Patent Publication Number: US-2007112277-A1

Title: Apparatus and method for the measurement and monitoring of bioelectric signal patterns

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application claims the benefit of U.S. Provisional Patent Application No. 60/726,910, filed Oct. 14, 2005, U.S. Provisional Patent Application No. 60/726,895, filed Oct. 14, 2005, and U.S. Provisional Patent Application No. 60/727,154, filed Oct. 14, 2005, which are all hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to the field of medical monitoring. More particularly, the present invention is directed to an apparatus and method for continuous medical monitoring of bioelectric signal patterns employing at least one wireless measurement device having at least one electrode adaptable for insertion within the ear canal.  
      2. Description of the Related Art  
      Electroencephalography (EEG), electrooculography (EOG) and electromyography (EMG) are techniques used for measuring, respectively, the electrical patterns corresponding to brain activity, eye movement associated with the resting potential of the retina and muscle contraction. The practice of assessing bioelectric signal patterns associated with the aforementioned techniques are recognized for their roles in a plurality of therapeutic and diagnostic applications.  
      Assessing bioelectric signal patterns associated with an EEG, EOG and EMG can be very useful in identifying abnormalities and particular areas of impairment related, respectively, to brain function, eye movement and muscle response. For example, a disturbance or known variation in the bioelectric signature of a normal EEG may generally be used to determine the existence of a neurological impairment. Typically, bioelectric signal patterns associated with an EEG reading is used to detect occurrences of seizures, evaluate the extent of trauma and injuries to the brain, diagnose the effects of tumors in particular locations of the brain, identify various infections and degenerative diseases, and evaluate sleeping disorders. The bioelectric signal pattern of an EEG is also frequently used to confirm brain death in a comatose patient. Similarly, bioelectric signal patterns associated with an EMG reading may be useful for assessing a variety of sleeping disorders. For example, the electrical activity related to muscle contractions associated with nighttime bruxism (i.e., dysfunctional clenching and grinding of the teeth) can be diagnosed with proper placement of electrodes.  
      Bioelectric signal patterns associated with an EOG reading are typically useful for studying and analyzing movements associated with the eye. The eye is the source of a steady electric potential field that can be described as a fixed dipole with positive potential at the cornea and negative potential at the retina. The magnitude of this potential is in the range of 0.4-1.0 mV. The potential is not related to light stimulation and is not generated by excitable tissue, but rather it is attributed to the higher metabolic rate of the retina. This potential difference and the rotation of the eye are the basis for the bioelectric signal pattern associated with an EOG reading. The bioelectric signal pattern associated with an EOG reading is very useful for determining the onset of REM sleep, which is sleep associated with a relatively high degree of eye motion.  
      Providing a means for assessing bioelectric signal patterns associated with EEG, EOG and EMG readings are not only useful for identifying impairments or abnormalities, but are also tremendously useful for monitoring the effectiveness of rehabilitative measures and progress of recovery. Therefore, when properly assessed, bioelectric signal patterns can be significantly useful for assisting healthcare professionals in determining the most effective treatments and appropriate preventative measures to be implemented.  
      Modern devices for measuring and monitoring bioelectric signal patterns associated with EEG, EOG and EMG are typically only available in a laboratory setting and operated by trained technicians. However, there is obvious value in being able to provide a means for measuring these bioelectric signal patterns in a home setting for monitoring sleeping disorders, normal daily activities (e.g., work, recreation or operation of a vehicle) or perhaps for determining level of consciousness and cognitive performance of military personnel in the field. However, these particular monitoring applications are impeded by the need to place skin-contact electrodes at various prescribed locations on the body. Correct placement of skin-contact electrodes typically requires some level of training, not only to find the proper locations for electrode application, but also to observe the received signal in order to assure the signal quality associated with placement of the skin-contact electrodes are acceptable. In addition, modern skin-surface electrodes used in the measurement of bioelectric signal patterns are prone to disruption resulting from normal motions of the body. In a sleep study, for example, involuntary motions can disturb skin-surface electrodes typically affixed to the head or neck. Consequently, the resulting bioelectric signal pattern recordings contain artifacts, which thereby complicate analysis.  
      Moreover, these aforementioned assessment devices and techniques, although non-invasive, require the use of expensive and intricate equipment set-ups. Due to the sophistication and intricacies of these aforementioned assessment techniques, a lab or clinical type setting is typically required and, therefore, there exist obvious limitations on the scope for which these techniques can be used. For example, it is extremely difficult and costly to provide the aforementioned assessment techniques as a means for allowing continuous monitoring of individuals undergoing recovery due to the lack of mobility inherent with such lab-type equipment.  
