively focused in the vicinity of the muscle fibers to be measured and - the transients generated further away are dampened.

Figure 6 shows an embodiment of the invention, where the meter can use a switch on the measuring cable to select a selective measurement method or one that uses current measurement technology.

Figures 7 and 8 show a flow diagram of targeting the analysis to the signal of interest.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Figures 1 - 3 show the current state of the art EMG measurement. Figures 4-6 show some embodiments of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS AND DRAWINGS OF THE INVENTION

DESCRIPTION

In Figure 1, an EMG measurement describing the current state of the art, where a concentric needle electrode (10) measuring muscle electrical activity is inserted between muscle fibers, — the muscle tissue is shown as a cross-section. From the tip of the needle (11) and the stem of the needle, i.e. the cannula (12), the voltage is fed to the differential preamplifier (13), the voltage difference is amplified and filtered (14) and the signal is fed to the display device (e.g. oscilloscope display 15) and the audio amplifier (16). Picture 1 shows a damaged muscle fiber (20) inside the muscle, to which the nerve connection (30) has been cut. The tip of the needle (11) — is located right next to the thread and the equipment can be used to detect fibrillation (21), which describes the unstable activity of the muscle cell membrane, which repeats rhythmically. In this picture, the voltage fluctuation of the fibrillation is about 0.1 mV and the duration is 5 msec.

Figure 2 shows an EMG measurement that still describes the current state of the art. It activates — a motor unit (MU) inside the muscle, the muscle fibers of which are partially described.

The action potential travels through the intramuscular nerve fibers (30) to the muscle fibers, which are activated synchronously to form a motor unit potential (MUP) (22).

The measuring needle tip (11) and the needle shaft (12) between the muscle fibers measure the synchronous action potential (MUP) and the voltage difference is amplified and filtered (14) — and the signal is led to the display device (15) and the audio amplifier. MUP (22) Vamplitude is significantly larger than the fibrillation transient of Figure 1 (21) and in this figure 1.0 mV and duration 10 msec.

Figure 3 shows an EMG measurement that still describes the current level of technology, which combines

The events of Figure 1 and Figure 2 and where both fibrillation (21) and MUP (22) are activated inside the muscle. Both are registered as in Figure 1 and 2 and routed to the display device and audio amplifier. MUP significantly larger and longer lasting interferes with visual or automatic detection of fibrillation. — Figure 4 shows an application form of the invention. The concentric needle electrode (10), its tip (11) and stem (12) are located inside the muscle and the differential amplifier (13) amplifies the voltage difference between them as shown in figure 1-3. In addition to that, a separate surface electrode (40) has been placed on the surface of the skin and another corresponding differential amplifier (41) has been put into use, which amplifies the voltage difference between the stem part of the measuring needle (12) and the surface electrode. When — fibrillation (21) occurs, it is only visible in the signal of the differential amplifier 13, which measures the voltage difference at the tip of the needle. When MUP (22) occurs, it is reflected in both amplifier 13 and amplifier 41 signals. If the situation is favorable for the measurement, the user activates the signal analysis and processing module (50) with the switch (42).

The processing module consists of filters and a detection circuit (52), with which the characteristics of the signal 41 — are monitored. If the signal rises above the reference level (51) or the statistical characteristics of the signal are otherwise different from the reference signal, it indicates the presence of MUP. With the help of the delay circuit (53), the signal of the amplifier 13 is delayed. When MUP is detected in the signal of the amplifier (41) in the processing unit (50), the signal of the amplifier (13) is attenuated as strongly as possible. The suppression is continued like this — as long as the MUP occurs. During attenuation, no disturbing MUP signal can reach signal 13. The fibrillation transient is generated locally and is not visible in the signal of the amplifier 41 and is therefore not detected by the processing module. When fibrillation occurs, there is no damping and the fibrillation can be monitored from the amplifier's display device and the audio amplifier without distortion or damping. When disturbing MUP signals do not occur — the user releases the switch (42). In this case, the processing circuit is inactivated and the signal produced by the amplifier 13 is monitored as in figure 1-3 as a measurement according to the current state of the art.

In addition to the fixed detection level, an adaptive detection level can be used to replace — the switch 42. The signal of the amplifier 41 is digitally filtered and pre-processed using the computer software of the measuring device (50-52). Quantities describing the average noise of the signal are processed with the help of statistical processing of the amplitude variation of the signal. The values are used to evaluate when the signal contains MUP potentials.

Not only the amplitude of the voltage, e.g. threshold values, but also the surface integral of the voltage with respect to time, the rate of rise of the voltage fluctuation, the shape of the signal, etc. can be used as variables.

