WO2008015405A1 - Stimulateur electrique - Google Patents

Stimulateur electrique Download PDF

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Publication number
WO2008015405A1
WO2008015405A1 PCT/GB2007/002882 GB2007002882W WO2008015405A1 WO 2008015405 A1 WO2008015405 A1 WO 2008015405A1 GB 2007002882 W GB2007002882 W GB 2007002882W WO 2008015405 A1 WO2008015405 A1 WO 2008015405A1
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WO
WIPO (PCT)
Prior art keywords
electrodes
pairs
waveform
skin
user
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/GB2007/002882
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English (en)
Inventor
Ghazala Tabasam
Mark Ian Johnson
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Individual
Original Assignee
Individual
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Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of WO2008015405A1 publication Critical patent/WO2008015405A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N1/00—Electrotherapy; Circuits therefor
    • A61N1/18—Applying electric currents by contact electrodes
    • A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
    • A61N1/38—Applying electric currents by contact electrodes alternating or intermittent currents for producing shock effects

Definitions

  • the invention relates to electrical stimulators that cause pain when applied to the human body, for use in medical treatment of individuals prone to deliberate self-harm.
  • the invention also relates to methods of use of such devices.
  • Self-harm is one of the top five causes of acute medical admission in the UK (Hawton & Fagg, The British Journal of Psychiatry 161 : 816-823, 1992).
  • Self-harm involves intentional self-poisoning and self-injury such as head banging and laceration of the skin.
  • Self-laceration of the skin appears to serves two purposes. Firstly, to produce a painful sensation and secondly to produce a visible record of the injury e.g. blood or a scar.
  • Health care practitioners provide practical alternatives to self-harm such as flicking elastic bands against the skin. These practical alternatives attempt to generate a painful sensation without appreciable injury.
  • TENS Transcutaneous Electrical Nerve Stimulation
  • mild electric currents are applied across the intact surface of the skin by a battery powered pulse generator connected to two electrodes.
  • the electrical current administered excites nerve fibres underlying the electrodes and leads to pain relief.
  • TENS is used extensively across the world to provide pain relief for patients who suffer from conditions such as low back pain and osteoarthritis and for pregnant women during childbirth.
  • TENS-type and related electrical stimulation apparatus A number of configurations of TENS-type and related electrical stimulation apparatus are known, and the following are given by way of example:
  • US Patent Application US2004/0260359 describes a method and apparatus for treating neurogenic conditions by electrical stimulation.
  • the device applies a period electrical voltage to the skin of a patient of approximately 240- 440VoItS.
  • the waveform of the applied signal is substantially a square wave, operating at approximately two pulses per second, i.e. a pulse width of around 500ms.
  • UK Patent application GB2123698 (Biostim Inc.) describes electrical stimulators for relieving various types of pain.
  • the device applies voltages of less than 40VoItS having a pulse width of 40-220ms.
  • US Patent 6,023,642 (Biogenics) describes a TENS device for the reduction of the symptoms of acute and chronic pain.
  • the device applies an electrical signal to the skin of a patient, via "peel and stick" electrodes attached to the patient.
  • the electrical signal applied comprises an underlying bipolar waveform having a short positive spike followed by a much smaller, and slowly-decaying negative portion. This waveform is overlaid with a signal having a broad range of frequency components, extending into the gigahertz range.
  • US Patent 4,233,986 again describes a device for controlling pain by transcutaneous electrical stimulation.
  • the device applies the signal to a patient by large surface area electrodes (15 x 5 cm and 3.5 x 2.5 cm) stuck to a patient's skin for example on a patient's neck and back.
  • the electrical signal comprises a first impulse having a steeply- rising positive portion that decays, approximately exponentially and that reverses polarity before the voltage has completely decayed to form a second impulse comprising an exponential decay.
  • the interval between successive pulses is modulated to prevent habituation to the stimulus.
  • TENS and other related devices for pain relief are designed with output specifications that deliver currents that can generate a non-painful electrical paraesthesic sensation beneath the electrodes, indicative of pain relief.
  • US Patent 4,524,773 describes apparatus for inhibiting self-injurious behaviour in patients.
  • the apparatus provides a short shock to a patient, e.g. to their arm, on which is strapped a "stimulus module" containing a "ring electrode".
  • the shock is in the form a 2-20 pulses of an approximately square- wave signal with a voltage of approximately 120-18OVoItS, a pulse width of 15ms and a pulse repetition rate of approximately 80Hz.
