Abstract:
In accordance with the invention apparatus is provided for monitoring the activity of a surgeon. The apparatus comprises a plurality of wireless sensing units for producing an output indicative of nerve stimulation. A receiver takes the output of the receiver units and produces at its output a plurality of signals each corresponding to the output of one of the plurality of wireless sensing units. An analyzer unit receives the plurality of signals each corresponding to the output of one of the plurality of wireless sensing units from the receiver. An indicator responds to the output of the analyzer unit.

Description:
RELATED APPLICATION 
       [0001]    This application is a non-provisional application based on and claiming the priority of U.S. patent application Ser. No. 60/963,040. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to the monitoring of nerve responses during surgery, and, in particular, the monitoring of facial nerves during surgery with the object of preventing permanent nerve damage. 
       BACKGROUND 
       [0003]    In recent years, cosmetic surgery, and, in particular, cosmetic facial surgery is seeing dramatically increased use. This increase in the number of procedures performed each year is largely due to the fact that in the addition to the more elaborate and traditional face lift, other procedures, such as various versions of the S-lift are seeing widespread and increased performance. These procedures can be performed in one or two hours and require dramatically decreased recovery times. Moreover, such surgeries are often performed at relatively low-tech and small facilities, such as a doctor&#39;s office. Often such facilities specialize in that procedure only. 
       SUMMARY OF THE INVENTION 
       [0004]    One potential complication in facial surgery is the possibility of doing damage to the facial nerves, which can result in paralysis of a portion of the face. 
         [0005]    While equipment is available for monitoring the firing of a nerve, which can be detected (for example, by the twitching of a muscle) prior to the infliction of serious permanent injury, such systems are not using facial surgery because the wires connecting the nerve firing transducers interfere with the performance of the surgery. Accordingly, substantial numbers of individuals undergo facial surgery today and sometimes leave the operating table with permanent nerve injury. 
         [0006]    In accordance with the invention apparatus is provided for monitoring the activity of a surgeon. The apparatus comprises a plurality of wireless sensing units for producing an output indicative of nerve stimulation. A receiver takes the output of the receiver units and produces at its output a plurality of signals each corresponding to the output of one of the plurality of wireless sensing units. An analyzer unit receives the plurality of signals each corresponding to the output of one of the plurality of wireless sensing units from the receiver. An indicator responds to the output of the analyzer unit. 
         [0007]    The wireless sensing units may mechanically sense muscle movement. Alternatively, the wireless sensing units may comprise an inertial transducer. 
         [0008]    The wireless sensing units may be powered by a battery or by induced electricity from an external electromagnetic field. The receiver is coupled to an antenna contained within a headrest cushion supporting the head of a patient being operated on. The wireless sensing units may be imprinted with an alphanumeric or other visual indicator which appears on a display unit associated with the receiver. The receiver may be coupled to a personal computer and the visual indicator may be the display of the personal computer. 
         [0009]    The display of the personal computer may be a touchscreen, and control functions associated with the apparatus are implemented as touchably actuated icons on the touch screen. These functions may be varied and labeled in various ways by the computer. Moreover, the surgeon may select desired modes of display or labeling. In accordance with the invention, the display includes a plurality of individual displays, each of the individual displays being associated with one of the plurality of wireless sensing units. The individual displays many include an alphanumeric or other visual indicator which appears on a corresponding wireless sensing units. The individual displays may provide a meter-like indication of the amplitude of the signal produced by its respective wireless sensing units. The individual displays may change color in response to the amplitude of the signal produced by its respective wireless sensing unit. 
         [0010]    The display may comprise a plurality of screen indicators which are positioned with respect to each other in a manner which mimics the position of the wireless position transducers. The position of the wireless sensors maybe detected by the receiver and the indicator may be the screen of a personal computer, in which the position of the indicators are arranged to mimic the position of their respective wireless position transducers. 
         [0011]    Each of the wireless sensing units may be irreversibly programmed with an indication of a particular body portion or part or the like. 
         [0012]    In accordance with the invention, the output of the receiver may be stored for later retrieval in association with an authenticating timestamp signal. 
         [0013]    Alternatively, the wireless sensing units may output an analog or digital signal. 