      Accordingly, it is desirable to provide an improved apparatus and method for the measurement and monitoring of bioelectric signal patterns associated with EEG, EOG and EMG readings.  
     SUMMARY OF THE INVENTION  
      It is an object of the present invention to provide a minimally invasive bioelectric measurement device employing a lightweight and cost effective design, thereby further providing a less cumbersome and highly mobile means for monitoring bioelectric signal patterns.  
      It is another object of the present invention to provide a minimally invasive and mobile measurement device configured to provide a means for continuous monitoring of bioelectric signal patterns to evaluate the effectiveness of rehabilitative measures, drug efficacy and the progression of recovery or mental and physical deterioration.  
      It is another object of the present invention to provide a minimally invasive and mobile measurement device employing electrode sites that elicit the requisite bioelectric signals, have enhanced immunity to motion artifacts, are simple to apply and are comfortable for the wearer.  
      In light of the foregoing, these and other objects are accomplished in accordance with the principles of the present invention, wherein the novelty of the present invention will become apparent from the following detailed description and appended claims, and wherein a wireless apparatus employing a bioelectric measuring device having at least one electrode positioned within the ear canal and a remote monitoring device for analyzing measured bioelectric related data is provided.  
      The measurement device employs the use of three electrodes, wherein at least one of these electrodes is configured for positioning within the car canal of an individual under medical surveillance. Electrodes positioned within the ear canal provide exceptional contact, as well as robust measurement of bioelectric signal patterns associated with EEG, EOG and EMG readings. A plurality of alternative configurations are presented for the positioning of electrodes in close proximity to the ear canal, thereby providing optimal bioelectric measurement points for various medical applications. The bioelectric measurement device of the present invention is also configured to present acoustic stimulation directly into the ear canal for evoking brain activity and the subsequent measurement of bioelectric signal patterns associated with the evoked activity.  
      At least one remote monitoring device is configured to wirelessly receive and analyze bioelectrical signal patterns measured by the bioelectric measuring device. The remote monitoring device is further configured to detect abnormalities and execute predefined notification procedures in response to the detections, wherein the notification procedures may include transmission of bioelectric related data to a healthcare professional equipped with a medically enabled mobile device. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The above and other objects and advantages of the present invention will be apparent upon consideration of the following detailed description, taken in conjunction with the accompanying drawings, in which like reference characters refer to like parts throughout, and in which:  
       FIG. 1  is an exemplary block diagram of a wireless apparatus employing a bioelectric measurement device and remote monitoring device in accordance with an embodiment of the present invention.  
       FIGS. 2A and 2B  illustrate opposing side views of an exemplary bioelectric measurement device housing structure in accordance with an embodiment of the present invention.  
       FIGS. 3A and 3B  illustrate an exemplary bioelectric measurement device configured for placement between an auricle of the ear and an adjacent side of a head of an individual in accordance with an embodiment of the present invention.  
       FIGS. 4A and 4B  illustrate exploded views of an exemplary electrode equipped ear canal insert coupled to the housing structure of the bioelectric measurement device illustrated in  FIG. 1  and configured for insertion within an ear canal of an individual in accordance with an embodiment of the present invention.  
       FIGS. 5A and 5B  illustrate exploded views of an exemplary electrode equipped ear canal insert containing bioelectric measurement components therein and configured for insertion entirely within an ear canal of an individual in accordance with an embodiment of the present invention.  
       FIGS. 6A and 6B  illustrate an exemplary montage of electrode placement in accordance with an embodiment of the present invention.  
       FIGS. 7A and 7B  illustrate another exemplary montage of electrode placement in accordance with an embodiment of the present invention.  
       FIGS. 8A and 8B  illustrate another exemplary montage of electrode placement in accordance with an embodiment of the present invention.  
       FIGS. 9A and 9B  illustrate another exemplary montage of electrode placement in accordance with an embodiment of the present invention.  
       FIGS. 10A and 10B  illustrate another exemplary montage of electrode placement in accordance with an embodiment of the present invention.  
       FIG. 11  is a flowchart illustrating the steps employed in monitoring and analyzing bioelectric signal patterns associated with EEG, EOG and EMG readings of an individual in accordance with an embodiment of the present invention.  
       FIG. 12  is a flowchart illustrating the steps employed in evoking brain activity and monitoring the corresponding bioelectric signal pattern associated with an EEG reading of an individual in accordance with an embodiment of the present invention. 
    
    
      It is to be understood that the above-identified drawing figures are for purposes of illustrating the concepts of the present invention and may not be to scale, and are not intended to be limiting in terms of the range of possible shapes and proportions of the present invention.  
