Abstract:
An apparatus for accurately monitoring motor movements attributable to seizures and convulsions of patients having epilepsy or other seizure disorders, and motor movements attributable to periodic leg movements, tremors, respiration, mechanical cardiac functions, or any other motorics during periods of sleep. This monitoring function is achieved without attaching any detection apparatus to the patient. Embodiments measure patient movements essentially by relating mattress displacement to such motor movements. The preferred embodiment is constructed with a geophone configuration intended to receive an analog signal corresponding to mattress movement and to communicate this signal to an electrically interconnected detection assembly for monitoring and recording the patient&#39;s pattern of body movements. Other suitable movement sensing devices such as devices based upon piezoelectric, fiber optics, microwave, infrared, and ultrasound phenomena may be used either in addition to or instead of geophones. The analog signals received by these sensors are then communicated to a computerized detection assembly wherein these signals are converted from waveforms to digital signals for subsequent analysis and remedial medical treatment as appropriate.

Description:
RELATED APPLICATIONS 
     This application claims priority based upon Provisional U.S. application Ser. No. 60/134,465 filed May 17, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to seizure monitors, and more particularly relates to means for monitoring movements attributable to seizures and convulsions of patients having epilepsy or other seizure disorders. 
     As is well known by those skilled in the art, it is common practice to attach electrodes to patients to observe bio-electrical body functions. For instance, electrical activity of the heart may be monitored by electrodes interconnected with the body. Unfortunately, electrodes are inconvenient and tend to become detached from the patient, wherein false alarms and patient-anxiety are undesirable sideeffects. Furthermore, if and when, a patient awakes while being observed and monitored, electrodes are likely to result in physical and psychological discomfort, and inhibited mobility. Such adverse reactions to monitoring devices are obviously contrary to efforts to remedy and improve a patient&#39;s infirmity and to improve a patient&#39;s well-being. 
     In U.S. Pat. No. 4,320,766, Alihanka et al. attempt to improve the art with a “static charge sensitive bed” that records signals corresponding to a patient&#39;s body movements while disposed in a supine position in bed. Configured with an antenna assembly to communicate amplified signals for recording changes in static charges produced by body movements, this bed may be used to monitor a patient&#39;s motor activity during sleep. Instead of using electrodes or the like, the Alihanka bed is constructed with a built-in antenna assembly consisting of plates, nets, or rods arranged in a matrix contained in a supplemental mattress disposed either between the patient and the regular mattress or beneath the regular mattress. However this assembly is complicated and somewhat cumbersome to apply to patients, and to operate without inadvertent interference by patients. 
     Notwithstanding these and related developments in the art, there appears to be no apparatus which provides a means for providing accurate, reliable, and interference-free signals corresponding to the motor movements of patients experiencing seizures, convulsions, and other sleep disorders during periods of sleep. 
     Accordingly, these limitations and disadvantages of the prior art are overcome with the present invention, wherein a seizure monitoring apparatus is provided that is particularly useful for enabling accurate and unobtrusive monitoring and recording of movements attributable to seizures and convulsions of patients having epilepsy or other seizure disorders. 
     SUMMARY OF THE INVENTION 
     The present invention provides an apparatus for accurately monitoring a patient&#39;s body movements during periods of sleep. In particular, the present invention monitors motor movements attributable to seizures and convulsions of patients having epilepsy or other seizure disorders, and motor movements attributable to periodic leg movements, tremors, respiration, mechanical cardiac functions, or any other motorics during periods of sleep. As will be hereinafter described, the present invention achieves this monitoring function without attaching any detection apparatus to the patient. Embodiments of the present invention measure patient movements essentially by relating mattress displacement to such motor movements. In order to reliably and accurately monitor such movements, it has been found that accurate sensing devices such as geophones—representative of seismic sensors or velocity sensors—or the like should preferably be used. 