         [0014]    The indicator may be responsive to the analyzer to generate an alarm if a predetermined threshold is exceeded. The predetermined threshold may be a threshold in change in the output of a particular wireless sensing unit over a particular period of time. The predetermined threshold may be a threshold in change in the value of a particular wireless sensing unit. 
         [0015]    The wireless position transducers may be associated with alphanumeric or other visual indicators which correspond to corresponding indicators on the screen indicators. The appearance of the indicator may include an alphanumeric or other indication of the position of the area where damage may be occurring. 
         [0016]    The appearance or sound of the indicator may vary in a manner which signals the seriousness of the detected condition. 
         [0017]    Optionally, the indicator outputs a normalized signal. 
         [0018]    Optionally, the plurality of wireless sensing units are sequentially read. 
         [0019]    It accordance with the invention, a wireless neurophysiologic monitoring/myophysiologic monitoring tack-shaped transducer/transmitter that, for example, senses muscle movement and then transmits that data to a receiver either during an operation, or in other diagnostic settings. It may be powered wirelessly via an electromagnetic field. Alternatively, a small wafer-like battery in the transducer/transmitter housing may also be used to power the unit. In most applications, such battery power would be appropriate as it is likely that the same will function for as long as a few hours. 
         [0020]    In accordance with the invention, a re-usable, for example, “donut-shaped” (or U-shaped) cushioned headrest supports the head of the patient during surgery. A radio antenna contained within the headrest connected to a receiver senses the output of the transducer/transmitters due to nerve activity. This output which drives a personal computer or purpose built monitoring unit receives the output from the transducer/transmitters. Likewise, electrical components housed within the headrest may be used to power the transmitter/transducers. This may be done with an electromagnetic field. The headrest (which is waterproof and can be gas sterilized) places the receiver within ten inches of the transducer/transmitter. A device placed nearby the patient or within the operating room for the receiver portion of the invention should also be contemplated. 
         [0021]    The invention also contemplates the use of dissection instruments consisting of probes, dissecting forceps, dissecting scissors, etc. that can transmit a stimulating current, delivered to the nerve by the surgeon for purpose of locating nerves during surgery and confirming that they are either intact or damaged. The use of a milliamp stimulator “docking station” for a personal computer is contemplated in accordance with the invention. This allows the computer to control the milliamp output that his used to stimulate the nerve using the above various instruments. Additionally, a stimulator separate from the computer could be used for this purpose. 
         [0022]    An electronic stimulator that generates a stimulating current may be integrated with the sensing computer in accordance with the invention for the purpose of stimulating the nerve to determine the ability of the transducer/transmitter to detect nerve firing and resulting movement. In accordance with the invention it is contemplated that the surgeon or technician will control the amplitude of such stimulation. It is further contemplated that this may be done under the control of the personal computer. 
         [0023]    In accordance with the invention is contemplated that the transducer/transmitters will be disposable or reusable. 
         [0024]    The transducer/transmitters may contain a microchip that allows them to be selectively programmed as to the site of the body or nerve that they will be monitoring. Likewise, transducer/transmitters may also be programmed or otherwise designed so that their electronic outputs are labeled separately from each other when sensed by the receiver/computer. A hand-held programming “pen” may be used at the time of transducer/transmitter placement. The transducer/transmitter may also be irreversibly programmed at manufacture so that it can only be used for a specific area of the body (i.e., the facial nerve). 
         [0025]    The computer software has the capability of recording the EMG data from the patient, and is capable of generating an audible tone indicating nerve firing and possible nerve injury. The inventive system also contemplates recording the data from the entire operation so that it can be retrieved, and has a mechanism by which this data is tamper proof and time-stamped so that from a legal standpoint the data can be submitted in a court of law as evidence. 
         [0026]    The monitoring computer is provided with a screen which may show data similar to that shown by existing nerve action monitoring equipment. 
         [0027]    In accordance with the invention, it is contemplated that a personal computer, programmed with appropriate software, may be used to monitor and process data from the transducer/transmitters. 