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      The present invention is directed towards an apparatus and method for the wireless measurement of bioelectric signal patterns employing at least one bioelectric measurement device having at least one electrode adaptable for insertion into the ear canal. For purposes of clarity, and not by way of limitation, illustrative views of the present invention are described with references made to the above-identified drawing figures. Various modifications obvious to one skilled in the art are deemed to be within the spirit and scope of the present invention.  
      An exemplary wireless apparatus  10  is illustrated in  FIG. 1 . In accordance with a preferred embodiment of the present invention, apparatus  10  is comprised of a bioelectric measurement system  20 , a remote monitoring system  42  and mobile devices  56 . Bioelectric measurement system  20  is utilized in connection with a patient undergoing medical surveillance to measure bioelectric signal patterns associated with EEG, EOG and EMG readings. Remote monitoring system  42  and mobile devices  56  are configured to receive transmissions  60  of bioelectric related data from bioelectric measurement system  20 . Bioelectric related data may be transmitted via antenna  28  of bioelectric measurement system  20  and received via antennas  46  and  58  of remote monitoring system  42  and mobile devices  56 , respectively. Alternatively, bioelectric related data may be transmitted by remote monitoring system  42  and mobile devices  56  to bioelectric measurement system  20 . For example, instructions may be provided to system  20  from a healthcare professional via mobile device  56  to induce an acoustic stimulation for purposes of monitoring the resulting brain activity of a patient. It should be noted that bioelectric measurement system  20 , remote monitoring system  42  and mobile devices  56  are not limited to use of antennas  28 ,  46  and  58 , but rather are provided as exemplary means for transmitting and receiving transmissions  60  in accordance with the present invention described herein. Alternative transmitting and receiving means may be employed in, and are well within the scope of, the present invention.  
      Bioelectric measurement system  20  is comprised of electrodes  22 , an electronics unit  24 , a speaker  26  and an antenna  28 . Electronics unit  24  may include processing and wireless transmission components such as a processor  30 , an amplifying component  32 , an analog-to-digital converter (ADC) component  34 , a filtering component  36 , an auditory component  38 , a memory component  40  and a transceiver component  42 . Electrodes  22  and speaker  26  are coupled to signal processing unit  24  of bioelectric measurement system  20 .  
      Electrodes  22  includes an active electrode  22 a, a reference electrode  22 b and a ground electrode  22 c, which may be positioned at optimal EEG, EMG and EOG measurement points in the ear canal and at external points in close proximity to the ear (detailed description of various electrode arrangements and placement montages are provided in conjunction with  FIGS. 2-10 ). Speaker  26  may be an electronic device used to transform varying electric current into audible sound, a computer peripheral that reproduces speech and/or music, or any other suitable electro-acoustic transducer that converts electrical signals into sounds for presentation into the auditory canal of an individual undergoing medical surveillance via bioelectric measuring system  20 .  
      Remote monitoring system  42  may be located at various locations suitable for monitoring the bioelectric signal patterns transmitted by bioelectric measuring system  20 . In an alternative embodiment, there may be more than one remote monitoring system  42  for monitoring received bioelectric signal patterns. Remote monitoring system  42  is comprised of a transceiver  44  coupled to a user computer  48 . User computer  48  is comprised of a processor  50 , a display interface  52 , a notification interface  54  and a memory component  55 . Transceiver  44  is configured to transmit and receive data transmissions  60  via antenna  46  to and from transceiver  42  via antenna  28  of bioelectric measurement system  20 .  
      Mobile devices  56  may include a pager  56   a , a cellular or mobile telephone  56   b , a personal digital assistant (PDA)  56   c  or any other suitable mobile device enabled for secure and robust wireless connectivity. Bioelectric related data transmissions  60  may be received at or transmitted from mobile devices  56  via antenna  58 . Mobile devices  56  are preferably of the type that are medically enabled. For example, mobile devices  56  may be integrated with a wireless application protocol (WAP) in order to provide secure access to a hospital&#39;s computer network via a designated medical web site. Mobile devices  56  may also be equipped to run medically related applications or software. Such medically enabled devices provide healthcare personnel with an ability to work seamlessly regardless of their disparate locations. In addition, mobile devices  56  may provide e-mail and instant messaging services. For example, a doctor equipped with a medically enabled mobile device may receive captured images of an abnormal EEG pattern related to a patient from remote monitoring site  42  and prescribe instructions via the medically enabled mobile device back to remote monitoring site  42  or another medical staff member also equipped with a medically enabled mobile device.  
