WO2000059377A1 - Apparatus, system, and method for detecting peripheral neuropathies - Google Patents

Abstract

A screening apparatus (10), screening system, and method of screening for peripheral neuropathies. The screening apparatus (10) includes a surface (16) having an opening (19) therethrough, a surround (18) disposed about the opening (19), and a rod (20) with a specified contact area disposed within said opening for contact with a surface of the body. The rod (20) and surround (18) are each dimensioned such that principally Meissner corpuscles are stimulated. A vibratory device (22) is attached to the rod (20) and vibrates the rod at a single frequency within a predetermined frequency range, again such that primarily Meissner corpuscles are stimulated by the rod. Finally, an amplitude modulating device (14) is in communication with the vibratory device (22) for controlling the vibratory device such that an amplitude of vibration of the vibratory device is incrementally increased. In operation, a user places a surface of the body over the surround such that it rests upon the rod (20), the amplitude modulating device (14) controls the vibratory device (22) to induce vibration at the predetermined frequency, and the amplitude modulating device incrementally increases the amplitude of vibration of the vibratory device until the Meissner corpuscles are stimulated, causing the vibration to be felt by surface of the body.

Description

APPARATUS. SYSTEM. AND METHOD

FOR DETECTING PERIPHERAL NEUROPATHIES

CLAIM OF PRIORITY

This patent application claims the benefit of priority of United States Provisional Patent Application Serial Number 60 / 128,001, filed April 6, 1999.

FIELD OF THE INVENTION This invention relates generally to an apparatus for detecting sensory deficits in peripheral nerves and, in particular, to an apparatus for detecting sensory deficits associated with the median and ulnar nerves in the fingers, or other parts of the body . BACKGROUND OF THE INVENTION

Clinical assessment of early sensory deficits in peripheral neuropathies via screening methodologies is of considerable significance to the prevention of work- related sensory deficits. The financial burden to employers associated with lost worker productivity and medical interventions, coupled with the emotional burden to the worker associated with developing a work-related cumulative trauma disorder, make this an important workplace safety concern.

Clinical intervention and ergonomic modification of the workplace during the early stages of the onset of cumulative trauma disorders has proven effective at reducing the effects of these disorders. Therefore, the development of screening devices to detect these disorders at any early stage is an important step in their prevention.

Many provocative tests have long been used to predict the onset of work- related sensory deficits. These tests include the "Two-Point Discrimination" test, "Phalen's" test, "Tinel's" test, and the "Carpal Compression" test. However, for various reasons, each of these tests has been found to be ineffective. In addition, various sensory and motor conduction tests, considered by many to be the most effective at diagnosing work-related sensory deficits, are costly, require skilled technicians, and have been known to be non-diagnostic in low prevalence populations, due to the lack of availability of these devices to the general public. The effectiveness of the vibratory tests is dependent on many test parameters, such as vibrating frequency, dimensions of a vibrating rod contact area, a rod contact force on finger pulp, the gap formed between the rod and a surround, the shape of the surround, and the force exerted upon the surround. See Harada and Griffin, "Factors influencing vibration sense thresholds used to assess occupational exposures to hand transmitted vibration" Brit J Indust Med, vol. 48, pp. 185-192, 1991 ; and Maeda and Griffin, "A comparison of vibrotactile thresholds on the finger obtained with different equipment". Ergonomics, Vol. 37, No. 8, pp. 1391-1406, 1994. However, vibrometry tests have found limited acceptance in screening for sensory deficit as the existing technology has fallen short in optimizing these test parameters. These drawbacks have made existing vibrometry technologies ineffective in predicting onset neuropathy.

Mechanoreceptors in the finger pulp play a part in perception of vibration. Verrillo et al. have used psychological methods to demonstrate the presence of multiple mechanoreceptors that have different characteristics. See Verrillo, RT. "A duplex mechanism of mechanoreception." In: Kenshalo, DR, ed. The Skin Senses. Springfield, IL: Thomas, vol. 77, pp. 139-159, 1966; and Verrillo, RT. "Psychophysics of vibrotactile stimulation". J Acoust Soc Am, vol. 77, pp. 225-232, (1985). Vallbo and Johansson (1984) have studied characteristics of these mechanoreceptors with electrophysiological methods and divided the receptors into four types. See Vallbo and Johansson. "Properties of cutaneous mechanoreceptors in the human hand related to touch sensation". Human Neurobiology, vol. 3, pp. 3-14, (1984.) Fast adapting units (hereinafter "FA") include Meissner corpuscles (hereinafter "FAI") that are sensitive at frequencies between 5 Hz and 50 Hz. Another type of FA unit (hereinafter "FAII") is related to the Pacinian corpuscle and, possibly, to Golgi-Mazzoni bodies. The FAII units are sensitive at frequencies above about 50 Hz. Slowly adapting units (hereinafter "SA") include Merkel discs (hereinafter "SAI") and Ruffini endings (hereinafter "SAII") that are sensitive between 8 and 16 Hz. The stimulus characteristics of the FAI and FAII units are influenced by conditions of measurement such as contact area, contact force, surround, vibration frequency, and contact proximity relative to the depth of the rod. Harada and Griffin found that FAII units were highly susceptible to temperature of the finger pulp, contact pressure on the vibrating rod, mood, and somewhat sensitive to the surround, while the FAI units were primarily sensitive to temperature and the surround. Furthermore, longitudinal studies have found that vibration thresholds vary significantly from day to day when using FAII units for measurement. See White et al. "Vibrometry testing for carpal tunnel syndrome: a longitudinal study of daily variations". Arch Phys Med Rehabil, Vol. 75, pp. 25-28, 1994.

