Magnetic stimulation coil

Abstract

An apparatus comprises a magnetic stimulation device (20) comprising a magnetic stimulation coil (21) formed by a flat wire (33) wound, for example to form two circles (35) spaced apart from each other, the ratio between the width (W1) and the thickness of the flat wire being greater than 3: 1. The magnetic stimulation device also includes a housing (38) housing the magnetic stimulation coil. Other embodiments are also described.

Description

Cross-reference to Related Applications

[0001] This application claims priority to U.S. Provisional Application No. 63 / 435,011, filed on Dec. 23, 2022, by Fogel et al., titled “Magnetic-stimulation coil,” the disclosure of which is incorporated herein by reference. Field of Embodiments of the Invention

[0002] The present invention relates to methods and devices for medical procedures, and more particularly to devices and methods for applying magnetic stimulation. Background

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

[0004] For the past seven decades, electrophysiological measurements have been widely used to characterize and monitor brain network activity. Electrophysiological measurements can generally be divided into two groups of parameters: network integrity, which is the connectivity and coherence of the network, and network plasticity, also known as “neuroplasticity” or “brain plasticity.” Network connectivity relies on the synchronous activation of neurons. Network coherence refers to the level of synchronization 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 demands. Neuronal plasticity allows the brain to reorganize neuronal networks in response to environmental stimuli, remember information, and recover from brain and spinal cord injuries. Neuronal plasticity is crucial for the establishment and maintenance of brain circuits.

[0005] Magnetic stimulation is a non-invasive brain stimulation method that allows for the in vivo study of human cortical function. By combining magnetic stimulation with the recording of electrically evoked responses such as electroencephalogram (EEG), the use of this stimulation to examine human cortical function is enhanced. EEG provides the opportunity to directly measure the brain response to magnetic stimulation (i.e., measure cortical evoked potentials). An important feature of the evoked potential topographies is that even when only one cortical hemisphere is stimulated, a bilateral EEG response with different characteristics is evoked. The activity induced by magnetic stimulation propagates ipsilaterally from the stimulation site through commissural fibers, contralaterally through the corpus callosum fibers, and to subcortical structures through projection fibers. A single stimulus pulse delivered to the primary motor cortex (M1) results in a series of positive and negative EEG peaks at specific latencies (typically, negative peaks at 45 ms (N45) and 100 ms (N100) after stimulation, and positive peaks at 60 ms (P60) and 180 ms (P180) after stimulation). This response pattern indicates synaptic activity. These induced cortical potentials persist for up to 300 ms both near the stimulation and in remotely interconnected brain regions. Overview of the embodiments

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

[0007] For some applications, a plurality of electrodes configured to record the electrical response of the brain to stimulation are arranged within a cap configured to be worn on the patient's head. For example, the cap can be shaped to define a plurality of electrode holding orifices shaped to hold the electrodes. Alternatively or additionally, the magnetic stimulation device is configured to be reversibly coupled to the cap. Generally, 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 includes a sheet of material and a plurality of coupling pads coupled to the sheet of material. The magnetic stimulation device includes a coil housing and one or more (e.g., four) straps coupled to the coil housing, each strap being configured to couple to any one of the coupling pads (e.g., via a hook-and-loop fastener) so as to couple the coil housing to the cap when the cap is worn on a patient's head. The magnetic stimulation device further includes a coil that is housed within the coil housing and configured to magnetically stimulate a patient's brain when the coil housing is coupled to the cap.

[0009] Generally, the magnetic stimulation coil includes a flat wire (i.e., a wire shaped as a strip or ribbon) that is wound into two circles spaced apart from each other. For some applications, the width of the flat wire is greater than 4 mm (e.g., greater than 5 mm) and / or less than 7 mm (e.g., less than 6 mm), such as 4 mm - 7 mm or 5 mm - 6 mm. Alternatively or additionally, the thickness of the flat wire 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), such as 0.8 mm - 1.6 mm or 1 mm - 1.4 mm. Alternatively or additionally, the ratio between the width of the flat wire and the thickness of each flat wire is greater than 3:1 (e.g., greater than 4:1) and / or less than 6:1 (e.g., less than 5:1), such as between 3:1 and 6:1 or between 4:1 and 5:1.

[0010] For some applications, each circle includes between 6 and 10 complete turns of the flat wire, e.g., 8 complete turns of the flat wire. For other applications, each circle includes between 10 and 16 complete turns of the flat wire, e.g., 12 - 14 complete turns of the flat wire. For some applications, the circles formed by the flat wire are spaced apart from each other (i.e., the outer edges of each circle are spaced apart) by greater than 10 mm (e.g., greater than 12 mm) and / or less than 18 mm (e.g., less than 16 mm), such as 10 mm - 18 mm or 12 mm - 16 mm.

[0011] Advantageously, as further described below with reference to Figure 5A a coil having the parameters as 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 if desired) on the cap, e.g., by reversibly coupling to the cap as described above. In addition, the coil can provide a strong enough magnetic field at a desired depth within the patient's brain without overheating and without generating an overly strong magnetic field at the patient's scalp that could cause discomfort to the patient.