      Transceiver  42  of bioelectric measurement system  20 , transceiver of remote monitoring system  42  and mobile devices  56  may be transceivers that are compatible with Wi-Fi standard IEEE 802.11, BLUETOOTH™ enabled, a combination of local area network (LAN), wide area network (WAN), wireless area network (WLAN), personal area network (PAN) standards or any other suitable means to permit robust wireless transmission of bioelectric related data. For example, transceiver  42  of bioelectric measurement system  20 , transceiver of remote monitoring system  42  and mobile devices  56  may be BLUETOOTH™ enabled, thereby providing a means for connecting and exchanging bioelectric related information between devices such as a personal digital assistants (PDAs), cellular phones, notebook and desktop computers, printers, digital cameras or any other suitable electronic device via a secured short-range radio frequency. It should be noted that the aforementioned are provided merely as exemplary means for wireless transmission of bioelectric related data. Other suitable wireless transmission and receiving means may be employed in the present invention.  
      Electrical activity associated with EEG, EOG and EMG readings are typically measured using, respectively, skin-surface electrodes on the scalp, skin-surface electrodes at locations on the skin that are vertical or horizontal in position to the eyes and skin-surface electrodes or needles in muscular contraction areas of interest. However, the present invention employs a means for measuring bioelectrical signal patterns associated with EEG, EOG and EMG readings by utilizing electrodes positioned within and in close proximity to an individual&#39;s ear canal. Bioelectrical measurements taken via electrodes positioned primarily within the ear canal are advantageous in that the ear canal is in close proximity to the cerebral cortex and the eyes, yet not on the exterior surface of the skin. This particular positioning of electrodes provides for relatively strong bioelectric signal patterns to be recorded, while also providing reduced exposure to disruption of measurements due to motion.  
      In providing a means for measuring bioelectrical signal patterns associated with EEG, EOG and EMG readings via the ear canal, a hearing aid type device may be employed to house the electronic components necessary to process bioelectric readings received by electrodes  22  and transmit the processed bioelectric readings to remote monitoring system  42  of  FIG. 1 . Such an exemplary hearing aid type device is described with reference to  FIGS. 2A and 2B . A bioelectric measurement device  200  of  FIG. 2A  may be utilized for measuring bioelectric signal patterns and is comprised of an external housing  202 , a flexible processing extension  204  and a moldable ear canal insert  304  or  400 , respectively, having electrodes  306   a  and  306   b  or electrode  402  affixed thereon (illustrated in corresponding  FIGS. 3B-4B ). Bioelectric measurement device  200  may also include external electrodes  206  and  208  on the inside surface of housing  202 , as depicted in  FIG. 2B  (for particular applications to be described).  
      Exterior housing  202  of measurement device  200  is constructed to house electronics unit  24  of  FIG. 1 , thereby providing a wireless capable processing means for continuous medical surveillance of an ambulatory individual. Flexible processing extension  204  is coupled to a soft ear canal insert having at least one electrode disposed thereon, thereby providing an electrical connection between disposed electrodes and processing unit  24 . The body of flexible processing extension  204  is preferably made of a pliable material in order to easily conform and conceal flexible processing extension  204  behind the curvature of the ear.  
      Affixing electrodes on a soft ear canal insert, as illustrated in  FIGS. 3-5 , has many advantages over modern bioelectric measurement devices in that the electrodes&#39; locations and spacing in the present invention are predetermined by their affixed positions on the ear canal insert, rather than requiring a healthcare professional to be trained in the proper positioning of electrodes on the external surface of the skin. Therefore, proper electrode locations may be achieved automatically when the electrode outfitted ear canal insert is positioned within the ear canal, thereby significantly simplifying the means for measuring bioelectric signal patterns. Exemplary electrode outfitted ear canal inserts are illustrated in  FIGS. 3B-5B  and described in the following corresponding detailed description.  
      A preferred attachment of bioelectric measurement device  200  to an individual under medical surveillance is illustrated in  FIGS. 3A-3B . In  FIGS. 3A-3B , measurement device  200  is constructed so as to be situated only partially within the ear canal of an individual. For example, as illustrated in  FIGS. 3A and 3B , exemplary measurement device  200  is comprised of housing  202 , flexible processing extension  204  and electrode outfitted ear canal insert  304 . Measurement device  200  is configured for suitable placement between an auricle  302  of the ear and a side of the head  300  of an individual. As illustrated in the enlarged view of  FIG. 3B , housing  202  is shaped to the curved contour of the ear of an individual. Flexible processing extension  204  extends from an end of housing  202  to ear canal insert  304 , which is inserted within ear canal  301  of the individual.  