  • the short-duration shock is initiated either by a motion detector mounted on the patient's forehead and activated by head-banging activity, or by the use of a remote activator under the control of e.g. an attending clinician. In this way, the device provides a form of aversion therapy.
  • an electrical stimulation device for delivery of painful sensations to a user, in use, comprising: a signal generator, to generate an output electrical waveform, said waveform comprising a sequence of pairs of voltage spikes, each member spike of said pairs being temporally separated by between 0.2 and 5 milliseconds; and electrodes, operably connected or connectable to said signal generator; so that, in use, the electrodes may be pressed against the skin of a user to deliver said output electrical waveform thereon; and wherein at least one of said electrodes has a skin- contacting surface area of less than 100 mm 2 .
  • at least one (and more preferably both) of said electrodes is metal, and preferably domed.
  • the invention also provides an electrical stimulation device, for delivery of painful sensations to a user, in use, comprising: a signal generator, to generate an output electrical waveform, said waveform comprising a sequence of pairs of voltage spikes, each member spike of said pairs being temporally separated by between 0.2 and 5 milliseconds; and electrodes, operably connected or connectable to said signal generator; so that, in use, the electrodes may be pressed against the skin of a user to deliver said output electrical waveform thereon; and wherein at least one of said electrodes is a metal electrode.
  • at least one (and more preferably both) of said electrodes has a skin-contacting area of less than 100 mm 2 .
  • each member spike of said pairs of voltage spikes has an amplitude of between +/-80 and +/-140 Volts.
  • the electrodes are provided at a fixed spacing, either attached to the signal generation device, or on a separate hand-held unit attached to the signal generator by e.g. a flying lead. By providing such a fixed spacing, it is ensured that the signal will be substantially non-injurious to the user, whilst also providing a sensation that has in the desired painful characteristics.
  • an electrode spacing of less than about 3cm is particularly effective, and preferably in the range of 1 to 3 cm , and more preferably 2-3 cm. More preferably, said electrode spacing is adjustable. In this way, a user can adjust the sensation felt when the device is in use, to more closely mimic the sensation they desire.
  • each member spike of said pairs of voltage spikes is of different polarity. This is particularly effective at creating the desired sensation.
  • the series of voltage spikes comprises a succession of pairs of voltage spikes, each member of the said pairs being of different polarity, and wherein the time interval between each successive pair of voltage spikes is substantially greater than the time interval between the spikes comprising the said pair of voltage spikes.
  • the member spikes of said pairs of voltage spikes are of substantially equal amplitude, preferably within approximately 20% of each other.
  • successive pairs of voltage spikes are generated at a frequency of between 1 and 200Hz.
  • successive pairs of spikes are generated at time intervals of between 5ms and Is.
  • the pairs of voltage spike are generated at a frequency of between 1 and 100Hz.
  • the skilled addressee will, with routine trials, be able to match an appropriate separation of the spikes forming the spike pairs with such a spike-pair repetition frequency.
  • this pulsed waveform it is particularly advantageous if it is generated by amplification and modification of a control signal, said control signal comprising an asymmetric and substantially square wave having a pulse repetition rate and a pulse width, and wherein said control signal pulse width is greater than 0.2 milliseconds and less than 5ms.
  • this pulse width has been found to be particularly advantageous.
  • At least one, and preferably both electrodes comprise raised (especially domed) electrically-conductive projections, e.g. of metal, rather than the self-adhesive and substantially flat, flexible hydrogel pads used in TENS machines.
  • This allows application of the voltage to a smaller area of skin than used in TENS machines, and provides a more appropriate painful stimulation at a localised site.
  • the use of non-adhesive electrodes allows a user of the device to initiate the painful sensation at will, and to achieve a sensation close to that felt by cutting (for example the sensation of cold metal pressing on then skin) in order to satisfy the need to self-harm, but in a substantially non-injurious fashion.
  • Preferred configurations of at least one of the electrodes (and preferably both) would have an in-use skin contact area of less than 100 mm 2 , and preferably less than 50 mm 2 , and most preferably less than 25 mm .
  • Preferred ranges are frequencies up to 25Hz; frequencies up to 50Hz; frequencies up to 75Hz; and frequencies up to 100Hz.
  • no "high frequency” electrical component is superimposed on the basic electrical waveform.
  • “high frequency” we mean frequencies in excess of IMHz 5 and especially frequencies in excess of 1 GHz as described in US6023642, as these are associated with pain relief, rather than with the production of the present desired painful sensation.
  • the device is configured to be able to deliver the electrical stimulation to the skin in a continuous fashion (i.e. for a period of at least 0.2s, preferably for longer than 0.5s, and more preferably for longer than Is), rather than as a short-duration shock.