         [0028]    While the intended device and method is described in the context of monitoring the facial nerve, other types of neurophysiologic, neurosensory, and motor evoked response data is contemplated as part of this invention. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0029]    Several nonlimiting exemplary embodiments of the present invention are illustrated in the attached drawings, in which: 
           [0030]      FIG. 1  is a block diagram of a nerve response transducer/transmitter constructed in accordance with the present invention; 
           [0031]      FIG. 2  is a block diagram of instrumentation for monitoring the output of the transmitter/transducer of  FIG. 1 ; 
           [0032]      FIG. 3  is a block diagram of a transmitter similar to that of  FIG. 1 , except providing information in digital form; 
           [0033]      FIG. 4  is a block diagram of an alternative embodiment of the present invention useful in conjunction with the transmitter/transducer illustrated in  FIG. 3 ; 
           [0034]      FIG. 5   a  shows a placement of the inventive transmitter/transducers on a facial surgery patient; 
           [0035]      FIG. 5   b  is a view similar to  FIG. 5   a , but including wires; 
           [0036]      FIG. 6  is a top plan view of a transmitter/transducer constructed in accordance with the present invention and incorporating the circuitry of, for example,  FIG. 1  or  FIG. 2 ; 
           [0037]      FIG. 7  is a perspective view of the transmitter/transducer of  FIG. 6 ; and 
           [0038]      FIG. 8  is a flowchart illustrating the operation of the method of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0039]    Referring to  FIG. 1 , a transmitter/transducer  10  constructed in accordance with the present invention and useful in the practice of the method of the present invention is illustrated. Transmitter/transducer  10  comprises a transducer  12 , of conventional design, which is adapted to detect firing of a nerve and produce an electrical output proportional to the amplitude of such firing. The same may be a movement detector such as an inertial detector, and the computer to which its output is sent, as detailed below, may have software to prevent the detection of a benign movement as a twitch signaling the onset of nerve damage. Alternatively, any other type of detector, such as electrodes similar to those used in electrocardiogram systems, may be used. 
         [0040]    Thus, each transducer/transmitter may operate at its own unique carrier signal frequency. 
         [0041]    The output of transducer  12  it is sent to an ample our forte in which amplifies a signal and sends it to a mixer  16  which acts as a modulator. Mixer  16  multiplies the output of amplifier  14  by the output of oscillator  18 , forming an amplitude modulation signal with the carrier frequency equal to the frequency of oscillator  18 . This amplitude modulated signal is sent to a bandpass filter  20 , which removes unwanted modulation products. The filtered carrier signal with transducer information modulated onto it is then received by and amplified by amplifier  22  and output to antenna  24 . 
         [0042]    In accordance with the present invention, it is anticipated that a plurality of transducer/transmitters  10  will be placed on the face of a patient during surgery. Each of the transducer/transmitters  10  operates at a different carrier frequency, and, accordingly, transmits a separate identifiable and several the detectable signal indicating nerve function and, in particular, nerve firing. 
         [0043]    These signals from a plurality of transducer/transmitters  10  may be picked up by an antenna  26  on a receiver  28 . Receiver  28  comprises a tuned circuit  30  which receives the output of antenna  26  in a conventional fashion and provides its output to an RF amplifier  32 . The output of RF amplifier  32  is sent to a mixer  34 , which is driven by a heterodyne oscillator  36  to produce a plurality of heterodyne signals which are coupled to a plurality of signal buses  38 - 52 , which while they each carry all heterodyne products, are each assigned to a particular heterodyne product. Heterodyne oscillator  36  operates at frequency F h . Signal buses  38 - 52  are associated with heterodyne modulation products F h -F 1 , F h -F 2 , F h -F 3 , F h -F 4 , F h -F 5 , F h -F 6 , F h -F 7 , and F h -F 8 . 
         [0044]    Buses  38 - 52  drive heterodyne product bandpass filters  54 - 68 , respectively, which in turn drive detectors  70 - 84 , respectively. The outputs of detectors  70 - 84 , are provided to analog to digital converters  86100 , respectively. The outputs of these analog-to-digital converters are provided to programmable digital logic circuit  102 , which may be a microprocessor, personal computer, or any other suitable device. 