     The preferred embodiment of the present invention is constructed with a geophone configuration intended to receive an analog signal corresponding to mattress movement and to communicate this signal to an electrically interconnected detection assembly for monitoring and recording the patient&#39;s pattern of body movements. According to the preferred embodiment, a plurality of insulated and padded geophones is parked upon a bed proximal to a patient situated thereon in a supine position. These geophones may alternatively be attached to the head-board, side-rail or the foot board of the bed. Any patient body movements cause corresponding displacements in the underlying mattress and the bed-frame that are, consequently, received by the plurality of geophones or the like. It will be appreciated that the present invention also contemplates that other suitable movement sensing devices such as devices based upon piezoelectric, fiber optics, microwave, infrared, and ultrasound phenomena may be used either in addition to or instead of geophones, so long as the sensitivity contemplated by the present invention is obtained. As will be appreciated by those skilled in the art, to achieve the objectives of the present invention, such sensors may require positioning on the bed or, in case of microwave, infrared, and ultrasound motion sensors, may require hanging positioning from a wall near the bed or from the ceiling thereabove. 
     The analog signals received by these sensors are then communicated to a computerized detection assembly wherein these signals are converted from waveforms to digital signals for subsequent analysis and remedial medical treatment as appropriate. Once these digital signals are analyzed, if seizures or convulsions or other sleep disorders appear to be occurring, then medical professionals or other healthcare personnel, including family members, are notified either locally or remotely. 
     It is an object of the present invention to provide an apparatus for accurately monitoring a patient&#39;s body movements during periods of sleep. 
     It is still another object of the present invention to provide an apparatus for promoting the safety and health of patients suffering from epilepsy, seizures, and other sleep disorders. 
     It is yet another object of the present invention to provide an apparatus that detects most patients&#39; motor seizures during periods of sleep. 
     It is yet another object of the present invention to provide an apparatus that detects some patients&#39; complex partial motor seizures during periods of sleep. 
     It is still another object of the present invention to provide an apparatus that detects patients&#39; motor movements attributable to epileptic convulsive seizures and other deviant movements including periodic leg movements, tremors, respiration, mechanical cardiac functions, or any other motorics during periods of sleep, without attaching any detection apparatus to the patient. 
     These and other objects and features of the present invention will become apparent from the following detailed description, wherein reference is made to the figures in the accompanying drawings. 
    
    
     IN THE DRAWINGS 
     FIG. 1 depicts a simplified frontal perspective view of a preferred embodiment of the present invention. 
     FIG. 2 depicts a simplified frontal perspective view of an alternative embodiment of the present invention. 
     FIG. 3 depicts an isolated frontal view of a portion of the preferred embodiment depicted in FIG.  1 . 
     FIG. 4 depicts a simplified schematic block diagram of the preferred embodiment depicted in FIG.  1 . 
     FIG. 5A depicts a waveform representing a patient&#39;s normal sleep activity recorded by an embodiment of the present invention. 
     FIG. 5B depicts a waveform representing a patient&#39;s 80-second seizure activity recorded by an embodiment of the present invention. 
     FIG. 5C depicts a waveform representing a patient&#39;s series of three 30-second seizures recorded over a three-hour period by an embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION 
     Now referring to FIG. 1, there is shown a simplified perspective view of the preferred embodiment of the present invention  2  comprising plurality of sensing means  5  disposed upon mattress  110  and adjacent or proximal to bed  100 . Plurality of geophone sensing means  5  is electrically interconnected with detection assembly SO. As will be appreciated by those skilled in the art, according to the present invention, a patient is sleeping upon mattress  110  with geophones  10  and  15  of plurality of geophones  5  disposed upon the mattress adjacent or proximal to the patient. As patient body movements occur during sleep, corresponding displacements of mattress  110  occur. These displacements are communicated to at least one of geophones  10  and  15 , which, in turn, communicate these signals to detection apparatus  50  within its housing  55  as will be hereinafter described in detail. 