United States Patent 5,230,345, issued to Curran et al., describes a system and method for detecting carpal tunnel syndrome in a patient utilizing a vibratory waveform having a discrete frequency and a variable amplitude. The system includes control circuitry for generating an electrical signal having the discrete frequency, specifically 60 Hz, and a computer, including memory for controlling the circuitry to vary the amplitude of the electrical signal and to generate associated amplitude data for storage in the memory. The system includes a speaker for converting the signal into the vibratory waveform. A finger of the patient rests directly on the cone of the speaker so that the vibratory waveform is applied directly to the finger.

The system disclosed by Curran et al. suffers from stimulating the Pacinian corpuscles (FAII units) which have been known to be extremely sensitive to blood flow, mood, age, temperature and sex of the patient. Therefore, the data gathered is hard to interpret and requires an extremely skilled technician. Furthermore, Werner et al. found that FAI units had a high correlation to median sensory latency while the FAII units had a low correlation. See Werner et al. "Comparison of multiple frequency vibrometry testing and sensory nerve conduction measures in screening for carpal tunnel syndrome in an industrial setting". Am J Phys Med Rehabil, Vol. 74, No. 2, pp.101 -106, (1995). Finally, the volatility of the stimulus effects of the vibratory frequency disclosed by Curran et al., and the failure to administer tests under ergonomically neutral wrist positions, make these tests unreliable.

United States Patent 5,673,703, issued to Fisher et al., describes an apparatus for automatic testing of vibrotactile responses of a patient. In the preferred embodiment of the invention, a general -purpose computer functions to control the operation of the system and to record and store the patient's responses. Indentations and vibrations are produced by off-axis rotation of a stimulation probe. A frequency- modulated signal generated by the computer is used to control a motor, which drives the stimulation probe. This apparatus also falls short as it requires a complex stimulus probe. This complexity increases the possibility of calibration problems and, accordingly, degrades testing reliability.

United States Patent 5,381,805, issued to Tuckett et al., and United States Patent 5,022,407, issued to Horch et al., each describe an automatic apparatus for testing tactile responses of a patient. The automatic apparati require complex sets of measurements to be taken to provide information such as patient's response to thermal stimuli, response to touch, response to vibration, response to skin pricking, and response to Two-Point Discrimination tests. The apparati then take this information into account when calculating their results. Unfortunately, these systems are relatively costly. In addition, the use of the results of multiple tests makes these systems prone to diagnostic abnormalities due to the compounding of the calibration errors inherent in each test. Such compounding of errors decreases the overall reliability of the test results obtained from the system.

Therefore, there is a need for a testing method and system for predicting the onset of work-related sensory deficits that utilizes commonly available and relatively inexpensive testing equipment, that does not require the intervention of a skilled laboratory technician, that does not require complex calibration, that provides reliable results, and that provides optimal conditions for testing.

SUMMARY OF THE INVENTION The invention is a screening apparatus, a screening system, and a method of screening for peripheral neuropathies. In its most basic form, the screening apparatus includes a surface having an opening therethrough, a surround disposed about the opening, and a rod with a specified contact area disposed within said opening for contact with the pulp of a finger. The rod and surround are each dimensioned such that principally Meissner corpuscles are stimulated. A vibratory device is attached to the rod and vibrates the rod at a single frequency within a predetermined frequency range, again such that primarily Meissner corpuscles are stimulated by the rod. Finally, an amplitude modulating device is in communication with the vibratory device for controlling the vibratory device such that an amplitude of vibration of the vibratory device is incrementally increased. In operation, a user places a finger over the surround such that it rests upon the rod, the amplitude modulating device controls the vibratory device to induce vibration at the predetermined frequency, and the amplitude modulating device incrementally increases the amplitude of vibration of the vibratory device until the Meissner corpuscles are stimulated, causing the vibration to be felt by the finger.

The preferred apparatus includes a pressure sensor for sensing a pressure exerted by the finger upon the surround to ensure that pressure applied to the finger is within an acceptable range, a means for ensuring continuous contact with the pulp of the finger and the rod, means for adjusting amplitude according to compliance of the skin on the fingertip, and an internal calibration system for ensuring test reliability. The preferred vibratory device is a piezoelectric actuator that vibrates the rod at a single frequency within a frequency range of between about 20 Hz and about 50 Hz, where the preferred frequency is 40 Hz. The preferred amplitude modulating device is an piezoelectric bimorph driver circuit that is controlled by a personal computer. The preferred rod has a tip having a flat circular shape and a maximum cross sectional area of about 0.008 square centimeters.

In its most basic form, the system of the present invention includes a housing with a top surface through which a surround and an opening are disposed. A rod is disposed within the opening in the housing for contact with the finger pulp. A vibratory device is attached to the rod for vibrating the rod at a single frequency within a predetermined frequency range such that principally Meissner corpuscles are stimulated by the rod. An amplitude modulating device, mounted within the housing, is in communication with the vibratory device and controls displacement by the vibratory device. A computer having a storage medium and a user input is connected to the amplitude modulating device via an input/output. The computer is programmed to control the output to the amplitude modulating device such that, once contact between the rod and finger pulp is assured and pressure is found not to exceed an upper threshold, an amplitude of vibration of the vibratory device is incrementally increased. The computer is programmed to store a value corresponding to the amplitude of vibration in the storage medium upon receipt of an input signal from the user input.