      Ear canal insert  304  is outfitted with at least one electrode. However, for purposes of illustration, and not by way of limitation, ear canal insert  304  of  FIG. 3B  is shown with two bioelectric sensing electrodes  306   a  and  306   b , spaced about 180 degrees apart on the surface of ear canal insert  304 . It should be understood that the number of electrodes provided on ear canal insert  304  may vary depending on the optimal measurement points determined for a particular medical application. For example, in  FIGS. 4A-4B , ear canal insert  400  provided within ear canal  301  is outfitted with only one electrode  402 .  
      In an alternative embodiment, an exemplary bioelectric measurement device  500 , as illustrated in  FIGS. 5A-5B , may be provided. Similar to the electrode equipped ear canal inserts of  FIGS. 3B-4B , measurement device  500  is constructed and configured to provide a means for inserting a bioelectric sensing electrode within ear canal  301  of an individual. Measurement device  500  is comprised of a housing  501 , perforated section  502 , moldable exterior shell  503  and bioelectric sensing electrodes  504   a  and  504   b . Rather than have electronics unit  24  provided in a housing structure residing outside the ear canal (as shown in measurement device  200  illustrated in  FIGS. 3B-4B ), the signal processing and wireless transmission components of electronics unit  24  may all be incorporated entirely within housing  501  of the ear canal shaped insert of measurement device  500 .  
      Perforated section  502  allows for audible sounds to be communicated from measurement device  500  into ear canal  301  of an individual. For example, speaker  16  of  FIG. 1  may be positioned adjacent to perforated section  502  of housing  501  in order to provide a means for transmitting audible tones and messages through perforated section  502  and into ear canal  301  for purposes of, for example, evoking brain activity in response to acoustical stimuli.  
      A moldable exterior shell  503  may be provided circumferentially about the exterior surface of housing  501  of measurement device  500 . Moldable exterior shell  503  is preferably constructed of a soft, yet durable, material capable of conforming to the interior walls of an individual&#39;s auditory canal in order to provide a comfortable and secure fitting of measurement device  500  within ear canal  301 . For example, moldable exterior shell  503  may be constructed of a memory foam that can be compressed and inserted into the auditory canal. When the memory foam is released it expands and provides a secure custom fitting within the individual&#39;s auditory canal. It will be understood that the use of a memory foam is only one of many suitable materials that may be used to construct a moldable exterior shell  503  and is merely provided as an example for purposes of illustrating the present invention. In addition, ear canal inserts  304  and  400  illustrated in  FIGS. 3B-4B  may similarly be constructed with a moldable exterior shell  503  (not shown) to provide a secure custom fitting within the auditory canal of the individual. A soft compressible insert provides the advantage of securely holding electrodes installed on a soft ear canal insert in contact with the surface via the restoring force of the compressible insert.  
      Electrodes  306   a  and  306   b  illustrated in  FIG. 3B , electrode  402  illustrated in  FIG. 4  and electrodes  504   a  and  504   b  illustrated in  FIG. 5B  may be fabricated from typical materials suitable for bioelectrical measurement. For example, the electrodes may be fabricated from various conductive polymers and metal films. Since the electrodes are, in most circumstances, located within ear canal  301  of an individual via a compressible insert, the need for adhesives and gels, typically used with skin-contact electrodes, are not required.  
      Although bioelectric signal patterns associated with EEG, EOG and EMG readings can feasibly be measured with the use of only two electrodes, typically referred to as an active electrode and a reference electrode, three electrodes are commonly used. The use of three electrodes allows an individual under medical surveillance to be isolated from ground so that contact with an electric source would not result in the individual creating a path to ground. In addition, three electrodes are preferably used to eliminate electrical noise sources common to both the active and reference electrodes during measurement.  
      In EEG electrode arrangements utilizing the ear canal, it is advantageous to use three electrodes. There are a variety of montages that can be implemented to produce usable bioelectric signal patterns associated with EEG readings. In general it is desirable to increase the spatial separation between active and reference electrodes since large separations tend to increase signal strength of the EEG. Similar to bioelectric signal patterns associated with EEG readings, a number of considerations determine the optimal electrode placement for bioelectric signal patterns associated with EOG readings using electrode outfitted ear canal inserts. Again, it is desirable to provide a spatial separation of active and reference electrodes such that the electrodes are spaced on opposite sides of the eye, with a spatial separation oriented in the same direction as the expected eye motions (e.g., active and reference electrodes above and below the eye to measure a vertical EOG).  
