Pain measurement system and method

• US 6,113,552 A
• Filed: 11/18/1998
• Issued: 09/05/2000
• Est. Priority Date: 11/18/1998
• Status: Expired due to Term

• Current Assignee: International Medical Device Partners, Inc.
• Original Assignee: International Medical Device Partners, Inc.
• Inventors: Sagara, Kuniko, Shimazu, Hideaki
• Primary Examiner(s): HINDENBURG, MAX F
• Application Number:
  US09/193,945
• Time in Patent Office: 657 Days
• Field of Search: 600/552, 600/553, 600/554, 600/555, 600/557
• US Class Current: 600/557
• CPC Class Codes: A61B 5/4824 Touch or pain perception evaluation A61B5/4821 takes precedence

Abstract

Disclosed is a pain measurement system and method that make possible the quantitative measurement of human clinical pain. The perception of the pain generated by the subject'"'"'s source of preexisting pain is compared with a pseudo pain feeling which is produced by a gradual change in an electric stimulus generated by the system. This device measures the point at which the subject'"'"'s perception of actual pain approximates the intensity of the pseudo pain feeling generated by the system. In this way the magnitude of the source of pain [x] is estimated quantitatively. The minimum perception level of a subject is also determined and a ratio of current level for actual pain to current level for minimum perception level is taken to quantify the pain.

Claims

1. A system for measuring the magnitude of pain experienced by a subject, comprising:

a contact adapted to be applied to a subject to deliver a tactile stimulus;

an energy source connected to the contact to provide a controllable magnitude of tactile stimulus to the subject through the contact;

a processor connected to the energy source to control the magnitude of tactile stimulus applied to the subject;

an indicator switch connected to the processor and adapted to be activated to provide a tactile indication signal to the processor that a magnitude of tactile stimulus has been experienced by the subject;

wherein the processor is adapted to receive a first tactile indication signal, determine the first magnitude of tactile stimulus applied to the subject at the time of receipt of the first tactile indication signal, and store the first magnitude of tactile stimulus; and

wherein the processor is further adapted to receive a second tactile indication signal, determine the second magnitude of tactile stimulus applied to the subject at the time of receipt of the second tactile indication signal, and compare the second magnitude of tactile stimulus to the first magnitude of tactile stimulus and provide a comparison signal.

2. A system for measuring the magnitude of pain experienced by a subject, comprising:

a contact adapted to be applied to a subject to deliver a pseudo-pain stimulus;

an energy source connected to the contact to provide a controllable magnitude of pseudo-pain stimulus to the subject through the contact;

a processor connected to the energy source to control the magnitude of pseudo-pain stimulus applied to the subject;

an indicator switch connected to the processor and adapted to be activated to provide a pseudo-pain indication signal to the processor that a magnitude of pseudo-pain has been experienced by the subject;

wherein the processor is adapted to receive a first pseudo-pain indication signal, determine the first magnitude of pseudo-pain stimulus applied to the subject at the time of receipt of the first pseudo-pain indication signal, and store the first magnitude of pseudo-pain stimulus; and

wherein the processor is further adapted to receive a second pseudo-pain indication signal, determine the second magnitude of pseudo-pain stimulus applied to the subject at the time of receipt of the second pseudo-pain indication signal, and compare the second magnitude of pseudo-pain stimulus to the first magnitude of pseudo-pain stimulus and provide a comparison signal.

3. The system of claim 2, wherein the indicator switch is adapted to be activated by the subject to provide a pseudo-pain indication signal to the processor that a magnitude of pseudo-pain has been experienced by the subject.

4. The system of claim 2, wherein the contact comprises an electrode adapted to deliver electric energy to the subject.

5. The system of claim 2, wherein the energy source provides energy to the contact with a steadily increasing magnitude until receipt by the processor of a pseudo-pain indication signal at which time the processor controls the energy source to cease delivery of electric energy to the contact.

6. The system of claim 2, further comprising a display, wherein the processor provides the comparison to the display to be displayed thereon.

7. The system of claim 2, further comprising a memory, wherein the processor provides the comparison to the memory to be stored.

8. The system of claim 7, further comprising a display, wherein the processor is adapted to provide the comparison signal to the display for display thereon.

