Neurotrauma assessment device

Abstract

A portable, on-site spinal cord injury assessment device (10) and method (70) for monitoring of neural damage is disclosed which includes a transcranial electrical stimulator (12) operated by a portable power supply for delivering a programmed sequence of electrical pulses to the motor cortex resulting in elicit nerve action potentials in the motor cortex of the brain (25) and travelling via the spinal cord (27) to a plurality of peripheral nerves (18). A pair of hairbrush electrodes (16) each having a plurality of conductive bristles (17) applied across the midline on a scalp (13) to make an electrical contact with the scalp (13) and distribute a stimulation current from the transcranial electrical stimulator (12). A rectal probe connecting tube (21) having an anal sphincter pressure or force sensor (20, 60) inserted into a rectum to measure contraction of the sphincter (22) in response to the transcranial electrical stimulation and to monitor a peripheral motor response. The time of stimulation is synchronized with measurement of the peripheral motor response so that the latency as well as an amplitude of response is measured to monitor assessment of the nerve damage due to trauma and if the sphincter (22) contraction is absent, diminished in size, or of longer than normal latency then injury to the brain (25), the spinal cord (27) or the peripheral nerves (18) is indicated and appropriate care is provided.

Description

NEUROTRAUMA ASSESSMENT DEVICEFIELD OF THE INVENTION

[0001] The present invention relates to a neurotrauma assessment device, particularly, a non-invasive technique for detection and assessment of traumatic injury of the Spinal Cord and Central Nervous System and more particularly relates to a portable neurophysiological monitoring device to assess the function of the brain, spinal cord and peripheral nerves that is suitable for use at an accident site or a hospital casualty division.BACKGROUND OF THE INVENTION

[0002] Traumatic injury to the head and trunk results in a neurological injury to the brain, spinal cord and peripheral nerves. If the tissue is not handled carefully following such an injury the recovery from the nerve damage may be impossible. If the nature, extent and location of the nerve damage is identified at the site of accident, then appropriate precautions can be taken to prevent further damage and protect the tissue until full medical attention is provided.

[0003] Conventional approaches for the assessment of the neural pathway from brain to the peripheral sensor motor organs require extensive instrumentation and expertise. Normally, such testing is done under clinical conditions and often in an operation theatre. On site neurological damage assessment following trauma is done by medical personnel using various subjective measures of motor reflex, pupil dilation, voluntary movement, etc., all of which are imprecise and variable depending on the person administering the assessment.

[0004] Majority of prior art for neurological damage assessment use elaborate electrophysiological instrumentation or a blood biochemical assessment and are intended only for intraoperative use during surgeries. These are not suitable for quickand effective assessment of spinal cord injury at the site of accident and are ineffective or produce adverse side effects. Additionally, such existing approaches are not fieldportable (handheld) which makes it impractical for various field applications and are unable to provide immediate information critical to timely intervention. Furthermore, the prior art electrophysiological measurement for measuring the motor response to brain stimulation requires substantial care in recording and is not accurate in emergency situations.

[0005] Hence, there is a need for that art to provide a solution to address the above-mentioned problems. The present invention relates to an improved spinal cord injury assessment device and method that is portable and suitable not only for on-site monitoring but also for continuous monitoring till the patient is handed over to the concerned doctor / hospital. The monitoring of the nervous pathway from the brain to the peripheral nervous system is achieved by applying a stimulus to the brain and measuring a peripheral neuronal response, as described in greater detail herein. Further, the neuromonitoring device can be used relatively painlessly in awake subjects and is very useful in situations outside the operation theatre.SUMMARY OF THE INVENTION

[0006] The following summary is provided to facilitate an understanding of some of the innovative features unique to the disclosed embodiments and is not intended to be a full description. A full appreciation of the various aspects of the embodiments disclosed herein can be gained by taking the entire specification, claims, drawings, and abstract as a whole.

[0007] It is, therefore, one aspect of the present invention to provide for an improved portable spinal cord injury assessment device and method for on-site and bedside monitoring of the neuronal pathway from the brain to the peripheral nervous system by applying a stimulus to the brain and measuring a neuromotor peripheral response.

[0008] It is another aspect of the present invention to provide for an improved portable spinal cord injury assessment device and method for assessing a functional integrity of a neural pathway for on-site and bedside monitoring of the neurological deficits.

[0009] It is a further aspect of the present invention to provide for an improved spinal cord injury assessment device and method for identifying nature, extent and location of the nerve damage at the site of accident to enable the onsite medical person to take necessary precautions during transfer and transport of the accident victim.