  • Also included within the scope of the invention is a method of eliciting pain in an individual comprising attaching the electrodes of a device described herein to the skin of said individual and delivering an electrical stimulus thereon.
  • Figure 1 is a schematic block diagram of an embodiment of the invention
  • Figure 2 is an electrical circuit diagram of an embodiment of the invention
  • Figure 3 is an arrangement of a control panel of an embodiment of the invention
  • Figure 4 shows illustrative waveforms of a control signal and pulsed waveform.
  • FIG. 1 shows a schematic block diagram of an electrical stimulation device, generally indicated by 1 , according to the present invention.
  • the device has a pulse generator 2 to generate a control signal 51.
  • the pulse generator 2 is controlled by a pulse width controller 3 that controls the duty cycle (ratio of positive part to the negative, or zero part) of the control signal 51 generated by the pulse generator 2.
  • the pulse generator 2 is also controlled by a frequency controller 4 that controls the rate of repetition of the control signal 51 (i.e. the pulse frequency) generated by the pulse generator 2.
  • the pulse generator 2, and other parts of the circuitry, are powered by a power source, 5; for portability of the device, the power source is preferably batteries or rechargeable cells.
  • the final output waveform 55 can be manually altered to allow for the pulse width and pulse duration to be changed for the purpose of carrying out laboratory tests in real life scenarios, and for tailoring the output of the device for individual users or requirements.
  • the output of the pulse generator 2 is fed into a two-stage amplifier stage 6 in order to limit the current and amplify the voltage.
  • This amplifier 6 in turn is controlled by the current limiting circuitry 7.
  • the current limiting circuitry 7 allows the amplification ratio to be controlled thus allowing the total current at the output electrodes to be controlled in a linear fashion.
  • the output of the amplifier 6 is fed into an isolation stage 8 that contains a transformer and a capacitor charge mechanism.
  • the transformer feeds the amplified waveform into the electrodes without making any electrical contact between the electrodes and the amplifier thus magnetically de-coupling the two circuits.
  • FIG 2 is an electrical circuit diagram of an electrical stimulation device 1 according to the present invention.
  • the various elements described above, and illustrated schematically in Figure 1 are indicated by the dashed boxes and underlined numerals using the same numbering.
  • the circuit is depicted using standard electrical notation, and comprises eight resistors (labelled Rl -R8), six capacitors (labelled C0-C5), two diodes (labelled D1-D2), two transistors (labelled T1-T2), an integrated circuit (a 555 timer, labelled ICl), a transformer (labelled TRl) and a power source in the form of a battery (labelled B).
  • Figure 3 illustrates an arrangement of a control panel, generally indicated by 10, to present controls to a user or attending clinician.
  • the panel has a frequency control 12 to select the base frequency, i.e. the pulse repetition rate, of the control signal 51 (and thus the final output waveform 55); a pulse width control 13 to control the pulse width (duty cycle) of the control signal 51 and an amplitude control 14 to allow setting the voltage of the final output waveform 55.
  • the frequency control 12 allows the user to select one of the four pre-set frequencies (25, 50, 75 or 100 Hz).
  • the frequency selector switch has a total of 6 positions out of which 4 allow the user to select one of the desired test frequencies while the other 2 positions (on each end) are idle.
  • the frequency selector switch should always be on one of the four pre-set positions.
  • Figure 4 shows a graphical representation of both the control signal 51 (Figure 4a) and the final output waveform 55 ( Figure 4b).
  • the control signal varies between approximately +5V and OV 5 and has the form of an asymmetric square wave.
  • the frequency (f) from the frequency control 12 defines the period, or pulse repetition rate, of the square wave as indicated, and the pulse width control 13 defines the proportion of the square wave that is at the nominal +5 V state within any one period.
  • Figure 4b illustrates the final output waveform 55, after amplification.
  • the characteristics of the amplifier are such that the final output waveform (the "pulsed waveform") has the form of a series of voltage spikes 52 produced in pairs; four such pairs are indicated by 53.
  • the time interval between each successive pair 53 is indicated as 54. It can be seen that this time interval is substantially greater than the time interval between the spikes 52 comprising the pair of spikes; this shorter time interval is indicated by 56.
  • the final output waveform varies between approximately +110V and — 110V.
  • a lower effective limit for this voltage is +/- 80V, and preferably +/-100V.
  • An upper effective, and safe limit is +/- 140V, and preferably +/-120V.
  • the amplitude control 14 acts to further attenuate this voltage.
  • the current limiter acts to limit the output current to a maximum of 6OmA.
  • Preferred embodiments incorporate a variable maximum output limit, selectable between 1 and 6OmA.