     Geophone  20  is preferably disposed proximal to bed, e.g., on the floor, to establish a baseline or reference for signals that are attributable to environmental conditions, i.e., that are extraneous to the patient. Such environmental conditions may include vibrations from walking or from nearby elevators or escalators, vehicular traffic, etc. It will be understood by those skilled in the art that patient movements will always generate stronger signals in geophones  10  and  15 , placed upon the mattress, compared to geophone  20 , placed on the floor or on a structure away from the bed. It will be appreciated that the sensitivity of the plurality of geophones may be changed in order to obtain optimal results. It will also be understood that a plurality of sensors may also be used, if necessary, to properly monitor vibrations attributable to environmental conditions extraneous to a patient&#39;s body movements. 
     Another embodiment of the present invention is depicted in FIG. 2, wherein instead of a plurality of geophones to sense a patient&#39;s motor movements during sleep, a plurality of fiber optics sensors  70  is used. U.S. Pat. No. 5,194,847 generally describes the benefits and applicability of fiber optics for sensing movements and the like. According to the present invention, plurality of fiber optics sensors  70  should preferably be disposed in a sheet-like layer that may be conveniently snugly placed immediately above the mattress cover obviously disposed around mattress  110  or, alternatively, disposed immediately beneath the top sheet. 
     Now referring to FIG. 3, there is seen an isolated perspective view of a typical geophone contemplated by the embodiment depicted in FIG. 1. A commonly used geophone contemplated under the present invention consists of a magnetic device that detects movements. Using a suspended magnet, the geophone, upon movements occurring in its proximity, produce a proportional voltage (preferably measured in millivolts) through its winding. As will be understood by those skilled in the art, the amplitude of the output voltage is proportional to the intensity of the movement detected. Core-less DC motor member  45 , akin to the motor incorporated into commonly used pager-vibrators, is typically affixed atop the sensor&#39;s housing. This motor is turned on periodically to test the functionality of the geophone and detection system. 
     Thus, in FIG. 3, geophone  10  is shown having housing  35  and mounted upon base plate  30 . Since, as is known by those skilled in the art, geophones occasionally fail to properly obtain signals, vibrator motor member  45  is used to assure proper operation of geophone  10 . By periodically activating vibrator member  45 , a small movement is engendered in geophone  10 . If the signal conditioning circuit  120  fails to receive a response from the geophone under these artificial, test circumstances, then a warning alarm or the like is preferably generated, alerting the operator that a geophone malfunction has occurred. 
     Geophone  10  is preferably adapted to include cushion means  25  the surrounding housing  35  and base plate  30 , functioning as both electrical insulation and as a physical barrier to prevent patient discomfort should inadvertent contact therewith occur. 
     Other aspects of the computer system contemplated by the present invention include an LED light  220  to indicate if the system is operational. In the preferred embodiment, the LED light should blink whenever the trigger threshold is exceeded: in FIG. 1, this condition corresponds to the amplitude of the waveform generated from each geophones  10  and  15  disposed on the patient&#39;s bed being higher than the amplitude of the waveform generated from geophone  20  disposed on the floor. On the other hand, the LED light should remain illuminated once an alarm condition has been met, or under a malfunction-situation When a malfunction or a real alarm situation occurs, LCD  210  should display the nature of the malfunction or the alarm condition. 
     Since the alarm aspect of the present invention is inherent in the integrity and reliability of the monitoring function, to prevent accidental alarm-deactivation, the process of silencing an alarm should preferably require sequential pressing of two keys. According to the teachings of the preferred embodiment of the present invention, even after an alarm is deactivated, the LED should stay on until another, confirming sequence of keys is pressed. It will be understood that, when a malfunction occurs, there should preferably be simultaneous audio alarm and illumination of the LED light. The alarm may, of course, be deactivated as usual, but it should recur every 5 minutes or the like unless the malfunction has been corrected or unless the present invention has been switched off presumably because more than just immediate remedial action is needed for normal operation. It should be understood, of course, that if a system malfunction has occurred, the malfunction alarm or equivalent signal means should be readily distinguishable from a warning tone or other signal means, and the LED display will indicate that a malfunction or the like has occurred. 