[0010] According to one aspect of the present invention, a portable onsite spinal cord injury assessment device for monitoring of spinal cord injury is disclosed which includes a transcranial electrical stimulator with multi-contact electrodes operated by a portable power supply for delivering a programmed sequence of electrical pulses with controlled distributed current to deliver a programmed volley to the brain, resulting in a volley of nerve action potentials in the motor cortex of the brain and via the spinal cord to a plurality of peripheral nerves. A pair of “hairbrush” electrodes each having a plurality of conductive bristles formed as a set of spring-loaded conductive rods with rounder or shaped tips applied across the midline on the scalp to make an electrical contact with the scalp and distribute a stimulation current from the transcranial electrical stimulator. A rectal probe connecting tube having an anal sphincter pressure or force sensor inserted into rectum to measure contraction of the sphincter in response to the transcranial electrical stimulation of the brain and to monitor a peripheral motor response. In another aspect of the invention, biopotential recording of limb muscle myoelectric signals is measured along with or instead of the rectal pressure measurement. The time of stimulation is synchronized with measurement of the peripheral motor response so that the latency as wrell as the amplitude of response is measured to monitor assessment of the nerve damage due to trauma; if the sphincter contraction or myoelectric is absent, diminished in size, or of longer than normal latency then injury to the brain, the spinal cord or the peripheral nerves is indicated and appropriate care can be provided.

[0011] The transcranial electrical stimulator comprises a microcontroller, a rapid high voltage generator, a multi-channel controlled current output, a controlled direction of current via electrode cables, and portable battery to deliver the required transcranial stimulation to initiate the motor excitation in the brain. The stimulation current is delivered to the scalp in a distributed manner through the bristles of the electrode. The transcranial electrical stimulator delivers a current controlled pulse of 2-8 pulses with an inter-pulse interval of 2ms-50ms (20Hz- 500Hz) and a total pulse strength of 80-800mA with a total sequence duration of 0.05ms to 0.5ms so that a current of at least l-5mA. reach the neurons in the target area in the motor cortex. In contrast to peripheral nerve stimulation, every stimulation pulse delivered to the brain will not result in descending action potentials. A programmed set of stimulation pulses of appropriate number and interpulse interval is required to achieve descending motor action potential. The microcontroller controls the switched mode high-voltage generator that supplies the required stimulus current to the current controlled H-bridges to deliver monophasic or biphasic pulses to the scalp via the hairbrush electrodes. Each bristle of the hairbrush electrodes goes through the hair to reach the scalp to make effective electrical contact. The bristles are connected to wires and collected together in an electrode cable that connects to the stimulator. The multiple bristles distribute the current so as to reduce the current density per electrode thereby providing painless transcranial stimulation. This provides the important advantage of delivering relatively painless transcranial stimulation that can be used in awake subjects outside an operation theatre, including fully awake states.

[0012] The anal sphincter pressure or force sensor comprises a fluid filled rectal insert connected to a pressure transducer or a prong type load cell sensor. The fluid filled rectal insert is inserted into the anal canal and pressure by the sphincter contraction in response to the transcranial stimulation in the rectal insert is measured by the pressure transducer. The alternative sensor, the prong type load cell sensor comprises a strain gauge-based load cell sandwiched between two beams that provides an end-supported centre-loaded structure to measure force anywhere along the length of the beams and measures the sphincter contraction in response to the transcranial stimulation. The analsphincter pressure or force sensor transfers the measured pressure or force electronically to an amplifier for displaying, recording and storing the force variation with time. The anal sphincter pressure or force sensor measures full contraction of the rectal sphincter if the motor pathway from the brain, via the spinal cord to the rectal sphincter is intact and if such a contraction is absent, very weak or delayed or delayed then loss of neural communication is indicated. The device can optionally monitor a myoelectric signal from a lower or upper limb for electrophysiological recording.

[0013] According to another aspect of the present invention, a method for on-site monitoring of spinal cord injury is disclosed. A rectal probe connecting tube having an anal sphincter pressure or force sensor is quickly placed by a medical person at the time and place of a traumatic injury. A pair of hairbrush electrodes having a plurality of conductive bristles connected to a battery operated transcranial electrical stimulator is applied to the scalp. The bristles of the hairbrush electrodes easily pass between the hair fibres and reach the scalp, thereby avoiding the need for special scalp preparation. A programmed sequence of electrical pulses from the transcranial electrical stimulator is delivered to the scalp at sufficient strength and appropriate pattern to elicit a brief volley of nerve action potentials in the motor cortex of the brain and travelling via the spinal cord to a plurality of peripheral .nerves. The contraction of the anal sphincter in response to the transcranial electrical stimulation is measured by the anal sphincter pressure or force sensor and a peripheral motor response is monitored. The time of stimulation is synchronized with measurement of the peripheral motor response so that the latency as well as the amplitude of response is measured to assess the nerve damage due to trauma