[0012] Typically, the magnetic stimulation coil is fully (and usually airtightly) encapsulated by a cover (also hereinafter referred to as "housing"). For some applications, the cover includes two pieces of plastic welded together, namely a lower side and an upper side. In some embodiments, the cover also contains one or more printed circuit boards (PCBs) that include circuitry for facilitating stimulation, such as one or more light-emitting diodes (LEDs) and / or temperature sensors. One or more filters protect the circuitry from significant 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 includes a magnetic stimulation coil formed of a flat wire that is wound, for example, to form two circles spaced apart from each other, and the ratio between the width and the thickness of the flat wire is greater than 3:1. The magnetic stimulation device further includes a housing that houses the magnetic stimulation coil.

[0014] In some embodiments, the inner diameter of each circle 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 such that each of the two circles includes between 6 and 10 complete turns of the flat wire.

[0017] In some embodiments, the flat wire is wound such that each of the two circles includes between 10 and 16 complete turns of the flat wire.

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

[0019] In some embodiments, the housing includes a compartment and a cover that are welded to each other.

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

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

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

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

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

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

[0026] In some embodiments, the distance between two circles is greater than 10 mm from each other.

[0027] In some embodiments, the distance between two circles is greater than 12 mm from each other.

[0028] In some embodiments, the distance between two circles is between 10 mm and 18 mm from each other.

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

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

[0031] According to some embodiments of the present invention, a system is further provided, including: a device; a plurality of electrodes; and at least one computer processor, which is configured to: drive a magnetic stimulation device to apply magnetic stimulation to a patient's brain via a magnetic stimulation coil, receive a signal induced by magnetic stimulation detected by the electrodes, and diagnose the patient by analyzing the signal induced by magnetic stimulation.

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

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

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

[0035] In some embodiments, a plurality of electrodes are arranged in a cap, and the cap is 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 also provided a device, the device including a coil and a printed circuit board, the coil being configured to magnetically stimulate a patient's brain during a stimulation program. The printed circuit board includes a circuit configured to generate an output for facilitating the stimulation program, and at least one filter line configured to protect the circuit by filtering a common mode voltage from the coil. The device further includes a housing that houses the coil and the printed circuit board.

[0038] In some embodiments, the housing hermetically seals the coil.

[0039] In some embodiments, the housing includes a compartment and a lid that are welded to each other.

[0040] In some embodiments, the circuit includes one or more light emitting diodes configured to emit light indicating a stage of the stimulation program.

[0041] In some embodiments, the circuit includes one or more temperature sensors configured to output a signal indicating the temperature inside the housing.

[0042] According to some embodiments of the present invention, there is also provided a system, the system including a cap configured to be worn on a patient's head, the cap including a sheet of material and a plurality of coupling pads coupled to the sheet of material. The system further includes a magnetic stimulation device including a coil housing, one or more straps coupled to the coil housing, and a coil, each strap being configured to be coupled to any one of the coupling pads so as to couple the coil housing to the cap when the cap is worn on the patient's head, the coil being housed inside the coil housing and configured to magnetically stimulate the patient's brain when the coil housing is coupled to the cap.

[0043] In some embodiments, the cap is shaped to define a plurality of electrode holding apertures shaped to hold respective electrodes configured to record an electrical response of the brain to the stimulation.

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

[0045] In some embodiments, the coupling pad includes a hook and the strap includes a loop configured to be coupled 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, and the magnetic stimulation device is configured to emit a test electromagnetic pulse in response to a press 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 coupling pads are positioned on a sheet of material such that when the cap is worn on a patient's head, the coil housing can be coupled to the cap above the frontal cortex of the patient's brain.

[0050] In some embodiments, the coupling pads are positioned on a sheet of material such that when the cap is worn on a patient's head, the coil housing can be coupled to the cap above the primary motor cortex of the patient's brain.

[0051] In some embodiments, the coupling pads are positioned on a sheet of material such that when the cap is worn on a patient's head, the coil housing can be coupled to the cap above the dorsolateral prefrontal cortex of the patient's brain.

[0052] In some embodiments, the coupling pads are positioned on a sheet of material such that when the cap is worn on a patient's head, the coil housing can be coupled to the cap above the parietal cortex of the patient's brain.

[0053] In some embodiments, the coupling pads are positioned on a sheet of material such that when the cap is worn on a patient's head, the coil housing can be coupled to the cap above the occipital cortex of the patient's brain.

[0054] In some embodiments, the coupling pads are positioned on a sheet of material such that when the cap is worn on a patient's head, the coil housing can be coupled to the cap above the temporal cortex of the patient's brain.

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

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

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

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

[0059] In some embodiments, the coaxial cable further includes: one or more insulated control wires passing through the inner conductor; and another inner sheath insulating the control wires from the inner conductor.

[0060] The present invention will be more fully understood from the following detailed description of embodiments of the invention in conjunction with the accompanying drawings, in which: Brief Description of the Drawings Figure 1Schematic diagram of a clinician using a diagnostic system to perform a diagnostic procedure on a patient according to some embodiments of the present invention; Figure 2A Schematic diagram of a control unit of a magnetic stimulation device according to some embodiments of the present invention; Figure 2B Schematic diagram of a magnetic stimulation device connected to a cable according to some embodiments of the present invention; Figure 3 Schematic diagram of a cross-sectional view of a cable according to some embodiments of the present invention; Figure 4 Schematic diagram of a cap according to some embodiments of the present invention; Figure 5A Schematic diagram of a coil housing according to some embodiments of the present invention; Figure 5B Schematic diagram of a compartment of a coil housing according to some embodiments of the present invention; and Figure 6 Shows the results of simulated magnetic stimulation using a coil with parameters according to some embodiments of the present invention. Detailed description

[0061] First refer to Figure 1 , which is a schematic diagram of a clinician 10 using a diagnostic system 28 to perform a diagnostic procedure on a patient 12 according to some embodiments of the present invention. For example, if a patient 12 is suspected of having a neurodegenerative disorder, a diagnostic procedure can be performed.

