~.
`(12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)
`World Intellectual P
`rt
`Ss
`
`—=
`World tneletual Property
`{)
`=
`InternationalBureau
`o—
`(43) International Publication Date
`14 September 2023 (14.09.2023) WIPO: PCT
`
`OUTTAA
`(10)InternationalPublication Number
`WO 2023/169614 Al
`
`J
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`(51) Internationa! Patent Classification:
`AGIB 5/24 (2021.01)
`AGIN 1/36 (2006.01)
`A6IN 1/04 (2006.01)
`AGIN1/02 (2006.01)
`
`AGIN1/08 (2006.01)
`(21) InternationalApplication Number:
`
`PCT/CZ2023/000009
`
`(22) International Filing Date:
`
`08 March 2023 (08.03.2023)
`Crech
`English
`
`(25) Filing Language:
`(26) Publication Language:
`(30) Priority Data:
`CZ
`09 March2022 (09.03.2022)
`PV 2022-110
`(71) Applicant: DEYMED DIAGNOSTICS.R.O, [CZ/CZ];
`Kudrnacova 533, 549 31 Hronov (CZ).
`
`(72) Inventor: MORAVEC, Miroslav; Husova 76, 549 31
`Hronov (CZ).
`.
`
`.
`
`1
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`j
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`45
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`(74) sce PAVLICA, Tomas, Lohniskeho 846, 15200 Praha
`(81) Designated States (unless otherwise indicated, for every
`kind ofnational protection available). AE, AG, AL, AM,
`AO, AT, AU, AZ, BA, BB, BG, BH, BN, BR, BW,BY, BZ,
`CA, CH, CL, CN, CO, CR, CL, CV, CZ, DE, DJ, DK, DM,
`DO, DZ, EC, EE, EG, ES, FI, GB, GD, GE, GH, GM, GT,
`HN, HR, HU, ID, IL, IN, 10, IR, IS, IT, JM,JO, JP, KE,
`KG, KH, KN, KP, KR, KW, KZ, LA, LC, LK, LR, LS, LU,
`LY, MA, MD, MG,MK, MN, MW, MX, MY, MZ, NA, NG,
`NI, NO, NZ, OM, PA, PE, PG, PH, PL, PT, QA, RO, RS,
`RU.RW,SA,SC. SD,SE, SG,SK,SL, ST, SV, SY, TH,
`TJ, TM, TN, TR, TT, TZ, UA, UG, US, UZ. VC, VN, WS,
`ZA, ZM, ZW.
`
`(54) Title: METHOD OF REDUCING STIMULATION ARTIFACT INDUCED BY AN ELECTRICAL STIMULATORIN NEU-
`ROPHYSIOLOGY AND ELECTRICAL STIMULATION DEVICE FOR PERFORMING THIS METHOD
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`PMYMRCREGN +
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`Fig. 3a
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`(57) Abstract: A method of reducing stimulation artifact when performing electrical stimulation, in whicha stimulation pulse is gen-
`erated by anelectrical stimulator connected to a stimulation electrode. A closcd equipotential surface is created around the electrical
`stimulator by complete electrical shielding of the electrical stimulator from the rest of the electrical stimulator and from the surround-
`ings, a low capacitive coupling is ensnred betweenthe electrical stimulatoritself and the rest of the device structure, the shielding ofthe
`stimulationelectrode is connected to the closed equipotential surface of the electrical stimulator and to the closed equipotential surface
`electrical stimulators and/or a collection electrode designed to be placed on the patient is connected to the siuelding of the stimulation
`electrode. The stimulation artifact reducing electrical stimulation device comprises an electrical stimulator (1) designed to connect to
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`[Continued on nextpage]
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`wo2023/169614AIIMINOTNINIRTMITTACUTEAACAA
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`WO2023/169614 AL TINUE HT AACATAA
`
`(84) Designated States (unless otherwise indicated, for every
`kind of regional protection available): ARTPO (BW,CV,
`GII, GM, KE, LR, LS, MW, MZ, NA, RW, SC. SD,SL, ST,
`SZ, TZ, UG, ZM, ZW), Eurasian (AM. AZ, BY, KG, KZ,
`RU, TJ, TM), European (AL, AT, BE, BG, CH, CY, CZ,
`DE, DK, EE, ES,FI, FR. GB, GR,IIR, IU,I,IS, IT, LT,
`LU, LV, MC, ME, MK, MT, NL, NO, PL, PT, RO, RS, SE,
`SI, SK, SM, TR), OAPI (BF,BJ, CF, CG, CI, CM, GA, GN,
`GQ, GW, KM. ML, MR, NE, SN, TD, TG).
