magnetic stimulation coil

Abstract

The idea is to magnetically stimulate the patient's brain. The device includes a magnetic stimulation device (20) including a magnetic stimulation coil (21) formed from a flat wire (33) wound to form two separated circles (35), the ratio of the width (W1) to the thickness of the flat wire being greater than 3:1. The magnetic stimulation device further includes a housing (38) that contains the magnetic stimulation coil. Other embodiments are also described.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Provisional Patent Application No. 63 / 435,011 to Fogel et al., entitled "Magnetic-stimulation coil," filed December 23, 2022, the disclosure of which is incorporated herein by reference.

[0002] FIELD OF THE INVENTION The present invention relates to methods and devices for use in medical procedures, and in particular to devices and methods for applying magnetic stimulation. [Background technology]

[0003] In the world of neuropsychiatry, our ability to address the growing risk of age-related brain disorders, such as Alzheimer's disease (AD) and other neurodegenerative psychiatric disorders, is limited by the tools available for assessing and monitoring brain health. For example, while techniques such as magnetic resonance imaging (MRI) and computed tomography (CT) provide high-resolution images of the structural topology of the brain's neural networks, these techniques lack the ability to directly monitor brain functionality. Functional MRI (fMRI) and positron emission tomography (PET-CT) are used for indirect measurements, such as measuring blood flow, which correlate with regional changes in the level of brain activity, but cannot be used to directly assess the logical topology of the network. Furthermore, these tools may not provide any useful insights when assessing brain health during normal aging or age-related pathological deterioration.

[0004] Electrophysiological measurements have been widely used to characterize and monitor brain network activity over the past 70 years. Electrophysiological measurements can generally be categorized into two groups of parameters: network integrity (i.e., network connectivity and coherence) and network plasticity (also known as "neuroplasticity" or "brain plasticity"). Network connectivity depends on the synchronous activation of neurons. Network coherence refers to the level of synchrony between two or more brain regions and is used to determine the strength of connectivity between specific brain regions. Neuroplasticity is the brain's ability to continuously adapt its functional and structural organization to changing requirements. Neuroplasticity enables the brain to reorganize neuronal networks in response to environmental stimuli, store information, and recover from brain and spinal cord injuries. Neuroplasticity is essential for the establishment and maintenance of brain circuits.

[0005] Magnetic stimulation is a noninvasive brain stimulation technique that allows for the study of human cortical function in vivo. The use of magnetic stimulation to examine human cortical function is enhanced by combining such stimulation with recordings of electrical evoked responses, such as electroencephalography (EEG). EEG provides the opportunity to directly measure the brain's response to magnetic stimulation, measuring cortical evoked potentials (EPPs). A key feature of EPP topography is that stimulation of only one cortical hemisphere elicits bilateral EEG responses with distinct characteristics. Magnetic stimulation-evoked activity propagates from the stimulation site ipsilaterally via association fibers, contralaterally via transcallosal fibers, and to subcortical structures via projection fibers. A single stimulation pulse delivered over the primary motor cortex (M1) produces a series of positive and negative EEG peaks at specific latencies (typically negative peaks at 45 ms (N45) and 100 ms (N100) post-stimulus, and positive peaks at 60 ms (P60) and 180 ms (P180) post-stimulus). This response pattern indicates synaptic activity. These evoked cortical potentials last up to 300 ms in both the vicinity of the stimulus and in remote interconnected brain regions. Summary of the Invention

[0006] According to some applications of the present invention, a diagnostic procedure is performed on a patient in which a magnetic stimulation device magnetically stimulates the patient's brain. Typically, the magnetic stimulation device includes one or more magnetic stimulation coils configured to generate a magnetic field. Typically, an electrical response in the patient's brain induced by the magnetic stimulation is detected using an electrical signal detector, such as an electroencephalogram (EEG) detector. Typically, the electrical signal detector includes a plurality of electrodes configured to be placed in contact with the patient's head. Typically, a computer processor drives the magnetic stimulation device to magnetically stimulate the patient's brain and receives detected magnetic stimulation-induced signals from the electrical signal detector. Based on one or more parameters of the detected signals, the computer processor performs a diagnosis of the patient. Typically, the computer processor outputs the results of the diagnosis to an output device, such as a display. In some applications, the computer processor determines that the patient is suspected of suffering from a degenerative disorder, such as Parkinson's disease, vascular dementia, Alzheimer's disease, or frontotemporal dementia. In some applications, the computer processor performs a differential diagnosis based on one or more parameters of the detected signals.

[0007] For some applications, a plurality of electrodes configured to record the brain's electrical response to stimulation are disposed within a cap configured to be worn on the patient's head. For example, the cap may be shaped to define a plurality of electrode-retaining orifices shaped to retain the electrodes. Alternatively or additionally, the magnetic stimulation device is configured to reversibly couple to the cap. Typically, this reversible coupling maintains the position of the magnetic stimulation device relative to the patient's head, even when the patient moves their head.

[0008] For example, in some embodiments, the cap comprises a strip of material and a plurality of coupling pads coupled to the strip of material. The magnetic stimulation device comprises a coil housing and one or more (e.g., four) straps coupled to the coil housing, each configured to couple to one of the coupling pads (e.g., via hook-and-loop fasteners) to couple the coil housing to the cap while the cap is worn on the patient's head. The magnetic stimulation device further comprises a coil contained within the coil housing and configured to magnetically stimulate the patient's brain while the coil housing is coupled to the cap.

[0009] Typically, the magnetic stimulation coil includes two separate, circularly wound, flattened wires (i.e., wires shaped as bands or strips). In some applications, the width of the flattened wires is greater than 4 mm (e.g., greater than 5 mm) and / or less than 7 mm (e.g., less than 6 mm), e.g., between 4 mm and 7 mm, or between 5 mm and 6 mm. Alternatively or additionally, the thickness of the flattened wires is greater than 0.8 mm (e.g., greater than 1 mm) and / or less than 1.6 mm (e.g., less than 1.4 mm), e.g., between 0.8 mm and 1.6 mm, or between 1 mm and 1.4 mm. Alternatively or additionally, the ratio of the width of the flattened wires to the thickness of each flattened wire is greater than 3:1 (e.g., greater than 4:1) and / or less than 6:1 (e.g., less than 5:1), e.g., between 3:1 and 6:1, or between 4:1 and 5:1.