[0062] The system 28 includes a magnetic stimulation device 20, which is configured to be placed near the head of the patient 12, for example, by being placed above a cap 30 worn on the head (e.g., coupled to a cap 30 worn on the head). The device 20 includes at least one coil, which is configured to generate a magnetic field that stimulates the activity within the brain of the patient 12. Generally, the device 20 can be placed above any suitable part of the frontal cortex (e.g., the primary motor cortex or the dorsolateral prefrontal cortex), occipital cortex, parietal cortex, or temporal cortex of the patient's brain in order to stimulate that part of the brain.

[0063] The system 28 also includes a plurality of electrodes 61 ( Figure 4 ), which are configured to record the signals generated by the brain in response to the stimulation. The electrodes 61 can be coupled to the patient's head via a low-impedance adhesive material. Alternatively, the electrodes can be coupled to the cap 30 (e.g., via electrode holding apertures 22 in the cap) such that when the cap 30 is suitably placed above the patient's head, the electrodes contact the head.

[0064] System 28 also includes a control unit 24 which includes a signal generator 34 and other circuitry such as analog-to-digital (A / D) conversion circuitry and / or noise reduction circuitry. Generally, the control unit 24 is connected to the device 20 via a cable 36. A computer processor 32 (which may belong to the control unit 24 or to an external device such as a laptop computer that communicates with the control unit 24 (e.g., via a Universal Serial Bus (USB) cable)) is configured to drive the signal generator 34 to generate an electrical signal. These signals flow through the device 20 via the cable 36, causing the device to generate a magnetic field which in turn induces signals (or "potentials") in the patient's brain. These signals are recorded by electrodes and transmitted from the electrodes to the control unit via respective leads 47 ( Figure 4 ), or via wireless transmission. After optional noise reduction and digitization within the control unit 24, the processor 32 receives the signals.

[0065] The processor 32 is also configured to process the signals in order 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 additionally outputs an output indicating the diagnosis; for example, the processor may display the output on a display 26.

[0066] Generally, when processing the signals, the processor calculates one or more measures of the neurophysiological activity exhibited in the signals. For example, the processor may compare the measures to corresponding thresholds, or input the measures into a model calibrated to output a diagnosis, such as a neural network or a logistic regression model.

[0067] In some embodiments, the calculated measure of neurophysiological activity includes a waveform fit measure that quantifies the similarity between the waveform of a portion of the signal and the waveform of a corresponding portion of a reference signal, which may be obtained, for example, from the relevant literature. Generally, the reference signal represents the response of a normal subject.

[0068] One such waveform fit measure is a wide waveform fit measure that quantifies the similarity over a relatively long (or "wide") portion of the signal. For example, this portion may start 15 - 55 ms after the start of the signal (i.e., after the end of the stimulus) and have a duration of 300 - 350 ms.

[0069] Another such waveform fit measure is a late waveform fit measure that quantifies the similarity over a relatively late portion of the signal. For example, this portion may start at least 60 ms (e.g., at least 80 ms) after the start of the signal. The duration of this portion may be, for example, between 120 ms and 160 ms.

[0070] Yet another such waveform fit metric is an early waveform fit metric that quantifies the similarity on a relatively early part of the signal. For example, this part can start within 50 ms from the start of the signal. The duration of this part can be, for example, between 120 ms and 160 ms. As a specific example, this part can start 35 ms after the stimulus and have a duration of 145 ms.

[0071] Alternatively or additionally, the metric of the computed neurophysiological activity includes a cortical excitability metric based on the amplitude of a part of the signal. For example, the cortical excitability metric can be based on the integral of the signal (which depends on the amplitude) or on a statistic of the amplitude, such as the mean average deviation of the amplitude.

[0072] Alternatively or additionally, the metric of the computed neurophysiological activity includes a waveform excitability metric of a part of the signal, which is based on both the amplitude and the similarity of the waveform of this part of the signal to a reference waveform.

[0073] Alternatively or additionally, the metric of the computed neurophysiological activity includes an interhemispheric connectivity metric that quantifies the similarity between the response of the right side of the patient's brain to the stimulus and the response of the left side of the patient's brain to the stimulus.

[0074] Alternatively or additionally, the metric of the computed neurophysiological activity includes a peak latency metric that quantifies the latency of the peak in the signal, the slope of the line passing through two peaks, and / or the difference between two latencies.

[0075] Now refer to Figure 2A , which is a schematic diagram of a control unit 24 with a magnetic stimulation device 20 according to some embodiments of the present invention. Also refer to Figure 2B , which is a schematic diagram of a magnetic stimulation device 20 connected to a cable 36 according to some embodiments of the present invention.