[0014] The presence of traumatic injury to the brain, spinal cord or peripheral nerves is indicated if the sphincter contraction is absent, diminished in size, or of longer than normal latency to provide appropriate care. A current controlled pulse of 2-8 pulses with an inter-pulse interval of 2ms-50ms (20Hz-500Hz) and a total pulse strength of 80-800mA with a total sequence duration of 0.05ms to 0.5ms so that a current of at least l-5mA reach the neurons in the target area in the motor cortex by the transcranial electrical stimulator. Each bristle of the hairbrush electrodes goes through the hair toreach the scalp to make effective electrical contact. The bristles are connected to wires and all the wires are collected together in an electrode cable that connects to the stimulator. The multiple bristles distribute the current so as to reduce the current density per electrode thereby providing painless transcranial stimulation. The measured muscle force is electronically transferred to a circuitry for displaying, recording and storing the force variation with time. The anal sphincter pressure or force sensor comprises a fluid filled rectal insert connected to a pressure transducer or alternatively a prong type load cell sensor that measures full contraction of the rectal sphincter if the motor pathway from the brain, via the spinal cord to the rectal sphincter is intact and if such a contraction is absent, very weak or delayed then loss of neural communication is indicated.BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The disclosed embodiments may be better understood by referring to the figures, in which like reference numerals refer to identical or functionally similar elements throughout the separate views, to further illustrate the present invention and, together with the detailed description of the invention, serve to explain the principles of the present invention.

[0016] FIG. 1 illustrates an overall schematic view of a portable spinal cord injury assessment device for onsite and bedside monitoring of neurological deficits, in accordance with an exemplary embodiment of the present invention.

[0017] FIG. 2 illustrates a schematic block diagram of a transcranial electrical simulator, in accordance with an exemplary embodiment of the present invention.

[0018] FIG. 3 illustrates a schematic view of a hairbrush electrode with 9 bristle contacts, in accordance with an exemplary embodiment of the present invention.

[0019] FIG. 4 illustrates a schematic view of an anal sphincter pressure sensor using a fluid filled rectal insert connected to a pressure transducer, in accordance with an exemplary embodiment of the present invention.

[0020] FIG. b illustrates a cross-sectional view of an anal sphincter force sensor using a prong type load cell sensor having a strain gauge-based load cell sandwiched between two beams that provide an end-supported centre-loaded structure, in accordance with an exemplary embodiment of the present invention; and

[0019] FIG. 6 illustrates a flow chart of operations illustrating a method for onsite and bedside monitoring of a nervous pathway from the brain to the peripheral nervous system by applying a stimulus to the brain and measuring a peripheral neuronal response, in accordance with an exemplary embodiment of the present invention.

[0020] Biopotential recording for the myoelectric signal from the limb muscles is not showm as it is a standard technique not specific to the present invention.DETAILED DESCRIPTION OF THE INVENTION

[0021] The particular values and configurations discussed in these non-limiting examples can be varied and are cited merely to illustrate at least one embodiment and are not intended to limit the scope thereof.

[0022] In the following, numerous specific details are set forth to provide a thorough description of various embodiments. Certain embodiments may be practiced without these specific details or with some variations in detail. In some instances, certain features are described in less detail so as not to obscure other aspects. The level of detail associated with each of the elements or features should not be construed to qualify the novelty or importance of one feature over the others.

[0023] The claimed subject matter has been provided here with reference to one or more features or embodiments. Those skilled in the art will recognize and appreciate that, despite the detailed nature of the exemplary embodiments provided here, changes and modifications may be applied to said embodiments without limiting or departing from the generally intended scope. These and various other adaptations and combinations of the embodiments provided here are within the scope of the disclosed subject matter as defined by the claims and their full set of equivalents. Like numbers refer to like elements throughout.

[0024] The present invention relates to a simple, efficient and portable neurotrauma assessment device and method for monitoring of nervous pathway from brain to the peripheral nervous system by applying a stimulus to the brain and measuring a peripheral neuronal response. The present invention assesses the functional integrity of the neural pathway for bedside or on-site monitoring of neurological deficits resulting from traumatic injury. The portable spinal cord injury assessment device and method identifies nature, extent and location of the nerve damage at the site of accident and to enable the onsite medical person to take necessary precautions during transfer and transport of the accident victim. The spinal cord injury assessment device and method provides the important advantage of delivering relatively painless transcranial stimulation that can be used in awake subjects outside an operation theatre. The present invention is portable, inexpensive, dependable and fully effective in accomplishing its intended and other purposes.The invention allows recording the response at several muscles in the lower body in response to transcranial electrical stimulation to assess spinal cord injury between the brain and spinal levels, L3 (Quadriceps muscle CMAP), L4 (Tibialis Anterior muscle CMAP), SI (Soleus / Gastronemius muscle CMAP) and S4-S5 (anal sphincter twitch) as shown in Fig.8,