`
`Declarations under Rule 4.17:
`
`— as to applicant's entitlement to apply Jor and be granted a
`patent (Rule 4.17(ii))
`— ofinventorship (Rule 4.17(iv))
`Published:
`
`;
`;
`;
`;
`/
`;
`;
`;
`;
`—__ with international search report (Art. 21(3))
`a stimulation electrode. The electrical stimulator (1) is provided with a shield G) with anelectrically shielding surface for shielding
`the electrical stimulator by creating an equipotential conductive surface surroundingthis electrical stimulator (1), whereinthe shielding
`is provided with a connection connector for connection to the shielding of the stimulation electrode or is directly connected to this
`shielding, and that the shielding (3) of the electrical stimulator (1) and/or to the shielding of the stimulating electrode is designed to be
`comnectedto the collecting electrode (6) or is connectedto the collecting electrode (6), and that at least betweentheelectrical stimulator
`(1) and the remaining parts of the device create a low capacitive coupling.
`
`

`

`WO 2023/169614
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`PCT/CZ2023/000009
`
`1
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`A method of reducing stimulation artifact induced py an electrical stimulator in neurophysiology and
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`an electrical stimulation device for performing this method
`
`Field of the invention
`
`The invention relates to a method of reducing stimulation artifact during electrical stimulation with
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`an electrical stimulator In neurophysiclogy and an electrical stimulation device for performing this
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`method in neurophysiological examinations, wherein the device contains an electrical stimulator and
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`exhibits reduced stimulation artifact.
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`State of the art
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`Stirnulation artifact is a disturbing phenomenon in the electrophysiological signal that appears in
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`neurophysiological measurements almast everywhere whereelactrical stimulationis used. It is
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`caused by the penetration of disturbing voltages and currents escaped from the elactrical stimulator,
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`the stimulation electrode and from the stimulated parts of the patient into the tissues from which
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`the electrophysiological resporises are measured, respectively. penetrating directly inta the
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`measuring circuits.
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`in neurophysiology, various methods of electraphysiciogical examination are used, which use
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`electrical stimulators to simulate the organism and the registration part to determine the reaction of
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`the organismto this electrical stimulation, while the following fleids are mainly invalved:
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`electromyography (EMG), electrocorticography (ECoG), transcranial electrical stimulation (TES},
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`intraoperative monitoring (}OM}), deep brain stimulation with feedback (close joop VANS} and others.
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`The most common use of electrical stimulators is currently In electromyography, where devices
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`allowing this tyne of neurophysiciogical examination currently represent the majority of electrical
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`stimulator applications. in order to induce an electrophysioclogical response, the vast majarity of
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`current types are chosen, in which a constant size of the stimulation current is maintained during the
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`entire course of stimulation, regardiess of the output loacl impedance. in the vast majority, such
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`stimulators are used for transcutaneous ithrough intact skin} stimulation, but under restrictive
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`conditions they can also be used together with needie electrodesfor direct stimulation of nerves or
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`muscles,
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`Devices used in electromyography, hereinafter referred to as EMG devices, but aiso devices used in
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`other methods of clectroghysidiogical examinations mentioned above, contain an electrical
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`stimulator performing electrical stimulation and a registration part performing an evaluation of the
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`

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`WO 2023/169614
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`PCT/CZ2023/000009
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`2
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`organism's response to this electrical stimulation. An slectrical stimulator generating an electrical
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`stimulation signal is used, for example, in EMG to stimulate nerve tissue, or directly te the muscle.
