Abstract:
Devices and methods for detecting one or more symptoms of stroke, such as motor function deficits and cognitive function deficits. By way of example, not limitation, the present invention provides devices and methods for detecting various forms of hemiparesis, ataxia, aphasia, and/or dysarthria, which may be measured alone or in any combination.

Description:
CROSS-REFERENCE TO RELATED CASES  
       [0001]    The present application claims the benefit of U.S. Provisional Patent Application No. 60/407,370 filed Aug. 31, 2002, entitled STROKE DETECTION DEVICE AND METHOD, U.S. Provisional Patent Application No. 60/429,101 filed Nov. 26, 2002, entitled STROKE DETECTION DEVICE AND METHOD, and U.S. Provisional Patent Application No. 60/460,525 filed Apr. 4, 2003, entitled STROKE SYMPTOM RECOGNITION DEVICE AND METHOD. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention generally relates to medical diagnostic devices and methods. More specifically, the present invention relates to medical devices and methods for diagnosing symptoms of stroke.  
         BACKGROUND OF THE INVENTION  
         [0003]    Stroke is a leading cause of death and disability in industrialized nations. Nearly 500,000 people in the United States suffer from stroke syndromes annually, at a cost of $23 billion. Strokes are caused primarily by an abrupt interruption of blood flow to a portion of the brain, due to arterial blockage. A less common cause of stroke is hemorrhaging due to a ruptured cerebral aneurysm.  
           [0004]    Since strokes affect only one side of the brain, symptoms typically involve only one side of the body. Common symptoms include muscle weakness, numbness, paralysis, vision problems, loss of balance, loss of coordination, and speech impairment. These symptoms are often subjective, and often not easily discernable by the user. Furthermore, symptoms of stroke are rarely painful, unlike those in a heart attack. Therefore, people suffering from stroke are often not aggressive and inherently reluctant in seeking medical attention.  
           [0005]    However, prompt medical attention is crucial for implementing treatment modalities that can dramatically minimize the long-term impact of the stroke for the user. One such therapy is the use of thrombolytic agents (“clot busters”) to restore blood flow to the ischemic zone. But, the effectiveness of this treatment drops off rapidly after the first hours following stroke. Moreover, after 3 hours of symptom onset, use of thrombolytics dramatically increases the risk of hemorrhaging, substantially worsening the outlook for the user.  
           [0006]    Studies have indicated that only about 25% of stroke users arrive to a hospital in less than 2 hours, while approximately 60% arrive after 6 hours, well beyond the time window for effective treatment. The primary cause of this delay is the delay in the user deciding to seek medical attention. Clearly, public health care would be greatly benefited if more stroke users could present to a hospital in a more timely fashion.  
           [0007]    There is therefore a great need for a user-implemented diagnostic tool to quickly, easily, and objectively diagnose symptoms related to the onset of stroke. Such a tool would help a user suffering a stroke to seek prompt medical attention.  
         SUMMARY OF THE INVENTION  
         [0008]    The present invention provides exemplary embodiments of devices and methods for detecting one or more symptoms of stroke, such as motor function deficits and cognitive function deficits. By way of example, not limitation, the present invention provides devices and methods for detecting various forms of hemiparesis, ataxia, aphasia, and/or dysarthria, which may be measured alone or in any combination. Generally speaking, the devices and methods of the present invention provide for the measurement of various indicia of the above symptoms, and provide for various actions (e.g., alert signal, EMS notification, etc.) if the measurement(s) meet certain predefined conditions (e.g., above or below a threshold value).  
           [0009]    In some embodiments of the present invention, devices and methods are provided for detecting hemiparesis. Hemiparesis, a very common symptom of stroke, is a muscular weakness or partial paralysis restricted to one side of the body. Exemplary embodiments are disclosed for detecting hemiparesis by measuring differences in hand strength or arm drift.  
           [0010]    In other embodiments of the present invention, devices and methods are provided for detecting ataxia. Ataxia is an impaired ability to perform smooth coordinated voluntary movements. Exemplary embodiments are disclosed for detecting ataxia by measuring dexterity.  
           [0011]    In still other embodiments of the present invention, devices and methods are provided for detecting aphasia, including receptive aphasia and expressive aphasia. Aphasia is a cognitive disorder marked by an impaired ability to comprehend (receptive aphasia) or express (expressive aphasia) language. Exemplary embodiments are disclosed for detecting receptive aphasia by positing written or oral instructions to the user, followed by measuring the correctness and/or time delay of the response from the user. Exemplary embodiments are also disclosed for detecting expressive aphasia by positing an image of an object to the user, prompting the user to identify or name the object, and measuring the correctness and/or time delay of the response from the user.  
           [0012]    In yet other embodiments of the present invention, devices and methods are provided for detecting dysarthria. Dysarthria is a disorder of speech articulation (e.g., slurred speech). Exemplary embodiments are disclosed for detecting dysarthria by prompting the user to say a word or phrase that is recorded for subsequent comparison by voice pattern recognition techniques or evaluation by medical personnel.  
           [0013]    The devices and methods of the present invention may be implemented in devices dedicated to detecting one or more stroke symptoms. Alternatively, the devices and methods of the present invention may be incorporated into a device wherein the diction of stroke symptoms is an ancillary function. For example, the devices and methods of the present invention may be incorporated into a personal digital assistant (PDA), a cellular phone, or other portable electronic device. In addition, the methods described herein may be completely or partially implemented in hardware or software (e.g., executable code) of such portable electronic devices.  