[0076] Generally, the device 20 includes a coil housing 38 that houses at least one stimulation coil 21 ( Figure 5A ). Generally, the coil housing 38 is attached to a handle 42.

[0077] In some embodiments, the device 20 further includes one or more strips 40 that are coupled to the coil housing 38, for example, via a coupling knob 49 on the coil housing, and are configured to be coupled to the cap 30, for example, via a hook-and-loop fastener ( Figure 1 ). As referred to above Figure 1As described above, the magnetic stimulation device 20 is typically connected to the control unit 24 via a cable 36. For example, the cable 36 can include: 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 an opposite end of the cable, the second connection interface 41 being configured to connect to a complementary connection interface 43 in the handle 42. In some embodiments, the control unit 24 includes a holder 45 configured to hold the device 20 when not in use.

[0078] In some embodiments, the device 20 further includes a button 25, which can be located, for example, at an end of the handle 42 opposite to the end where the handle is connected to the cable. In some such embodiments, the device 20 is configured to emit a test electromagnetic pulse in response to pressing of the button 25. The emission of the test pulse can help set the patient-specific amplitude for the stimulation pulse.

[0079] Now refer to Figure 3 , which is a schematic cross-sectional view of the cable 36 as shown in some embodiments of the present invention. Figure 2B

[0080] Generally, the cable 36 is coaxial, including an inner conductor 46 and an outer conductor 44 coaxial with the inner conductor 46. Generally, the inner conductor 46 carries current from the control unit to the magnetic stimulation device, while the outer conductor 44 carries current from the magnetic stimulation device to the control unit. The outer sheath 48 insulates the outer conductor 44 from the surrounding environment (e.g., from the patient and the clinician), while the inner sheath 50 insulates the two conductors from each other.

[0081] In some embodiments, the cable 36 further includes one or more insulated control lines 52, which pass through the inner conductor 46 (e.g., at the center of the cable 36), and another inner sheath 54 insulates the control lines from the inner conductor 46. For example, Figure 3 shows six control lines 52 surrounding a filler 56 at the center of the cable.

[0082] In some embodiments, the magnetic stimulation device 20 further includes one or more temperature sensors, which can be included, for example, within the coil housing 38, as described below with reference to Figure 5B . In such embodiments, generally the control lines 52 include lines for powering the temperature sensors and for serial communication with the temperature sensors. Alternatively or additionally, as described below with reference to Figure 5B , the magnetic stimulation device includes an electrically activated status indicator (e.g., a light-emitting diode (LED)), and the control lines 52 include lines connected to these indicators.

[0083] ​Advantageously, in addition to providing electrical insulation, the outer sheath 48 and the inner sheaths 50 and 54 also provide structural stability as they hold the conductive elements of the cable 36 in place. However, the cable 36 is small enough, light enough, and flexible enough such that the magnetic stimulation device 20 ( Figures 2A - 2B ) can be comfortably worn. For example, the outer sheath 48 (and thus the cable) can have an outer diameter of less than 1.4 cm (e.g., between 0.6 cm and 1.4 cm). Alternatively or additionally, the mass of the cable 36 can be less than 700 g (e.g., between 300 g and 700 g). Alternatively or additionally, the bend radius of the cable 36 can be less than five times the outer diameter of the cable (e.g., between one time and five times).

[0084] Now refer to Figure 4 , which is a schematic illustration of the cap 30 according to some embodiments of the present invention.

[0085] The cap 30 includes a sheet 58 of material, which in some embodiments is framed by an elastic frame 62. Generally, the material is stretchable to facilitate a better fit; for example, the material can include synthetic rubber and / or spandex. In some embodiments, the sheet 58 includes a plurality of smaller sheets that are joined (e.g., stitched) together during the manufacture of the cap.

[0086] The cap 30 also includes a plurality of coupling pads 64 coupled to the sheet 58 of material. Each strip 40 ( Figure 2A ) is configured to be coupled to any one of the coupling pads 64 in order to couple the coil housing to the cap. For example, the coupling pads 64 can include loops and the strips 40 can include hooks configured to couple to the loops, or the coupling pads 64 can include hooks and the strips 40 can include loops configured to couple to the hooks such that the magnetic stimulation device is coupled to the cap via a hook-and-loop fastener.

[0087] Generally, the cap 30 is shaped to define a plurality of electrode holding apertures 22 that are shaped to hold corresponding electrodes 61, which are configured to record the electrical response of the brain to magnetic stimulation. Generally, the electrodes 61 are held within the electrode holding apertures 22 such that when the cap 30 is worn by a patient, the electrodes contact the patient's head.

[0088] Advantageously, the coupling pads 64 are distributed over the surface of the cap 30 such that the magnetic stimulation device 20 can be coupled to the cap at various locations and thus, various regions of the patient's brain can be stimulated. Additionally, at each location, the coupling pads guide the placement of the magnetic stimulation device, thereby facilitating more effective stimulation. Generally, for greater stability, the magnetic stimulation device 20 includes a plurality (e.g., four) of strips and each strip is coupled to a different corresponding coupling pad.

[0089] For example, the coupling pad may be positioned on the sheet 58 of material such that when the cap is worn on the patient's head, the coil housing can be coupled to the cap above the right primary motor cortex or the left primary motor cortex or the dorsolateral prefrontal cortex of the patient's brain.