     Additionally, it is contemplated that switching-off embodiments of the present invention should also preferably consist of a two step process. Thus, the turn-off keys should be programmed such that the sequential keys are not close to each other. It has been found that providing backup battery for power failure up to 12 hours long is advantageous for uninterrupted monitoring of patients&#39; sleep even under conditions of adverse weather and the like. The present invention also provides circuit protection well known in the art for the patient during monitoring, thereby preventing any 115V current from being communicated to a geophone situated on the patient&#39;s bed. Software of the present invention should preferably be programmed to pick up sustained seizures lasting for more than a preset length of time and a preset number of short but frequent seizures. Those skilled in the art will, of course, understand that, generally, the various settings prerequisite for accommodating the present invention to a patient&#39;s needs and specific seizure-type are programmable in software, ROM, or the like, in a manner known in the art. Thus, the duration of a patient&#39;s seizure and the frequency thereof prerequisite to triggering an alarm condition depends upon the patient&#39;s particular needs. Such patient-parameters will, of course, be input to the present invention as hereinbefore described for proper monitoring of the patient&#39;s seizures and the like. 
     It has been found that blanketing an embodiment of the sensing apparatus of the present invention with suitable padding  25  is preferable for the patient&#39;s comfort. As hereinbefore described, the plurality of geophones  5  or the like that detect patient movements may be either placed on a patient&#39;s bed or disposed on the bed side-rail or even affixed to the head-board or foot-board. Plurality of wires  40  interconnect geophone  10  with detection assembly  50  (FIG.  1 ). More particularly, pair of wires  42  A, B interconnect the geophone circuitry with the detection circuitry while pair of wires  44  A, B interconnect vibrator  45  with detection circuitry. 
     Referring now to FIG. 4, there is shown a simplified schematic in block diagram form of the detection and analysis circuitry  50  comprising the preferred embodiment of the present invention  2  depicted in FIG.  1 . By comparing the cumulative analog signals received by plurality of geophones  10  and  15  disposed upon mattress  110  or alternatively received by various other types of motion sensors known in the art, or a combination thereof, and the base line signal received by geophone  20  disposed upon the floor or the like, the incidences of motor movements engendered by a sleeping patient may be continuously monitored by conditioning circuit  120 . 
     In a manner well known in the art, this conditioning circuit uses filters and other components to amplify or attenuate the waveform incoming from the plurality of geophones  5  to a sufficient amplitude that may be input to the peak detectors circuit  130  that counts the peaks every second. Ergo, the geophones&#39; signals are terminated and then amplified to 0-2.5 V full-scale signals. These conditioned signals are calibrated such that the voltage conditioned from each geophone is equal to the same intensity of the movement at each geophone. It should be clear that peak detecting via circuit  130  is used to measure the highest voltage generated at each geophone. This detection is preferably performed every second to measure the highest intensity of the movement every interval (second). According to the preferred embodiment, this peak is reset by software every second. A low-pass filter is included in peak detectors circuit  130  to filter any 50-60 Hz power noise from the input signals. 
     The peak voltages that are preferably detected each second are then read through analog-to-digital converter  140 . These analog signals are converted to a digital signal, e.g., an eight-bit digital byte, representing the peak intensity that is proportional to the highest movement intensity during the 1-second interval. As will be understood by those skilled in the art, a microcontroller or microprocessor  150  is preferably used to perform a plurality of tasks as will be hereinafter described. Upon power up, microcontroller/microprocessor  150  executes a conventional start-up sequence. In particular, microcontroller/microprocessor  150  resets all the circuitry depicted in FIG. 4, and fetches the firmware from its non-volatile memory. It next interfaces with the user through keypad  230  and liquid crystal display (“LCD”)  210  to set the intervals, movement intensity threshold, number of movement episodes to constitute an alarm condition, number of repeated movements in sequence to trigger alarm  250 , and to set the operating mode to monitor, idle, and setup modes. 