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`The registration part then monitors the arganism’s physiological reaction to this stimulus and is made
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`up mainlyof a signal amplifier, with registration electrodes connected to this signa! ampifier. in
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`these methods, electrical stimulators generate short and relatively intense electrical current
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`stimulation pulses of selectable polarity, while the electrophysislagical response of the nerve is
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`registered, or muscle, or inducing mechanical movement of the muscle, which is measured ina
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`different way. The width of the electrical stimulation pulses ranges from aporox. 20 ys to approx. 2
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`ms. The repetition of these pulses then reaches a frequency of up to 300 Hz, but in this case only a
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`shert sequence of individual pulses is used, anproximately un to ten guises. The dependenceof the
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`intensity of excitation of an individual neuron is not linearly dependent on the intensity of
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`stimulation, but ii has a threshold character. [s order to induce full irritation, the threshold
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`polarization of its calf membrane, which is on the order of terns of millivolts, needs to be
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`approximately equalized. When the stimulation imoulse has a lnwer intensity, irritation would neat
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`occur, After the creation of the stimulation signal, the reaction of the organism to the irritation is
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`recorded in the registration part. This reaction has a character of an electromhysiciogical response of
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`neurans that are connected to the stimulated neurons, or of directly stimulated neurons, or also the
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`response of the respective muscle, which is innervated by excitation leading neurons.
`
`Flectric current stimulators used in the above-mentioned diagnostic mathods of electrophysialogicai
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`axaminations, especially in electromyography, mainly contain:
`
`- high-voltage amplifiers with current output ensuring a constant size of the stimufation current
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`regardiass of the load imoeciance,
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`~ anergy storage, most often capacitars, providing enough energy and power for shart Intense
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`stimulation, sa that a powerful source is not necessary, whersas such powerful source would
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`urviecessarily enlarge the structure of the stimulator and make ft more expensive, while the Jimited
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`power output of the rechargeable source also contributes to increasing the safety of the device,
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`-enamolifier with a current cutout with a maximum amelitude of the qutnut current from aparox. ¢
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`15 mA to approx. £ 1 A, typically 100 mA, while the magnitude ofthe voltage ranges from approx, 30
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`V to approx, 1000 V depending on the size of the loadimpedance, the voltage typically having a values
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`of around 400 Vv;
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`- a voltage limitation detection circuit of a current output in case of a load having high impedance,
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`when the further increase in voltage is no longersufficient to supply the set level of the stimulation
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`carrer,
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`

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`WO 2023/169614
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`PCT/CZ2023/000009
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`These electrical stimulators are connectedto control circuits controlling a start of the electrical
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`stimulation and the also controlling the registration part for monitoring the electrophysiclogical
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`response to the electrical stimulation.
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`The output of the electrical stimulator is connected to the stimulation electrode. A pair of stimulation
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`ogies, anade and cathode, which are connected to the patient, is called a stimulation electrode for
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`the gurposes of this invention. This pair of stimulation poles is mast often fixed together, thanies to
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`which a defined distance between the anode and the cathade is ensured. itis known that the anade-
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`cathode spacing of the stimulation electrode is simply a compromise between accuracy and depth of
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`the stimulation. With a large anode-cathode spacing, it is possible that the stimulation will be carried
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`out even in distant structures fram the cathode, on the contrary, with a smail anode-cathode
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`spacing, stimulation of the nerve tissue may not occur at a necessary depth, because the electric
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`current induced bythe stimulating electrode would not reflably reach the necessary intensity. The
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`spacing between the cathode and the anode cf the stimulation electrode in human medicine usually
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`ranges from 20 mm to 40 mmi, for children ft can aven be as little as 10 mm, e.g. in
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`electromyography, electrodes with a spacing between the centers of the cathode and the anode of
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`23 mm are most often used.
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`The recording electrodes are connected to the recording part, so that they are essentially oart of it,
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`and serve to sense the rasponse to the electrical impulse at the desired location of the patient's
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`body. The registration electrodes are placed on the patient at the required distance from the
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`stimulation electrode. For example, in electromyography, the electrical stimulation described abave
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`is most often used Insuch a way that the stimulation electrode is placed, for example, on a finger of
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`the hand, while the recording electrodes are placed, jor example, on the wrist, elbow, shoulder,
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`spine or on the scalp, the stimulation siectrode can aise be placed, for example, on an ankle of the
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`leg, while the registration electrodes are placed, for example, under the knee, on the spine or an the
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`scalp.
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`As already mentioned, during electrical stimulation, so-called stimulation artifacts arise, which make
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`avaluation of the measured clectrophysiological response difficult and negatively affect it, e.g. by
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`making the estimation of the beginning of the response difficult, for example. The amplitude of the
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`initial stimulation artifact is nat so decisive for the quality of the evaluation of the
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`electraphysiclogical response to the electrical stimulus, Out esoeciaily the arnplitude and duration of
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`the so-called decayartifact, which follows it, intervening in time up to the response itself being
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`measured.