[0090] Typically, the cap 30 also includes a plurality of buckles 66 configured to couple to a chin strap, which helps to secure the cap on the patient's head.

[0091] Typically, the cap 30 is further shaped to define a plurality of access apertures 68 through which access to the patient's head can be gained. Thus, for example, an impedance reducing gel can be applied to the patient's head via the access apertures 68, which reduces the impedance encountered by the electrodes.

[0092] Now refer to Figure 5A , which is a schematic view of the coil housing 38 according to some embodiments of the present invention.

[0093] The coil housing 38 includes a compartment 70 and a lid 72, the compartment 70 houses the coil 21, and the lid 72 is configured to cover the coil 21 such that the coil is fully encapsulated by the coil housing and is generally airtight. In some embodiments, the coil housing includes a layer 76 of a material such as epoxy resin, and the coil is sandwiched between the layer 76 and the lid 72. Thus, the layer 76 helps to encapsulate the coil and generally helps to provide an airtight seal for the coil.

[0094] Typically, the compartment 70 and the lid 72 are made of plastic. Further typically, during the manufacture of the coil housing, the lid 72 is welded (e.g., ultrasonically welded) to the compartment 70 after the coil is inserted.

[0095] During use, the handle 42 ( Figures 2A - 2B ) is coupled to the compartment 70 opposite the lid 72 (i.e., at the opposite side of the compartment not shown in Figure 5A ), and the coil housing 38 is placed above the patient's head such that the lid 72 faces the head. For example, the lid 72 can contact the cap 30 ( Figure 4 ).

[0096] Typically, a magnetic stimulation coil includes a flat wire 33, i.e., a wire formed as a strip or a bar. The wire 33, which is covered along its length by a thin electrical insulation covering, is wound in two windings 31 in opposite directions, i.e., the wire is wound clockwise in one winding 31 and counterclockwise in the other winding. Although the windings 31 can have any suitable shape (e.g., oval or square), the windings 31 are typically circular (i.e., disk-shaped) and are thus referred to herein as circles 35. The circles 35 are spaced apart from each other (i.e., the outer edges of the circles are spaced from each other at their closest approach) by a distance D1, which is typically greater than 10 mm (e.g., greater than 12 mm) and / or less than 18 mm (e.g., less than 16 mm), such as 10 mm - 18 mm or 12 mm - 16 mm.

[0097] Relative to a single wire loop, the advantage of two circles is higher magnetic field localization. In particular, the two circles cancel each other out at the edges of the coil and interfere constructively near the middle of the coil (especially between the two circles), such that the magnetic field is concentrated near the center of the coil. The distance D1 affects the distance from the coil where the magnetic field is concentrated; in particular, the latter distance is an increasing function of D1. Typically, it is desirable for the magnetic field to be concentrated at least 2 cm below the patient's scalp, with the smallest possible near-field effects that may cause discomfort to the patient. The exemplary values of D1 provided above typically satisfy this goal.

[0098] For some applications, the width W1 of the flat wire is greater than 4 mm (e.g., greater than 5 mm) and / or less than 7 mm (e.g., less than 6 mm), such as 4 mm - 7 mm or 5 mm - 6 mm. Alternatively or additionally, the thickness of the flat wire (i.e., the dimension of the wire entering Figure 5A the page) 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), such as 0.8 mm - 1.6 mm or 1 mm - 1.4 mm. Alternatively or additionally, the ratio between the width of the flat wire and the thickness of the flat wire is greater than 3:1 (e.g., greater than 4:1) and / or less than 6:1 (e.g., less than 5:1), such as between 3:1 and 6:1 or between 4:1 and 5:1.

[0099] Typically, the advantage of a larger width and / or a smaller thickness, as opposed to a smaller width and / or a larger thickness, is that the current flowing through the coil is concentrated near the patient's head, such that a sufficiently strong magnetic field can be generated without overly increasing the size or mass of the coil. The above exemplary ranges provide this advantage without overly thinning or widening the wire.

[0100] For example, in some embodiments, due to the small size of the coil, the length L2 of the housing is less than 150 mm, such as less than 140 mm, and / or the width W2 of the housing is less than 75 mm, such as less than 65 mm, and / or the thickness of the housing is less than 9 mm, such as less than 8 mm. Alternatively or additionally, due to the small mass of the coil, the combined mass of the coil and the housing is less than 500 g, such as less than 400 g.

[0101] It can be seen by simulation that if the inner diameter d0 of each circle is too small, the magnetic field strength is adversely affected. Thus, generally the inner diameter d0 of each circle is between 21 mm and 31 mm, such as between 24 mm and 28 mm. This range of d0 values is beneficial for the relatively small size of the coil without adversely affecting the magnetic field strength.

[0102] For some applications, each circle includes a flat wire with between 6 and 10 complete turns, for example, a flat wire with 8 complete turns. For other applications, each circle includes a flat wire with between 10 and 16 complete turns, such as 12 - 14 complete turns. Generally, a larger number of turns increases the magnetic field strength (provided that d0 remains large enough, as described above).