In operation, the preferred system runs a self check to insure test reliability. A user places a hand upon the top surface of the housing such that a finger is disposed upon the rod and the system verifies that contact has been made and that a predetermined maximum force has not been exceeded. This maximum force is chosen to limit the stimulation of Pacinian corpuscles, which are sensitive to contact pressure. The computer then sends an output to the amplitude modulating device to control the vibratory device such that the vibratory device induces the rod to vibrate at the predetermined frequency, with the displacement of the rod adjusted based upon the compliance of the skin of the fingertip. The amplitude modulating device then incrementally increases the amplitude of vibration of the vibratory device until the Meissner corpuscles are stimulated, causing the vibration to be felt by the finger, and the user manipulates the user input such that an input signal is sent to the computer causing the computer to store a value in the storage medium corresponding to the amplitude of vibration when the vibration was felt. In the preferred method, the time and amount of each incremental increase is randomized to prevent a user from circumventing the test.

It is therefore an aspect of this present invention to provide an apparatus for detecting the on-set and progression of upper extremity work-related cumulative trauma disorders having a low cost, ease of use, and high prognostic capability. It is a further aspect of the present invention to provide an apparatus to accurately and reproducibly determine a patient's response threshold to vibrotactile stimulation at lower cost than existing systems.

It is a further aspect of the present invention to provide an apparatus that is easy to use and does not require special expertise to use. It is a further aspect of the present invention to provide an apparatus to measure vibrotactile thresholds and record them via a personal computer over time which may include days, weeks, months, and, at times, years.

It is a further aspect of the present invention to provide an apparatus to measure vibrotactile thresholds via personal computer structures and, in particular, an apparatus that may be housed in a functional computer mouse.

It is a further aspect of the present invention to provide an apparatus that facilitates neutral wrist posture via the housing.

It is a further aspect of the present invention to provide an apparatus that is easily interfaced with existing personal computers.

It is a further aspect of the present invention to provide an apparatus that stimulates primarily the Meissner corpuscles, which are substantially insensitive to age, mood, and contact pressure.

It is a further aspect of the present invention to provide an apparatus that self- tests for calibration to insure test parameters are met to maintain reliability.

It is a further aspect of the present invention to provide an apparatus that may induce randomness and variation in a test sequence to avoid a user circumventing the test.

It is a further aspect of the present invention to provide an apparatus that detects extraneous influences, such as the exertion of too much or too little pressure on the surround or rod, that could affect screening results.

It is a still further aspect of the present invention to provide an apparatus to automatically record identified vibrotactile threshold information and to maintain continually time-recorded information over days, weeks, months, and, at times, years. It is a still further aspect of the present invention to provide an apparatus that insures that continuous contact is made with the rod during testing.

It is a still further aspect of the present invention to provide an apparatus that is capable of self-adjusting based upon fingertip compliance.

It is a still further aspect of the present invention to provide an apparatus and method that may randomize a time between variations in amplitude levels in order to avoid circumvention of the test by the test subject.

These aspects of the invention are not meant to be exclusive and other features, aspects, and advantages of the present invention will be readily apparent to those of ordinary skill in the art when read in conjunction with the following description, appended claims and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view schematic diagram of portions of one embodiment of the screening apparatus of the present invention with the hand of a user disposed upon the device in a screening position. FIG. 2 is a side view of one embodiment of the rod of the screening apparatus of the present invention.

FIG. 3 is a side view of a preferred rod of the screening apparatus of the present invention.

FIG. 4 is a side view schematic diagram of portions of the preferred screening apparatus of the present invention with the hand of a user disposed upon the device in a screening position.

FIG. 5 is a schematic view of one embodiment of the screening system of the present invention.

FIG. 6 is a top view of the preferred housing of the apparatus and system of the present invention.

FIG. 7 is a side view of the housing of FIG. 4.

FIG. 8 is an exemplary graph showing the use of the statistical data in the method of the present invention.

FIG. 9 is an exemplary graph of tuning curves showing sensory response thresholds relative to stimulus intensity and stimulus frequency for Meissner and Pacinian corpuscles.

FIG. 10 is an exemplary graph showing vibrotactile threshold as a function of frequency for a range of contact areas.