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`

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`WO 2023/169614
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`PCT/CZ2023/000009
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`4
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`Different methods are known for removing stimuletion artefacts caused byrepetitive electrical
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`stimulation from a native electraphysiological signal, these methods being based on finding a
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`regularly repeating pattern of the artefact, but from the principle of their function they alsa remove
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`thelr own evoked response, being used for applications that are intended for evaluation of native
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`activity without analyzing ane's own evoked response, Furthermore, methods based on the modeling
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`of the artifact during subthreshold stimulation using the strong nonlinearity of the
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`alectrophysiclogical response to the stimutus intensity are also known. Therefore, they mainly
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`analyze the signal during ane or several subthreshold stimulations of diferent Intensity, when the
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`own electrophysiological response is not present or is present only in a very small amplitude.
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`Subsequentiy, a mocel of the stimulation artifact is created, which is subsequently subtracted from
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`the evoked response, Furthermore, there are known methods using the modeling of an indirect
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`stimufation artifact based on its aoproximately known parameters, and many others. However, none
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`of the known software methods addresses a rellable and sufficient removal of stimulation artifacts.
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`Subject of the invention
`
`The above-mentioned comoatcations caused by stimulation artifacts are ellminated or at igast
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`substantially reduced by a method of reducing the stimulation artifact caused by the electrical
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`stimulator in neurophysiology and the electrical stimulation davice according to the prasent
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`invention, For the purposes of this invention, by the termelectrical stimulation a creation of an
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`electrical impulse by an electrical stimulator of this alectrica! stimulation davice is meant, its
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`apnication tc an organism's bady, or an a patient, and subsequent measurement of the reaction to
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`this stimulation impulse by registration electrodes olaced at the appropriate piace on the arganism's
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`body, ar on the patient, the registration electrodes being connected to the registration pari of the
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`device for electrical stimulation.
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`According to one aspect of the present invention, a method of reducing stimulation artifact during
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`electrical stimulation is disclosed, in which a stimulation pulse is generated by an electrical stimulator
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`connerted to a stimulation electrade ina device for performing the electrical stimulation, the
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`stimulation pulse being subsequently measured by a recording electrode cannected to a recording
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`sart of the davice for serforming the electrical stimulation, whereby:
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`a} a closed equipotential surface around the siectrical stimulator is created, wherein this closad
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`equipotentiai surface is created by completely electrically shielding the electrical stimulator by
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`means of an electrical shielding;
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`

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`WO 2023/169614
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`PCT/CZ2023/000009
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`5
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`b) a low capacitive coupling is srovided between the electrical stimulator and the rest of the parts. of
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`the device for performing electrical stimulation,
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`c} a shielded stimulation electrode is connected to the closed equipotential surface of the electrical
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`stimulator, while its shielding is electrically connected to tha electrical shielding of the electrical
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`stimulator;
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`d} the closed equipotential surface of the electrical stimulator and/or the electrical shielding of the
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`stimulation electrode js electrically connected to a collection electrode designed to be placed on the
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`patient, the collection electrode being placed between the stimulation electrode and the recarding
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`giectrode at a distance corresponding to at most 4 of the distance between the recording electrode
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`and the stimulation electrode.
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`far the purposes of this invention, by a lowcapacitive coupling [s called a coupfing having an order of
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`oF units. Said low capacitive coupling between theelectrical stimulator and the rest of the electrical
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`stimulation device is important in order to create an isolated peninsula, said isolated peninsula will
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`be described below. The term“the rest of the parts of the device for carrying out electrical
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`stimulation” incorporates in particular the registration mart with the registration electrode,
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`preferably the contral part as well, the power supaly part, the communication part and any ather
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`parts of this device.
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`Low capacitive coupling is mainly achieved by using the battery power supply of the electric
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`stimulator or by asing an electric stimulator power source with a jow coupling capacity against the
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`surroundings,
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`According toa particularly advantageous embodiment of the method according to the oresant
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`invention, formation of a current loop in the patient, oypassing the connection paint of the
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`callectian elecirode during the stimulation is avoided. If such a current loop were to be created, for
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`example by touching the end of the stimulated limb with the patient's body behind the saint of
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`connection of the callecting electrode on the patient, the equalizing currents created could affect the
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`resulting signal sensed by the recording alectrocde cannected to the recording part. Likewise,it is
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`particularly desirable to avoid creating a current loca when implanting the entire pacemaker into the
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`patient.