[0103] Due to the small size and weight of the coil, the magnetic stimulation device can be easily positioned (and if needed, re - positioned) adjacent to the cap 30 ( Figure 4 ) without causing discomfort to the patient, for example, directly on the cap. In contrast, a larger or heavier coil would cause discomfort or require support from a bracket. As described above with reference to Figure 4 , for some applications, the magnetic stimulation device is reversibly coupled to the cap, for example, using hook - and - loop fasteners. Generally, this maintains the position of the magnetic stimulation device relative to the patient's head even if the patient moves their head.

[0104] As described above with reference to Figure 1 , generally the magnetic stimulation coil 21 is used for diagnostic procedures rather than transcranial magnetic stimulation (TMS) treatment procedures. As described above with reference to Figure 1 and Figure 4 further described, in addition to the magnetic stimulation device 20, the system 28 also includes a plurality of electrodes 61, which are generally arranged within the cap 30 that is placed on the patient's head. The system 28 also includes at least one computer processor 32. To perform a diagnostic procedure, the magnetic stimulation device 20 is reversibly coupled to the cap 30, for example, as described above with reference to Figure 4 . Subsequently, the processor 32 drives the magnetic stimulation device to apply magnetic stimulation to the patient's brain via the magnetic stimulation coil, receives the magnetically - evoked signals detected by the electrodes, and diagnoses the patient by analyzing the magnetically - evoked signals.

[0105] Typically, the processor 32 drives the magnetic stimulation device to apply magnetic stimulation to a depth of at least 2 cm from the patient's scalp. In other words, the processor supplies power to the coil 21, which, given the parameters of the coil described herein, is sufficient to cause the magnetic field to penetrate to that depth with an intensity sufficient to stimulate the patient's brain. Advantageously, due to the parameters of the coil, the stimulation is applied to that depth without overheating the coil and without causing discomfort to the patient by heating the scalp.

[0106] For some applications, the frequency of the magnetic stimulation within each pulse is between 2 kHz and 4 kHz, such as between 2.5 kHz and 3.5 kHz. Alternatively or additionally, the length of each pulse is between 200 microseconds and 400 microseconds, such as between 250 microseconds and 350 microseconds. Alternatively or additionally, the magnetic stimulation is applied with an amplitude between 4000 A and 6000 A (e.g., between 4500 A and 5500 A).

[0107] Now refer to Figure 5B , which is a schematic view of the compartment 70 according to some applications of the present invention. Figure 5B The view of the compartment 70 shown in Figure 5A corresponds to the view of

[0108] where the coil 21 and the layer 76 are hidden from the view.

[0109] In some embodiments, the magnetic stimulation device includes at least one printed circuit board (PCB) 78, which includes a circuit 80 configured to generate an output for facilitating a stimulation program. Each PCB 78 includes at least one filter line 86 configured to protect the circuit 80 by filtering the common-mode voltage from the coil 21, such that the coil housing can accommodate the coil and the PCB without the common-mode voltage damaging the circuit. For example, each PCB can be contained within the compartment 70.

[0109] In some embodiments, the circuit 80 includes one or more LEDs 84 configured to emit light indicating the stage of the stimulation program. Typically, the LEDs are controlled via a control signal that passes from the control unit 24 ( Figure 1 ) through the cable 36, for example, as described above with reference to Figure 3 . As the stage of the program changes (e.g., as the magnetic stimulation starts or ends), the control signal turns the LEDs on or off. In some embodiments, different respective filter lines 86 at least partially surround each LED.

[0110] Typically, light from the LED passes through the light guide 27, which extends from the LED to the outside of the coil housing, enabling the user to determine the status of the device from the light guide 27. Typically, the handle 42 includes the exposed (and visible) end of the light guide 27; for example, the exposed end of the light guide can surround the button 25. (This embodiment is also shown in Figure 2B as well.) Alternatively or additionally, the circuit 80 includes one or more temperature sensors 88 configured to output a signal indicative of the temperature within the coil housing. (For embodiments where the device also includes an LED 84, the temperature sensor 88 and the LED 84 are typically disposed on different respective PCBs.) Typically, the signal is transmitted via the cable 36 ( Figure 1 ), for example, as described above with reference to Figure 3 . In some embodiments, a filter line 86 extends along one face of the PCB (e.g., near the perimeter of the PCB), the one face being opposite the face on which the temperature sensor 88 is disposed.

[0111] Typically, the filter line 86 is floating, i.e., not connected to any voltage source. Further typically, the filter line 86 is shaped to define a series of rectangular waves 90, the nature of which determines the nature of the filter.

[0112] Typically, one or more openings 82 in the compartment 70 facilitate the passage of wires connected to the button 25, the coil 21, the PCB, and the cable, and / or promote air flow.

[0113] It should be noted that the embodiments described with reference to Figure 5B can be combined with any suitable coil configured to magnetically stimulate a patient's brain during a stimulation procedure for diagnostic or therapeutic purposes.