DETAILED DESCRIPTION OF THE DRAWINGS Referring first to FIG. 1, one embodiment of the screening apparatus of the present invention is shown. The screening apparatus 10 includes a vibratory assembly 12, an amplitude-modulating device 14 in communication with the vibratory assembly 12 and a surface 16 through which a surround 18 and opening 19 are disposed. The vibratory assembly 12 includes a rod 20 that is attached to a vibratory device 22. The rod 20 extends through the opening 18 and is dimensioned for contact with the pulp of the finger 24 of the user such that primarily Meissner corpuscles are stimulated. The vibratory device 22 is adapted to vibrate the rod 20 at a single frequency within a predetermined frequency range such that primarily Meissner corpuscles in the finger 24 are stimulated by the rod 20. The amplitude-modulating device 14 is in electrical communication with the vibratory device 22 and controls the vibratory device 22 such that the amplitude of the vibration of the vibratory device 22 is incrementally increased. In operation, the device first performs a self check and an internal calibration. A user then places a finger 24 over the opening 19 such that the pulp of the finger 24 rests upon the surround 18, and thus on the force-sensing device 26 housed on the edge of the surround 18. The user provides pressure on the force sensing device 26 until the finger pulp 24 makes contact with the rod 20. As further described with reference to FIG. 4, the preferred embodiment utilizes a pin diode to confirm that contact has been made between the finger pulp 24 and the rod 20. However, in other embodiments, contact of the finger pulp 24 with the rod 20 is confirmed via the completion of an electrical circuit between the conductive rod 20, the conductive edge of the surround 18 and the finger pulp 24 in contact with both. At this time, a lower threshold is established indicating the minimal force acceptable on the force-sensing device 26. The upper threshold for the force sensing device 26 is pre-determined in reference to the lower threshold and is chosen to avoid stimulation of Pacininan corpuscles, which are sensitive to contact pressure. Provided that continuous contact between the rod 20 and the finger pulp 24 is maintained, and provided that the user supplies a pressure to the surround 18 within an acceptable range, then the amplitude-modulating device 14 signals the vibratory device 22 to induce vibration at a predetermined frequency and amplitude. The amplitude- modulating device 14 then incrementally increases the amplitude of vibration of the vibratory device 22 until the Meissner corpuscles in the pulp of the finger 24 are stimulated. When the stimulation of the Meissner corpuscles in the pulp of the finger 24 is sufficient to cause the vibration to be felt by the finger 24, the user records, via user input, the amplitude of vibration at the time when it is felt by the finger 24. This value may then be compared to a previous threshold history of the user, alerting the user of the possibility of on-coming peripheral neuropathies via trend changes, and/or if the recorded amplitude of vibration exceeds a predetermined amplitude of vibration that may typically indicate the presence of an existing neuropathy.

It is noted that, despite the intention to design the system to stimulate only Meissner corpuscles, other mechanoreceptors, such as the Pacinian corpuscles, Golgi- Mazzoni bodies, Merkel discs and/or Ruffini endings, may be stimulated by the vibration of the rod. Accordingly, as used herein, the phrase "stimulation of primarily Meissner corpuscles" means that the user experiences a sensation from the stimulation of these corpuscles before experiencing a sensation from the stimulation of other mechanoreceptors.

The stimulation of primarily Meissner corpuscles is accomplished by controlling the frequency of vibration of the rod 20, the shape and area of the tip of the rod 20, the shape of the surround 18 and the gap between the rod 20 and the surround 18. FIG. 9 shows an exemplary graph of tuning curves showing sensory response thresholds relative to stimulus intensity and stimulus frequency for Meissner and Pacinian corpuscles. As can be seen from FIG. 9, feeling due to stimulation of Meissner corpuscles (referred to as Meissner endings) is maximized at frequencies nearing 30 Hz; i.e. such stimulation may be felt at a minimum amplitude of vibration. Conversely, Pacinian corpuscles are maximally sensitive at frequencies of about 250 Hz. It is noted that an overlap in the sensitivity of Meissner and Pacinian corpuscles occurs at about 40 Hz. However, at frequencies greater than about 70 Hz, the stimulation of Pacinian corpuscles is felt at lower amplitudes then the stimulus of Meissner corpuscles. Accordingly, the present invention utilizes a vibratory device 22 that vibrates the rod 20 at a single frequency within a frequency range of between about 20 Hz and about 50 Hz, with the preferred frequency being 40 Hz. This frequency range has been chosen to specifically target the Meissner corpuscles, while limiting the stimulation of Pacinian corpuscles, and slowly adapting units, such as Merkel discs and Ruffini endings, which are sensitive at frequencies between about 8 and 16 Hz. The preferred vibratory device 22 is a bimorph piezoelectric actuator. This device is preferred over other types of vibratory devices due to its fast response time, low profile and small overall size, high resistance to vibration and shock, and high field reliability. However, it is recognized that other art recognized vibratory devices 22, such as modified speakers, rotary solenoids, and the like, may be utilized to achieve similar results.

As noted above, the rod 20 is also dimensioned to stimulate primarily Meissner corpuscles. FIG. 10, taken from Verillo's paper "CONTACTOR AREA AND THE VIBROTACTILE THRESHOLD", shows a plot of vibrotactile threshold as a function of frequency, displacement, and rod area, in which a gap between the rod and surround is kept constant. As can be seen from FIG. 10, small cross-sectional rod contact areas are somewhat less affected by changes in the frequency of stimulation. However, in order to avoid stimulation of Pacinian corpuscles, the rod contact area should be below 0.02 square centimeters and the frequency below about 50 Hz.

FIG. 2 shows the rod 20 of the present invention. The rod 20 was designed to fall within the above parameters and, accordingly, has a tip 34 with a contact area of between about 0.005 and about 0.02 square centimeters. This contact area allows the rod 20 to be felt at minimum amplitudes within the range of frequencies at which the rod 20 is vibrated. The tip 34 preferably has a cross sectional contact area of 0.008 square centimeters. This relatively small cross sectional contact area limits the stimulation of the Pacinian corpuscles and, thus, controls the testing volatility inherent in screening methodologies dependent upon such Pacinian stimulation.