[0010] For some applications, each of the circles includes between 6 and 10 complete turns of flattened wire, e.g., 8 complete turns of flattened wire. For other applications, each of the circles includes 10 to 16 complete turns of flattened wire, e.g., 12 to 14 complete turns of flattened wire. For some applications, the circles formed by the flattened wire are separated from one another (i.e., the outer edges of each of the circles are separated from one another) by more than 10 mm (e.g., more than 12 mm) and / or less than 18 mm (e.g., less than 16 mm), e.g., 10 mm to 18 mm or 12 mm to 16 mm.

[0011] Advantageously, as further described below with reference to FIG. 5A, a coil having the parameters described herein allows the magnetic stimulation device to have a relatively low weight and / or volume relative to conventional coils. This allows the magnetic stimulation device to be easily and comfortably positioned (and repositioned as needed) on a cap, for example, by reversibly coupling to the cap as described above. Furthermore, the coil can provide a sufficiently strong magnetic field to a desired depth within a patient's brain without overheating or generating an excessively strong magnetic field at the patient's scalp that could cause patient discomfort.

[0012] Typically, the magnetic stimulation coil is completely (typically hermetically) enclosed by a cover, hereinafter also referred to as a "housing." In some applications, the cover includes two plastic pieces, a lower portion and an upper portion, that are welded together. In some embodiments, the cover also includes one or more printed circuit boards (PCBs) that include circuitry to facilitate stimulation, such as one or more light-emitting diodes (LEDs) and / or temperature sensors. One or more filters protect the circuitry from large common-mode voltages generated by the coil.

[0013] Thus, according to some embodiments of the present invention, there is provided an apparatus including a magnetic stimulation device, the magnetic stimulation device including a magnetic stimulation coil formed from a flattened wire wound to form two separated circles, the flattened wire having a width to thickness ratio greater than 3:1, and the magnetic stimulation device further including a housing that contains the magnetic stimulation coil.

[0014] In some embodiments, the inner diameter of each of the circles is between 21 mm and 31 mm.

[0015] In some embodiments, the inner diameter is between 24 mm and 28 mm.

[0016] In some embodiments, the flat wire is wound so that each of the two circles contains 6 to 10 complete turns of the flat wire.

[0017] In some embodiments, the flat wire is wound so that each of the two circles contains 10 to 16 complete turns of the flat wire.

[0018] In some embodiments, the housing encloses the magnetic stimulation coil.

[0019] In some embodiments, the housing includes a compartment and a cover welded together.

[0020] In some embodiments, the ratio between the width and thickness of the flattened wire is between 3:1 and 6:1.

[0021] In some embodiments, the ratio between the width and thickness of the flattened wire is greater than 4:1.

[0022] In some embodiments, the width of the flattened wire is greater than 4 mm.

[0023] In some embodiments, the width of the flattened wire is greater than 5 mm.

[0024] In some embodiments, the thickness of the flattened wire is less than 1.6 mm.

[0025] In some embodiments, the thickness of the flattened wire is less than 1.4 mm.

[0026] In some embodiments, the two circles are separated from each other by more than 10 mm.

[0027] In some embodiments, the two circles are separated from each other by more than 12 mm.

[0028] In some embodiments, the two circles are separated from each other by 10 mm to 18 mm.

[0029] In some embodiments, the magnetic stimulation coil is configured to generate a magnetic field having a field strength; The ratio of the magnetic field strength at a distance of 2 cm from the surface of the coil along the central axis of the coil to the magnetic field strength at the surface of the coil is greater than 2:3.

[0030] In some embodiments, the ratio of the magnetic field strength at a distance of 2 cm from the surface of the coil along the central axis of the coil to the magnetic field strength at the surface of the coil is greater than 1:1.

[0031] According to some embodiments of the present invention, there is provided a system, comprising: The device, A plurality of electrodes; at least one computer processor, wherein the at least one computer processor: driving the magnetic stimulation device to apply magnetic stimuli to the patient's brain via the magnetic stimulation coil; receiving a magnetic stimulation-induced signal detected by the electrode; A system is further provided that is configured to diagnose a patient by analyzing magnetic stimulation-evoked signals.

[0032] In some embodiments, the at least one computer processor is configured to drive the magnetic stimulation device to apply the magnetic stimulation to a depth of at least 2 cm below the patient's scalp.

[0033] In some embodiments, the magnetic stimulation coil is configured to not overheat when the magnetic stimulation is applied to a depth of at least 2 cm.

[0034] In some embodiments, the magnetic stimulation coil is configured so as not to cause discomfort by heating the patient's scalp when the magnetic stimulation is applied to a depth of at least 2 cm.

[0035] In some embodiments, the plurality of electrodes are disposed within a cap configured to be placed on the patient's head.

[0036] In some embodiments, the magnetic stimulation device is configured to be reversibly coupled to the cap.

[0037] According to some embodiments of the present invention, there is further provided a device including a coil configured to magnetically stimulate a patient's brain during a stimulation procedure, and a printed circuit board. The printed circuit board includes circuitry configured to generate an output to facilitate the stimulation procedure and at least one filtering wire configured to protect the circuitry by filtering common-mode voltages from the coil. The device further includes a housing that contains the coil and the printed circuit board.

[0038] In some embodiments, the housing encloses the coil.

[0039] In some embodiments, the housing includes a compartment and a cover welded together.

[0040] In some embodiments, the circuitry includes one or more light emitting diodes configured to emit light indicative of a stage of the stimulation treatment.

[0041] In some embodiments, the circuitry includes one or more temperature sensors configured to output a signal indicative of the temperature within the housing.

[0042] According to some embodiments of the present invention, there is further provided a system including a cap configured to be worn on a patient's head, the cap including a strip of material and a plurality of bonding pads coupled to the strip of material, the system further including a magnetic stimulation device including a coil housing, one or more straps coupled to the coil housing, each of the straps configured to couple to one of the bonding pads to couple the coil housing to the cap while the cap is worn on the patient's head, and a coil contained within the coil housing, the coil housing configured to magnetically stimulate the patient's brain while the coil housing is coupled to the cap.