[0025] Referring to FIG. 1 an overall schematic view of a portable spinal cord injury assessment device (10) for onsite and bedside monitoring of neurological deficits is illustrated, in accordance with an exemplary embodiment of the present invention.Note that in FIGS. 1-6, identical or similar parts or components are generally indicated by identical reference numerals. The illustration in FIG. 1 shows a sketch of the brain (25), the spinal cord (27) and an anal sphincter (22). The neurotrauma assessment device (10) includes a transcranial electrical stimulator (12) operated by a portable power supply for delivering a programmed sequence of electrical pulses with controlled distributed current to deliver a programmed volley to the brain (25), resulting in a volley of nerve action potentials in the motor cortex of the brain (25) and travelling via the spinal cord (27) to a plurality of peripheral nerves (18). In general, the peripheral nervous system consists of the nerves that branch out from the brain (25) and the spinal cord (27).

[0026] A pair of hairbrush electrodes (16) each having a plurality of conductive bristles (17) formed as a set of spring-loaded conductive rods with shaped or rounded tips (19) is applied across the midline on the scalp (13). The transcranial electrical stimulator (12) is connected to the electrodes (16). The hairbrush electrodes (16) with the conductive bristles (17) make an electrical contact with the scalp (13) and distribute the stimulation current from the transcranial electrical stimulator (12). A rectal probe connecting tube (21) having an anal sphincter pressure or force sensor (20, 60) inserted into the rectum to measure the anal sphincter (22) contraction in response to the transcranial electrical stimulation of the brain and to monitor a peripheral motor response. In a preferred embodiment, the anal sphincter pressure sensor (20) comprises a fluid filled rectal insert (55) connected to a pressure transducer (24) or the anal sphincter force sensor (60) comprises a prong type load cell sensor (65), based on design consideration.

[0027] The time of stimulation is synchronized with measurement of the peripheral motor response so that the latency as well as the amplitude of response is measured to monitor assessment of the spinal cord injury and nerve damage due to trauma. If the sphincter (22) contraction is absent, diminished in size, or of longer than normal latency then injury to the brain (25), the spinal or the peripheral nerve (18) is indicated, and appropriate care is provided. The anal sphincter pressure or force sensor(20, 60) transfers the measured pressure or force electronically to an amplifier (26) for displaying, recording and storing (28) the force variation with time. The transcranial electrical stimulator (12) also sends a synchronization signal to the recording from the peripheral muscles. The mechanical measurement of muscle force is particularly easy in the case of sphincter (22) and the radial pressure is simply measured in the sphincter (22) cavity or centre without worrying about the muscle origin and insertion. In a preferred embodiment, the portable power supply comprises a portable battery (34) for operating the neurotrauma assessment device (.10), based on design consideration.

[0028] As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features that are commonly used on the nervous pathways from the brain to the peripheral nervous system, may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for the claims and / or as a representative basis for teaching one skilled in the art to variously employ the present invention.

[0029] Referring to FIG. 2 a schematic block diagram of the transcranial electrical simulator (12) is illustrated, in accordance with an exemplary embodiment of the present invention. The transcranial electrical stimulator (12) initiates nerve excitation in the brain (25), and the rectal probe connecting tube (21) is used to monitor the peripheral motor response. In a preferred embodiment, the transcranial electrical stimulator (12) is battery operated and includes a battery with voltage of 7.2V to 14.4V, based on design consideration. The 14.4V battery is made with 4 Li-Ion cells. The battery voltage is regulated (3.3V) to power a microcontroller (32) which forms the core brain of the device (10). The transcranial electrical stimulator (12) includes the microcontroller (32), a rapid high voltage generator (30), a multi-channel-controlled intensity and direction current output (36, 38, and 40), a controlled direction of current via an electrode cable (41), and the portable battery (34) to deliver the requiredtranscranial stimulation to initiate the motor excitation in the brain (25). In a preferred embodiment the multi-channel-controlled intensity and direction current output (36, 38, and 40) comprises current controlled H-bridges (36, 38, and 40) to control the flow of c urrent to the hairbrush electrodes (16).

[0030] The microcontroller (32) controls the switched mode high-voltage generator (30). This high-voltage generator (30) generates a voltage of about 800-1000V so that it can supply the required stimulus current. This high-voltage is used by current controlled H-bridges (36, 38, and 40) to deliver the actual stimulus. The current controlled stimulus ensures that the set current is delivered to the scalp (13) regardless of the electrode- tissue impedance (as long as the electrode-tissue impedance is on the order of few kilo Ohms or few tens of kilo Ohms). The H-bridge (36, 38, and 40) allows the operator to select the direction of stimulus by selecting either one of the hairbrush electrodes (16) to be the anode and the other to be the cathode. In a preferred embodiment the transcranial electrical stimulator (12) delivers either monophasic or biphasic pulses using the H-bridge (36, 38, and 40), based on design consideration.