           [0014]    Thus, with the devices and methods of the present invention, a stroke victim is better able to ascertain symptoms associated with the onset of stroke, and more quickly seek medical attention, thereby reducing the time for implementation of time sensitive therapies (e.g., thrombolytic therapy) and improving the patient&#39;s long term outcome. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    [0015]FIG. 1A is a flow chart illustrating a method of detecting hemiparesis using a bilateral strength measurement device;  
         [0016]    [0016]FIG. 1B is a flow chart detailing a step of the method illustrated in FIG. 1A;  
         [0017]    [0017]FIG. 2 is a flow chart illustrating a method of detecting hemiparesis using a unilateral (or bilateral) strength measurement device;  
         [0018]    [0018]FIG. 3 is a schematic functional illustration of a bilateral strength measurement device incorporating electronic circuitry;  
         [0019]    [0019]FIG. 4 is a schematic functional illustration of a unilateral strength measurement device incorporating electronic circuitry;  
         [0020]    [0020]FIG. 5 is a schematic block diagram of a (bilateral or unilateral) strength measurement device incorporating an electronics module with a processor and a memory;  
         [0021]    [0021]FIG. 6 is a plan view of a bilateral finger strength measurement device;  
         [0022]    [0022]FIG. 7 is a cross-sectional view of a single body interface and a single transducer;  
         [0023]    [0023]FIG. 8 is a cross-sectional view of two body interfaces and a differential transducer;  
         [0024]    [0024]FIG. 9 is a plan view of a bilateral hand strength measurement device;  
         [0025]    [0025]FIG. 10 is a plan view of a pneumatic bilateral hand strength measurement device;  
         [0026]    [0026]FIG. 11 is a plan view of a bilateral arm and leg strength measurement device;  
         [0027]    FIGS.  12 A- 12 C are top, bottom, and side views, respectively of an alternative bilateral finger strength measurement device;  
         [0028]    [0028]FIGS. 13A and 13B are schematic plan views of an arm drift measurement device;  
         [0029]    [0029]FIGS. 14A and 14B are schematic views of an example of an inclinometer for use in the arm drift measurement device shown in FIGS. 13A and 13B;  
         [0030]    [0030]FIGS. 15A and 15B are schematic plan views of an alternative arm drift measurement device; and  
         [0031]    [0031]FIGS. 16 and 17 are schematic plan views aphasia detection devices. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0032]    The following detailed description should be read with reference to the drawings in which similar elements in different drawings are numbered the same. The drawings, which are not necessarily to scale, depict illustrative embodiments and are not intended to limit the scope of the invention.  
         [0033]    Hemiparesis Detection Devices &amp; Methods  
         [0034]    With reference to FIG. 1A, a method  100  of detecting hemiparesis using a bilateral strength measurement device is shown. In this illustrative method, a bilateral device (not shown) may be utilized to measure strength, such the bilateral device is schematically illustrated in FIG. 3. For purposes of the following description of method  100 , the bilateral device generally includes a right side body interface, a left side body interface, and a strength gauge.  
         [0035]    The method starts with step  102 , which may correspond to powering on the bilateral device. The interfaces of the bilateral device are connected to the respective right and left sides of the user, and the user applies force independently to each of the interfaces, preferably at (approximately) the same time. To ensure that forces are applied at approximately the same time, a timer (clock) with a pre-set time interval may be used to define a sampling window in which the forces must be applied to generate strength values  106 .  
         [0036]    With the interfaces connected to the right and left sides of the user, and upon the application of force (e.g., compression, torsion, etc.), one or more strength measurements are taken  104  to generate strength values  106 . The measured strength values  106  may comprise one or more discrete measurements of the right and left sides, or one or more differential measurements between the right and left sides. The one or more strength measurements may be taken during a given sample period, and multiple measurements may be averaged over the sampling period.  
         [0037]    The measured strength values  106  may be stored as strength data  108  in a suitable memory storage device. The strength data  108  may be used to generate or derive threshold values  110 , which may also be stored in the memory storage device. For purposes of storing the threshold values, the memory storage device may comprise a mechanical indicator or stop mechanism, an electronic circuit, or a computer-based memory storage device, for example. The threshold values  110  may be specific to the user, or based on population data. The threshold values  110  may correspond to strength measurements (discrete or differential) of the user or population in a non-hemiparetic (i.e., healthy) condition, and thus may serve as a basis for comparison  112  to the measured strength values  106 .  
         [0038]    The basis for comparison  112  may be a function of the type of measured strength values  106  and the type of threshold values  110 . For example, if discrete lateral (one-side) measurements are taken, the measured right strength value may be compared to a threshold right strength value, and the measured left strength value may be compared to a threshold left strength value. Alternatively, if a differential measurement is taken, the measured strength differential may be compared to threshold strength differential. The comparison may be performed manually (i.e., by the user), or automatically, such as by electronic circuitry or an algorithm stored in memory and executed by a microprocessor.  
         [0039]    As shown in step  114 , if the comparison  112  shows that the measured strength value(s) is (are) greater than or equal to the threshold value(s)  110 , a negative hemiparesis indicator  122  may be triggered. If the comparison shows that the measured strength value(s) is (are) less than the threshold value(s), a positive hemiparesis indicator  116  may be triggered, which may be indicative of hemiparesis and stroke. This indicator  116  urges the user to seek medical attention as soon as possible to maximize the opportunity to quickly diagnose and treat a stroke event.  
         [0040]    In the alternative, such as when no reliable basis for comparison is available, the measured values may simply be compared to each other (i.e., right compared to left or left compared to right). A significant difference between the right and left strength measurements may be indicative of hemiparesis and stroke.  