The rod 20 may be manufactured from a variety of materials and has a tip 34 that may be formed into a plurality of shapes. As shown in FIG. 2, the rod 20 may be cylindrical in cross section and includes a substantially flat tip 34. The preferred rod 20, shown in FIG. 3, also includes a cylindrical top portion 33 that terminates in a substantially flat tip 34. However, the preferred rod 20 includes a conical base portion 37 that extends outward to prevent the rod 20 from bending. It is noted that rods 20 having different tip shapes may also be utilized, provided that the tip 34 includes an edge structure 35 to produce the flutter necessary to stimulate the Meissner corpuscles.

The surface 16 and surround 18 may take many forms. However the preferred surface 16 is dimensioned such that the hand is in a neutral position when the screening process is performed. As used herein, a neutral position is defined as when the wrist is up to 7 degrees extended with 0 degrees deviation. The surround 18 has a flat surface and surrounds the opening 19, which is preferably circular in cross section and dimensioned to form an approximately 1mm gap between the edge of the surround 18 and the edge of the vibrating rod 20. This dimensioning of the opening 19 relative to the rod 20 also acts to provide stimulation primarily of the Meissner corpuscles. The amplitude-modulating device 14 may take many forms, but is preferably an electronic amplifier controlled by a computer to incrementally increase the amplitude of vibration of the rod 20. This preferred embodiment is described in detail with reference to the system of the present invention, but it is recognized that other amplitude modulating devices may also be utilized. For example, an amplifier connected to a manually controlled potentiometer may be utilized to manually provide the incremental increase in amplitude. Similarly, timing circuits with capacitors could be used.

Referring again to FIG. 1, the screening apparatus 10 may include a pressure sensor 26 that is adapted to sense the pressure exerted by the finger 24 on the surround and the rod 20. The preferred pressure sensor 26, shown in FIG. 4, is a force sensing resistor such as those sold by Interlink. However, it should be recognized that other art recognized pressure sensors 26, or other art recognized methods of alerting the user of the proper finger force upon the rod and also the surround, may be utilized to achieve similar results. As shown in FIG. 1, the sensor 26 is in communication with an indicator 28 and sends a signal to the indicator 28 when the pressure exerted by the finger 24 falls within, or outside, of a predetermined range of acceptable testing pressures. This predetermined range is based, primarily, upon a minimal pressure required to establish contact between the rod 20 and the finger, the maximum allowable pressure that may be exerted upon the vibratory device 22, and maximum allowable pressure that may be exerted by the finger pulp on the surround in order to generate reliable sensitivity measures while not causing skin stress. In embodiments of the apparatus utilizing the preferred bimorph piezoelectric actuator driven at 50 VDC, this force is between 0 and 1.1 ounces. However, it is recognized that this force range may vary depending upon the particular vibratory device 22 that is utilized.

The indicator 28 of FIG. 1 is a light that is illuminated when the finger pressure is within the range of acceptable testing pressures. However, in other embodiments, the indicator 28 is a light or an LED that is illuminated when the finger pressure is outside of the range of acceptable testing pressures, when contact is not made, or when contact is not continuous. In other embodiments, the indicator 28 is a sound generating device, such as a speaker, buzzer, bell, that produces an audible sound when the pressure is either within or outside of the range of acceptable testing pressures, when contact is not made with the rod 20, or when contact with the rod 20 is not continuous. In the preferred embodiment, however, the indicator 28 is eliminated and the sensor sends a signal to a computer (not shown) which may be programmed to alert a user, or to discard the test results, when the testing pressure is above a maximum testing pressure, when contact is not made, or when contact is broken.

Referring now to FIG. 4, the preferred apparatus 10 of the present invention is shown. The preferred apparatus 10 includes a housing 16 and a vibratory device 22, and utilizes a force sensing resistor as the pressure sensor 26. The preferred apparatus 10 also includes a means for ensuring continuous contact between the finger pulp and the rod, and an internal calibration system 41 for insuring that the test data is not corrupted by errors in the apparatus 10. As shown in FIG. 4, the preferred means for ensuring continuous contact between the finger pulp and rod 20 includes a pin diode 43 and a reflector 45 disposed upon the bottom of the vibratory device 22. In this embodiment, the pin diode 43 is disposed in a predetermined position such that it is perpendicular to the reflector 45 when there is no downward force applied upon the rod 20. The pin diode 43 emits pulses of light, which reflect off of the reflector 45 and back to the pin diode 43, which captures the reflected light to effectively complete the circuit. In this arrangement, the completion of the circuit indicates that the finger is not contacting the rod 20. When a user places a finger upon the rod 20, the vibratory device 22 deflects in response to the load, causing the reflector 45 to move out of perpendicular orientation with the pin diode 43. When this occurs, the pulses of light emitted by the pin diode 43 are scattered and, accordingly, are not reflected back to the pin diode 43 to complete the circuit. Thus, the lack of a completed circuit indicates that the finger is contacting the rod 20. However, in other embodiments, the reflector 45 is positioned such that scatter occurs when contact is not made with the rod 20. In these embodiments, the placement of the finger pulp upon the rod 20 moves the reflector 45 into perpendicular alignment with the pin diode 43, which captures the reflected light and completes the circuit.

