Sudomotor function for peripheral diabetic neuropathy evaluation

Abstract

A method for assessing sudomotor function of a patient for evaluating diabetic and autonomous neuropathy is disclosed. The method is performed in a system comprising electrodes intended to be placed on different regions of the patient body, and an adjustable DC source. The method includes applying on the electrodes DC voltage pulses of varying voltage values in order to stress sweat glands, the voltage pulses lasting given durations allowing the stabilization of electrochemical phenomena in the body, near the electrodes; collecting data representative of the current between the electrodes, and of the potential generated on the electrodes for the different DC voltages; from the data, computing results representative of the electrochemical skin conductance of the patient; reconciling the latter data with reference data obtained in the same conditions on patients identified as suffering or not from sudomotor, and identifying the patient as suffering or not from sudomotor dysfunction.

The invention claimed is: 
     
         1 . A sudomotor diagnostic device comprising:
 (a) foot-contacting electrodes each having a surface area of at least fifty cm 2 ;   (b) hand-contacting electrodes each having a surface area of at least fifty cm 2 ;   (c) direct current operably sent to at least one of the electrodes; and   (d) a computer connected to the electrodes, the computer operably determining electrical skin conductance by calculating a relationship between current generated through the electrodes which are active and a resulting voltage drop between the electrodes which are anodes and cathodes, and the computer making the determination within two minutes from the direct current initially being sent.   
     
     
         2 . The device of  claim 1 , wherein voltage applied on the anode electrodes induces, through reverse iontophoresis, a voltage on the cathode electrodes which generates the current sent to the computer, and the direct current applied to a patient's hands and feet by the electrodes in less than ten volts. 
     
     
         3 . The device of  claim 1 , wherein the computer compares the determined conductance to reference data, the computer diagnoses if a sudomotor dysfunction exists and displays results on a computer-controlled display. 
     
     
         4 . The device of  claim 1 , further comprising an adjustable direct current source sending the direct current to the electrodes. 
     
     
         5 . The device of  claim 1 , wherein each of the electrodes includes nickel material which contacts substantially all of a palm surface of the associated hand or sole surface of the associated foot. 
     
     
         6 . The device of  claim 1 , wherein each of the electrodes includes stainless steel which contacts substantially all of a palm surface of the associated hand or sole surface of the associated foot. 
     
     
         7 . The device of  claim 1 , wherein the computer determines if a patient has diabetes. 
     
     
         8 . The device of  claim 1 , wherein the computer determines if a patient has diabetes polyneuropathy. 
     
     
         9 . The device of  claim 1 , wherein the computer uses data based on peripheral vibration sensation of a patient through evaluation of a vibration perception threshold. 
     
     
         10 . The device of  claim 1 , wherein the computer uses data based on cardiac autonomic neuropathy assession. 
     
     
         11 . The device of  claim 1 , wherein the computer uses data based on a neuropathy assessment through a Michigan neuropathy screening instrument. 
     
     
         12 . A sudomotor diagnostic device comprising:
 (a) electrodes having a surface area of at least fifty cm 2 ;   (b) an adjustable direct current source adapted to feed at least some of the electrodes with direct current to operably cause reverse iontophoresis;   (c) the electrodes being alternately used as an anode and a cathode with current pulses, each of one second or less, being applied at the anode of less than ten volts; and   (d) a computer adapted to diagnose sudomotor dysfunction and output its results on a display within two minutes from initial reverse iontophoresis.   
     
     
         13 . The device of  claim 12 , wherein the electrodes include patient hand-contacting electrodes and patient foot-contacting electrodes. 
     
     
         14 . The device of  claim 13 , wherein each of the electrodes includes nickel material which contacts substantially all of a palm surface of the associated hand or sole surface of the associated foot. 
     
     
         15 . The device of  claim 13 , wherein each of the electrodes includes stainless steel which contacts substantially all of a palm surface of the associated hand or sole surface of the associated foot. 
     
     
         16 . The device of  claim 12 , wherein the computer compares measured patient electrochemical data to previously stored healthy patient data. 
     
     
         17 . The device of  claim 12 , wherein the computer determines if a patient has diabetes. 
     
     
         18 . A sudomotor diagnostic device comprising:
 (a) electrodes each being adapted to contact against substantially all of a sole surface of a patient's foot;   (b) additional electrodes each being adapted to contact against substantially all of a palm surface of a patient's hand; and   (c) a computer connected to the hand and foot electrodes and being adapted to determine patient sudomotor dysfunction, if present, when direct current of less than ten volts is operably sent to at least one of the electrodes to cause eccrine sweat glands of the patient to produce an electrochemical change measured by the computer.   
     