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`A closed equisotential surface around the electrical stimulator is created by performing electrical
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`shielding of this electrical stimulator. The term electrical shielding of the electrical stimulator means
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`that the electrical stimulator is electrically shielded from the rest of the devicefor the electrical
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`stimulation, especially from its registration part with registration electrodes. This electrical shielding
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`WO 2023/169614
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`PCT/CZ2023/000009
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`6
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`of the electrical stimulater can be done in many ways, ¢.g. by enclosing the electrical stimulatorina
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`cover mace of electrically conductive material /¢.g. aluminum, sheet metal, etc.}, by enclosing the
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`electric stimulator in a cover made of electrically non-conductive materia! provided on the outside
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`and/or inside with electrically conductive material, for example by complete fclling with an
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`electrically conductive foil or by spraying an electrically conductive paint, etc. The resistance of this
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`electrically conductive material should be at most about 100 Ohm per square, more preferably 10
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`Ohmper square and most preferably 1 Ohm per square. To ensure a closed equipotentia! surface, all
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`connections of the electrical stimulater, eg. the stimulation electrode connection, are made isolated
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`from the electrically conductive surface, if connection with this surface is not required, lke in case of
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`the callection electrode or in case of the shielding of the stimulation electrode. Due to the
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`requirement to create a low capacitive cougiing of the electrical stimulator to the rest of the
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`electrical stimulation equipment, the power supply of the elactrical stimulator is particularly
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`advantageausly carried out by a battery supply or by a power supply with a very low coupling
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`electrical capacitance between the electrical stimulator and the power circult, the coupling
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`capacitance being at most units of pF. According ta a particularly advantageous Implementation of
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`the device for performing electrical stimulation according to the invention, this requirement far a low
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`coupling capacity also applies to the connectien of the electrical stimulator with the contrai element
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`and all possible communication elements. For the connection of the stimulation electrode, it is
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`sufficient to use a shielded conductor with a standard shielding quality, possibly using a shielding
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`spray of an electroconductive fol, with the above-mentioned electrical resistance. A common
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`electrode with one oole, identical in type to the grounding electrode,is preferably used as the
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`collecting electrade. it is more advarttageous te use a collection electrode with a larger active
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`surface, due to the achievement of a lowertransient impedance and thus a higher suppression of the
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`stimulation artifact.
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`According te the second aspect of the present invention, a device for electrical stimulation reducing
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`stimulation artifact is pravided, camorising in particular an electrical stimulator and a registration
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`part, where this electrical stimulator is provided with an electrically shielded stimulation electrode
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`far conducting electrical stimulation, anc this electrical stimulatar is further provided with electrical
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`shielding for its complete electrical shielding and has a connected, electrical shielding of the
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`stimulation electrode with the electrical shielding of the electrical stimulator, or is designed for thelr
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`cannection, whilethe electric stimulator is further provided with a collecting electrade, wherein this
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`collecting electrode is connected, or designed to be connected to the electrical shielding of the
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`electrical stimulator and/or the electrical shielding of the stimulation electrode in order io minimize
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`the electrical capacitance between the electrical stimulator and the patient.
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`

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`WO 2023/169614
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`PCT/CZ2023/000009
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`According to a particularly advantageous implementation of the device accarding to the invention, at
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`least the electric stimulatar, possiblyalsa the registration part, has the smallest possible dimensians,
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`thus reducing their mutual electric capacity and the capacity of the electric stimulator with respect to
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`room in which the device is located. There is a rue, that ahjects having a cubnid-like shape with a
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`small aspact ratic of their walls, disclase their electrical capacity in pF, with respect to the room, ina
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`value of approximately half the sizeof ihe largest dimensionof said object in cm.