         [0041]    Although a direct comparison is described herein for purposes of illustration, it is also possible to mathematically alter the measured strength values, the threshold values and/or the algorithm defining the comparison to meet the same or similar objective of detecting a decrease in strength, particularly isolated to one side of the body, which may be indicative of hemiparesis and stroke.  
         [0042]    If a positive hemiparesis indicator  116  is triggered, a physician and/or an emergency medical service (EMS), such as a public medical emergency service (911), a private medical emergency service, or a hospital emergency room, may be automatically notified  118  of the hemiparetic event utilizing a telecommunications link, for example. The EMS and/or physician then have the opportunity to contact the user and/or provide medical attention to the user as soon as possible to maximize the opportunity to quickly diagnose and treat a stroke event. Whether a positive hemiparesis indicator  116  or a negative hemiparesis indicator  122  is triggered, the measured strength values  106  may be transmitted  120  to a medical database (e.g., physician&#39;s network), which allows the physician to track the user&#39;s status and, for example, contact the user if the data suggests a gradual change in condition.  
         [0043]    With reference to FIG. 1B, the step  104  of obtaining bilateral strength measurement(s) is detailed. Obtaining  104  the strength measurements begins with the user holding  104 A or otherwise engaging the interfaces of the bilateral device. The user then applies and holds a force (e.g., compression, torque, etc.)  104 B to the interfaces, which starts a timer clock  104 C and triggers a sampling start indicator  104 D (e.g., audible, visible) which notifies the user to continue to apply (maximum) force to the interfaces. Strength measurements are then sampled  104 E periodically (e.g., every 0.01 seconds) during the sampling period until the expiration of time as dictated by timer loop  104 F. Once the time has expired, the sampling is complete  104 G and a sampling finish indicator is triggered  104 G which notifies the user that he/she may stop applying force to the interfaces. From the sampled strength data, certain strength measurement values are selected  104 I, such as the maximum value, average value(s), or values obtained during the sampling period.  
         [0044]    With reference to FIG. 2, a method  130  of detecting hemiparesis using a unilateral (or bilateral) strength measurement device is shown. In this illustrative method, a unilateral or bilateral device (not shown) may be utilized to measure strength, such the unilateral device schematically illustrated in FIG. 4 or the bilateral device schematically illustrated in FIG. 3. The method  130  described with reference to FIG. 2 is particularly suited for and is described with reference to a unilateral device, which generally includes a single lateral side interface and a strength gauge. Note that some of the bilateral devices described herein may be used as a unilateral device by using only one side of the interfaces.  
         [0045]    The illustrated method  130  starts with step  132 , which may correspond to powering on the unilateral device. The interface of the unilateral device is connected to either the right or left side of the user, and the user applies force to the interface to obtain a first side strength measurement  134 . The first side strength measurement  134  is then associated  136  with either the right or left side, which may be accomplished manually (e.g., manual input) or automatically (e.g., a predefined process which dictates that the user start with a particular side). Upon the application of force to the interface, a clock (timer) may be started  138  to ensure that forces are applied within a desired time interval. The interface of the unilateral device is then connected to the opposite side of the user, and the user applies force to the interface to obtain a second side strength measurement  140 . The second side strength measurement  140  is then associated  142  with either the right or left side, which may be accomplished manually (e.g., manual input) or automatically (e.g., a predefined process which assumes the opposite association as the first measurement  143 ). When the second side measurement is taken, the clock (timer) is stopped  144 , and the elapsed time is compared  146  to the preset time interval to see if the measurements were taken within the desired sampling window. If the measurements were not taken sufficiently close in time as defined by the preset time interval, the process begins again and new strength measurements may be obtained. If the measurements were taken within the desired sampling period, the strength measurements become strength values  146 .  
         [0046]    The measured strength values  146  may comprise discrete measurements of the right and left sides, and may be stored as strength data  150  in a suitable memory storage device. The strength data  150  may be used to generate or derive threshold values  152 , which may also be stored in the memory storage device. For purposes of storing the threshold values, the memory storage device may comprise a mechanical indicator or stop mechanism, an electronic circuit, or a computer-based memory storage device, for example. The threshold values  152  may be specific to the user, or based on population data. The threshold values  152  may correspond to strength measurements of the user or population in a non-hemiparetic (i.e., healthy) condition, and thus may serve as a basis for comparison  154  to the measured strength values  148 . For example, the measured right strength value may be compared to a threshold right strength value, and the measured left strength value may be compared to a threshold left strength value. Alternatively, difference between the right and left measured strength values may be compared to a threshold value corresponding to difference between the right and left strength. The comparison may be performed manually (i.e., by the user), or automatically, such as by electronic circuitry or an algorithm stored in memory and executed by a microprocessor.  
         [0047]    As shown in step  156 , if the comparison  154  shows that the measured strength values are greater than or equal to the threshold values  152 , a negative hemiparesis indicator  158  may be triggered. If the comparison shows that the measured strength values are less than the threshold values, a positive hemiparesis indicator  160  may be triggered, which may be indicative of hemiparesis and stroke. In the alternative, such as when no reliable basis for comparison is available, the measured values may simply be compared to each other (i.e., right compared to left or left compared to right). A significant difference between the right and left strength measurements may be indicative of hemiparesis and stroke. Although a direct comparison is described herein for purposes of illustration, it is also possible to mathematically alter the measured strength values, the threshold values and/or the algorithm defining the comparison to meet the same or similar objective of detecting a decrease in strength, particularly isolated to one side of the body, which may be indicative of hemiparesis and stroke.  