[0031] Multiple modules of the current controlled H-bridge (36, 38, and 40) are incorporated and each is connected to one of the bristle conductors (17) of the hairbrush electrodes (16). The transcranial electrical stimulator (12) delivers a sequence of pulses to elicit a brief volley of nerve action potentials in the motor cortex. These nerve action potentials travel through the nerves from the brain (25), via the spinal cord (27) to the peripheral nerves (18). The transcranial electrical stimulator (12) delivers current controlled pulses with an amplitude of up to 800mA so that a current of at least l-5mA reaches the target neurons in the motor cortex. The stimulation is delivered in a sequence of 2-8 pulses with interpulse intervals of 5-50ms which will ensure an effective volley of excitation to the peripheral motor system. The electrical stimulator (12) is battery operated and portable.

[0032] Referring to FIG. 3a schematic view of the hairbrush electrode (16) with 9 bristle contacts is illustrated, in accordance with an exemplary embodiment of the present invention. The transcranial electrical stimulator (12) uses the hairbrush typeelectrode (16) to make effective electrical contact with the scalp (13) through the hair. The hairbrush electrode (16) includes the bristles (17) each having an individual insulated electrode holder (56) and a set of spring-loaded conductive rods with shaped or rounded tips (19). The spring-loaded feature allows the multiple bristles (17) to accommodate the shape of the head for different people. Each bristle (17) Is connected to a wire and all the wires are collected together in the electrode cable (14) via an insulated electrode base (54).

[0033] The multiple bristles (17) of the hairbrush electrodes (16) are also used to distribute the stimulation current thereby greatly reducing the current density at the scalp (13) and reducing sensation and pain at the scalp (13). The hairbrush electrode (16) with 9 bristle contacts is described for purposes of clarity and specificity; however, they should not be interpreted in any limiting way. However, it will be apparent to those of skill in the art that more or less number of bristles can be utilized as desired without departing from the scope of the invention. The hairbrush electrode (16) is designed to pass electrical current through the hair quickly and reach the scalp (13) to make effective electrical contact and to distribute the electrical current among 6-24 bristle contacts so that the current density at any one contact is not more than 120mA to ensure that the stimulation is quite painless. The hairbrush electrode (16) can also have more br istles (.17) than the number of the current-controlled H-bridge modules (36, 38, and 40) with several bristles (17) connected to a module for different distribution of current.

[0034] Referring to FIG. 4 a schematic view of the anal sphincter pressure sensor (20) using the fluid filled rectal insert (55) connected to a pressure transducer (24) is illustrated, in accordance with an exemplary embodiment of the present invention. The anal sphincter pressure sensor (20) includes the finger-sized rectal insert (55) with a cylindrical flexible component designed to be easily inserted into the rectum. The rectal insert (55) is made of inelastic but collapsible rubber or polymer filled with incompressible fluid. Therefore, the placement of the fluid filled rectal insert (55) in the rectal cavity is not critical and is suitable for use in the field or the site of accident. The fluid in the sensing rectal insert (55) is connected to the pressure transducer (24) using an inelastic, flexible tube. Therefore, the pressure in the rectal insert (55) is measuredby the pressure transducer (24). The measured pressure or force can be transferred electronically to an amplifier (26) for displaying, recording and storing (28) the force variation with time.

[0035] FIG. 5 illustrates a cross-section view of the anal sphincter force sensor (60) using the prong type load cell sensor (65) having a strain gauge-based load cell (64) sandwiched betw een two beams (62, 68), in accordance with an exemplary embodiment of the present invention. The prong type load cell sensor (65) comprises the strain gauge-based load cell (64) sandwiched between two beams (62, 68) that provides an end-supported centre-loaded structure to measure force anywhere along the length of the beams (62, 68) and measures the sphincter (22) contraction in response to the transcranial stimulation. This is shown schematically in FIG. 5. The prong type load cell sensor (65) is fabricated using standard methods such as a beam with strain gauges on the two surfaces of flexion using a protective polymer sheath (66). This design alkws measurement of force anywhere along the length of the beams (62, 68).