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`The method and device according to the prasant invention are based of an idee of removing
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`influence of the relatively high in oarailel connected elactrical capacitance of the stimulation
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`electrode cable and achleving a lowelectrical capacitance of the aiectrical stimulator against the
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`patient, wherein thanks to the features of the invention an “Insulated peninsula”is assentiaily
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`created around the electrical stimulator, the stimulating electrode and the stimulated part the body
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`of the patient by conmecting the electrical
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`shield of the electrical stimulator with the caflection
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`electrode, sald “Insulated peninsula” prevents stimulation artifact from entering the registration: site,
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`as will be described below. Ry creating this “isalatec! peninsula” there (6 reduced canacitive coupling
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`between the stimulation eiectrade of the electrical stimulator and the non-stimulated biclagical
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`tissues on which the registration electrodes are fixed, through which the necessary measurement is
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`verformad. This “isolated peninsula” can be created,
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`for example, on a stimulated finger or the entire
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`iimb. Accordingto this invention, either by anplying the method according to the Invention or thanks
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`io the features of the device for implementing this method, the majority of the electric charge
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`generated during electrical stimulation fs lad back to the collecting alectrode, thereby prevanting the
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`further spread of the majority of the electric charge to the registration site. A certain amount of the
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`charge spreads further, but it has a significantly tower size and no longersignificantly affects the
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`measured response. This invention can also be viewed in such @ way that thanks to it a T cell is
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`created dividing the coupling capacitance inte two separate capacities and grounding its dividing in
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`thereby interrupting the transmission using the coupling capacitance.
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`To ansura the rellable removal of unwanted artifacts, the camtact of an end of the fimb with the
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`patient's body shoauid be avoided, e¢ an equalization current would begin to Now through the limb,
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`which would negatively affect the corract function of the proposed solution. ff this rule is known, itis
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`easy in practice fo ensure its observance.
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`

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`WO 2023/1696i4
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`PCT/CZ2023/000009
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`Description of drawings
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`The invention will be tore easily and clearly understood from the following examples of
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`implementation and frorn the accompanying drawings, in which:
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`Fig, 1 shows @ comparison of the stimulation artifact in the device according to the state of the art
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`with the stimulation artifact in the device according to the sublect of the invention,
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`Fig. 2a shows a simplified device cannection model according to thestate of the art,
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`Fig. 2b is a schematic drawing showing the propagation of the direct stimulation artifact induced by
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`the electrical stimulator,
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`Fig. 3a shows a schematic flustration of the connection of the device according to the invention to
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`the natient,
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`Fig. 36 shows a simpilfied device connection model according ta the state of the art,
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`Fig. 4a schematically shows the connection of the electrical stimulator of the device according to the
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`invention to the patient's finger,
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`Fig. 4b shows schematically the connection of the electrical stimulator of the device accerding to the
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`invention to the limb of the patient,
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`Fig. Sa shows the dependence of tha shape of the stimulation artifact on the distance fram the
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`stimulation site in devices according to the state of the art,
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`Fis. 5b shows the dependence of the shape of the stimulation artifact on the distance from the
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`stimulation site in the device accarding to the invention,
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`Fig. 6 shows the result of the examination of somatosensory evoked potentials on the device
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`according to the Invention,
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`Fig. 7a shows a comparison of the results cf the examination of the sensory nerveon the device
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`according to the invention with the results of the examination on the device according to the state of
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`the art,
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`Fis. 7b corresponds to the image from Fig. 7a with reduced sensitivity,
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`Fig. 84 and Sb represent the dependence of the size of the stimulation artifact for several distances
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`of the connection point of the collaction electrode from the stimulation site,
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`Fig. 9 showsthe device according to the invention corinected to the upper limb of the patient
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`including the registration part.
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`WO 2023/169614
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`PCT/CZ2023/000009
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`Embodiments of the Invention
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`For a better understanding of the electrical stimulator according te the present invention,
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`ambodiments ofits advantageous implementation will now be described. Even specific embodiments
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`will be used to describe the Invention, with 4 reference to cartain drawings, the invention is not
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`imited te the described emoadiments and is limited anly oy the claims. The attached drawings are
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`schematic only and are in ne way intended to limit the invention to the embodirnents shown. In the
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`drawings, the size of same elements. may be exaggerated for Nustrative purposes and these may not
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`be drawn to scale, The dimensions and their relative propartians may not correspond to the actual
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`dimensions. Furthermore, although some embodiments cf the invention described herein include
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`only some elements, not the other elements, while these other elements are Included in other
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`embodiments, combinations of elements fram different embodiments are possible to fall within the
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`scope of the invention and form embodiments other than thase described herein, which wiil be fully
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`understandable te men skilled in the art. For example, the embodiments described in the exemplary
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`embodiments may be used in any sultable combination. Similar parts of the device for electrical
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`stimulation are marked with the same reference numbers in the individual drawings. Furthermore, it
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`should be noted that the features of the device in the ernbodiment of the Invention in the individual
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`images can be combined in any way,if itis possible.