         [0048]    If a positive hemiparesis indicator  160  is triggered, a physician and/or an emergency medical service (EMS) may be automatically notified  162  of the hemiparetic event utilizing a telecommunications link, for example. Whether a positive hemiparesis indicator  160  or a negative hemiparesis indicator  158  is triggered, the measured strength values  148  may be transmitted  164  to a medical database (e.g., physician&#39;s network).  
         [0049]    With reference to FIG. 3, a schematic diagram of a bilateral device  170  is shown for measuring the strength of one or both of the right and left sides of a user, either simultaneously or sequentially. Further detailed exemplary embodiments of bilateral devices are described with reference to FIGS.  6 - 11 . The bilateral device  170  generally includes a bilateral interface  172  connected to a strength gauge  178 . The bilateral interface  172  includes a right side force input interface  174  and a left side force input interface  176  which connect to the right and left sides, respectively, of the user and operate independently such that the user may actuate the right side interface independently of the left side interface. The interfaces  174 / 176  may be configured to interface with the user&#39;s fingers, hands, arms or legs, for example. Any of the bilateral devices described herein may be implemented as a unilateral device by using only one of the interfaces  174 / 176 .  
         [0050]    The strength gauge  178  may comprise two individual strength gauges  180 / 182  or a single differential gauge  184 , for example. The individual and differential strength gauges  180 / 182 / 184  may comprise transducers, pressure gauges, or force gauges (e.g., strain gauge, spring gauge, etc.), for example. Depending on the type of gauge utilized, for example if a transducer or other electronic gauge is utilized, the strength gauge  178  may be connected to a signal processor  186  which processes (e.g., amplifies, filters, etc.) the output signal(s) from the strength gauge  178 .  
         [0051]    A comparator  188  is connected to the signal processor  186 , or directly to the strength gauge  178  if a signal processor  186  is not utilized. The comparator  188  is connected to a memory storage device  190  which may contain measured strength data and threshold value data. The memory storage device  190  may be coupled to an input device  192  for manually inputting threshold values. The comparator  188  performs the comparison function as described with reference to FIGS. 1 and 2, and is connected to a display or indicator  194  which may be used to display or indicate measured strength data, threshold value data, positive hemiparesis, and/or negative hemiparesis. The signal processor  186 , the comparator  188 , and the memory storage device  190  may be manifested as conventional electronic signal processing circuitry, or as a microprocessor device as will be described in more detail with reference to FIG. 5.  
         [0052]    With reference to FIG. 4, a schematic diagram of a unilateral device  200  is shown for measuring the strength of the right and/or left sides of a user, individually or sequentially. Any of the exemplary embodiments of bilateral devices described with reference to FIGS.  6 - 11  may function as a unilateral device by incorporating and/or utilizing only one of the interfaces. The unilateral device  200  generally includes a unilateral interface  202  connected to a strength gauge  206 . The unilateral interface  202  includes a single side force input interface  204  which is configured to individually connect to the right and left sides of the user. The interface  204  may be configured to interface with the user&#39;s fingers, hands, arms or legs, for example.  
         [0053]    The strength gauge  206  may comprise an individual strength gauge  208  such as a transducer, pressure gauge, or force gauge (e.g., strain gauge, spring gauge, etc.), for example. Depending on the type of gauge utilized, for example if a transducer or other electronic gauge is utilized, the strength gauge  206  may be connected to a signal processor  210  which processes (e.g., amplifies, filters, etc.) the output signal from the strength gauge  206 .  
         [0054]    A side association device  212  is connected to the signal processor  210  for associating the measured strength value with the particular side (right or left) measured. The side association device may manually associate the right or left side with the measured value by utilizing an input device  216 . Alternatively, the side association device may automatically associate the right or left side with the measured value by the order in which the measurements are taken (e.g., right first then left; or left first then right), wherein the user is instructed or prompted that the measurements are to be performed in a predefined order (e.g. by an instruction manual or by display  220 ).  
         [0055]    A comparator  214  is connected to the signal processor  210 , or directly to the strength gauge  206  if a signal processor  210  is not utilized. The comparator  214  is connected to a memory storage device  218  which may contain measured strength data and threshold value data. The memory storage device  218  may be coupled to an input device  216  for manually inputting threshold values, in addition to side association. The comparator  214  performs the comparison function as described with reference to FIG. 2, and is connected to a display or indicator  220  which may be used to display or indicate measured strength data, threshold value data, positive hemiparesis, and/or negative hemiparesis. The signal processor  210 , the side association device  212 , the comparator  214 , and the memory storage device  218  may be manifested as conventional electronic signal processing circuitry, or as a microprocessor device as will be described in more detail with reference to FIG. 5.  
         [0056]    With reference to FIG. 5, a schematic block diagram of a bilateral or unilateral device  230  is shown including an electronics module  236 . The device  230  may comprise the bilateral device shown in FIG. 3, the unilateral device shown in FIG. 4, or any of the other devices illustrated in FIGS.  6 - 11 . The electronics module  236  is connected to a strength gauge  234  (which may comprise the strength gauge  172  shown in FIG. 3 or the strength gauge  206  shown in FIG. 4) connected to a body interface  232  (which may comprise bilateral interface  172  shown in FIG. 3 or unilateral interface  202  shown in FIG. 4).  
         [0057]    The electronics module  236  includes a data processor  250  which may execute an algorithm to perform, among other tasks, the comparison process discussed previously. The data processor  250  is connected to memory storage device  252 , which may contain the algorithm, store threshold data, store measured strength data, etc. as described previously. An input device  254  (e.g., buttons, key pad, key board) is connected to the data processor  254  to input data, commands, etc. and otherwise interact with the processor  250 , memory  252  and associated algorithm. An output device  258  (e.g., LCD display, LED indicators, audio transducer, etc.) is connected to the data processor  250  to display, indicate or otherwise communicate strength data, threshold data, positive hemiparesis, negative hemiparesis, and/or any other information pertinent to the device  230  or use thereof.  