MUP detection can therefore take place adaptively with varying threshold values and not with a fixed voltage level (51) as in Figure 4. When the user wants to investigate the occurrence of fibrillation, he selects the equipment's measurement program, which contains the application of the invention.

The software monitors the signal of the amplifier 13 and displays it on the screen. A delay line is included in the processing of the signal, through which the signal is also transferred to the screen of the measuring device for visual analysis and to the speaker for audiological evaluation. At the same time, the software processes the amplifier 41 signal statistically. If the signal 41 contains features on the basis of which a MUP (22) can be detected, the signal of the amplifier 13 is attenuated for the duration of the MUP occurrence and in the measurement a favorable fibrillation (21) can be detected. Signal

Figure 5 shows the use of the invention when one wants to measure several MUP transients (30 and 130) and at the same time make sure that the measuring tip of the needle electrode is as close as possible — preferably near the muscle fibers to be measured in the area of the motor unit and one wants to dampen the effect of potentials generated far from the needle tip on the analysis. As shown in figure 4, the measurement takes place with two channels. The concentric needle electrode (10), its tip (11) and stem (12) are located inside the muscle and the differential amplifier (13) amplifies the voltage difference between them as shown in figure 1-3. In addition to that, a separate — surface electrode (40) has been placed on the surface of the skin and another corresponding differential amplifier (41) has been put into use, which amplifies the voltage difference between the stem part of the measuring needle (12) and the surface electrode. When transients occur locally near the needle measuring tip, they can be measured primarily in the signal of the differential amplifier 13. When more distant activity and transients occur, they can be measured in the signal of both amplifier 13 and amplifier 41. — The signal analysis and processing module (50-53) is determined by statistical analysis, correlating the distribution of the signal to the tip of the needle. When the signal (30A) from the amplifier (13) is statistically different (amplitude, rate of rise, frequency content, etc.) measured through the tip compared to the signal (41) coming through the stem, the measurement is preferably aimed at the threads near the tip of the needle and can be performed, e.g. operation — reliability ( internal shape variation of the transient, jitter, jitter) of the parameters reflecting the distribution of fibers (transient amplitude, shape, complexity, duration, area) reliably and the obtained statistical variables accurately describe the physiological function of the measured fibers. When the signal (130A) is statistically similar (amplitude, rate of rise, frequency content, etc.) as measured through the tip versus through the shaft — to the signal (130B), the signal generators are far from the needle tip and are not advantageous to include in medical analysis.

Figure 6 shows a measurement arrangement in which both the selective needle tip measurement according to the invention and the state-of-the-art needle measurement can be advantageously used. As shown in figure 4 and 5, the measurement takes place with two channels. The concentric needle electrode (10), its tip (11) and stem (12) are located inside the muscle and the differential amplifier (13) amplifies the voltage difference between them as shown in figure 1-3. In addition to that, a separate surface electrode (40) has been placed on the surface of the skin and another corresponding differential amplifier (41) has been put into use, which amplifies the voltage difference between the stem part (12) of the measuring needle and the surface electrode (40). When transients occur locally near the needle measuring tip, they can be measured primarily in the signal of the differential amplifier 13. When more distant activity and transients occur, they can be measured in the signal of both amplifier 13 and amplifier 41. With the help of the switch 61, the measurer can choose whether he takes the measurement according to the selective invention — the needle tip measurement or the measurement according to current technology. The switch is located in the connector of the needle cable so that the user can change the alignment of the measurement by pressing it. Alternatively, the switch can also be a foot switch or another part of the measuring device that the user can control (sound, speech, etc. control). An analyzing computer program can also be used, which indicates the presence of disturbing transients and — suggests to the user a system according to the invention visually, auditorily or by other signs. In this case, the measurer can choose the type of analysis he wants to perform with the switch 61. The computer program can also monitor the existence of disturbing transients and, if the user allows and chooses to do so, it can automatically implement the statistical processing, damping and filtering of signals according to the invention.

Flowchart 7 shows the computer analysis used in the inventive application. There, the user notes an interesting small transient in the concentric needle measurement. 1. An interesting signal found in the concentric measurement — 2. Let's compare the statistical properties of the signal with the needle stem measurement 3. The needle stem measurement finds a statistical correlation — reject and move to point 1 4. The needle stem measurement does not detect a statistically correlated transient 5. The desired statistical properties in the concentric measurement are analyzed 6. let's move to a new measurement and point 1.