[0043] In some embodiments, the cap is shaped to define a plurality of electrode-retaining orifices shaped to retain respective electrodes configured to record the brain's electrical response to stimulation.

[0044] In some embodiments, the coupling pad includes a loop and the strap includes a hook configured to couple to the loop.

[0045] In some embodiments, the coupling pad includes a hook and the strap includes a loop configured to couple to the hook.

[0046] In some embodiments, the magnetic stimulation device includes four straps.

[0047] In some embodiments, the magnetic stimulation device further includes a button, the magnetic stimulation device configured to emit a test electromagnetic pulse in response to depression of the button.

[0048] In some embodiments, the mass of the coil housing with the coil is less than 500 g.

[0049] In some embodiments, the bonding pads are positioned on the piece of material such that when the cap is placed on the patient's head, the coil housing is bondable to the cap over the frontal cortex of the patient's brain.

[0050] In some embodiments, the coupling pads are positioned on the piece of material such that when the cap is placed on the patient's head, the coil housing is capable of coupling to the cap over the primary motor cortex of the patient's brain.

[0051] In some embodiments, the coupling pads are positioned on the piece of material such that when the cap is placed on the patient's head, the coil housing is capable of coupling to the cap over the dorsolateral prefrontal cortex of the patient's brain.

[0052] In some embodiments, the bonding pads are positioned on the piece of material such that when the cap is placed on the patient's head, the coil housing is bondable to the cap over the parietal cortex of the patient's brain.

[0053] In some embodiments, the bonding pads are positioned on the piece of material such that when the cap is placed on the patient's head, the coil housing is bondable to the cap over the occipital cortex of the patient's brain.

[0054] In some embodiments, the bonding pads are positioned on the piece of material such that when the cap is placed on the patient's head, the coil housing can be bonded to the cap at the temporal cortex of the patient's brain.

[0055] In some embodiments, the material is stretchable.

[0056] In some embodiments, the material comprises synthetic rubber.

[0057] In some embodiments, the material comprises spandex.

[0058] According to some embodiments of the present invention, there is further provided an apparatus including a coaxial cable. The coaxial cable includes an inner conductor, an outer conductor coaxial with the inner conductor, an inner jacket insulating the inner conductor from each other, and the outer jacket insulating the outer conductor from the ambient environment and having an outer diameter of less than 1.4 cm. The coaxial cable has a mass of less than 700 g and a bend radius of the coaxial cable of less than 5 times the outer diameter.

[0059] In some embodiments, the coaxial cable comprises: one or more insulated control wires passing through the inner conductor; and a separate inner jacket that insulates the control wire from the inner conductor.

[0060] A more complete understanding of the present invention will be obtained from the following detailed description of the embodiments of the present disclosure when read in conjunction with the drawings. [Brief explanation of the drawings]

[0061] [Figure 1] 1 is a schematic diagram of a clinician performing a diagnostic procedure on a patient using a diagnostic system, according to some embodiments of the present invention. [Figure 2A] FIG. 1 is a schematic diagram of a control unit with a magnetic stimulation device, according to some embodiments of the present invention. [Figure 2B] FIG. 1 is a schematic diagram of a magnetic stimulation device connected to a cable, according to some embodiments of the present invention. [Figure 3] 1 is a schematic diagram of a cross-section of a cable according to some embodiments of the present invention. [Figure 4] 1 is a schematic diagram of a cap according to some embodiments of the present invention. [Figure 5A] 1 is a schematic diagram of a coil housing, according to some embodiments of the present invention. [Figure 5B] 1 is a schematic diagram of a section of a coil housing, according to some embodiments of the present invention. [Figure 6] 10 shows the results of simulated magnetic stimulation using a coil having parameters according to some embodiments of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0062] Referring first to Figure 1, Figure 1 is a schematic illustration of a clinician 10 performing a diagnostic procedure on a patient 12 using a diagnostic system 28, according to some embodiments of the present invention. The diagnostic procedure may be performed, for example, when the patient 12 is suspected of suffering from a neurodegenerative disorder.

[0063] System 28 includes a magnetic stimulation device 20 configured to be positioned near (e.g., coupled to) the head of patient 12, for example, by being placed on a cap 30 worn on the head. Device 20 includes at least one coil configured to generate a magnetic field that stimulates activity in the brain of patient 12. Generally, device 20 can be positioned over any suitable portion of the frontal cortex (e.g., primary motor cortex or dorsolateral prefrontal cortex), occipital cortex, parietal cortex, or temporal cortex of the patient's brain to stimulate that portion of the brain.

[0064] System 28 further includes a plurality of electrodes 61 (FIG. 4) configured to record signals generated by the brain in response to stimulation. Electrodes 61 may be coupled to the patient's head via a low-impedance adhesive material. Alternatively, the electrodes may be coupled to cap 30 (e.g., via electrode-retaining orifices 22 in the cap) such that the electrodes contact the head when cap 30 is placed snugly on the patient's head.

[0065] System 28 further includes a control unit 24 that includes a signal generator 34 and other circuits, such as analog-to-digital (A / D) conversion circuitry and / or noise reduction circuitry. Typically, control unit 24 is connected to device 20 via cable 36. A computer processor 32, which may reside in control unit 24 or an external device, such as a laptop, that communicates with control unit 24 (e.g., via a universal serial bus (USB) cable), is configured to drive signal generator 34 to generate electrical signals. These signals flow through device 20 via cable 36, thus generating magnetic fields in the device, which in turn induce signals (or “potentials”) in the patient's brain. These signals are recorded by electrodes and passed from the electrodes to the control unit via respective leads 47 ( FIG. 4 ) or via wireless transmission. After optional noise reduction and digitization within control unit 24, processor 32 receives the signals.

[0066] The processor 32 is further configured to process the signals to perform a diagnosis, such as a differential diagnosis for conditions such as Parkinson's disease, vascular dementia, Alzheimer's disease, or frontotemporal dementia. The processor further provides an output indicative of the diagnosis; for example, the processor may display the output on the display 26.