     
         19 . The device of  claim 18 , wherein the computer measures and stores electrode voltage and current data, and the computer causes the electrodes to be electrically reversed such that an anode of the electrodes becomes a cathode of the electrodes and vice-versa. 
     
     
         20 . The device of  claim 18 , wherein the computer determines electrical skin conductance of the patient from current generated through active of the electrodes and a resulting voltage drop between an anode and a cathode of the electrodes, with the computer outputting the determination using a display. 
     
     
         21 . The device of  claim 18 , wherein voltage applied on an anode of the electrodes induces, through reverse iontophoresis, a voltage on a cathode of the electrodes which generates current sent to the computer. 
     
     
         22 . The device of  claim 18 , further comprising an adjustable direct current source sending the direct current to at least some of the electrodes, and the computer comparing measured data associated with the patient electrochemical change to previously stored healthy patient data 
     
     
         23 . The device of  claim 18 , wherein the computer determines if the patient has diabetes. 
     
     
         24 . The device of  claim 18 , wherein the computer determines the sudomotor dysfunction within two minutes of when the direct current is initially sent to the electrodes. 
     
     
         25 . The device of  claim 18 , wherein the computer assesses severity of the sudomotor dysfunction. 
     
     
         26 . The device of  claim 18 , wherein the computer uses data from at least one test among the following: peripheral vibration sensation through evaluation of a vibration perception threshold, cardiac autonomic neuropathy (CAN) assessment, or neuropathy assessment through a Michigan neuropathy screening instrument (MNSI). 
     
     
         27 . The device of  claim 18 , wherein the computer reconciles computed electrochemical skin conductance values with at least one other measurement, as a co-indicator of sudomotor dysfunction and diabetic polyneuropathy severity. 
     
     
         28 . The device of  claim 18 , wherein the computer determines severe sudomotor dysfunction by low electrochemical skin conductance values in correlation with a high sensory perception threshold. 
     
     
         29 . The device of  claim 18 , wherein the computer determines severe peripheral neuropathy by low electrochemical skin conductance values in correlation with high number of abnormal CAN results. 
     
     
         30 . The device of  claim 18 , wherein the computer determines severe peripheral neuropathy by low electrochemical skin conductance values in correlation with data assessed by MNSI. 
     
     
         31 . A sudomotor diagnostic device comprising:
 (a) foot-contacting electrodes;   (b) hand-contacting electrodes;   (c) a direct current power source connected to the electrodes;   (d) a computer connected to the electrodes;   (e) voltage applied on an anode of the electrodes inducing, through reverse iontophoresis, a voltage on a cathode of the electrodes which generates a signal sent to the computer which it uses to determine electrochemical skin conductance values; and   (f) the computer additionally receiving data associated with at least one of: (i) peripheral vibration sensation through evaluation of a vibration perception threshold, (ii) cardiac autonomic neuropathy assessment (CAN), or (iii) neuropathy assessment through a Michigan neuropathy screening instrument (MNSI), as a co-indicator of at least one of: sudomotor dysfunction or diabetic polyneuropathy severity.   
     
     
         32 . The device of  claim 31 , wherein the computer compares measured patient electrochemical data to previously stored healthy patient data. 
     
     
         33 . The device of  claim 31 , wherein the computer compares the determined patient conductance with reference data, the computer diagnoses if a patient sudomotor dysfunction exists and displays results on a computer-controlled display. 
     
     
         34 . The device of  claim 31 , wherein each of the electrodes includes nickel material which contacts substantially all of a palm surface of an associated hand or sole surface of an associated foot. 
     
     
         35 . The device of  claim 31 , wherein each of the electrodes includes stainless steel which contacts substantially all of a palm surface of an associated hand or sole surface of an associated foot. 
     
     
         36 . The device of  claim 31 , wherein the computer measures and stores electrode voltage and current data, and the computer causes the electrodes to be electrically reversed such that an anode becomes a cathode and vice-versa. 
     
     
         37 . The device of  claim 31 , wherein the computer determines electrical skin conductance from current generated through active of the electrodes and a resulting voltage drop between an anode and a cathode of the electrodes, with the computer outputting the determination using a display. 
     
     
         38 . The device of  claim 31 , wherein the computer determines the sudomotor dysfunction within two minutes when direct current is initially sent to the electrodes.