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`Fir. i shows a comparison of signal curves measured by the recording electrodes during the
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`stimulation performed by a device according to the state of the art and by a device according to the
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`sutiect of the invention with a current of 6.5 mA and a duration of 200 us, which was large enough
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`to ensure the completeness of the response. As can be seen from Fig. 1, in the initial phase up to
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`about 6.2 ms, the curve Is Influenced by the stimulation imvouise itself, which is follawed by a decay
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`artifact in the stimulator according to the state of the art, followed in about 1,5 ms by the organism's
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`response to the stimulation impulse, which starts at the point marked with an index /marker/ {. An
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`amplitude of the response is then marked with indices /rnarkers/ A+, A-.
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`Subsequently, a method according to the Invention wil be described as well as a device far
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`performing said method. Fig. 1 shows neurograms of a sensitive nerve scanned by recording
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`electrodes in a device according to the state of the art. and ina device on which the artefact
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`reduction method accarding to the Invention was applied. As can be seen fram Fig. 1, in the initial
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`chase up to about 0.2 ms, the curve js influenced by the stimulation impulse itself, which fs followed
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`by a decay artifact in the state-of-the-art stimulator, followed in about 1.5 ms by the response of the
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`nerve to the performed stimulation, where this respanse begins at the point indicated by the
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`indexfmarker/ |. The arnplitude rangeof the response is then Indicated by theindices /markars/ A+,
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`

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`WO 2023/169614
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`PCT/CZ2023/000009
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`10
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`A-. AS can be seen from the upper graph, it is difficult for the prior art device to find out where the
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`intrinsic response begins, because uo to the point |, which marks the beginning of the response, the
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`curve rises due to the artifact and the saint | is difficult to identity on it. In the lower curve, on the
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`other hand, thare is no. artifact and the point | indicating the Beginning of the answrer is easy to find.
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`it is clear fram Fig. i that the stimulation artifact consists of Iwo parts, the initial stimulation artifact,
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`labeled as “stimulation,” and the subsequent decay artifact, labeled as decay. The initial stimulation
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`artifact is not as serious for response measurement as the decay artifact, because ft is clearly limited
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`in time and lasts very briefly, basically only for the duration of the stimulation, while the decay
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`artifact decays for a very jong time, on the order of tens of ms, and as shown in Fig. 1 obvious, itis
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`difficult to distinguish from if when the response of the nerve begins, compared to the well-defined
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`beginning of the response of the device according to the state of the art “without decay artifact”),
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`The amplitude of the initial stimulation artifact frmarked as “STIMULATION®in Fig. 1} fs therafare nat
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`sc decisive for the quality of the evaluation of the electrophysiolagica! rasponse to an electrical
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`stimulus, gut rather the arnpiitinie and duration af the so-called decay artifact (marked as "DECAY" in
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`fig. 1} which follows if and extends in time to the respanse Nsalf (rnarked as “RESPONSE"} that is
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`measured,
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`Fig, Za shows a simplified connection mode! of a state-of-the-art electrical stimulation device
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`cormected to the patient. This device inciudes an electrical stimulator 1, a contre! unit 2, a
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`stimulation elactrade with anode 3 and cathode 4, a registration part 7 with registration electrodes 8
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`and a ground electrode 9. The following quantities are further shown In Fig. 2a:
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`Zc is the transition impedance between the cathode of the stimulation electrode end the patient
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`2s is the transition impedance between the anade of the stimulation alectrode and the patient
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`Cow is the capacity between the shielding of the connection cable of the stimulation electrode and
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`ane wire tc connect the ancde, or cathodes
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`Ew.wis the capacitarice between the anode and cathode leads of the stimulation electrode
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`connection cable
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`Cools the capackance between the electrical stimulator and the patient
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`Csyis the capacitance between the electrical stimulator and the control unit
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`Caasis The capacitance between the registration part and the corral unit
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`“3.2 is the capacitance between the electrical stimulator and