9. The system of claim 8, wherein the processor is adapted to store multiple comparison signals in the memory and to provide multiple stored comparison signals simultaneously to the display for display thereon.

10. The system of claim 2, wherein the pseudo-pain stimulus signal comprises a current of steadily increasing amperage.

11. The system of claim 2, wherein the pseudo-pain stimulus signal comprises a voltage having a duty cycle of less than 100 percent.

12. The system of claim 2, wherein the stimulus signal comprises a voltage signal having a frequency of approximately 50 Hertz.

13. A system for measuring the magnitude of preexisting pain experienced by a subject, comprising:

an electrode adapted to be applied to a subject to deliver an electric stimulus signal;

an energy source connected to the electrode to provide the electric stimulus signal, the energy source capable of controlling the magnitude of the electric stimulus signal;

a processor connected to the energy source to control the magnitude of the electric stimulus signal applied to the subject;

a display;

a memory;

a pseudo-pain indicator switch connected to the processor and adapted to be activated by the subject to provide a pseudo-pain indication signal to the processor that a magnitude of pseudo-pain has been experienced by the subject;

wherein the processor receives a first pseudo-pain indication signal, determines the first magnitude of stimulus applied to the subject by the energy source at the time of receipt of the first pseudo-pain indication signal, and stores the first magnitude of stimulus in the memory;

wherein the processor receives a second pseudo-pain indication signal, determines the second magnitude of stimulus applied to the subject by the energy source at the time of receipt of the second pseudo-pain indication signal, compares the second magnitude of stimulus to the first magnitude of stimulus, and provides a comparison signal; and

wherein the processor provides the comparison signal to the display for display thereon.

14. The system of claim 13, wherein the processor provides a first steadily increasing stimulus signal to the subject and upon receipt of the first pseudo-pain indication signal, stores the first magnitude of stimulus as a sensation threshold signal;

wherein the processor provides a second steadily increasing stimulus signal to the subject and upon receipt of the second pseudo-pain indication signal, divides the second stimulus signal by the first stimulus signal to provide the comparison signal;

wherein the processor provides the comparison signal to the display for display thereon.

15. The system of claim 13, wherein the stimulus signal comprises a current of steadily increasing amperage.

16. The system of claim 13, wherein the stimulus signal comprises a voltage having a duty cycle of less than 100 percent.

17. The system of claim 13, wherein the stimulus signal comprises a voltage signal having a frequency of approximately 50 Hertz.

18. The system of claim 13, wherein the energy source provides electric energy to the electrode in a steadily increasing magnitude until receipt by the processor of a pseudo-pain indication signal at which time the processor controls the energy source to cease delivery of energy to the electrode.

19. The system of claim 13, wherein the processor is adapted to store multiple comparisons in the memory and to provide multiple stored comparison signals to the display for display thereon.

20. A system for measuring the magnitude of pain experienced by a subject, comprising:

a contact adapted to be applied to a subject to deliver a pain stimulus;

an energy source connected to the contact to provide a controllable magnitude of pain stimulus to the subject through the contact;

a processor connected to the energy source to control the magnitude of pain stimulus applied to the subject;

an indicator switch connected to the processor and adapted to be activated to provide a pain indication signal to the processor that a magnitude of pain stimulus has been experienced by the subject;

wherein the processor is adapted to receive a first pain indication signal, determine the first magnitude of pain stimulus applied to the subject at the time of receipt of the first pain indication signal, and store the first magnitude of pain stimulus; and

wherein the processor is further adapted to receive a second pain indication signal, determine the second magnitude of pain stimulus applied to the subject at the time of receipt of the second pain indication signal, and compare the second magnitude of pain stimulus to the first magnitude of pain stimulus and provide a comparison signal.

21. A method for measuring the magnitude of pain experienced by a subject, comprising the steps of:

applying an electric stimulus of an increasing magnitude to the subject via an electrode;

measuring the magnitude of the electric stimulus;

monitoring a signal from the subject to determine when the first magnitude of the applied electric stimulus corresponds to a first subject condition; and

recording the first magnitude of the applied electric stimulus that corresponds to the subject condition;

monitoring a signal from the subject at a second time to determine when the second magnitude of the applied electric stimulus corresponds to a second subjects condition;

comparing the second magnitude to the first magnitude.