         [0058]    The electronics module  236  may incorporate, if necessary a signal processor  262  to interface with the strength gauge  234  and process (amplify, filter, A/D conversion, etc.) signals generated by the strength gauge  234 . A battery  264  or other portable power source is connected to the signal processor  262  and data processor  250  to provide the necessary electrical power to run the electronics module  236 , and provide power to the strength gauge  234  if necessary. A clock circuit  260  may be connected to the data processor  250  to execute the timer functions discussed previously, or the algorithm contained in memory  252  and executed by data processor  250  may include a clock subroutine to perform the same timer functions.  
         [0059]    An I/O interface  258  is connected to the data processor  250  to interface with external devices such as a telemetry or telecommunications device  238  (e.g., wireless transceiver, modem, cell phone, land phone, etc.). The communication device  238  is able to call, transmit data, and/or receive data to/from an EMS or physician telephone  240  or computer network  244  via telecommunication link  242  to perform, for example, the functions described with reference to FIGS. 1 and 2.  
         [0060]    With reference to FIG. 6, a plan view of a bilateral finger strength measurement device  300  is shown. Bilateral finger device  300  is sized to be readily portable and carried in the user&#39;s clothing, pockets, or purse, much like a keyless remote for an automobile. For purposes of illustration, the size of the device  300  may be appreciated with reference to a conventional automobile key  310 . To promote use and ease of access, the device  300  may be connected to the user&#39;s key ring  312  together with other important keys  310 .  
         [0061]    Bilateral finger device  300  includes a housing  302  which contains the strength gauge and electronics (not shown) discussed with reference to FIGS.  3 - 5 . Housing  302  also contains a display  308  which may function as any of the displays, indicators, or output devices described previously. In this exemplary embodiment, the display shows a strength value (“1234”) together with an alert signal (“!!”). The strength gauge (not visible) contained in housing  302  may comprise, for example, two discrete gauges as discussed with reference to FIG. 7 or a differential gauge as discussed with reference to FIG. 8.  
         [0062]    Housing  302  further contains a pair of buttons  304 / 306  movably disposed therein which protrude from the top surface of the housing. The buttons  304 / 306  and the bottom surface (not visible) of the housing collectively define the right and left interfaces, which are configured to provide independent force inputs (as opposed to force inputs acting in opposition of each other). The buttons  304 / 306  and the bottom surface of the housing are configured to be grasped or pinched between the user&#39;s right and left thumbs and the user&#39;s right and left (index) fingers, respectively. The buttons  304 / 306  and the bottom surface of the housing may include surface irregularities (e.g., texture, protrusions, etc.) to give the user tactile feedback indicating when the interfaces are properly engaged.  
         [0063]    With reference to FIG. 7, a single button and transducer assembly  326  is shown in cross-section, two of which may be used in device  300 . The assembly  326  includes a button  304 / 306  disposed in bore defined by a portion  322  of the housing  302 . A transducer  326  (e.g., piezoelectric or piezoresistive transducer) is disposed in the bottom of the bore defined by housing portion  322 , and is coupled to the button  304 / 306  by a compressible connector  324 . A biasing member  328  (e.g., helical spring, leaf spring, etc.) may be disposed in the bore to resist movement of the button  304 / 306  with respect to the transducer  326  and urge the button  304 / 306  to protrude from the top surface of the housing  302 .  
         [0064]    With reference to FIG. 8, a dual button and differential transducer assembly  330  for use in device  300  is shown in cross-section. The assembly  330  includes a pair of buttons  304 / 306  disposed in right and left bores, respectively, defined by a portion  332  of the housing  302 . A differential transducer  340  is disposed in the housing portion  332  between the buttons  304 / 306 . In this illustrative embodiment, the differential transducer  340  comprises a differential pressure transducer. The differential pressure transducer  340  is in fluid communication with a piston  334  and barrel  344  assembly associated with right button  304  via conduit  342 , and a piston  336  and barrel  346  assembly associated with left button  306  via conduit  348 .  
         [0065]    With reference to FIG. 9, a plan view of a bilateral hand strength measurement device  350  is shown. Bilateral hand device  350  includes a right side interface housing  352  and a left side interface housing  354  connected together by a center housing  356 . Center housing  356  contains the electronics (not shown) discussed with reference to FIGS.  3 - 5 . Center housing  356  also contains a display  380  which may function as any of the displays, indicators, or output devices described previously. In this exemplary embodiment, the display  380  shows a strength value (“1234”) together with an alert signal (“!!”). Center housing  356  may further contain a power button  382  to turn the electronics on or off and a memory button  384  to scroll through measured strength values and threshold values stored in memory.  
         [0066]    The right and left side interface housings  352 / 354  are ergonomically curved to be readily grasped by the user&#39;s hands, with the palms engaging large buttons  362 / 364 , and the fingers engaging contoured grip surfaces  372 / 374 , respectively. Upper flanges  366 / 368  and lower flanges  376 / 378  are disposed on opposite ends of the right and left interface housings  352 / 354 , respectively, to serve as guides to position the user&#39;s hands thereon. Large buttons  362 / 364  are movably disposed in the right and left housings  352 / 354 , and may actuate strength gauges (not visible) in a manner as discussed with reference to FIGS. 7 and 8. The strength gauge (not visible) may comprise, for example, two discrete gauges contained in right side interface housing  352  and left side interface housing  354 , respectively, or a differential gauge contained in center housing  356 . The large buttons  362 / 364  and the surfaces  372 / 374  collectively define the right and left interfaces, respectively, which are configured to provide independent force inputs (as opposed to force inputs acting in opposition of each other).  