      With respect to the third electrode, a ground electrode, there are a number of options for placement. The ground electrode may be positioned within the ear canal, near an outer portion of the ear canal (e.g., between the head and auricle of the ear canal) or on the back of the neck. The potential of both active and reference leads are measured relative to this common ground electrode and only their difference is amplified. Since a subject is capacitively coupled to ground, noise sources common to the active and reference electrodes (e.g., 60 Hz noise) may be significantly reduced. It is therefore desirable to position the ground electrode in a position where it will be able to detect sources of electrical noise common to both the active and reference electrodes, while maintaining a position as far as possible from the active electrode. Thus, the exact placement of the ground electrode is in most cases dependent upon the specific sites chosen for the active and reference electrodes and the electrical interference expected from the surrounding monitoring environment.  
      The various electrode placement montages for achieving sufficient spatial separations are illustrated in  FIGS. 6-10 . In  FIG. 6 , a back view ( FIG. 6A ) and side views ( FIG. 6B ) of an individual equipped with a bioelectrical measurement device is shown. Either measurement device  200  (illustrated in  FIGS. 2-4B ) or measurement device  500  ( FIGS. 5A-5B ) may be utilized in the electrode placement montage  600  of  FIG. 6 . In montage  600 , active electrode  602 , reference electrode  604  and ground electrode  606  are all provided on a single ear canal insert  601 . In this particular arrangement of electrodes, the maximum spatial separation between active electrode  602  and reference electrode  604  is achieved by affixing the electrodes  180  degrees apart along the surface of the ear canal insert  601 , as well as spacing electrodes  602  and  604  as far apart laterally along the body of ear canal insert  601 . Ground electrode  606  is provided in close proximity to reference electrode  604 , but sufficiently distanced from active electrode  602 , to detect sources of electrical noise common to both electrodes  602  and  604 . Electrode placement montage  600  may be suitable for the measurement of bioelectric signal patterns associated with an EEG reading.  
      In  FIG. 7 , a back view ( FIG. 7A ) and side views ( FIG. 7B ) of an individual equipped with dual bioelectrical measurement devices (one in each ear) is shown. Either measurement device  200  (illustrated in  FIGS. 2-4B ), measurement device  500  ( FIGS. 5A-5B ) or a combination of both (one of each for use in opposing ears) may be utilized in electrode placement montage  700  of  FIG. 7 . In montage  700 , active electrode  702  and reference electrode  704  are provided on separate ear canal inserts  701   a  and  701   b . In this particular arrangement of electrodes, the maximum spatial separation between active electrode  702  and reference electrode  704  is achieved by affixing the electrodes in opposing ear canals. Similar to ground electrode  606  ( FIG. 6 ), ground electrode  706  is provided in close proximity to reference electrode  704 , but sufficiently distanced from active electrode  702 , to detect sources of electrical noise common to both electrodes  702  and  704 . It can be seen from the illustration of this particular arrangement that ground electrode  706  is affixed outside the ear canal against the mastoid portion of the temporal bone behind the auricle of the ear. This may be achieved, for example, by utilizing measurement device  200  having electrode contact  206  provided on the lower inside surface of housing  202  ( FIG. 2 ). Electrode placement montage  700  may be suitable for the measurement of bioelectric signal patterns associated with EEG and horizontal EOG readings.  
      In  FIG. 8 , a back view ( FIG. 8A ) and side views ( FIG. 8B ) of an individual equipped with a bioelectrical measurement device is shown. Here, the use of measurement device  200  is required in the electrode placement montage  800  of  FIG. 8 . In montage  800 , active electrode  802 , reference electrode  804  and ground electrode  806  are all provided in close proximity to a single ear canal, wherein active electrode  802  and ground electrode  806  are positioned within the ear canal via ear canal insert  801  and reference electrode  806  is positioned at the mastoid portion of the temporal bone behind the auricle of the ear. Measurement device  200  provides the means for locating electrodes  802 ,  804  and  806  in this particular manner. Electrode contact  206  may be used as reference electrode  804 . Again, in this particular arrangement of electrodes, the maximum spatial separation between active electrode  802  and reference electrode  804  is achieved. Electrode placement montage  800  may be suitable for the measurement of bioelectric signal patterns associated with an EEG reading.  