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  • Health & Medical Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Biomedical Technology (AREA)
  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • Radiology & Medical Imaging (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Electrotherapy Devices (AREA)

Abstract

L'invention concerne un dispositif de stimulation électrique, pour produire des sensations douloureuses sur un utilisateur et servant dans le traitement et la gestion des individus enclins à une automutilation délibérée, comprenant : un générateur de signal générant une forme d'onde électrique, ladite forme d'onde comprenant une séquence de paires de pointes de tension, chaque pointe desdites paires étant séparée d'un intervalle compris entre 0,2 et 5 millisecondes; et des électrodes qui peuvent être appuyées contre la peau de l'utilisateur pour produire le stimulus. Dans des modes de réalisation préférés, les électrodes sont de taille réduite, avec une surface inférieure à un centimètre carré, sont en métal ou sont montées au niveau d'une séparation fixe mais réglable.
PCT/GB2007/002882 2006-07-29 2007-07-27 Stimulateur electrique Ceased WO2008015405A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0615179A GB0615179D0 (en) 2006-07-29 2006-07-29 An electrical stimulator
GB0615179.9 2006-07-29

Publications (1)

Publication Number Publication Date
WO2008015405A1 true WO2008015405A1 (fr) 2008-02-07

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Application Number Title Priority Date Filing Date
PCT/GB2007/002882 Ceased WO2008015405A1 (fr) 2006-07-29 2007-07-27 Stimulateur electrique

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GB (1) GB0615179D0 (fr)
WO (1) WO2008015405A1 (fr)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3834379A (en) * 1972-09-25 1974-09-10 M Grant Deterrent for self-destructive actions
EP0099662A1 (fr) * 1982-07-15 1984-02-01 John Kenneth Wilmot Appareil de stimulation transcutanée électrique de nerfs
US4440160A (en) * 1982-01-19 1984-04-03 The Johns Hopkins University Self-injurious behavior inhibiting system
US4524773A (en) * 1983-08-24 1985-06-25 The John Hopkins University Apparatus for inhibiting self-injurious behavior (SIB) in patients
EP0414248A2 (fr) * 1989-08-25 1991-02-27 Staodynamics Inc. Dispositif électronique de stimulation commandé par microprocesseur et délivrant des impulsions biphasées

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3834379A (en) * 1972-09-25 1974-09-10 M Grant Deterrent for self-destructive actions
US4440160A (en) * 1982-01-19 1984-04-03 The Johns Hopkins University Self-injurious behavior inhibiting system
EP0099662A1 (fr) * 1982-07-15 1984-02-01 John Kenneth Wilmot Appareil de stimulation transcutanée électrique de nerfs
US4524773A (en) * 1983-08-24 1985-06-25 The John Hopkins University Apparatus for inhibiting self-injurious behavior (SIB) in patients
EP0414248A2 (fr) * 1989-08-25 1991-02-27 Staodynamics Inc. Dispositif électronique de stimulation commandé par microprocesseur et délivrant des impulsions biphasées

Also Published As

Publication number Publication date
GB0615179D0 (en) 2006-09-06

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