         [0045]    In accordance with the invention, the outputs of a plurality of transducer/transmitters such as those illustrated in  FIG. 1  are continuously monitored by programmable digital logic  102  to provide information respecting nerve firings. Such information may be of an analog nature and may be indicated with an analog display. Alternatively, alarms may be sounded if a dangerous condition is detected. In accordance with the present invention, it is also possible to combine, for example, one or more of such alarms as visible alarms, analog readouts, audible alarms, and so forth. 
         [0046]    One potential monitoring device is console display  104 . Display  104  may be a dedicated device with suitable display members and mechanical buttons. Alternatively, display  104  may be a liquid crystal display monitor typically associated with a personal computer. In accordance with a particularly preferred embodiment of the present invention, display  104  may be a computer monitor provided with a touchscreen feature which enables the actuation of icons by the finger of a user. 
         [0047]    In accordance with the invention, display  104  is provided with a number of indicators  106 - 120 . In accordance with preferred embodiment illustrated in  FIG. 2 , display  104  is a liquid crystal touchscreen display device of conventional design. Likewise, in accordance with the preferred embodiment of the invention, programmable digital logic  102  is a personal computer. 
         [0048]    Indicators  106 - 120  include numerals  122  which identify the transducer with which they are associated. Likewise, in the event that there is an indication of an alarm condition, a display  125  indicates the location of the alarm condition. The same may also be accompanied by an audible alarm. 
         [0049]    The amplitude of signal detection is shown by conventional bar graph indicator segments  124  which may have low or normal values as illustrated in four example, indicator  106  or high values as indicated by indicator  118 . In addition, color coding may be used, for example indicator segments  124  may be green during normal operation, amber to signify a heightened alert condition, and red to indicate a dangerous condition. In accordance with the invention, it is contemplated that different audible cues will be associated with different levels of alert. For example, an amber heightened alert may be indicated by a beep, while a red dangerous condition may be indicated by a repetitive siren-like sound. 
         [0050]    In accordance with the invention, it is contemplated that individual transmitters will be associated with a particular body part or portion of the face, for example. This may be done in a number of fashions, First the transmitter may be encoded to transmit a particular body portion identification. Alternatively, a particular use may be programmed. For example, a transducer with the number “1” printed on it may be placed by the physician and then “Select” icon  126  pushed until indicator  106  begins to blink. The surgeon or assistant would then push “Set” icon  128 . The “Select” icon  126  may then be pushed repeatedly to close the sequential display of various face portion areas in display  125 . Once the proper face portion appears in display  125 , “Set” button  128  is depressed. Pressing “Select” button  126  then causes the next indicator  106 - 122  be selected. 
         [0051]    It is also noted that, in accordance with the present invention, buttons for surgeon or surgeon&#39;s assistant may be made to change depending on their function, with the appropriate buttons being presented at the appropriate times. Such changing may be done in systems employing a liquid crystal display device or other display device having a touch screen. 
         [0052]    Referring to  FIG. 3 , an alternative digital version of the transmitter/transducer  210  constructed in accordance with the present invention and useful in the practice of the method of the present invention is illustrated. Transmitter/transducer  210  comprises a transducer  212 , of conventional design, which is adapted to detect firing of a nerve and produce an electrical output proportional to the amplitude of such firing. 
         [0053]    The output of transducer  212  is sent to an analog to digital converter  213 , which in turn, has its output sent to an amplifier  214  which amplifies the signal and sends it to a mixer  216  which acts as a modulator. Mixer  216  multiplies the output of amplifier  214  by the output of oscillator  218 , forming an amplitude modulation signal with the carrier frequency equal to the frequency of oscillator  218 . This amplitude modulated signal is sent to a bandpass filter  220 , which removes unwanted modulation products. The filtered carrier signal with transducer information modulated onto it is then received by and amplified by amplifier  222  and output to antenna  224 . 
         [0054]    Frequency modulation may also be used. 
         [0055]    The digital transducer/transmitter illustrated in  FIG. 3  has the advantage of having a numerical output guy you at the receiver which is independent of the quality of the channel coupling the transmitter to the receiver. However, the receiver is of somewhat different design, as illustrated in  FIG. 4  where similar or analogous components have been numbered with numbers  200  higher than those of the corresponding components in the embodiment of  FIG. 2 . 