In an alternative embodiment, the means for ensuring continuous contact between the finger pulp 24 and the rod 20 includes an impedance system. In such a system, finger contact is sensed throughout the test by completing an electrical circuit between a conductive portion of the rod 20, a conductive portion of the area of the surface surrounding the hole 19, and the finger pulp 24 of a user. When the finger 24 is removed, the circuit is broken, causing a signal to be sent to the indicator 28 or computer as discussed above. The preferred internal calibration system 41 includes means for ensuring that the rod 20 is vibrated at sufficient amplitude, means for ensuring that the rod 20 is maintained in an upright position within the opening 19, and means for ensuring the bimorph piezoelectric actuator is not bent. As shown in FIG. 4, in embodiments utilizing a piezoelectric actuator as a vibratory device, 22, the preferred means for ensuring that the rod 20 is vibrated at sufficient amplitude includes a second pin diode 47 and reflector 49 that combine to measure scatter of reflected light at a point near the base of the vibratory device 22. This scatter is compared to the scatter found by the pin diode 43 and reflector 45 adjacent to the rod 20 to determine whether the piezoelectric actuator is deflecting at the desired amplitude. This allows the system to compensate for variations in fingertip compliance due to heavily callused or unusually soft fingertips, allowing more accurate control of the actual amplitude of vibration under load.

As also shown in FIG. 4, the preferred means for insuring that the rod is maintained in an upright position within the opening 19 is a rod 20, such as that shown in FIG. 3, having a wide base portion. As noted above, by widening this base portion, the rod 20 is prevented from bending and, thus, is maintained in an upright position within the opening 19. In an alternative embodiment, however, this function is accomplished by a capacitance sensor. Such a sensor operates by sensing the capacitance between the rod 20 and the surround 18. This capacitance is dependent upon the direction and distance between the surround 18 and the rod 20 and, therefore, will change if the rod 20 is disposed a different distance from the surround 18. Accordingly, if the capacitance between the rod 20 and surround 18 is different than a baseline capacitance, or if the circuit is bridged by the rod 20 touching the surround 18, a fault will be recognized. Referring now to FIG. 5, one embodiment of the screening system 50 of the present invention is shown. The screening system 50 includes a housing 54 that includes a top surface 16 having an opening 19 disposed therethrough and an area of said surface 16 surrounding said opening 19. The rod 20 extends through the opening 19 for contact with the pulp of a finger and is attached to the vibratory device (not shown). The electronic amplifier 56 is in communication with the vibratory device and controls the vibratory device. A computer 58 communicates with the electronic amplifier 56 through an input/output port 60 to control the output of the electronic amplifier 56 such that the amplitude of vibration of the vibratory device is adjusted for compliance with the fingertip and is incrementally increased based upon this adjustment. The computer 58 includes the input/output port 60, a storage medium (not shown), and a user input 62. A software program, stored within the storage medium, directs the computer to store a value corresponding to the amplitude of vibration upon receipt of an input signal from the user input 62.

The preferred screening system 50 operates in a similar fashion to the screening apparatus 10 described with reference to FIGS. 1 - 4. The internal calibration system performs a self-check to insure that the rod 20 is in an upright position, that the bimorph piezoelectric actuator is not bent, and that full displacement is attained. The user disposes a finger over the surround 18 such that the finger pulp contacts the rod 20 and the system verifies that this contact has been made. Once contact has been made, the system verifies that the force upon the rod 20 and surround 18 does not exceed a maximum force and continuously monitors this force to insure that it is below the maximum. The rod 20 is then induced to vibrate by the vibratory device at a single frequency, with amplitude being adjusted for fingertip compliance. The induction of vibration and the subsequent increase in the amplitude of vibration is automated by the computer, which randomizes the modulation of the amplitude of vibration by controlling the output of the electronic amplifier 56 via a control program stored within the storage medium.

In addition to the above stated functions, the computer 58 also eliminates the need to manually record the amplitude of vibration at the time that the user feels the vibration of the rod 20, as is required in some embodiments of the screening apparatus 10. Rather, the user simply manipulates the user input 62 when the vibration is felt and the computer 58 accepts the input signal from the user input 62, determines the amplitude of vibration at the time the input signal is received, and automatically stores the amplitude of vibration within the storage medium. These stored amplitudes of vibration may be tracked over time and statistically manipulated to provide data useful for screening for peripheral neuropathies.

The screening system 50 of FIG. 3 includes a computer monitor 64 that may be utilized to display values of the amplitude of vibration recorded by a user, graphs of recorded amplitudes of vibration over time, indications of improper test conditions such as those described with reference to the pressure sensor and indicator of FIG. 1 and pin diode of FIG. 4, improper calibration, lack of contact of the rod with the finger pulp, or any other information that may be useful to the screening process. In some embodiments, a touch screen type monitor may also be utilized to serve both as a display and a user input 62. The user input of computer 58 is preferably a standard computer keyboard 62, such as those commonly employed with personal computers. However, as mentioned above, the keyboard user input 62 may be replaced, or augmented by a touch screen type computer monitor. Similarly, the user input 62 may simply be a mouse button 66 on a computer mouse 52 within which the rod 20 and vibratory device 22 are disposed. Finally, the user input 62 may be integrated into the pressure sensor 26, described with reference to the screening apparati of FIGS. 1 and 4. In this embodiment, the user would release the pin 20 upon feeling vibration, causing the pressure sensor 26 to send a signal to the computer 58 indicating that the vibration had been felt. However, this embodiment is not preferred, as such an arrangement is prone to creating spurious results.

Although the electronic amplifier 56 is shown outside the housing 54 in FIG. 5, the electronic amplifier 56 is preferably disposed within the housing 54 and the input/output 60 extends into the housing 54 where it is connected to the electronic amplifier 56. The input/output 60 is preferably a cable, but may also be any art recognized infrared or radio frequency input/output.