      In  FIG. 9 , a back view ( FIG. 9A ) and side views ( FIG. 9B ) of an individual equipped with a bioelectrical measurement device is shown. Similar to montage  800  of  FIG. 8 , the use of measurement device  200  is preferred in the electrode placement montage  900  of  FIG. 9  due to the availability of an electrode on the body of housing  202  for positioning at the mastoid portion of the temporal bone behind the auricle of the ear. In montage  900 , active electrode  902 , reference electrode  904  and ground electrode  906  are all separated, but kept in close proximity to the ear canal. Active electrode  902  is located in the ear canal via electrode outfitted ear canal insert  901 , reference electrode  904  is located at the mastoid portion of the temporal bone behind the auricle of the ear and ground electrode  906  is positioned on the back of the neck. An optional electrode lead (not shown) similar to flexible processing extension  204  may be provided at the base of housing  202  to extend the back of the neck area  905  for connected ground electrode  906 . Similar to all previously described montages, the maximum spatial separation between active electrode  902  and reference electrode  904  is achieved. Electrode placement montage  900  may be suitable for the measurement of bioelectric signal patterns associated with an EEG reading.  
      In  FIG. 10 , a back view ( FIG. 10A ) and side views ( FIG. 10B ) of an individual equipped with a bioelectrical measurement device is shown. Similar to montages  800  and  900 , the use of measurement device  200  is preferred in electrode placement montage  1000  of  FIG. 10  due to the availability of optional electrode contacts  206  and  208  on the body of housing  202  for positioning, respectively, against the mastoid portion of the temporal bone behind the auricle of the ear and a location in proximity to the temple that is above the horizontal plane of the eye. In montage  1000 , active electrode  1002 , reference electrode  1004  and ground electrode  1006  are all provided in close proximity to the ear canal. Active electrode  1002  is located outside the ear canal proximate to a temple location  1003  crossing above the horizontal plane of the eyes via electrode contact  208 . Reference electrode  1004  is positioned within the ear canal via ear canal insert  1001 . Ground electrode  1006  is positioned at the mastoid portion of the temporal bone residing behind the auricle of the ear. Measurement device  200  provides the means for locating electrodes  1002 ,  1004  and  1006  in this particular manner in that electrode contact  208  may be used as active electrode  1002  and electrode contact  206  may be used as ground electrode  1006 , thereby providing sites above and below the eye for measuring a vertical EOG reading. Again, in this particular arrangement of electrodes, the maximum spatial separation between active electrode  802  and reference electrode  804  is achieved. Therefore, electrode placement montage  1000  may be suitable for the measurement of bioelectric signal patterns associated with EEG and vertical EOG readings.  
       FIG. 11  is an illustrative depiction of the general steps employed by systems  20  and  42  of apparatus  10  for monitoring and analyzing bioelectrical signal patterns of EEG, EOG and EMG readings. In order to initiate the monitoring process of bioelectrical signal patterns at step  1102  the electrodes of measurement device  200 , measurement device  500  or alternatively a combination of both must be positioned within and/or in proximity to the ear canal of an individual under medical surveillance. Once properly positioned, electrodes of the corresponding measurement devices may measure detected bioelectrical signal patterns associated with EEG, EOG and EMG readings at step  1104 . Detected readings are subsequently processed, at step  1106 , by processor  30  provided within electronics unit  24 . The processing of detected bioelectrical signal patterns includes converting the detected potentials from analog to digital signals for processing by processor  30 . The processing of detected bioelectrical signal patterns additionally includes execution of amplification and appropriate biopotential filtering schemes, at step  1108 , in order to distinguish the various bioelectrical readings detected by the electrodes. For example, it is preferable to utilize a biopotential filtering scheme for separating and EMG, EOG and EMG readings detected by the electrodes.  
      Processed bioelectrical signal patterns may then be temporarily stored in memory component  40  ( FIG. 1 ) to be transmitted, at step  1110 , to a remote monitoring station  42 . Additional processing may be performed by processor  50  of user computer  48  at remote monitoring system  42 . Alternatively, steps  1106  and  1108  may be performed after transmission step  1110  by incorporating similar processing components provided in electronics unit  24  with processor  50  of user computer  48 , thereby transmitting raw bioelectrical signal pattern data from system  20  to system  42  to be similarly processed.  
      Filtered EEG, EOG and EMG readings are analyzed at step  1112 . The filtered readings may be displayed via display interface  52  of user computer  48  ( FIG. 1 ). These filtered readings associated with the transmitting individual are quantified and stored at step  1114 , for example, in memory component  55 . Alternatively, bioelectric related data for a patient under constant medical surveillance may be stored at a remote location. If a predefined emergency characteristic is detected in any of the analyzed and quantified readings at step  1116 , system  42  may be directed to activate notification interface  54 , thereby transmitting, at step  1118 , the appropriate data and/or predefined notification alarms and messages via transceiver  44  to a medically enabled mobile device  56 . A healthcare professional (e.g., an individual&#39;s personal physician) may then effectively analyze and prescribe the appropriate action to be taken. For example, an individual&#39;s primary physician may receive an alert and corresponding images of an abnormal bioelectrical signal pattern via a medically enabled PDA device  56   c . It should be understood that the notification procedures described above are provided merely as examples and that various notification procedures may be implemented in accordance with the principles of the invention.  