[0114] Now referring to Figure 6 , which shows the results of an analog magnetic stimulation using a coil with parameters according to some embodiments of the present invention. Figure 6 Shown are the simulated flux densities (B) at different distances from the surface of the coil, which in an actual stimulation procedure will face the patient's head. The flux density is measured along the central axis 74 of the coil, as Figure 5A shown, the central axis 74 extending perpendicular to the compartment 70. Figure 6 The word "surface" marked in

[0115] refers to the outer surface of the housing (e.g., the outer surface of the cover 72), and the distance indicated along the x-axis is measured from the surface of the coil itself. The outer surface of the housing is typically less than 2 mm, e.g., less than 1 mm, from the surface of the coil; in an actual stimulation procedure, this surface will contact the patient's head. In some embodiments, the magnetic stimulation coil is configured to at the coil surface (corresponding toFigure 6 a magnetic field having a flux density (B) of less than 0.5 Tesla (e.g., less than 0.4 Tesla or 0.3 Tesla) is generated at the zero distance (in Figure 6 the zero distance) within the housing and / or a magnetic field having a flux density of less than 0.5 Tesla (e.g., less than 0.4 Tesla or 0.35 Tesla) is generated at the surface of the housing. Nevertheless, at a 2 cm distance along the central axis 74, the flux density is generally greater than 0.3 Tesla (e.g., greater than 0.35 Tesla). Thus, the magnetic field is strong enough for stimulation at 2 cm, but not too strong at the patient's scalp. One reason is that due to the characteristics of the coil described herein, the flux density changes relatively slowly along the central axis 74. For example, as

[0116] shown, the flux density can reach a maximum at a distance greater than 4 mm (e.g., greater than 6 mm or 7 mm) from the surface of the coil before gradually decreasing. Thus, the flux density is maximum within the brain (where stimulation is needed) and is relatively high even at 2 cm. In contrast, for other coils, (i) the flux density outside the brain may be maximum, and / or (ii) in order to be high enough at 2 cm, the flux density would need to be uncomfortably high at the patient's scalp.

[0117] Alternatively or additionally, the magnetic stimulation coil generates a dB / dt of less than 8e -3 (e.g., less than 7e -3 ) Tesla / microsecond at the coil surface and a dB / dt of greater than 7e -3 (e.g., greater than 7.5e -3 ) Tesla / microsecond at a 2 cm distance along the central axis 74. Alternatively or additionally, the ratio of the dB / dt at 2 cm to the dB / dt at the coil surface is greater than 2:3, e.g., greater than 1:1 or 1:0.9.

[0118] The application 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 conjunction with a computer or any instruction execution system (e.g., computer processor 32). For the purposes of this description, a computer-usable or computer-readable medium can be any apparatus that can contain, store, communicate, propagate, or transport the program for use by or in conjunction with the instruction execution system, apparatus, or device. The medium can be an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system (or apparatus or device) or a propagation medium. Generally, a computer-usable or computer-readable medium is a non-transitory computer-usable or computer-readable medium.

[0119] Examples of computer-readable media include semiconductor or solid state memory, magnetic tape, removable computer floppy disk, random access memory (RAM), read only memory (ROM), rigid magnetic disk, and optical disk. Current examples of optical disks include compact disk read only memory (CD-ROM), compact disk read / write (CD-R / W), and DVD.

[0120] A data processing system suitable for storing and / or executing program code will include at least one processor (e.g., computer processor 32) coupled directly or indirectly to memory elements through a system bus. The memory elements can include local memory employed during actual execution of the program code, bulk storage, and cache memory that provides temporary storage of at least some program code in order to reduce the number of times code must be retrieved from bulk storage during execution. The system can read the instructions of the present invention on a program storage device and follow these instructions to perform the methods of embodiments of the present invention.

[0121] A network adapter can be coupled to the 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 some of the currently available types of network adapters.

[0122] The computer program code for carrying out operations of the present invention can be written in any combination of one or more programming languages, including object-oriented programming languages such as Java, Smalltalk, C++, etc., and conventional procedural programming languages such as the C programming language or similar programming languages.

[0123] A computer processor 32 is typically a hardware device programmed with computer program instructions to produce a special-purpose computer. For example, when the computer processor 32 is programmed to execute the algorithms described with reference to the accompanying drawings, the computer processor 32 typically acts as a special-purpose diagnostic computer processor. Generally, the operations performed by the computer processor 32 herein convert the physical state of a memory (which is a real physical article) into a different magnetic polarity, charge, etc., depending on the memory technology used. For some applications, the operations described as being performed by the computer processor 32 are performed by multiple computer processors in combination with each other.

[0124] Those skilled in the art will recognize that the invention is not limited to what has been specifically shown and described above. Rather, the scope of the invention includes combinations and sub-combinations of the various features described above, as well as variations and modifications of these features that are not in the prior art and that will occur to those skilled in the art upon reading the foregoing description.

Claims

1. An apparatus, comprising: a magnetic stimulation device, comprising: a magnetic stimulation coil formed of a flat wire, the flat wire being wound to form two circles spaced apart from each other, a ratio between a width and a thickness of the flat wire being greater than 3:1; and a housing that houses the magnetic stimulation coil.

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

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

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

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

6. The device according to claim 1, wherein The housing hermetically seals the magnetic stimulation coil.

7. The apparatus according to claim 1, wherein The housing comprises a compartment and a lid welded to each other.

8. The apparatus according to any one of claims 1-7, wherein, The ratio between the width and the thickness of the flat wire is between 3:1 and 6:

1.

9. The device according to claim 8, wherein, The ratio between the width and the thickness of the flat wire is greater than 4:

1.