         [0067]    With reference to FIG. 10 a plan view of a bilateral pneumatic hand strength measurement device  400  is shown. Bilateral pneumatic hand device  400  includes a right side interface bulb  402  and a left side interface bulb  404  connected together by a center housing  406 . Center housing  406  contains the electronics (not shown) discussed with reference to FIGS.  3 - 5 . Center housing  406  also contains a display  420  which may function as any of the displays, indicators, or output devices described previously. In this exemplary embodiment, the display  420  shows a strength value (“1234”) together with an alert signal (“!!”). Center housing  406  may further contain a power button  422  to turn the electronics on or off and a memory button  424  to scroll through measured strength values and threshold values stored in memory.  
         [0068]    The right and left side interface bulbs  402 / 404  are ergonomically shaped to be readily grasped by the user&#39;s hands, with the thumbs positioned in recesses  416 / 418 , and the fingers engaging contoured grip surfaces  412 / 414 , respectively. The right and left side interface bulbs  402 / 404  are configured to provide independent force inputs (as opposed to force inputs acting in opposition of each other) and may comprise closed hollow compressible volumes in fluid communication with a strength gauge (e.g., discrete pressure gauges or a single differential pressure gauge) contained in center housing  406  via tubes  410 / 408 . Tube  410  may comprise, for example, a rigid tube structure to control the position of the housing  406  with respect to the left interface  404 , and tube  408  may comprise, for example, a flexible tube to permit relatively free movement and positioning of the right side interface  402  with respect to the left side interface  404 .  
         [0069]    With reference to FIG. 11, a plan view of a bilateral arm and leg strength measurement device  430  is shown. Bilateral arm/leg device  430  includes a right side interface  432  and a left side interface  434  connected together by a chamber  440  and piston  442  assembly, respectively. The piston  442  assembly is movably disposed in the chamber housing  440  to actuate a differential strength gauge (not visible) disposed in the chamber housing  440 . Chamber housing  440  contains the electronics (not shown) discussed with reference to FIGS.  3 - 5 , in addition to a display  450  which may function as any of the displays, indicators, or output devices described previously. In this exemplary embodiment, the display  450  shows a strength value (“1234”) together with an alert signal (“!!”). Chamber housing  440  may further contain a power button  452  to turn the electronics on or off and a memory button  454  to scroll through measured strength values and threshold values stored in memory. The right and left side interfaces  432 / 434  are ergonomically curved to define concave contours  436 / 438  that readily engage the right and left inside forearms or right and left inside thighs of the user, respectively. The right and left side interfaces  432 / 434  are configured to provide to force inputs acting in opposition of each other (as opposed to independent force inputs).  
         [0070]    With reference to FIGS.  12 A- 12 C, top, side and bottom views, respectively, of a bilateral finger strength measurement device  500  are shown. Bilateral finger device  500  is sized to be readily portable and carried in the user&#39;s clothing, pockets, wallet or purse, much like a credit card, or attached to a commonly carried item such as a key chain. For purposes of illustration, the size of the device  500  may be approximated as a credit card or parking card, while possibly thicker to accommodate the electronics and other workings therein.  
         [0071]    Bilateral finger device  500  includes a housing  502  which contains the strength gauge and electronics (not shown) discussed with reference to FIGS.  3 - 5 . Housing  502  also contains a display  508  which may function as any of the displays, indicators, or output devices described previously. In this exemplary embodiment, the display shows a strength value (“1234”) together with an alert signal (“!!”). The strength gauge (not visible) contained in housing  502  may comprise, for example, two discrete gauges as discussed with reference to FIG. 7 or a differential gauge as discussed with reference to FIG. 8.  
         [0072]    Housing  502  further contains a pair of buttons  504 / 506  movably disposed therein which protrude from the top surface  512  of the housing. The buttons  504 / 506  and the bottom surface  514  of the housing collectively define the right and left interfaces, which are configured to provide independent force inputs (as opposed to force inputs acting in opposition of each other). The buttons  504 / 506  and the bottom surface  514  of the housing are configured to be grasped or pinched between the user&#39;s right and left thumbs and the user&#39;s right and left (index) fingers, respectively. Housing  502  may further contain a power button  516  to turn the electronics on or off and a memory button  518  to scroll through measured strength values and threshold values stored in memory.  
         [0073]    The buttons  504 / 506  and the bottom surface of the housing  502  may include surface irregularities (e.g., texture, protrusions, etc.) to give the user tactile feedback indicating when the interfaces are properly engaged. In addition, top stop members  510  may be placed adjacent the buttons  504 / 506  on top side  512  to engage the tips of the user&#39;s thumbs, and bottom stop members  511  may be provided on the bottom side  514  (shown in phantom) to engage the index fingers of the user. For example, the top and bottom stop members  510 / 511  may comprise raised ridges extending from the surface of the housing  502 . The top and bottom stop members  510 / 511  further ensure that the thumbs are consistently positioned and that the interfaces are properly engaged.  
         [0074]    With reference to FIGS. 13A and 13B, plan views of an arm drift measurement device  600  are shown. Arm drift measurement device  600  is similar to the strength measurement devices described previously, with the general exception that device  600  compares the ability of the right and left sides of the user to maintain the same position and/or force application. In this exemplary embodiment, arm drift measurement device  600  compares the ability of the user to maintain both arms in a symmetrical extended level (horizontal) position over a period of time. Those skilled in the art will recognize that the device  600  may be used for other anatomical and positional comparisons, such as measuring finger, hand, arm, or leg drift in horizontal, vertical or other positions.  