[0036] The transcranial electrical simulator (12) delivers the electrical pulses delivered to the scalp (13) at a sufficient strength and appropriate pattern to stimulate the motor cortex so as to elicit a descending volley of nerve action potentials to the peripheral nervous system. The transcranial electrical stimulation pulses with a strength of 200mA-800mA, and pulse duration of 0.05ms to 0.5ms, in trains of 2-8 pulses at intervals of 2ms-50ms (i.e., frequency of 20Hz-500Hz) is delivered to produce effective stimulation. The pair of multi-point electrodes (16) formed as the bristles (17) of the hairbrush are used to distribute the delivered electric current so as to reduce the current density per electrode thereby providing painless transcranial stimulation. This provides the important advantage of delivering relatively painless transcranial stimulation that can be used in awake subjects outside an operation theatre.

[0037] The hairbrush electrodes (16) readily pass through the hair and contact the scalp (13) so that depilation is unnecessary to get the full stimulation. The descending v olley of nerve action potentials activates the peripheral muscles that are measured by the sphincter pressure or force sensor (20, 60). The electrophysiological measurement of thecompound muscle action potential or myoelectric signal in limb muscles can also be measured and recorded using a bio-potential amplifier (23). The device (10) monitors a myoelectric signal from a lower or upper limb for the electrophysiological recording (29). In a preferred embodiment the mechanical measurement of contraction of the rectal sphincter (22) is easier to perform under emergency conditions.

[0038] The assessment of spinal cord injury damage due to trauma is performed using the pressure or force sensor (20, 60) in the anal cavity. The pressure sensor (20) for measuring the anal sphincter (22) pressure is fabricated as the finger size fluid-filled rectal insert (55) connected to the pressure transducer (24). The force sensor (60) for measuring the anal sphincter (22) force is fabricated by using the load cell (64) sandwiched between two outer beams (62, 68) so that the load cell (64) is loaded as an end-supported, centre-loaded beam. The pen-sized sphincter pressure or force sensor (20, 60) is easily inserted into the anal canal, and used to measure the sphincter (22) contraction in response to the transcranial stimulation. The full rectal sphincter (22) contraction is measured if the motor pathway from the brain (25), via the spinal cord (27), to the rectal sphincter (22), is intact, and if such a contraction is absent or very weak, then loss of neural communication has resulted.

[0039] Referring to FIG. 6 a flow chart of operations illustrating a method (70) for on-site and bedside monitoring of a nervous pathway from the brain to the peripheral nervous system by applying a stimulus to the brain and measuring a peripheral neuronal response is illustrated, in accordance with an exemplary embodiment of the present invention. A rectal probe connecting tube (21) having an anal sphincter pressure or force sensor (20, 60) is quickly placed by a medical person at the time and place of a traumatic injury, as shown at block (72). A pair of hairbrush electrodes (16) having a plurality of conductive bristles (17) connected to a battery (34) operated transcranial electrical stimulator (12) is applied to a scalp (13), as depicted at block (74). A programmed sequence of electrical pulses from the transcranial electrical stimulator (12) is delivered to the scalp (13) at sufficient strength and appropriate pattern to elicitnerve action potential in the motor cortex from the brain (25) and travelling via the spinal cord (27) to a plurality of peripheral nerves (18), as indicated at block (76),

[0040] The contraction of the sphincter (22) in response to the transcranial electrical stimulation is measured by the pressure or force sensor (20, 60) and a peripheral motor response is monitored, as shown at block (78). The time of stimulation is synchronized with measurement of the peripheral motor response so that the latency as well as an amplitude of response is measured to monitor assessment of the nerve damage due to trauma, as indicated at block (80). The measured pressure or force is electronically transferred to circuitry for displaying, recording and storing force variation with time, as shown at block (82). A determination is made whether the motor response is normal, as depicted at block (84). The presence of traumatic injury to the brain (25), the spinal cord (27) or the peripheral nerves (18) is indicted if the sphincter (22) contraction is absent, diminished in size, or of longer than normal latency to provide appropriate care, as indicated at block (88). Otherwise, the spinal cord (27) is normal as depicted at block (86).

[0041] The current controlled pulses of 2-8 pulses with inter-pulse intervals of 2ms-50ms (20Hz-500Hz), and total pulse strength of 80-800mA is delivered with a total sequence duration of 0.05ms to 0.5ms so that a current of at least l-5mA. reach the neurons in the target area in the motor cortex by the transcranial electrical stimulator (12). Each bristle (17) of the hairbrush electrodes (16) is connected to a wire and collected together in an electrode cable (14) to distribute the delivered stimulation current through the hair quickly and reach the scalp (13) to make effective electrical contact so as to reduce the current density per electrode thereby providing painless transcranial stimulation. The anal sphincter pressure or force sensor (20, 60) comprises the fluid filled rectal insert (55) connected to the pressure transducer (24) or alternatively the prong type load cell sensor (65) that measures full contraction of the rectal sphincter (22) if the motor pathway from the brain (25), via the spinal cord (27) to the rectal sphincter (22) is intact and if such a contraction is absent or very weak or delayed then loss of neural communication is indicated. Tills present inventionidentifies the nature, extent and location of the nerve damage at the site of accident, so that appropriate precaution is taken to prevent further damage and protect the tissue until full medical attention is provided. Furthermore, the neuromonitoring device for spinal cord injury is used relatively painlessly in awake subjects in situations outside the operation theatre. This will enable the onsite medical person to take necessary precautions during transfer and transport of the accident victim.