[0067] Typically, in processing the signal, the processor calculates one or more measures of the neurophysiological activity indicated in the signal. For example, the processor may compare the measures to respective thresholds or input the measures into a model, such as a neural network or logistic regression model, calibrated to output a diagnosis.

[0068] In some embodiments, the calculated measures of neurophysiological activity include waveform adherence measures that quantify the similarity between the waveform of a portion of the signal and the waveform of a corresponding portion of a benchmark signal, which may be obtained, for example, from relevant literature. Typically, the benchmark signal represents the response of a normal subject.

[0069] One such waveform adherence measure is a wide waveform adherence measure, which quantifies similarity over a relatively long (or "wide") portion of the signal. For example, this portion may begin 15 ms to 55 ms from the onset of the signal (i.e., from the end of the stimulus) and have a duration of 300 ms to 350 ms.

[0070] Another such waveform adherence measure is a slow waveform adherence measure, which quantifies similarity over a relatively late portion of the signal. For example, this portion may begin at least 60 ms (e.g., at least 80 ms) from the onset of the signal. The duration of this portion may be, for example, between 120 ms and 160 ms.

[0071] Yet another such waveform adherence measure is an early waveform adherence measure that quantifies similarity over a relatively early portion of the signal. For example, this portion may begin less than 50 ms from the onset of the signal. The duration of this portion may be, for example, between 120 ms and 160 ms. As a specific example, this portion may begin 35 ms after stimulation and have a duration of 145 ms.

[0072] Alternatively or additionally, the calculated measures of neurophysiological activity include cortical excitability measures based on the amplitude of a portion of the signal, for example, the cortical excitability measure may be based on amplitude statistics such as the integral of the signal (which is amplitude dependent) or the mean deviation of the amplitude.

[0073] Alternatively or additionally, the calculated measure of neurophysiological activity includes a waveform excitability measure of a portion of the signal based on both the amplitude of the portion of the signal and the similarity of the waveform to a benchmark waveform.

[0074] Alternatively or additionally, the computed measures of neurophysiological activity include interhemispheric connectivity measures that quantify the similarity between the response of the right side of the patient's brain to the stimuli and the response of the left side of the patient's brain to the stimuli.

[0075] Alternatively or additionally, the calculated measures of neurophysiological activity include the latency of the main peak of the signal, the slope of a line passing through two main peaks, and / or a main peak latency measure that quantifies the difference between the two latencies.

[0076] Reference is now made to Figure 2A, which is a schematic illustration of control unit 24 with magnetic stimulation device 20, according to some embodiments of the present invention. Reference is also made to Figure 2B, which is a schematic illustration of magnetic stimulation device 20 connected to cable 36, according to some embodiments of the present invention.

[0077] Typically, device 20 includes a coil housing 38 (FIG. 5A) that houses at least one stimulation coil 21. Typically, coil housing 38 is attached to a handle 42.

[0078] In some embodiments, device 20 further comprises one or more straps 40 coupled to coil housing 38, e.g., via coupling knob 49 on the coil housing, and configured to couple to cap 30 ( FIG. 1 ), e.g., via hook-and-loop fasteners. As described above with reference to FIG. 1 , magnetic stimulation device 20 is typically connected to control unit 24 via cable 36. For example, cable 36 may comprise a first connection interface 39 configured to connect to a complementary connection interface 37 in the control unit, and a second connection interface 41 at the opposite end of the cable, configured to connect to a complementary connection interface 43 in handle 42. In some embodiments, control unit 24 comprises a holder 45 configured to hold magnetic stimulation device 20 when it is not in use.

[0079] In some embodiments, device 20 further comprises a button 25, which may be located, for example, at the end of handle 42 opposite the end where the handle connects to the cable. In some such embodiments, device 20 is configured to emit a test electromagnetic pulse in response to depression of button 25. Emission of the test pulse may serve to set a patient-specific amplitude for the stimulation pulse.

[0080] Reference is now made to FIG. 3, which is a schematic illustration of a cross section of cable 36 shown in FIG. 2B, according to some embodiments of the present invention.

[0081] Typically, cable 36 is coaxial and includes an inner conductor 46 and an outer conductor 44 that is coaxial with inner conductor 46. Typically, inner conductor 46 carries current from the control unit to the magnetic stimulation device, while outer conductor 44 carries current from the magnetic stimulation device to the control unit. An outer jacket 48 insulates outer conductor 44 from the surrounding environment (e.g., from the patient and clinician), while an inner jacket 50 insulates the two conductors from each other.

[0082] In some embodiments, the cable 36 further comprises one or more insulated control wires 52 that pass through the inner conductor 46 (e.g., in the center of the cable 36), with a separate inner jacket 54 insulating the control wires from the inner conductor 46. For example, Figure 3 shows six control wires 52 surrounding a filler 56 in the center of the cable.

[0083] In some embodiments, magnetic stimulation device 20 further includes one or more temperature sensors, which may be housed, for example, within coil housing 38, as described below with reference to FIG. 5B. In such embodiments, control wires 52 typically include wires for supplying power to the temperature sensors and wires for serial communication with the temperature sensors. Alternatively or additionally, as described below with reference to FIG. 5B, the magnetic stimulation device includes electrically activated status indicators (e.g., light-emitting diodes (LEDs)), and control wires 52 include wires connected to these indicators.

[0084] Advantageously, in addition to providing electrical insulation, outer jacket 48 and inner jackets 50 and 54 provide structural stability in that they hold the conductive elements of cable 36 in place. Nevertheless, cable 36 is small, light, and flexible enough to allow comfortable wearing of magnetic stimulation device 20 (FIGS. 2A-2B). For example, outer jacket 48 (and thus cable) may have an outer diameter of less than 1.4 cm (e.g., 0.6 cm to 1.4 cm). Alternatively or additionally, cable 36 may have a mass of less than 700 g (e.g., 300 g to 700 g). Alternatively or additionally, cable 36 may have a bend radius of less than 5 times (e.g., 1 to 5 times) the outer diameter of the cable.

[0085] Reference is now made to Figure 4, which is a schematic illustration of a cap 30 according to some embodiments of the present invention.