As shown in FIG. 5, the housing 54 is a housing of a working computer mouse 52 that functions both as a screening apparatus and to manipulate the computer 58 during normal operations. The computer mouse 52 may take a number of forms and include a number of different input types. For example, the computer mouse may be a standard two or three button mouse, a mouse with a side mounted rollerball, a mouse with a centrally mounted rollerball, such as the MICROSOFT INTELLIMOUSEO marketed by the Microsoft Corporation of Redmond, Washington, or a track ball type mouse having a roller ball in the center and a plurality of buttons disposed about the roller ball. In one embodiment, the computer mouse includes an umbo and a thumb support upon one side of the computer mouse. The umbo is a contoured surface that allows a user's hand to be placed in a neutral position during both screening and during normal use. In some embodiments, the surround is disposed through one of the mouse buttons and the rod is adapted to retract when it is not being used for testing purposes. This arrangement allows the hand to remain in the neutral position at all times and helps to prevent the repetitive stresses upon the hands that cause peripheral neuropathies.

The preferred housing 54 of the present invention is shown in FIGS. 6 and 7. The preferred housing 54 is not a housing of a working computer mouse, but rather is a molded plastic housing 54 having a top surface 16 that tapers upward from the tail end 74 of the housing 54 to a substantially flat portion 76 through which the opening 19 is disposed. The tapered portion 78 of the top surface 16 is dimensioned to accept the palm of a user's hand such that the hand is in a neutral position during testing. In the preferred housing, the angle a, representing the bend of a user's wrist, should be no more than seven degrees extended. The housing 54 is designed to be used by either a left or a right hand. Disposed through the top surface 16 is the opening 19, bounded by the surround 18. The rod 20 is disposed within the opening 19 and is accessible by the user through the opening 19.

The screening apparatus 10 and screening system 50 of the present invention may be utilized in a number of different methods of screening for peripheral neuropathies. In these methods, the application of vibration at frequencies to stimulate primarily Meissner corpuscles, the tracking of trend data over time, the ability to alert a user of the possibility of testing inaccuracies due to problems identified through internal calibration and/or excessive or insufficient force upon the rod, adjustments to the amplitude of vibration based upon fingertip compliance, and the ability to randomize the test process to avoid false results, provide significant improvements over current screening methods.

The preferred method involves the use of the screening system 50 in an office environment. Here, the integration of the rod 20 and vibratory device 22 into the housing 54 makes the system easy to integrate into existing work spaces. It is contemplated that the computer software within the computer 58 will prompt the worker to screen themselves after a predetermined period of work, at a predetermined time of day, or after a predetermined number of keystrokes. This prompt is important as screening data may vary significantly from tests taken after periods of rest to tests taken after periods of repetitive motion. Once the test has been performed, the screening data is stored in the storage medium of the computer and is compared with data taken previously and with data representing acceptable and unacceptable amplitudes of vibration required before it is felt by the worker.

As shown in FIG. 8, screening data may be plotted to show a trend over time. In the preferred method, this data is displayed upon the worker's computer monitor. In addition, a warning occurs if the trend shows an increase in the required amplitude above a predetermined baseline for a given period of time.

In other embodiments of the method, the screening apparatus 10 is disposed upon a factory floor and utilized by workers performing repetitive tasks. In these methods or in an office setting there may be provided a computerized data collection system that authenticates the worker being screened via an employee number, bar coded identification, or the like, and sends data to a central computer system for processing of baseline and trend data. Similarly, there may be a central screening station that allows workers to privately and anonymously screen themselves.

Although the present invention has been described in considerable detail with reference to certain preferred versions thereof, other versions would be readily apparent to those of ordinary skill in the art. For example, it is intended that body parts other than fingers may be tested utilizing the apparatus, system and method of the present invention. Such testing would have applicability in screening of, for example, diabetes or stroke patients for sensory loss. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred versions contained herein.

Claims

What is claimed is:

/• A screening apparatus for peripheral neuropathies comprising: a housing having a top surface comprising an opening defined by a surround, said opening having a predetermined dimension; a rod disposed within said opening, said rod being dimensioned such that primarily Meissner corpuscles are stimulated by said rod; a vibratory device attached to said rod for vibrating said rod at a single frequency within a predetermined frequency range such that primarily Meissner corpuscles are stimulated by said rod; and an amplitude modulating device in communication with said vibratory device for controlling said vibratory device such that an amplitude of vibration of said vibratory device is incrementally increased; wherein a surface of a body is placed upon said rod, said amplitude modulating device controls said vibratory device to induce vibration at said predetermined frequency, and said amplitude modulating device incrementally increases said amplitude of vibration of said vibratory device until said Meissner corpuscles are stimulated, causing said vibration to be felt by said surface of said body.

2. The apparatus as claimed in claim 1 further comprising a pressure sensor for sensing a pressure exerted by said surface of said body upon said surround.

3. The apparatus as claimed in claim 2 further comprising an indicator, in communication with said pressure sensor, for indicating when said pressure is within a predetermined acceptable testing range.

4. The apparatus as claimed in claim 2 further comprising: means for ensuring continuous contact between said surface of said body and said rod; and an internal calibration system for ensuring test reliability.

5. The apparatus as claimed in claim 4 wherein said internal calibration system comprises at least one means chosen from a group consisting of: means for ensuring that said rod is vibrated at a sufficient amplitude; means for ensuring that said rod is maintained in an upright position within said opening; and means for ensuring that said vibratory device is functioning properly.