[0042] It will be appreciated that variations of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Also, various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.

[0043] REFERENCE NUMERALS:Neurotrauma assessment device - (10)Transcranial electrical stimulator - (12)Scalp - (13)Electrode cable - (14)Pair of hairbrush electrodes - (16)Conductive bristles - (17)Peripheral nerves - (18)Conductive rods with shaped or rounded tips - (19)Anal sphincter pressure sensor - (20)Rectal probe connecting tube - (21)Sphincter - (22)Bio-potential amplifier - (23)Pressure transducer - (24)Brain - (25)Amplifier - (26)Spinal cord - (27)Storage and display - (28, 29)Rapid high voltage generator - (30)Microcontroller - (32)Portable battery - (34)Multi-channel-controlled intensity and direction current output - (36, 38, and 40)Electrode cable - (41)Insulated electrode base - (54)Fluid filled rectal insert - (55)Insulated individual electrode holders - (56)Anal sphincter force sensor - (60)Strain gauge-based load cell - (64)Prong type load cell sensor- (65)Protective polymer sheath - (66)Two beams - (62, 68)Load cell sensor - (60)Headband - (67)Graduated Electrode Holder (69)Method - (70)Method steps - (72-88)

Claims

CLAIMS1. A neurotrauma assessment device - spinal cord injury assessment device (10), comprising: a transcranial electrical stimulator (12) operated by a portable power supply for delivering a sequence of electrical pulses to elicit nerve action potentials in the motor cortex from the brain (25) and travelling via the spinal cord (27) to a plurality of peripheral nerves (18); a pair of hairbrush electrodes (16) each having a plurality of conductive bristles (17) formed as a set of spring-loaded conductive rods with shaped or rounded tips (19) applied across the midline on a scalp (13) to make an electrical contact with the scalp (13) and distribute a stimulation current from the transcranial electrical stimulator (12); a rectal probe with connecting tube (21) having an anal sphincter pressure or force sensor (20, 60) inserted into a rectum to measure contraction of the sphincter (22) in response to the transcranial electrical stimulation and to monitor a peripheral motor response, a set of biopotential electrodes (23) placed on muscles of the leg to monitor the compound muscle action potentials in response to the transcranial electrical stimulation and to monitor a peripheral muscle response, wherein the transcranial electrical stimulator (12) initiate nerve excitation in the brain (25), and the rectal probe connecting tube (21) is adapted to monitor the peripheral motor response; and the time of stimulation is synchronized with measurement of the peripheral motor response so that the latency as well as an amplitude of response is measured to monitor assessment of the nerve damage due to trauma and if the sphincter (22) contraction is absent, diminished in size, or of longer than normal latency then injury to the brain (25), the spinal cord (27) or the peripheral nerves (18) is indicated.

2. The device (10) as claimed in claim 1, wherein the transcranial electrical stimulator (12) comprises a microcontroller (32), a rapid high voltage generator (30), a multi-channel controlled intensity and direction current output (36, 38, 40), a controlleddirection of current via an electrode cable (41), and a portable battery (34) to deliver the required transcranial stimulation to initiate the motor excitation in the brain (25).

3. The device (10) as claimed in claim 1, wherein the transcranial electrical stimulator (12) delivers a current controlled train of 2-8 pulses with an inter-pulse interval of 2ms-50ms (20Hz-500Hz) and a total pulse strength of 80-800mA with a total sequence duration of 0.05ms to 0.5ms so that a current of at least l-5mA reach the target neurons in the motor cortex.

4. The device (10) as claimed in claim 1, wherein the microcontroller (32) controls the switched mode high-voltage generator (30) that supply the required stimulus current to the current controlled H-bridges (36, 38, and 40) to deliver monophasic or biphasic p ulses to the scalp (13) via the hairbrush electrodes (16).

5. The device (10) as claimed in claim 1, wherein each bristle (17) of the hairbrush electrodes (16) connected to a wire and collected together in an electrode cable (14) distributes the delivered stimulation current to the scalp, with the bristles (17) passing between the hair quickly and reaching the scalp (13) to make effective electrical contact so as to reduce the current density per electrode thereby providing painless transcranial stimulation.