     As hereinbefore described, microcontroller/microprocessor  150  coordinates the determination of whether detected movements are due to extrinsic causes. By comparing the signal level of geophones  10  or  15  with the reference level from floor geophone  20 , this determination is readily made. If only the floor movement is detected then, of course, the signal generated is deemed to be extraneous and is consequently ignored. As will be appreciated by those skilled in the art, suitable software or the like enables the three peak detected signals to be read from the plurality of geophones preferably disposed on the bed. The peak with the highest intensity is compared with the preset threshold value. If the movement is above the set intensity, then LED  220  is caused to blink, thereby indicating that a patient&#39;s movement has been detected. 
     Detected patient movements are recorded preferably in a non-volatile memory  280  for a period of up to twelve hours. As will be evident to those skilled in the art, the collected data may then be downloaded to a PC via RS 232  port  260 . RS 232 , of course, is an industry standard for serial asynchronous communications in which the signal is switched from +9V to −9V as Mark Signal. Microcontroller/microprocessor  150  communicates externally of the circuit of the present invention through input/output digital ports  180 . Numeral  290  represents an 8-bit addressable latch 1-of-8 decoder. Due to the limited number of digital I/O lines on microcontroller/microprocessor  150 , latch decoder means  290  is used to read a specific address code from the I/O port which, of course, corresponds to an address of an output device such as autodialer  270 , alarm  250 , LED  220 , and test motor  265 . Autodialer  270  comprises a contact switch well known in the art for activating an external autodialer device. In a manner well known in the art, a bit is set on Low or High to either reset or set the corresponding device. 
     Keypad  230  is provided for setting the time interval and period as contemplated by the present invention. By making a suitable keypad-based request to the operational software, the recorded time of a patient&#39;s motor movement may be displayed. A liquid crystal display  210  or the like is provided to display pertinent alphanumeric information indicative of the status of the patient&#39;s sleep behavior. In a manner well known in the art, Start/Stop switches are provided via a programmed set of preferably two numeric keys to start or stop monitoring a patient&#39;s sleep activity. The apparatus contemplated by the present invention is powered via conventional battery charger adapter  200 . Adapter  200  preferably comprises a commonly used lead-acid battery charger suited to battery  190 , and regulates and charges lead-acid battery  190  from a 120 vac power source. Leadacid battery  190  or the like is used to provide a source of DC power for operation without external power source. It should be evident, however, that any suitable battery and battery charger known in the art may be used to power embodiments of the present invention. Battery  190  is directly connected to adapter  200 . A toggle switch connected to the combination of adapter  200  and battery  190  provides a conventional and convenient way to switch off the system. As will be readily appreciated by those skilled in the art, if case power should fail, this battery assures continuous, uninterrupted operation of the apparatus taught by the present invention preferably for up to 12 hours. 
     If a patient is detected to have experienced a motor movement within an interval, then the time for such movement is recorded preferably in nonvolatile memory. This memory means should preferably have the capacity to store up to twelve hours of data in one-second intervals. If the patient&#39;s motor movement continues and exceeds the programmed value, the microprocessor/microprocessor will activate external and visual alarm  250 . 
     Referring now collectively to FIGS. 5 A, B, and C, there is depicted representative waveforms, collected by the plurality of sensors contemplated by the present invention, that are typically analyzed by detection and analysis circuitry  50  as hereinbefore described. More particularly, FIG. 5 A shows an illustration of a patient&#39;s normal sleep activity. On the other hand, FIG. 5B shows the waveform corresponding to a patient having a seizure approximately 80 seconds in duration. Under the preferred embodiment, such an illustrative waveform should, of course, trigger an alarm indicating that a seizure is occurring. Similarly, FIG. 5C shows an illustrative representation of three smaller seizures of about 30 seconds duration each, spread over a three-hour period. 
