TRANSCRANIAL MAGNET STIMULATION OF DEEP BRAIN TARGETS

• US 20090156884A1
• Filed: 11/26/2008
• Published: 06/18/2009
• Est. Priority Date: 11/27/2007
• Status: Active Grant

• Current Assignee: Brainsway, Ltd.
• Original Assignee: Cervel Neurotech, Inc.
• Inventors: Schneider, M. Bret, Mishelevich, David J.
• Granted Patent: US 8,267,850 B2
• Time in Patent Office: Days
• US Class Current: 600/14
• CPC Class Codes: A61N 2/006 for magnetic stimulation of nerve tissue
• CPC Class Codes: A61N 2/02 using magnetic fields produced by coils, including single turn loops or electromagnets A61N2/12 takes precedence

Abstract

The treatment of specific neurological and psychiatric illnesses using Transcranial Magnetic Stimulation (TMS) requires that specific neuroanatomical structures are targeted using specific pulse parameters. Described herein are methods of positioning and powering TMS electromagnets to selectively stimulate a deep brain target region while minimizing the impact on non-target regions between the TMS electromagnet and the target. Use of these configurations may involve a combination of physical, spatial and/or temporal summation. Specific approaches to achieving temporal summation are detailed.

Claims

1. A Transcranial Magnetic Stimulation (TMS) method for stimulating a brain region deep within a patient'"'"'s brain, the method comprising:

positioning a first TMS electromagnet outside of a patient'"'"'s head;

determining the distance between a target deep brain region and a sulcus, wherein the sulcus is within the range of a magnetic field emitted by the first TMS electromagnet;

determining stimulation parameters for the first TMS electromagnet based on the distance between the target brain region and the sulcus; and

applying energy to the first TMS electromagnet at the determined stimulation parameters.

2. The method of claim 1, wherein the step of positioning comprises aiming the TMS electromagnet at the sulcus, wherein the sulcus is adjacent to the target deep brain region.

3. The method of claim 1, wherein the step of positioning comprises aiming the TMS electromagnet at the target deep brain region.

4. The method of claim 1, wherein the step of determining the distance comprises determining the distance between the target deep brain region and a portion of the sulcus closest to the target deep brain region.

5. The method of claim 1, further comprising determining the direction of the pathway through the sulcus to the target deep brain region, and further wherein the step of determining the stimulation parameters comprises determining the stimulation parameters based on the direction of the pathway through the sulcus to the target deep brain region.

6. The method of claim 5, wherein the step of determining the direction of the pathway through the sulcus comprises determining an angle between the pathway through the sulcus and the target deep brain region.

7. The method of claim 5, further comprising aligning the TMS electromagnet based on the direction of the pathway through the sulcus and the angle between the pathway through the sulcus and the target deep brain region.

8. The method of claim 1, wherein the step of determining the stimulation parameters comprises determining the duration, rate and power for the first TMS electromagnet.

9. The method of claim 1, wherein the step of determining the stimulation parameters comprises estimating the power achieved at the target based on estimating the attenuation of the applied power using the distance from the target deep brain region and the sulcus.

10. The method of claim 1, further comprising positioning a second TMS electromagnet outside of the patient'"'"'s head.

11. The method of claim 10, further comprising determining stimulation parameters for the second TMS electromagnet based on the distance between the target brain region and a sulcus that is within the range of a magnetic field emitted by the second TMS electromagnet.

12. The method of claim 11, further comprising determining the direction of the pathway to the target deep brain region through the sulcus that is within the range of a magnetic field emitted by the second TMS electromagnet, and further wherein the step of determining the stimulation parameters for the second TMS electromagnet comprises determining the stimulation parameters based on the direction of the pathway to the target deep brain region through the sulcus that is within the range of a magnetic field emitted by the second TMS electromagnet.

13. The method of claim 12, wherein the step of determining the direction of the pathway to the target deep brain region through the sulcus that is within the range of a magnetic field emitted by the second TMS electromagnet comprises determining and angle between the pathway through the sulcus that is within range of the magnetic field emitted by the second TMS electromagnet and the target deep brain region.