[0086] Cap 30 comprises a piece of material 58, which in some embodiments is framed by an elastic frame 62. Typically, the material is stretchable to facilitate a better fit; for example, the material may include synthetic rubber and / or spandex. In some embodiments, piece of material 58 comprises multiple smaller pieces that are joined (e.g., sewn) together during manufacture of the cap.

[0087] Cap 30 further includes a plurality of bonding pads 64 coupled to strip 58. Straps 40 (FIG. 2A) are each configured to couple to one of bonding pads 64 to couple the coil housing to the cap. For example, bonding pads 64 may include loops and straps 40 may include hooks configured to couple to the loops, or bonding pads 64 may include hooks and straps 40 may include loops configured to couple to the hooks, such that the magnetic stimulation device is coupled to the cap via hook-and-loop fasteners.

[0088] Typically, cap 30 is shaped to define a plurality of electrode-retaining orifices 22 shaped to hold respective electrodes 61 configured to record the brain's electrical response to magnetic stimulation. Typically, electrodes 61 are held within electrode-retaining orifices 22 such that the electrodes contact the patient's head when cap 30 is worn by the patient.

[0089] Advantageously, the coupling pads 64 are distributed across the surface of the cap 30 so that the magnetic stimulation device 20 can be coupled to the cap at various positions, thereby stimulating various regions of the patient's brain. Furthermore, at each position, the coupling pads guide the placement of the magnetic stimulation device, thereby facilitating more effective stimulation. Typically, for greater stability, the magnetic stimulation device 20 includes multiple (e.g., four) straps, each coupled to a different respective coupling pad.

[0090] For example, the coupling pads may be positioned on the piece of material 58 such that when the cap is placed on the patient's head, the coil housing can couple to the cap over the right or left primary motor cortex or dorsolateral prefrontal cortex of the patient's brain.

[0091] Typically, the cap 30 further comprises a plurality of buckles 66 configured to connect to a chin strap, which helps secure the cap on the patient's head.

[0092] Typically, the cap 30 is further shaped to define a plurality of access orifices 68 through which the patient's head may be accessed. Thus, for example, an impedance-reducing gel that reduces the impedance seen by the electrodes may be applied to the patient's head through the access orifices 68.

[0093] Reference is now made to FIG. 5A, which is a schematic illustration of a coil housing 38, in accordance with some applications of the present invention.

[0094] Coil housing 38 includes a compartment 70 that houses coil 21 and a cover 72 configured to cover coil 21 such that the coil is completely enclosed, and typically hermetically sealed, by the coil housing. In some embodiments, the coil housing includes a layer 76 of material, such as epoxy, with the coil sandwiched between layer 76 and cover 72. Layer 76 thus facilitates sealing, and typically encapsulating, the coil.

[0095] Typically, the compartment 70 and cover 72 are made from plastic. More typically, during manufacture of the coil housing, the cover 72 is welded (e.g., ultrasonically welded) to the compartment 70 after the coil has been inserted.

[0096] In use, handle 42 (FIGS. 2A-2B) is coupled to section 70 opposite cover 72 (i.e., on the opposite side of the section not shown in FIG. 5A), and coil housing 38 is placed on the patient's head with cover 72 facing the head. For example, cover 72 may contact cap 30 (FIG. 4).

[0097] Typically, the magnetic stimulation coil includes a flattened wire 33, i.e., a wire shaped as a band or strip. The wire 33, covered along its length by a thin, electrically insulating covering, is wound into two windings 31 in opposite directions, i.e., the wire is wound clockwise in one winding 31 and counterclockwise in the other winding. While the windings 31 may have any suitable shape (e.g., oval or square), the windings 31 are typically circular (i.e., disc-shaped) and are therefore referred to herein as circles 35. The circles 35 are separated from one another by a distance D1 (i.e., the outer edges of the circles are closest to one another) that is typically greater than 10 mm (e.g., greater than 12 mm) and / or less than 18 mm (e.g., less than 16 mm), e.g., between 10 mm and 18 mm or between 12 mm and 16 mm.

[0098] The advantage of two circles is greater localization of the magnetic field compared to a single loop of wire. In particular, the two circles interfere destructively toward the edges of the coil and constructively near the center of the coil (particularly between the two circles), resulting in a magnetic field concentrated near the center of the coil. The distance D1 affects the distance from the coil at which the magnetic field is concentrated, and in particular, the latter distance is an increasing function of D1. In general, it is desirable to concentrate the magnetic field at least 2 cm below the patient's scalp, minimizing near-field effects that may cause discomfort to the patient. The exemplary value of D1 provided above typically meets this objective.

[0099] In some applications, the width W1 of the flattened wire is greater than 4 mm (e.g., greater than 5 mm) and / or less than 7 mm (e.g., less than 6 mm), e.g., between 4 mm and 7 mm, or between 5 mm and 6 mm. Alternatively or additionally, the thickness of the flattened wire (i.e., the dimension of the wire that enters the page of FIG. 5A ) is greater than 0.8 mm (e.g., greater than 1 mm) and / or less than 1.6 mm (e.g., less than 1.4 mm), e.g., between 0.8 mm and 1.6 mm, or between 1 mm and 1.4 mm. Alternatively or additionally, the ratio between the width of the flattened wire and the thickness of the flattened wire is greater than 3:1 (e.g., greater than 4:1) and / or less than 6:1 (e.g., less than 5:1), e.g., between 3:1 and 6:1, or between 4:1 and 5:1.

[0100] In general, an advantage of a larger width and / or smaller thickness compared to a smaller width and / or larger thickness is that the current flowing through the coil is concentrated closer to the patient's head, thereby generating a sufficiently strong magnetic field without excessively increasing the size or mass of the coil. The exemplary ranges described above provide this advantage without making the wires too thin or too wide.

[0101] For example, in some embodiments, the small size of the coil means that the length L2 of the housing is less than 150 mm, e.g., less than 140 mm, and / or the width W2 of the housing is less than 75 mm, e.g., less than 65 mm, and / or the thickness of the housing is less than 9 mm, e.g., less than 8 mm. Alternatively or additionally, the small mass of the coil means that the combined mass of the coil and housing is less than 500 g, e.g., less than 400 g.