      It can be seen from the aforementioned description that brain activity can be monitored without need for invasive sensors. However, the bioelectric measurement device described in the present invention is not only limited to providing a wirelessly enabled monitoring means of ambulatory individuals, but is also configured to evoke brain activity in response to predetermined stimuli for purposes of monitoring brain function and associated physiological states or diseases for particular individuals that would most benefit from such surveillance.  
      It is well understood that specific sensory stimulation may be presented to an individual in order to evoke brain activity. The brain activity that is generated in response to a known stimulus is called an evoked potential, particularly auditory evoked potentials (AEP), which is a well known means for evoking potential to monitor states of consciousness. The AEP of an EEG reading, for example, may be measured by presenting acoustic stimulation to an individual under medical surveillance and recording the corresponding EEG reading. The EEG that is elicited in response to the acoustic stimulus is then analyzed for characteristic features that are linked to the state of consciousness. These features are ultimately quantified to provide clinically useful bioelectric signal pattern measurements of an EEG reading.  
      In the present invention, bioelectric measurement devices are equipped to induce an AEP, as well as measure the corresponding bioelectric signal patterns (as previously described). For example, electronics unit  24  of  FIG. 1  is equipped with auditory component  38  and speaker  26  and may be integrated within exterior housing  202  of measurement device  200  or housing  501  of measurement device  500 . These electronic components in combination provide a means for producing an acoustic stimulus within the ear canal in order to induce an AEP and provide a bioelectrical signal pattern for measurement by electrodes strategically placed within and in close proximity to the ear canal.  
      An illustrative depiction of the general steps employed by systems  20  and  42  of apparatus  10  for inducing an AEP and analyzing the corresponding bioelectrical signal patterns of an EEG reading is described with reference to the flowchart of  FIG. 12 . The monitoring of bioelectrical signal patterns associated with an EEG reading generated in response to an AEP is initiated by first positioning, at step  1202 , the electrodes of measurement device  200 , measurement device  500  or alternatively a combination of both within and/or in proximity to the ear canal of an individual under medical surveillance. When the select measurement device and its electrodes are properly positioned, an acoustic stimulation is presented, at step  1204 , into the ear canal of the individual under surveillance via speaker  26 . The acoustic stimulation may be preprogrammed for specific time presentations or initiated on demand from a remote site via a wireless transmission of commands to the select measurement device. Presentation of acoustic stimulation may be regulated by auditory component  38  of electronics unit  24  provided within the select measurement device attached to the individual under medical surveillance. The acoustic stimulation may be a vocal dictation, tone or any other applicable sound for stimulating brain activity.  
      At step  1206 , bioelectric signal patterns associated with an EEG reading produced in response to the acoustic stimulation provided at step  1204  are appropriately measured and recorded. Measured signal patterns may be associated and recorded in synchrony with the acoustic stimulation and transmitted, at step  1208 , to a remote monitoring site for additional processing and analyzing at step  1210 . It is often important to measure latency time periods between acoustic stimulation and events evoked in an EEG reading. It is also important to perform mathematical averaging of a series of EEG responses to repeated acoustic stimulation to improve signal-to-noise characteristics of the bioelectric signal pattern. Therefore, the processing and analyzing that occurs at step  1210  may utilize processor  50  of remote monitoring system  42  to implement electronic processing means for synchronizing the collection of bioelectrical data received at the electrodes of the measurement device with the time of acoustic stimulation. Thereafter, at step  1212 , further analysis means are provided to quantify features of the evoked bioelectrical signal patterns associated with an EEG reading in order to provide a measure of clinically relevant quantity representing level of consciousness.  
      Abnormal EEG responses to acoustic stimulation may be detected at step  1214 . Known features indicative of abnormality and or emergency situations may be predefined and associated with a set of medically responsive procedures to be executed upon detection. One such response may be triggering of an alarm and transmission of a notification alert to the appropriate healthcare professional, as provided at step  1216 . Healthcare professionals may receive such notifications on medically enabled mobile devices  56  via a wireless transmission  60  received at antenna  58 . However, the aforementioned response procedure is provided merely as an example. Alternative notification procedures may be implemented and is well within the scope of the present invention.  
      One skilled in the art will appreciate that the present invention can be practiced by other than the described embodiments, which are presented for purposes of illustration and not by way of limitation, and the present invention is limited only by the claims that follow.