VOLTAGE LIMITED NEUROSTIMULATION

• US 20130184779A1
• Filed: 01/13/2012
• Published: 07/18/2013
• Est. Priority Date: 01/13/2012
• Status: Active Grant

• Current Assignee: City College of New York
• Original Assignee: City College of New York
• Inventors: Bikson, Marom, Minhas, Preet, Hahn, Christoph, Macuff, Shiraz A., Rahman, Asif, Rice, Justin Keith
• Granted Patent: US 8,818,515 B2
• Time in Patent Office: Days
• US Class Current: 607/45
• CPC Class Codes: A61N 1/0456 Specially adapted for transcutaneous electrical nerve stimulation [TENS]
• CPC Class Codes: A61N 1/0526 Head electrodes A61N1/0551 takes precedence
• CPC Class Codes: A61N 1/36025 for treating a mental or cerebral condition
• CPC Class Codes: A61N 1/36034 specified by the stimulation parameters

Abstract

Methods and systems for delivering voltage limited neurostimulation to a patient. In one aspect, a method includes initiating a flow of electrical current through a first electrode and a second electrode coupled to the patient and increasing the flow of electrical current toward a target value by increasing a voltage across the first electrode and second electrode. Prior to reaching the target value of electrical current, the method includes preventing the voltage across the first electrode and second electrode from increasing beyond a first predetermined limit; and subsequently, maintaining the voltage across the first electrode and second electrode at or within a predetermined range that does not exceed the first predetermined limit. The amplitude of the electrical current continues to increase toward the target value during at least part of a time when the voltage across the first electrode and the second electrode is maintained within the predetermined range.

Claims

1. A method of delivering neurostimulation to a patient, the method comprising:

initiating a flow of electrical current through a first electrode and a second electrode coupled to the patient;

increasing the flow of electrical current toward a target value by increasing a voltage across the first electrode and second electrode; and

prior to reaching the target value of electrical current;

preventing the voltage across the first electrode and second electrode from increasing beyond a first predetermined limit; and

subsequently, maintaining the voltage across the first electrode and second electrode at or within a predetermined range that does not exceed the first predetermined limit,

wherein the amplitude of the electrical current continues to increase toward the target value during at least part of a time when the voltage across the first electrode and the second electrode is maintained within the predetermined range.

2. The method of claim 1 further comprising:

adjusting the voltage across the first electrode and the second electrode after the target current has been reached to substantially maintain the electrical current at the target value.

3. The method of claim 2 wherein adjusting the voltage across the first electrode and the second electrode comprises reducing the voltage across the first and second electrode as a resistance of from the first electrode to the second electrode reduces.

4. The method of claim 2 further comprising:

substantially maintaining the electrical current at the target value for a period of time sufficient to produce a therapeutic effect in the patient.

5. The method of claim 4 wherein the target value of current is between about 1 milliamp and about 3 milliamps, and

wherein the period of time that the electrical current is substantially maintained at the target value is between about 10 minutes and 30 minutes.

6. The method of claim 4 further comprising:

delivering between about 600 millicoulombs and about 2400 millicoulombs of electric charge to the patient during the period of time that the electrical current is substantially maintained at the target value.

7. The method of claim 1 further comprising:

monitoring the flow of current, and

in response a determination that the monitored flow of current has not reached the target value within a predetermined amount of time, extending a period of time that the flow of current is to be delivered to the patient.

8. The method of claim 1 further comprising:

monitoring the flow of current, and

taking a responsive action to a determination that the monitored flow of current has not reached the target value within a predetermined amount of time,

wherein the responsive action is selected from the group consisting of alerting a human operator and extinguishing the flow of electrical current.

9. The method of claim 1 wherein a ramp-up period exists between a time that the flow of electrical current is initiated and a time that the voltage across the first electrode and the second electrode is prevented from increasing beyond the first predetermined limit,

wherein the ramp-up period is between about 1 second and about 30 seconds.

10. The method of claim 9 wherein the ramp-up period is about 10 seconds.

11. The method of claim 9 wherein the flow of electrical current increases during the ramp-up period at an average rate of no more than about 1.5 milliamps per 30 seconds.

12. The method of claim 1 wherein the neurostimulation is transcranial direct current stimulation.

13. The method of claim 1 further comprising:

monitoring the voltage across the first electrode and the second electrode; and

disconnecting the voltage across the first electrode and the second electrode if the voltage across the first electrode and the second electrode exceeds a second predetermined limit indicating a circuitry malfunction,

wherein the predetermined second value is above the predetermined first value.