[0102] Simulations can show that if the inner diameter d0 of each of the circles is too small, the strength of the magnetic field is adversely affected. Thus, typically, the inner diameter d0 of each of the circles is between 21 mm and 31 mm, such as between 24 mm and 28 mm. This range of values ​​for d0 facilitates a relatively small size of the coil without adversely affecting the strength of the magnetic field.

[0103] For some applications, each circle includes between 6 and 10 complete turns of flattened wire, e.g., 8 complete turns of flattened wire. For other applications, each circle includes 10 to 16 complete turns of flattened wire, e.g., 12 to 14 complete turns of flattened wire. In general, the more turns there are, the greater the strength of the magnetic field (provided d remains sufficiently large, as discussed above).

[0104] Due to the coil's small size and weight, the magnetic stimulation device can be easily positioned (and repositioned, if necessary) in close proximity to the cap 30 (FIG. 4), e.g., directly on the cap, without causing discomfort to the patient. In contrast, a larger or heavier coil would cause discomfort or require support from a stand. As discussed above with reference to FIG. 4, in some applications, the magnetic stimulation device is reversibly coupled to the cap, e.g., using hook-and-loop fasteners. Typically, this maintains the position of the magnetic stimulation device relative to the patient's head, even if the patient moves their head.

[0105] As described above with reference to FIG. 1, magnetic stimulation coil 21 is typically used in diagnostic procedures as opposed to transcranial magnetic stimulation (TMS) therapeutic procedures. As further described above with reference to FIGS. 1 and 4, system 28 includes, in addition to magnetic stimulation device 20, a plurality of electrodes 61, which are typically disposed within cap 30 that is placed on the patient's head. System 28 further includes at least one computer processor 32. To perform the diagnostic procedure, magnetic stimulation device 20 is reversibly coupled to cap 30, for example, as described above with reference to FIG. 4. Processor 32 then drives the magnetic stimulation device to apply magnetic stimuli to the patient's brain via the magnetic stimulation coil, receives magnetic stimulation-induced signals detected at the electrodes, and diagnoses the patient by analyzing the magnetic stimulation-induced signals.

[0106] Typically, processor 32 drives the magnetic stimulator to apply magnetic stimulation to a depth of at least 2 cm below the patient's scalp. In other words, the processor provides sufficient power to coil 21 to cause a magnetic field to penetrate to this depth with sufficient strength to stimulate the patient's brain, given the coil parameters described herein. Advantageously, the coil parameters allow stimulation to be applied to this depth without overheating the coil or causing discomfort by the coil heating the patient's scalp.

[0107] For some applications, the frequency of the magnetic stimulation within each pulse is between 2 kHz and 4 kHz, e.g., between 2.5 kHz and 3.5 kHz. Alternatively or additionally, the length of each pulse is between 200 microseconds and 400 microseconds, e.g., between 250 microseconds and 350 microseconds. Alternatively or additionally, the magnetic stimulation is applied at an amplitude between 4000 A and 6000 A, e.g., between 4500 A and 5500 A.

[0108] Reference is now made to Figure 5B, which is a schematic illustration of section 70, in accordance with some applications of the present invention. The view of section 70 shown in Figure 5B corresponds to the view in Figure 5A, with coil 21 and layer 76 hidden from view.

[0109] In some embodiments, the magnetic stimulation device includes at least one printed circuit board (PCB) 78 including circuitry 80 configured to generate an output to facilitate stimulation treatment. Each PCB 78 includes at least one filtering wire 86 configured to protect the circuitry 80 by filtering common-mode voltages from the coil 21, such that the coil housing can accommodate the coil and PCB without the common-mode voltage damaging the circuitry. For example, each PCB may be housed within compartment 70.

[0110] In some embodiments, circuitry 80 includes one or more LEDs 84 configured to emit light indicating a stage of stimulation treatment. Typically, the LEDs are controlled via control signals passing through cable 36 from control unit 24 (FIG. 1), e.g., as described above with reference to FIG. 3. The control signals cause the LEDs to turn on or off as the stage of treatment changes (e.g., as magnetic stimulation begins or ends). In some embodiments, a different respective filtering wire 86 at least partially surrounds each LED.

[0111] Typically, light from the LED passes through a light guide 27 that extends from the LED to the exterior of the coil housing, allowing a user to view the status of the device from the light guide 27. Typically, the handle 42 comprises the exposed (and visible) end of the light guide 27; for example, the exposed end of the light guide may surround the button 25. (This embodiment is also shown in FIG. 2B.)

[0112] Alternatively or additionally, circuitry 80 includes one or more temperature sensors 88 configured to output a signal indicative of the temperature within the coil housing. (In embodiments in which device also includes LED 84, temperature sensor 88 and LED 84 are typically located on different respective PCBs.) Typically, the signal is communicated to control unit 24 via cable 36 (FIG. 1), e.g., as described above with reference to FIG. 3. In some embodiments, filtering wire 86 extends along a side of the PCB opposite to the side on which temperature sensor 88 is located (e.g., near the periphery of the PCB).

[0113] Typically, the filtering wire 86 is floating, i.e., not connected to any voltage source, and more typically, the filtering wire 86 is shaped to define a series of square waves 90, the characteristics of which determine the characteristics of the filter.

[0114] Typically, one or more openings 82 in compartment 70 facilitate the passage of wires connected to button 25, coil 21, PCB, and cable, and / or facilitate airflow.

[0115] It should be noted that the embodiment described with reference to FIG. 5B may be combined with any suitable coil configured to magnetically stimulate a patient's brain during a stimulation procedure for diagnostic or therapeutic purposes.

[0116] Referring now to FIG. 6, simulated magnetic stimulation results using a coil having parameters according to some embodiments of the present invention are shown. FIG. 6 shows simulated magnetic flux density (B) at various distances from the surface of the coil that would face the patient's head in an actual stimulation procedure. The magnetic flux density is measured along the central axis 74 of the coil, which runs perpendicular to the section 70, as shown in FIG. 5A. The term "surface" shown in FIG. 6 refers to the outer surface of the housing (e.g., the outer surface of the cover 72), and the distance shown along the x-axis is measured from the surface of the coil itself. The outer surface of the housing is typically within 2 mm, e.g., within 1 mm, of the surface of the coil, which would contact the patient's head in an actual stimulation procedure.