         [0075]    In such embodiments, the degree of displacement (i.e., drift) and/or the amount of displacement over time (i.e., drift rate) of the right and left sides may be compared. Drift or drift rate above a predetermined threshold value may be indicative of hemiparesis. Accordingly, the arm drift measurement device  600  provides an alternative to the strength measurement devices described previously, but may be used in a similar manner. To this end, the same or similar signal processing electronics, computing hardware and software, and algorithms as described previously may be implemented with arm drift measurement device  600 .  
         [0076]    The arm drift measurement device  600  may be integrated into measurement device  500  as shown, or may comprise a stand-alone device. As shown in phantom in FIG. 13A, the components of the arm drift measurement device  600  may be retracted into and stored in measurement device  500 .  
         [0077]    The arm drift measurement device  600  includes an inclinometer  610  coupled to right grip  602  and left grip  604  by elongate members  606  and  608 , respectively. The grips  602  and  604  may be ergonomically configured to be grasped by the user&#39;s hand and/or fingers. In the illustrated embodiment, the right hand grip  602  comprises device  500  and the left hand grip  604  comprises a finger ring.  
         [0078]    The elongate members  606  and  608  are substantially equal in length and may be flexible or rigid. The right elongate member  606  may accommodate electrical leads to provide electrical communication between the inclinometer  610  and the electronics carried by device  500 . The end portions of the elongate members  606  and  608  and/or the connections at the ends of the elongate members  606  and  608  may be configured to have negligible torque transmission thus transmitting only linear forces along their length and permitting the inclinometer  610  to hang freely.  
         [0079]    In use, the arm drift measurement device  600  is protracted from its stored configuration, which may automatically turn on or otherwise activate the device  600 . With the right and left hands, the user holds the right grip  602  and the left grip  604 , respectively, such that the grips are substantially horizontally level (i.e., level with horizontal line  650 ) as shown in FIG. 13A. In this position, the inclinometer  610 , which is also horizontally level, may detect its level position and initiate a measurement sequence. Failure to establish a level horizontal position within a specified period of time may be indicative of hemiparesis and therefore trigger an alarm.  
         [0080]    Once a horizontal position is established, a timer carried by the electronics in device  500  may be started, and an indicator such as an audible signal may be trigger to notify the user to try to maintain the horizontal position. If the user is unable to maintain level arms as shown in FIG. 13B, the inclinometer  610  measures the degree of drift, and the timer permits calculation of drift rate. After a predefined test period has elapsed (e.g., 5 to 30 seconds), another indicator is triggered to notify the user that the test is complete. If the drift or drift rate during the test period exceeds a predetermined threshold value, hemiparesis is detected and further action may be taken in accordance with prior embodiments. If the drift or drift rate during the test period does not exceed the predetermined threshold value, hemiparesis is not detected.  
         [0081]    The inclinometer  610  may comprise any of a variety of miniature inclinometers known to those skilled in the art. The inclinometer  610  may function in a binary mode (i.e., activated or deactivated within a specified incline range; e.g., a mercury switch), a graduated/digital mode (i.e., degree of incline detected in increments) or a continuous/analog mode (i.e., degree of incline detected in continuum). By way of example, not limitation, an inclinometer  610  operating in a binary mode is schematically illustrated in FIGS. 14A and 14B.  
         [0082]    In the embodiment illustrated in FIGS. 14A and 14B, the inclinometer  610  includes a sealed tubular vessel  612  containing a relatively non-conductive gas fill  614  and a relatively conductive liquid droplet  616  (e.g., mercury), which may have a high degree of surface tension to maintain a unitary state. The tubular vessel  612  may be curved upward or downward to decrease or increase sensitivity, respectively, to changes in incline. For example, to detect gross deviations in drift, the vessel  612  may be curved upward as shown. The angle of curvature relative to horizontal level  650  may correspond to the threshold inclination value. As an alternative, the gas fill  614  and liquid droplet  616  may be interchanged with a non-conductive gas bubble  616  and a conductive liquid fill. In this alternative embodiment, the opposite effect of curvature may be expected.  
         [0083]    The inclinometer  610  further includes conductive pads  620 ,  622  and  624  exposed to the inside of the vessel  612 , with the common pad  620  disposed at the right and left ends of the vessel  612 , the right pad  622  disposed at the right end of the vessel  612 , and the left pad  624  disposed at the left end of the vessel  612 . The pads  620 ,  622  and  624  are connected to leads  630  which travel along elongate member  606  to the electronics contained in device  500 . When the vessel  612  is inclined a sufficient amount as dictated by the curvature of the vessel, the conductive liquid flows in the downward direction and establishes an electrical connection (closed circuit) between the common pad  620  and either the right pad  622  or he left pad  624 , depending on the direction of incline. Absent sufficient incline, no electrical connection is established (open circuit) between the pads  620 ,  622  and  624 . With this arrangement, inclination at or beyond a threshold degree to the right or left may be detected.  
         [0084]    With reference to FIGS. 15A and 15B, an alternative arm drift measurement device  700  is shown. Arm drift measurement device  700  is similar to arm drift measurement device  600 , with the general exception that the inclinometer  610  (shown in phantom) is incorporated into device  500 . A pair of right and left grips  702  and  704 , respectively, are connected to the device  500  by relatively rigid elongate members  706  and  708 , respectively. The elongate members  706  and  708  have substantially the same length and are pivotably connected to the device  500 . Both the grips  702  and  704  and the elongate members  706  and  708  may be retractably stored in the device  500 . The operation and function of arm drift measurement device  700  is otherwise substantially the same as arm drift measurement device  600 .  