         [0056]    The operation of receiver  228  illustrated in  FIG. 4  is substantially identical to that of the receiver illustrated in  FIG. 1 , except that because the output of detectors  270 - 284  is already in digital form, there is no need to convert to a digital number. However, standard integrate and dump circuits  286 - 300  are provided to improve noise immunity. 
         [0057]    As illustrated in  FIG. 5   a , transducer/transmitters  410  may be placed at various portions on the face while taking up minimal space and not interfering with the performance of an operation. This would be in contrast to an arrangement in which wires  411  extending between transducers and a monitoring instrument would tend to block the area where the surgeon is working, as illustrated in phantom lines in  FIG. 5   b.    
         [0058]    It accordance with the preferred embodiment, it is contemplated that transducer/transmitter units for  10  will be provided with, for example, suitable means of attachment comprising a layer of adhesive for a keen on their reverse sides, allowing them to be adhered to the skin on the face of the patient. 
         [0059]    As alluded to above and as illustrated in  FIGS. 6 and 7 , in accordance with the present invention, individual transducer/transmitters  410  are provided with an alphanumeric indicator  412  corresponding to the alphanumerical indicators  122  in  FIG. 2 . 
         [0060]    Transmitter/transducers  410  may be placed at various positions on the face  414  of a patient. Moreover, in accordance with the invention, the position of the transducers may be mimicked in the selection of receiver positions on the face of display  104 . See, for example, the spatial relationship of the transducer numbers in  FIG. 5  to the positions of the transducers in  FIG. 2  or  FIG. 4 . 
         [0061]    Antennas  26  and the radio receiver electronics may be housed in donut-shaped cushioned headset  416 . 
         [0062]    The inventive method of operation of the inventive systems is illustrated in  FIG. 8 . Method  510  begins with actuation of the system at step  512 . Upon actuation, the system is ready to receive a read command at step  514 . Upon the receipt of the read command, the system proceeds to read the signals output by the various transducer/transmitters placed by the surgeon on, for example, the face of the patient. The signals are read at step  516  and displayed at step  518 . 
         [0063]    At this point, the surgeon can look at the actual values being read by the transducers and determine whether the outputs are indicative of a good connection to the nerve. If a bad connection or faulty transducer/transmitter is detected, the transducer/transmitter may be reset, or replaced, as appropriate. 
         [0064]    If desired, the surgeon has the option of normalizing the outputs of the transducers. For example such normalization may take the form of reducing the output of all transducers to zero or an appropriate low value. The surgeon may input a calibration command at step  520 , causing the system to display the normalized signals on, for example, display  104  at step  522 . 
         [0065]    In accordance with the invention, the system is continuously and sequentially monitoring the outputs of all transducers/transmitters. Alternatively, such monitoring may be done simultaneously because of the frequency multiplexed nature of information transmission from individual nerves being monitored and receiver  28 . 
         [0066]    In accordance with the serial monitoring of transducer/transmitter outputs, a single transducer is read at step  524 . The value of the output signal is sent to storage at step  527 . The most recent value is then compared to the previous reading for that transducer at step  526  to determine potentially serious conditions. Such comparison is done by retrieving the previous value from memory. If the change in value exceeds a certain threshold, at step  528  the system proceeds to step  530  where, as appropriate, the desired visible and/or audible alarms are actuated. It accordance with the present invention, audible alarms or preferred as the surgeon need not look at the display. 
         [0067]    The system then proceeds to step  532  where the detected value produced by the transducer is compared to a standard second threshold value believed to be indicative of a dangerous condition. Likewise, if the value detected at step  526  is not found to exceed a threshold at step  528 , the system also proceeds to step  532 . If the difference between the second standard value and the actual value exceeds the set threshold, at step  534  the system proceeds to step  536  to actuate, as desired, visible and/or audible alarms. After the actuation of the alarms at step  536  the system advances to the next transducer signal at step  538 , as also occurs in the event that a determination is made that a threshold is not exceeded at step  534 . The system then returns to step  524  to read the next transducer and determine whether a dangerous condition exist and or whether certain alarms are to be actuated.