Flowchart 8 shows the characteristics of the selection switching in the application 1 according to the invention. The interesting signal is detected in a concentric measurement. 2. The user selects the position of the selection switch, with which the display of the concentric signal — is muted, when the simultaneous signal found in the arm measurement is detected in the arm measurement

Figures and flowcharts 1-8 show only some advantageous embodiments according to the invention. The invention is not limited to the solutions just described, e.g. according to the size, shape or physical properties of measuring sensors or statistical processing of computer analysis, but the inventive idea can be applied in numerous ways also by measuring corresponding measurement signals and comparing the electrical signal of muscle cells generated locally inside the muscle to another remote measurement point and by changing other features of the measurement such as measuring needle size, shape, signal filtering, — statistical analysis and its detailed features within the limits set by the patent requirements.

Forms of the invention implemented with digital signal processing have been described above, but the invention can be implemented by processing the signal with analog technology by filtering, amplifying, delaying and analyzing using analog electronic components, achieving advantageous embodiments according to the invention.

In particular, it should be noted that the functions described above take place in real time in the patterns, but the corresponding analysis can also be analyzed and printed from digitally or analogically recorded signals using the method according to the invention.

In this case, suitable recording equipment is connected to the measurement system.

From the recording equipment, the signals — can be transferred to the analysis system, which performs the analysis according to the invention and the presentation of the results.

Claims (10)

STANDARD 1. An electronic muscle electrical activity (electromyography, EMG) measurement system, comprising a needle-like EMG electrode (10) and a differential amplifier configuration (13, 41), characterized in that the system is adapted to produce at least two intramuscular, simultaneous, measurement signals of muscle electrical activity, at least one of which is produced by the first with a differential amplifier (13) from the voltage difference between the needle-like EMG electrode tip (11) and the stem (12) or other reference, and at least one of which is produced with another differential amplifier (41) from the voltage difference between the needle-shaped EMG electrode stem (12) and the separate measuring electrode (40). 2. The measurement system according to claim 1, characterized by the fact that it is adapted to process, dampen, filter and analyze the measurement signal produced by the tip of the needle (11) using the voltage variation of the same muscle activity, which has been measured simultaneously by the stem of the measuring needle (12) and of the statistical properties of the signal between the electrode (40) of at least one separate measurement point. 3. The measurement system according to claim 1, characterized in that it is adapted to process, dampen, filter and analyze (50, 52, 53) the measurement signal produced by the needle using the differences in the start, end and classification of processing, which are detected by measuring the voltage variation of the muscle activity, which has been measured simultaneously of the statistical characteristics of the signals between the separate (11, 12, 40) measuring points of the measuring needle. 4. The measurement system according to claims 1-3, characterized in that the processing of the measurement signal of the needle tip (11) carried out by it is continuous or it is started and stopped by mechanical or electrical selection (61) of a switch, push button, foot pedal etc. related to the system or by means of an automatic computer analysis program (50 , 52, 53) as initiated or indicated. 5. The measurement system according to claims 1-3, characterized in that the processing of the measurement signal of the needle tip (11) carried out by it is carried out by selecting . in the system, analog or digital processing performing analysis or N computer program (50, 52, 53) which processes, by attenuating N signals (30A, 130A) measured through the tip of the needle, the statistical variables of the simultaneous N signals (30B, 130B) measured through the needle shaft, such as amplitude, frequency , surface area, S 40 frequency content, rise rate, shape, shape complexity, shape variation © based on processing. N = A 6. A measurement system according to claims 1 to 3, characterized in that the processing of the measurement signal of the needle tip (11) carried out by it 3 45 is performed by selecting the analog or digital processing that performs the analysis in the R system or the S computer program that selectively processes the N measured through the needle tip for statistical and diagnostic analysis signal (30A, 130A) of simultaneous signals (30B, 130B) measured through the needle shaft statistical variables such as amplitude, frequency, area, frequency content, rate of rise, shape, shape complexity, shape variation based on processing. 7. The measurement system according to claims 1 to 3, characterized in that the measurement signal processing and visual and auditory presentation it implements takes place using the delay of measurement signals and the processing of signals analogically or digitally with computer software (50, 52, 53). 8. A system according to patent claims 2 to 7, characterized by the fact that the analysis it implements and the production of results takes place in real time. 9. A system according to patent claims 2 to 7, characterized in that the analysis it carries out and the production of results takes place at a later time from digitally or analogically stored and analyzed signals produced in accordance with the invention. 10. Use of a system according to any of claims 1-9 in measurements of muscle electrical activity. N N O N 3 40 00 N I Ao a S 45 O MN MN O N