[0117] In some embodiments, the magnetic stimulation coil is configured to generate a magnetic field having a magnetic flux density (B) of less than 0.5 Tesla (e.g., less than 0.4 or 0.3 Tesla) at the coil surface (corresponding to a distance of zero in FIG. 6 ) and / or less than 0.5 Tesla (e.g., less than 0.4 or 0.35 Tesla) at the surface of the housing. Nevertheless, the magnetic flux density is typically greater than 0.3 Tesla (e.g., greater than 0.35 Tesla) at a distance of 2 cm along the central axis 74. Thus, the magnetic field is strong enough for stimulation at 2 cm, but not too strong at the patient's scalp. One reason for this is that the magnetic flux density varies relatively slowly along the central axis 74 due to the characteristics of the coil described herein. For example, as shown in FIG. 6 , the magnetic flux density may reach a maximum at a distance of more than 4 mm, e.g., more than 6 mm or 7 mm, from the surface of the coil and then gradually decrease. As a result, the magnetic flux density is greatest within the brain (where stimulation is desired) and is relatively high even at 2 cm. In contrast, with other coils, (i) the magnetic flux density may be greatest outside the brain, and / or (ii) the magnetic flux density would need to be uncomfortably high at the patient's scalp to be high enough at 2 cm.

[0118] The advantageous characteristics of the magnetic field described above can be expressed as a ratio. For example, in some embodiments, the ratio of the magnetic field strength (linearly related to the magnetic flux density and conventionally designated "H") at a distance of 2 cm from the surface of the coil along the central axis 74 to the magnetic field strength at the surface of the coil is greater than 2:3, e.g., greater than 1:1 or 1:0.9.

[0119] Alternatively or additionally, the magnetic stimulation coil may have a surface area of ​​8e -3 Less than Tesla / microsecond (e.g., 7e -3 It produces a dB / dt of less than 1 / 2 tesla / microsecond and a 7e at a distance of 2 cm along the central axis 74 -3 Tesla / microsecond (e.g., 7.5e -3Alternatively or additionally, the ratio of dB / dt at 2 cm to dB / dt at the coil surface is greater than 2:3, e.g., greater than 1:1 or 1:0.9.

[0120] Applications of the invention described herein may take the form of a computer program product accessible from a computer-usable or computer-readable medium (e.g., a non-transitory computer-readable medium) that provides program code for use by or in connection with a computer, such as computer processor 32, or any instruction execution system. As used herein, a computer-usable or computer-readable medium may be any apparatus that can contain, store, communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. The medium may be an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system (or apparatus, or device) or propagation medium. Typically, the computer-usable or computer-readable medium is a non-transitory computer-usable or computer-readable medium.

[0121] Examples of a computer-readable medium include a semiconductor or solid-state memory, magnetic tape, a removable computer diskette, a random access memory (RAM), a read-only memory (ROM), a rigid magnetic disk, and an optical disk, current examples of which include compact disk-read-only memory (CD-ROM), compact disk-read / write (CD-R / W), and DVD.

[0122] A data processing system suitable for storing and / or executing program code includes at least one processor (e.g., computer processor 32) coupled directly or indirectly to memory elements via a system bus. The memory elements may include local memory used during the actual execution of the program code, mass storage devices, and cache memory that provides temporary storage of at least some of the program code to reduce the number of times the code must be retrieved from mass storage devices during execution. The system is capable of reading instructions of the present invention on the program storage devices and performing the methods of embodiments of the present invention in accordance with these instructions.

[0123] A network adapter may be coupled to a processor to enable the processor to be coupled to other processors or remote printers or storage devices through intervening private or public networks. Modems, cable modems, and Ethernet cards are just a few of the currently available types of network adapters.

[0124] Computer program code for carrying out operations of the present invention may be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Java, Smalltalk, C++, and conventional procedural programming languages, such as the C programming language or similar programming languages.

[0125] Computer processor 32 is typically a hardware device programmed with computer program instructions to create a special-purpose computer. For example, when programmed to execute the algorithms described with reference to the drawings, computer processor 32 typically functions as a special-purpose diagnostic computer processor. Typically, the operations described herein performed by computer processor 32 transform the physical state of memory, which is an actual physical item, to have different magnetic polarities, charges, etc., depending on the memory technology used. In some applications, the operations described as being performed by computer processor 32 are performed by multiple computer processors in combination with one another.

[0126] It will be appreciated by those skilled in the art that the present invention is not limited to what has been particularly shown and described above, but rather the scope of the present invention includes both combinations and subcombinations of the various features described above, as well as variations and modifications thereof which would occur to those skilled in the art upon reading the foregoing description and which are not in the prior art.

Claims

1. 1. An apparatus comprising: a magnetic stimulation device, the magnetic stimulation device comprising: a magnetic stimulation coil formed from a flat wire wound to form two separated circles, the flat wire having a width to thickness ratio greater than 3:1; a housing that contains the magnetic stimulation coil.

2. 2. The device of claim 1, wherein the inner diameter of each of the circles is between 21 mm and 31 mm.

3. The device of claim 2, wherein the inner diameter is between 24 mm and 28 mm.

4. 2. The device of claim 1, wherein the flat wire is wound such that each of the two circles contains 6 to 10 complete turns of the flat wire.

5. 2. The device of claim 1, wherein the flat wire is wound such that each of the two circles contains 10 to 16 complete turns of the flat wire.

6. The device of claim 1 , wherein the housing encloses the magnetic stimulation coil.

7. The device of claim 1 , wherein the housing comprises a compartment and a cover welded together.

8. 8. The device according to claim 1, wherein the flattened wire has a width to thickness ratio of 3:1 to 6:

1.

9. 9. The device of claim 8, wherein the flattened wire has a width to thickness ratio greater than 4:

1.

10. 8. The device of claim 1, wherein the flattened wire has a width greater than 4 mm.

11. The device of claim 10, wherein the flattened wire has a width greater than 5 mm.

12. 8. The device of claim 1, wherein the flattened wire has a thickness of less than 1.6 mm.