10. The device according to any one of claims 1 - 7, wherein, The width of the flat wire is greater than 4 mm.

11. The device according to claim 10, wherein, The width of the flat wire is greater than 5 mm.

12. The device according to any one of claims 1-7, wherein, The thickness of the flat wire is less than 1.6 mm.

13. The apparatus according to claim 12, wherein, The thickness of the flat wire is less than 1.4 mm.

14. The apparatus according to any one of claims 1-7, wherein The two circles are spaced apart from each other by more than 10 mm.

15. The device according to claim 14, wherein, The two circles are spaced apart from each other by more than 12 mm.

16. The apparatus according to claim 14, wherein, The two circles are spaced apart from each other between 10 mm and 18 mm.

17. The apparatus according to any one of claims 1 - 7, Among them, wherein the magnetic stimulation coil is configured to generate a magnetic field having a magnetic field strength, and wherein a ratio of the magnetic field strength at a distance of 2 cm from a surface of the coil along a central axis of the coil to the magnetic field strength at the surface of the coil is greater than 2:

3.

18. The apparatus according to 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. A system, comprising: the apparatus according to any one of claims 1 - 7, a plurality of electrodes; and at least one computer processor configured to: drive the magnetic stimulation device to apply magnetic stimulation to a patient's brain via the magnetic stimulation coil, receive a magnetic stimulation - evoked signal detected by the electrodes, and diagnose the patient by analyzing the magnetic stimulation - evoked signal.

20. The system according to 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 from a patient's scalp.

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

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

23. The system according to claim 19, wherein The plurality of electrodes are arranged in a cap configured to be placed on a patient's head.

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

25. An apparatus, comprising: a coil configured to magnetically stimulate a patient's brain during a stimulation program; a printed circuit board, comprising: a circuit configured to generate an output for facilitating the stimulation program; and At least one filter line configured to protect the circuit by filtering the common-mode voltage from the coil; and A housing that houses the coil and the printed circuit board.

26. The device according to claim 25, wherein, The housing hermetically seals the coil.

27. The apparatus according to claim 25, wherein, The housing includes a compartment and a cover welded to each other.

28. The apparatus according to claim 25, wherein, The circuit includes one or more light-emitting diodes configured to emit light indicating a stage of the stimulation program.

29. The device according to any one of claims 25 - 28, wherein, The circuit includes one or more temperature sensors configured to output a signal indicating the temperature inside the housing.

30. A system comprising: A cap configured to be worn on a patient's head, the cap including: A sheet of material; and A plurality of coupling pads coupled to the sheet of material; and A magnetic stimulation device including: A coil housing; One or more straps coupled to the coil housing, each of the straps being configured to be coupled to any one of the coupling pads to couple the coil housing to the cap when the cap is worn on the patient's head; and A coil housed in the coil housing and configured to magnetically stimulate the patient's brain when the coil housing is coupled to the cap.

31. The system according to claim 30, wherein, The cap is shaped to define a plurality of electrode-holding apertures shaped to hold corresponding electrodes configured to record the electrical response of the brain to the stimulation.

32. The system according to claim 30, wherein The coupling pads include loops, and the straps include hooks configured to be coupled to the loops.

33. The system according to claim 30, wherein, The coupling pads include hooks, and the straps include loops configured to be coupled to the hooks.

34. The system according to claim 30, wherein, The magnetic stimulation device includes four straps.

35. The system according to claim 30, wherein, The magnetic stimulation device further includes a button, and wherein the magnetic stimulation device is configured to emit a test electromagnetic pulse in response to a press of the button.

36. The system according to claim 30, wherein The mass of the coil housing with the coil is less than 500 g.

37. The system according to claim 30, wherein, The coupling pads are positioned on the sheet of material such that when the cap is worn on the patient's head, the coil housing can be coupled to the cap above the frontal cortex of the patient's brain.

38. The system according to claim 37, wherein, The coupling pads are positioned on the sheet of material such that when the cap is worn on the patient's head, the coil housing can be coupled to the cap above the primary motor cortex of the patient's brain.

39. The system according to claim 37, wherein, The coupling pads are positioned on the sheet of material such that when the cap is worn on the patient's head, the coil housing can be coupled to the cap above the dorsolateral prefrontal cortex of the patient's brain.

40. The system according to claim 30, wherein, The coupling pads are positioned on the sheet of material such that when the cap is worn on the patient's head, the coil housing can be coupled to the cap above the parietal cortex of the patient's brain.

41. The system according to claim 30, wherein, The coupling pads are positioned on the sheet of material such that when the cap is worn on the patient's head, the coil housing can be coupled to the cap above the occipital cortex of the patient's brain.

42. The system according to claim 30, wherein, The coupling pads are positioned on the sheet of material such that when the cap is worn on the patient's head, the coil housing can be coupled to the cap above the temporal cortex of the patient's brain.

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

44. The system according to claim 43, wherein The material includes synthetic rubber.

45. The system according to claim 43, wherein, The material includes spandex.

46. A device, comprising: A coaxial cable, comprising: An inner conductor; An outer conductor, coaxial with the inner conductor; An inner sheath that insulates the inner conductor and the outer conductor from each other; and An outer sheath 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, and The bending radius of the coaxial cable is less than five times the outer diameter.

47. The apparatus according to claim 46, wherein, The coaxial cable further comprises: One or more insulated control lines passing through the inner conductor; and Another inner sheath that insulates the control lines from the inner conductor.

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