14. The method of claim 1 wherein the predetermined range is within about 10% of the first predetermined limit.

15. The method of claim 1 wherein increasing the flow of electrical current toward a target value comprises increasing the flow of electrical current monotonically.

16. The method of claim 1 wherein the voltage across the first and second electrodes is an alternating current.

17. The method of claim 1 further comprising:

applying a test stimulation to the patient;

monitoring a test voltage and a test current associated with the test stimulation;

generating a circuit model based on the monitored test voltage and test current;

using the circuit model to set one or more parameters associated with the electrical current and voltage in the delivery of neurostimulation to the patient.

18. The method of claim 17 further comprising adjusting one or more stimulation parameters associated with the delivery of neurostimulation to the patient in real-time.

19. The method of claim 1 further comprising:

increasing the voltage to a voltage level in a manner that accelerates a decrease in resistance across the electrodes.

20. A system for delivering neurostimulation to a patient, the system comprising:

a source of electrical current with a pair of output terminals, wherein the source of electrical current is operable to;

initiate a flow of electrical current through the pair of output terminals;

increase the electrical current toward the target value by increasing a voltage across the pair of output terminals; and

prior to reaching the target value of electrical current;

prevent the voltage across the pair of output terminals from increasing beyond a first predetermined limit; and

subsequently, maintain the voltage across the pair of output terminals at or within a predetermined range below the predetermined limit,

wherein the amplitude of the electrical current continues to increase toward the target value for at least part of a time when the voltage across the pair of output terminals is maintained within the predetermined range.

21. The system of claim 20 further comprising:

a target current setting device configured for manipulation by a human operator to set a target value for current to be delivered by the source of electrical current;

22. The system of claim 20 further comprising:

a pair of electrically conductive cables coupled to the pair of output terminals, respectively, each cable having an electrode at a distal end thereof for coupling to the patient.

23. The system of claim 20 further comprising:

a stimulation duration setting device configured for manipulation by the human operator to set a duration that the source of electrical current will deliver the target current,

wherein the source of electrical current is further configured to adjust the voltage across the pair of output terminals after the target current has been reached to maintain the electrical current substantially at the target value for the set duration.

24. The system of claim 23 wherein adjusting the voltage across the pair of output terminals further comprises reducing the voltage across the pair of output terminals to maintain the electrical current substantially at the target value for the set duration as a resistance from a first one of the output terminals to a second one of the output terminals becomes smaller.

25. The system of claim 23 further comprising a timing indicator configured for indicating to the human operator, while the target value of current is being maintained, an amount of time remaining that the target value of current will continue to be maintained based on the set duration.

26. The system of claim 23 wherein the stimulation duration setting device facilitates setting a duration that, if the target value of electrical current is delivered to the patient for a period of time that corresponds to the set duration, a therapeutic effect in the patient will be produced.

27. The system of claim 23 wherein the source of current is configured to deliver a target value of current between about 1 milliamp and about 3 milliamps, and wherein the stimulation duration setting device is configured to enable the human operator to set the duration to a value between about 10 minutes and 30 minutes.

28. The system of claim 23 wherein the target current setting device and the stimulation duration setting device are configured to enable the human operator to set the source of current to deliver between about 600 millicoulombs and about 2400 millicoulombs of electric charge to the patient during the period of time that the electrical current is substantially maintained at the target value.

29. The system of claim 20 further comprising a voltage limit setting device configured for manipulation by the human operator to set the first predetermined limit.

30. The system of claim 20 further comprising an indication device for indicating to the human operator that the voltage across the pair of output terminals has reached and is being maintained at the first predetermined limit.

31. The system of claim 20 wherein the source of current is configured to ramp-up an amplitude of the electrical current between initiating electrical current flow and when the voltage across the output terminals is prevented from increasing beyond the first predetermined limit, wherein the ramp-up occurs over a period of time between about 1 second and about 30 seconds.

32. The system of claim 31 wherein the flow of electrical current increases during ramp-up at an average rate of no more than about 1.5 milliamps per 30 seconds.

33. The system of claim 20 wherein the neurostimulation is transcranial direct current stimulation.

34. The system of claim 20 further comprising a safety shut-down circuit, wherein the safety shut-down circuit is configured to:

monitor the voltage across the output terminals; and

disconnect the voltage across the output terminals if the voltage across the output terminals exceeds a second predetermined limit indicating a circuitry malfunction,

wherein the predetermined second value is above the predetermined first value.

35. The system of claim 20 wherein the voltage across the first and second electrodes is an alternating current.