6. The apparatus as claimed in claim 1 wherein said vibratory device vibrates said rod at a single frequency within a frequency range of between about 20 Hz and about 50 Hz.

7. The apparatus as claimed in claim 1 wherein said surround is substantially flat, wherein said opening is a circular opening and wherein said predetermined dimension is a gap of approximately one millimeter between said surround and an edge of said rod.

8. The apparatus as claimed in claim 1 wherein said amplitude modulating device is an electronic amplifier that is controlled by a computer.

9. The apparatus as claimed in claim 1 wherein said rod comprises a tip having a substantially flat circular shape.

10. The apparatus as claimed in claim 1 wherein said rod comprises a tip having a contact area of between about 0.005 and 0.02 square centimeters.

11. The apparatus as claimed in claim 1 wherein said surface of a body is a surface of a finger and wherein top surface of said housing is dimensioned to position a hand in a neutral position when said rod is contacted with the surface of the finger.

12. The apparatus as claimed in claim 1 further comprising means for automatically adjusting an amplitude of vibration based upon compliance of a skin at said surface of said body placed upon said rod.

13. A screening system for peripheral neuropathies comprising: a housing having a top surface comprising an opening defined by a surround, said opening having a predetermined dimension; a vibratory assembly disposed within said housing, said vibratory assembly comprising: a rod disposed within said opening for contact with a surface of a body, said rod being dimensioned such that primarily Meissner corpuscles are stimulated by said rod; and a vibratory device attached to said rod for vibrating said rod at a single frequency within a predetermined frequency range such that primarily Meissner corpuscles are stimulated by said rod; an amplitude modulating device in communication with said vibratory device of said vibratory assembly controlling said vibratory device such that an amplitude of vibration of said vibratory device is incrementally increased; and a computer comprising a storage medium, a user input and an input/output in electrical communication with said amplitude modulating device, wherein said computer is programmed to control said output to said amplitude modulating device such that an amplitude of vibration of said vibratory device is incrementally increased, and wherein said computer is programmed to store a value corresponding to said amplitude of vibration in said storage medium upon receipt of an input signal from said user input; wherein a user disposes said surface of said body upon said housing such that said surface of said body is in contact with said rod, said computer sends an output to said amplitude modulating device to control said vibratory device such that said vibratory device induces said rod to vibrate at said predetermined frequency, said amplitude modulating device incrementally increases said amplitude of vibration of said vibratory device until said Meissner corpuscles are stimulated and said vibration is felt by said surface of said body, and said user manipulates said user input such that an input signal is sent to said computer causing said computer to store a value corresponding to said amplitude of vibration in said storage medium.

14. The system as claimed in claim 13 wherein said vibratory assembly further comprises a pressure sensor for sensing a pressure exerted by said surface of said body upon said surround.

15. The system as claimed in claim 14 further comprising an indicator, in communication with said pressure sensor, for indicating when said pressure is within a predetermined acceptable testing range.

16. The system as claimed in claim 13, further comprising: means for ensuring continuous contact between the surface of the body and said rod; and an internal calibration system for ensuring test reliability.

17. The system as claimed in claim 16 wherein said internal calibration system comprises at least one means chosen from a group consisting of: a means for ensuring that said rod is vibrated at a sufficient amplitude; a means for ensuring that said rod is maintained in an upright position within said opening; and means for ensuring that said vibratory device is functioning properly.

18. The system as claimed in claim 13 wherein said vibratory device vibrates said rod at a single frequency within a frequency range of between about 20 Hz and about 50 Hz.

19. The system as claimed in claim 13 wherein said rod comprises a tip having a substantially flat circular shape.

20. The system as claimed in claim 13 wherein said rod comprises a tip having a contact area of between 0.005 and 0.02 square centimeters.

21. The system as claimed in claim 13 wherein surface of said body is a surface of a finger and wherein said top surface of said housing is dimensioned to position a hand in a neutral position when said rod is contacted with the surface of the finger.

22. The system as claimed in claim 13 further comprising means for automatically adjusting an amplitude of vibration based upon compliance of a skin at said surface of said body placed upon said rod.

23. The system as claimed in claim 13 wherein said user input to said computer is a computer keyboard.

24. A method of screening for peripheral neuropathies comprising the steps of: performing a self check; contacting a rod with a surface of a body; verifying that said rod has been contacted; verifying that a force is within a predetermined range of acceptable forces; vibrating said rod at a predetermined frequency of vibration; adjusting said predetermined amplitude of vibration based upon a compliance of said skin at said surface of said body; incrementally increasing said amplitude of said vibration until said vibration is felt by said user; recording said amplitude of said vibration at a time when said vibration is felt by said user; comparing said recorded amplitude of vibration with a predetermined amplitude of vibration; and alerting said user if said recorded amplitude of vibration exceeds said predetermined amplitude of vibration.

25. The method as claimed in claim 24 wherein said comparing step further comprises the steps of: comparing said amplitude of vibration with a plurality of amplitudes of vibration recorded over a predetermined time period; determining a baseline for said user based upon said plurality of amplitudes of vibration; and determining whether said amplitude of vibration exceeds said baseline.

26. The method as claimed in claim 25 wherein said alerting step comprises alerting said user when said amplitude of vibration exceeds a predetermined number of standard deviations away from said baseline.