13. 13. The device of claim 12, wherein the flattened wire has a thickness of less than 1.4 mm.

14. 8. The device of claim 1, wherein the two circles are separated from each other by more than 10 mm.

15. 15. The device of claim 14, wherein the two circles are separated from each other by more than 12 mm.

16. 15. The apparatus of claim 14, wherein the two circles are separated from each other by 10 mm to 18 mm.

17. the magnetic stimulation coil is configured to generate a magnetic field having a field strength; 8. The device of claim 1, wherein the ratio of the magnetic field strength at a distance of 2 cm along the central axis of the coil from the surface of the coil to the magnetic field strength at the surface of the coil is greater than 2:

3.

18. 18. The device of claim 17, wherein the ratio of the magnetic field strength at a distance of 2 cm from the surface of the coil along the central axis of the coil to the magnetic field strength at the surface of the coil is greater than 1:

1.

19. 1. A system comprising: An apparatus according to any one of claims 1 to 7; A plurality of electrodes; at least one computer processor; the at least one computer processor: driving the magnetic stimulation device to apply magnetic stimuli to the patient's brain via the magnetic stimulation coil; receiving a magnetic stimulation-induced signal detected by the electrode; The system is configured to diagnose the patient by analyzing the magnetic stimulation-evoked signals.

20. 20. The system of claim 19, wherein the at least one computer processor is configured to drive the magnetic stimulation device to apply the magnetic stimulation to a depth of at least 2 cm below the patient's scalp.

21. 21. The system of claim 20, wherein the magnetic stimulation coil is configured not to overheat when the magnetic stimulation is applied to a depth of at least 2 cm.

22. 21. The system of claim 20, wherein the magnetic stimulation coil is configured so as not to cause discomfort by heating the patient's scalp when the magnetic stimulation is applied to a depth of at least 2 cm.

23. 20. The system of claim 19, wherein the plurality of electrodes are disposed within a cap configured to be placed on the patient's head.

24. 24. The system of claim 23, wherein the magnetic stimulation device is configured to be reversibly coupled to the cap.

25. 1. An apparatus comprising: a coil configured to magnetically stimulate the patient's brain during a stimulation procedure; A printed circuit board, the printed circuit board comprising: a circuit configured to generate an output to facilitate the stimulation treatment; at least one filtering wire configured to filter common mode voltage from the coil and thereby protect the circuit; a housing that contains the coil and the printed circuit board.

26. 26. The device of claim 25, wherein the housing encloses the coil.

27. 26. The device of claim 25, wherein the housing comprises a compartment and a cover welded together.

28. 26. The device of claim 25, wherein the circuitry comprises one or more light emitting diodes configured to emit light indicating a stage of the stimulation treatment.

29. 29. Apparatus according to any one of claims 25 to 28, wherein the circuitry comprises one or more temperature sensors configured to output a signal indicative of a temperature within the housing.

30. 1. A system comprising:

1. A cap configured to be worn on a patient's head, said cap comprising: A piece of material, a cap comprising: a plurality of bond pads coupled to the piece of material; 1. A magnetic stimulation device, comprising: A coil housing; one or more straps coupled to the coil housing, each of the straps configured to couple to one of the coupling pads to couple the coil housing to the cap while the cap is worn on the patient's head; and a coil contained within the coil housing and configured to magnetically stimulate the patient's brain while the coil housing is coupled to the cap.

31. 31. The system of claim 30, wherein the cap is shaped to define a plurality of electrode-retaining orifices shaped to hold respective electrodes configured to record the brain's electrical response to the stimulation.

32. 31. The system of claim 30, wherein the coupling pad comprises a loop and the strap comprises a hook configured to couple to the loop.

33. 31. The system of claim 30, wherein the coupling pad comprises a hook and the strap comprises a loop configured to couple to the hook.

34. 31. The system of claim 30, wherein the magnetic stimulation device comprises four straps.

35. 31. The system of claim 30, wherein the magnetic stimulation device further comprises a button, the magnetic stimulation device configured to emit a test electromagnetic pulse in response to depression of the button.

36. 31. The system of claim 30, wherein the coil housing with the coil has a mass of less than 500 g.

37. 31. The system of claim 30, wherein the bonding pads are positioned on the piece of material such that when the cap is placed on the patient's head, the coil housing is bondable to the cap over the frontal cortex of the patient's brain.

38. 38. The system of claim 37, wherein the coupling pads are positioned on the piece of material such that when the cap is placed on the patient's head, the coil housing is coupleable to the cap over the primary motor cortex of the patient's brain.

39. 38. The system of claim 37, wherein the coupling pads are positioned on the piece of material such that when the cap is placed on the patient's head, the coil housing is coupleable to the cap over the dorsolateral prefrontal cortex of the patient's brain.

40. 31. The system of claim 30, wherein the coupling pads are positioned on the piece of material such that the coil housing is coupleable to the cap over the parietal cortex of the patient's brain when the cap is placed on the patient's head.

41. 31. The system of claim 30, wherein the bonding pads are positioned on the piece of material such that when the cap is placed on the patient's head, the coil housing is bondable to the cap over the occipital cortex of the patient's brain.

42. 31. The system of claim 30, wherein the bonding pads are positioned on the piece of material such that when the cap is placed on the patient's head, the coil housing is bondable to the cap over the temporal cortex of the patient's brain.

43. 43. The system of any one of claims 30 to 42, wherein the material is stretchable.

44. 44. The system of claim 43, wherein the material comprises a synthetic rubber.

45. 44. The system of claim 43, wherein the material comprises spandex.

46. 1. An apparatus comprising: A coaxial cable, an inner conductor; an outer conductor coaxial with the inner conductor; an inner jacket insulating the inner conductor and the outer conductor from each other; an outer jacket that insulates the outer conductor from the surrounding environment and has an outer diameter of less than 1.4 cm; The mass of the coaxial cable is less than 700 g, An apparatus comprising a coaxial cable, wherein the bend radius of the coaxial cable is less than five times the outer diameter.

47. The coaxial cable one or more insulated control wires passing through the inner conductor; 47. The device of claim 46, further comprising: a separate inner jacket insulating the control wire from the inner conductor.

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