     As will be appreciated by those skilled in the art, as hereinbefore described, the internal computer instructions contemplated by the present invention may be programmed and implemented in software or ROM or the like to accept keyboard input indicating whether such an incidence of small seizure intervals in a particular period should trigger an alarm. Thus, peak detectors of the present invention are driven by the underlying software or the like to detect and measure the peaks. Then, the microcontroller/microprocessor member  150  assess whether a particular series of waveforms are above the amplitude and length threshold; if such waveforms are below the threshold, then no motor movement is considered to have occurred. 
     It is another feature and advantage of the present invention that the warning alarms and associated display may be communicated either locally or remotely to medical practitioners, healthcare personnel, or family. If the patient does not deactivate a local alarm contained in the present invention, as will happen if the patient is, indeed, having a seizure, then microcontroller/microprocessor  150  will activate a remote alarm in another part of the house or in a nursing station or the like. This alarm may be connected to the monitor apparatus of the present invention with a wire or may comprise a wireless remote alarm controlled with electromagnetic signals or the like. For situations in which no one resides in the same house as a particular patient, the microcontroller/microprocessor of the present invention may be programmed to activate auto-dialer  270  to dial a predetermined telephone number and to play a prerecorded message. As will be evident to those skilled in the art, this telephone number preferably summons a monitoring station or may summon a family member or “ 911 .” As should be clear to those skilled in the art, a monitoring station will be able to interact with the microcontroller/microprocessor to deactivate the alarm and also change the monitoring settings, if needed. It should be understood that the duration of a patient&#39;s seizure and the frequency thereof that will trigger an alarm condition depends upon the patient&#39;s particular needs. Such patient-parameters will, of course, be input to the present invention as hereinbefore described for proper monitoring of the patient&#39;s seizures and the like. The auto-dialer function contemplated by the present invention is capable of calling a sequence of telephone numbers until a sequence of keys are pressed at the other end. 
     For battery operation or battery backup, the conventional combination of battery  190  and battery charger  200  assure an uninterrupted power source if power via normal mains should become unavailable. That is, when a power outage or failure occurs, battery backup automatically takes over as the power source. It will be appreciated that battery charger  200  keeps battery  190  charged at all times. Thus, the apparatus taught by the present invention has access to battery-power at all times. In case of power failure or the like, the battery sustains power to the device for approximately 12 hours, obviously depending upon battery-selection criteria well known in the art. 
     Thus, the present invention affords an apparatus heretofore unknown in the art wherein geophones and the like are used to afford very sensitive and reliable detection of patients&#39; minute movements for the purpose of monitoring seizures. By processing the clean signals generated by this superior movement detection, the circuitry and software of the present invention provide a means and method for effectively monitoring seizure-caused movements. 
     It is also within the concept of the present invention that geophones hereinbefore described may be placed upon a patient&#39;s bed not only by itself, but also with a plurality of plastic flexible strips that are spread under the bed sheet and connected to each other. Thus, a geophone may be placed atop this arrangement to promote its sensing function. It will be understood that, instead of such strips, suitable wires and the like may be used. As another alternative embodiment of the present invention, a water-filled mattress may be used to inherently promote the sensitivity of sensors to vibrations caused by a patient&#39;s motor movements during seizures, convulsions, or other sleep disorders. In this embodiment, one spot on one of the corners of the mattress may be made of low resistance plastic: a geophone may then be placed on this spot to pick up even the smallest vibrations manifest in the water. 
     It will also be appreciated that the present invention contemplates that other suitable patient-movement sensing devices based upon piezoelectrics, fiber optics, microwaves, infrared, and ultrasound may be used in addition to or instead of geophones. As hereinbefore described, such sensors may either be positioned upon a patient&#39;s bed or, particularly in case of microwave, infrared, and ultrasoundbased based motion sensors, may be situated from a wall adjacent or the ceiling above the bed. 
     Other variations and modifications will, of course, become apparent from a consideration of the structures and techniques hereinbefore described and depicted. Accordingly, it should be clearly understood that the present invention is not intended to be limited by the particular features and structures hereinbefore described and depicted in the accompanying drawings, but that the present invention is to be measured by the scope of the appended claims herein.