6. The device (10) as claimed in claim 1, wherein the two hairbrush electrodes (16) slide on a graduated band or scale (69) fixed on a headband (67) so that the distance between the electrodes can be fixed for a particular individual for repeatable stimulation of the same part of the brain,,7. The device (10) as claimed in claim 1, wherein the anal sphincter pressure or force sensor (20, 60) comprises a fluid filled rectal insert (55) connected to a pressure transducer (24) or a prong type load cell sensor (65).

8. The device (10) as claimed in claims 1 and 6, wherein the fluid filled rectal insert (55) is inserted into the anal canal and pressure by the sphincter (22) contraction inresponse to the transcranial stimulation in the rectal insert (55) is measured by the pressure transducer (24).

9. The device (10) as claimed in claims 1 and 6, wherein the prong type load cell sensor (65) comprises a strain gauge-based load cell (64) sandwiched between two beams (62, 68) that provides an end-supported centre-loaded structure to measure force anywhere along the length of the beams (62, 68) and measures the sphincter (22) contraction in response to the transcranial stimulation.

10. The device (10) as claimed in claim 1, wherein the anal sphincter pressure or force sensor (20, 60) transfers the measured pressure or force electronically to an amplifier (26) for displaying, recording and storing (28) the force variation with time.

11. The device (10) as claimed in claim 1, wherein the anal sphincter pressure or force sensor (20, 60) measures full contraction of the rectal sphincter (22) if the motor pathway from the brain (25), via the spinal cord (27) to the rectal sphincter (22) is intact and if such a contraction is absent, very w'eak or delayed then loss of neural communication is indicated.

12. The device (10) as claimed in claim 1, wherein the device (10) monitors a myoelectric signal from a lower or upper limb for electrophysiological recording (29).

13. A method (70) for on-site monitoring of spinal cord injury, said method comprising the steps of: quickly placing a rectal probe connecting tube (21) having an anal sphincter pressure or force sensor (20, 60) by a medical person at the time and place of a traumatic injury; applying a pair of hairbrush electrodes (16) having a plurality of conductive bristles (17) connected to a transcranial electrical stimulator (12) operated by a portable power supply to a scalp (13); delivering a sequence of electrical pulses from the transcranial electrical stimulator (12) to the scalp (13) at sufficient strength and appropriate pattern to elicit nerve action potential in the motor cortex from the brain (25) and travelling via thespinal cord (27) to a plurality of peripheral nerves (18); wherein the transcranial electrical stimulator (12) initiate nerve excitation in the brain (25), and the rectal probe connecting tube (21) is adapted to monitor the peripheral motor response; measuring contraction of the sphincter (22) in response to the transcranial electrical stimulation by the anal sphincter pressure or force sensor (20, 60) and monitoring a peripheral motor response; and indicating presence of the traumatic injury to the brain (25), the spinal cord (27) or the peripheral nerves (18) if the sphincter (22) contraction is absent, diminished in size, or of longer than normal latency so as to provide appropriate care.

14. The method (70) as claimed in claim 12, wherein the microcontroller (32) controls the switched mode high-voltage generator (30) that supply the required stimulus current to the current controlled H-bridges (36, 38, and 40) to deliver monophasic or biphasic pulses to the scalp (13) via the hairbrush electrodes (16).

15. The method (70) as claimed in claim 12, further comprising delivering a current controlled pulse of 2-8 pulses with an inter-pulse interval of 2ms-50ms (20Hz-500Hz) and a total pulse strength of 80-800mA with a total sequence duration of 0.05ms to 0.5ms so that a current of at least l-5mA reach the neurons in the target area in the motor cortex,16. The method (70) as claimed in claim 12, further comprising connecting each bristles (17) of the hairbrush electrodes (16) to a wire and collected together in an electrode cable (14) to distribute the delivered stimulation current, the bristles (17) passing through the hair quickly and reaching the scalp (13) to make effective electrical contact so as to reduce the current density per electrode thereby providing painless transcranial stimulation.

17. The method (70) as claimed in claim 12, further comprising determining the latency as well as an amplitude of response by synchronizing time of stimulation withmeasurement of the peripheral motor response to monitor assessment of the nerve damage due to traumatic nerve injury.

18. The method (70) as claimed in claim 12, further comprising electronically transferring the measured pressure or force to a circuitry for displaying, recording and storing the force variation with time.

19. The method (70) as claimed in claim 12, wherein the anal sphincter pressure or force sensor (20, 60) comprises a fluid filled rectal insert (55) connected to a pressure transducer (24) or a prong type load cell sensor (65) that measures full contraction of the rectal sphincter (22) if the motor pathway from the brain (25), via the spinal cord (27) to the rectal sphincter (22) is intact and if such a contraction is absent, very weak or delayed then loss of neural communication is indicated.

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