14. The method of claim 12, further comprising aligning the second TMS electromagnet based on the direction of the pathway through the sulcus that is within the range of a magnetic field emitted by the second TMS electromagnet and the angle between the pathway through the target deep brain region and the sulcus that is within the range of a magnetic field emitted by the second TMS electromagnet.

15. The method of claim 10, wherein the step of determining the stimulation parameters comprises limiting the power for each TMS electromagnet to be below the motor threshold at the cortical surface.

16. A Transcranial Magnetic Stimulation (TMS) method for stimulating a brain region deep within a patient'"'"'s brain, the method comprising:

positioning a plurality of TMS electromagnets outside of a patient'"'"'s head;

determining stimulation parameters for each TMS electromagnet based on the distance between a target deep brain region and a sulcus that is in the range of a magnetic field emitted by each TMS electromagnet; and

applying energy to each of the plurality of TMS electromagnets at the determined stimulation parameters.

17. The method of claim 16, wherein the step of determining the stimulation parameters comprises limiting the power for each TMS electromagnet to be below the motor threshold at the cortical surface.

18. A Transcranial Magnetic Stimulation (TMS) method for stimulating the cingulate region of a patient'"'"'s brain while leaving the outer cortex relatively undisturbed, the method comprising:

aiming a plurality of independently powerable TMS electromagnets at the cingulate region tracts of the patient'"'"'s brain;

determining stimulation parameters for each TMS electromagnet so that the power of the field emitted by each TMS electromagnet at the cortical surface is below the motor threshold; and

triggering pulses from the TMS electromagnets at phase-complementary angles, wherein pulses from two or more TMS electromagnets are triggered within the membrane time constant of the target cingulate region.

19. The method of claim 18, wherein the step of aiming comprises aiming the plurality of independently powerable TMS electromagnets at tracts of the cingulate region.

20. The method of claim 18 wherein the step of aiming comprises aiming the plurality of independently powerable TMS electromagnets at tracts of the patient'"'"'s anterior cingulate.

21. The method of claim 18, wherein the step of aiming comprises orienting each of the TMS electromagnets to stimulate the tracts of the cingulate region horizontally.

22. The method of claim 18, wherein the step of aiming comprises orienting each of the TMS electromagnets to stimulate the tracts of the cingulate region transversely.

23. The method of claim 18, wherein the step of aiming comprises aiming a plurality of independently powerable V-shaped TMS electromagnets.

24. The method of claim 18, wherein the step of triggering pulses comprises simultaneously triggering pulses from the two or more TMS electromagnets.

25. The method of claim 18, wherein the step of triggering pulses comprises triggering pulses from two or more TMS electromagnets within about 300 μ

s.

26. A Transcranial Magnetic Stimulation (TMS) method for stimulating the insula region of a patient'"'"'s brain while leaving the outer cortex relatively undisturbed, the method comprising:

positioning a plurality of independently powerable TMS electromagnets outside of the patient'"'"'s head;

aiming the plurality of independently powerable TMS electromagnets at the insula region of the patient'"'"'s brain;

determining stimulation parameters for each TMS electromagnet so that the power of the field emitted by each TMS electromagnet at the cortical surface is below the motor threshold; and

triggering pulses from the TMS electromagnets at phase-complementary angles, wherein pulses from two or more TMS electromagnets are triggered within the membrane time constant of the target insula region.

27. The method of claim 26, further comprising shielding the plurality of independently powerable TMS electromagnets to prevent mutual inductance.

28. The method of claim 27, wherein the step of shielding comprises shielding with a high-permeability mu-metal.

29. The method of claim 26, wherein the step of aiming comprises aiming a plurality of independently powerable V-shaped TMS electromagnets.

30. The method of claim 26, wherein the step of triggering pulses comprises simultaneously triggering pulses from the two or more TMS electromagnets.

31. The method of claim 26, further comprising moving one or more of the TMS electromagnets and triggering additional pulses from the TMS electromagnets.