         [0085]    As an alternative to the single inclinometer  610  utilized by the arm drift measurement devices  600  and  700  described above, two or more inclinometers  610  may be used. In this alternative embodiment, a first inclinometer may be secured to the user&#39;s right side (e.g., hand, forearm, or upper arm), and a second inclinometer may be secured to the user&#39;s left side in a symmetrical position (i.e., the same anatomical position: e.g., hand, forearm, or upper arm). The relative inclination of the right and left sides may then be compared in a similar manner as with the bilateral strength measurement devices described previously.  
         [0086]    Ataxia Detection Devices &amp; Methods  
         [0087]    The measurement devices described above (e.g., device  500 ) may be used in addition or in the alternative to detect ataxia by measuring dexterity. In this alternative embodiment, the strength measurement gauges may be replaced with switches (e.g., normally open momentary contact switches), contact sensors, or other components that may be readily activated and deactivated. In addition, the switches may incorporate the ability to illuminate.  
         [0088]    To measure dexterity, the switches (left right or both) may be activated (e.g., opened or closed) and the number of times the switches are activated within a given time frame, or the elapsed time taken to activate the switches a known number of times, or the frequency of actuation, may be measured. For example, the user may be prompted to actuate one side as many times as possible in a predetermined time frame, and subsequently or simultaneous actuate the other side as many times as possible in the same time frame. The user may be prompted by written instructions on the display, or by illuminating the switches in the desired sequence. The number of actuations or the frequency thereof (number divided by time frame) may be compared. For example, the left and right sides may be compared, the current measurements may be compared to historical data (e.g., left current to left historical and right current to right historical), and/or the current measurements may be compared to threshold values (e.g., left current to left threshold and right current to right threshold). Based on the comparison, a difference in the number or actuations or frequency thereof may be an indication of a loss in dexterity of the left or right side, which may be indicative of hemiparesis and stroke.  
         [0089]    Aphasia Detection Devices &amp; Methods  
         [0090]    With the same device (e.g., device  500 ) described above, receptive aphasia may be detected. To measure receptive aphasia, the user may be prompted to actuate one or both sides, and the user&#39;s response time and/or response correctness may be measured. The user may be prompted by written instructions on the display, or by illuminating the switches in the desired sequence. For example, the user may be prompted to press the right or left button a specific number of times as shown in FIG. 16, and the delay time and/or correctness of the response may be measured. Alternatively, the user may be prompted to actuate one or both sides in a specified sequence or pattern (e.g., right-left-right-both-right-left) and the delay time from prompt to correct actuation may be measured for each prompt. Optionally, the delay time may be weighted as a function of whether the correct switch is actuated. An incorrect response or a significant delay in response time may be indicative of receptive aphasia, and therefore stroke.  
         [0091]    With a similar device (e.g., device  500 ) as described above, expressive aphasia may be detected. To measure expressive aphasia, the user may be posited with an image of an object and prompted to name the object by a multiple choice selection or by an audible response which may be recorded and evaluated by the device using voice pattern recognition techniques or subsequently evaluated by a physician, for example. An illustrative example is shown in FIG. 17, wherein the display posits an image of a house, and the user is prompted to name the object as either a house or a car. Optionally, the response may optionally be weighted as a function of response time. An incorrect response or a significant delay in response time may be indicative of expressive aphasia, and therefore stroke.  
         [0092]    Dysarthria Detection Devices &amp; Methods  
         [0093]    With a similar device as described above (e.g., device  500 ), dysarthria may be detected. In this embodiment, the device may be modified to incorporate a microphone and recordation circuitry, and optionally incorporate voice pattern comparison capabilities. To measure dysarthria, the user may be prompted to say a word or phrase. The user may be prompted by displaying the text of the word or phrase or by audibly presenting a pre-recordation of the word or phrase, for example. The device then records the user&#39;s audible response. The recorded response may be compared to a previous recordation (e.g., by the user) of the same word or phrase utilizing voice pattern recognition techniques. Alternatively, the recorded response may be subsequently evaluated by medical personnel.  
         [0094]    Other Warning Signs  
         [0095]    In all embodiments of the measurement device, indicia of other warning signs of stroke may be provided to the user. The warning signs may be presented visually, audibly or by other means to alert the user of other signs of stroke which, when taken together with the measurement, may provide additional evidence or a higher confidence level of a stroke/non-stroke diagnosis. The most common warning signs of stroke according to the National Stroke Association and the American Heart Association are:  
         [0096]    Sudden numbness or weakness of the face, arm or leg, especially on one side of the body;  
         [0097]    Sudden confusion, trouble speaking or understanding;  
         [0098]    Sudden trouble seeing in one or both eyes;  
         [0099]    Sudden trouble walking, dizziness, loss of balance or coordination; and  
         [0100]    Sudden, severe headache with no known cause.  
         [0101]    With reference to FIG. 12C, the indicia may be provided to the user, for example, by including printed matter  520  on the measurement device (e.g., back side), by utilizing a speaker  522  or other audible transducer to audibly generate (e.g., speak) the warning signs, or by utilizing a visual display  524  such as an LCD to visually generate the warning signs. The indicia may be provided at all times as with the printed matter  520 , or the indicia may be generated at select times such as when the device is powered on or when a measurement has been taken.  
         [0102]    Those skilled in the art will recognize that the present invention may be manifested in a variety of forms other than the specific embodiments described and contemplated herein. Accordingly, departures in form and detail may be made without departing from the scope and spirit of the present invention as described in the appended claims.