Seizure therapy method and apparatus

• US 20050261542A1
• Filed: 05/24/2004
• Published: 11/24/2005
• Est. Priority Date: 05/24/2004
• Status: Active Grant

• Current Assignee: Neuronetics, Inc.
• Original Assignee: Neuronetics, Inc.
• Inventors: Riehl, Mark Edward
• Granted Patent: US 7,601,115 B2
• Time in Patent Office: Days
• US Class Current: 600/14
• CPC Class Codes: A61N 2/006 for magnetic stimulation of nerve tissue

Abstract

The invention provides a method for treating a patient for mental illnesses, such as depression, by applying a magnetic field to the patient, producing a seizure in the patient as a function of a strength of the magnetic field, and preventing further stimulation from the magnetic field when the seizure is in progress. Such Magnetic Seizure Therapy (MST) does not include many of the known side effects of electroconvulsive therapy (ECT).

Claims

1. A system for performing magnetic seizure therapy on a patient in need thereof, comprising:

a magnetic coil;

a power switch for applying a pulse of electrical current to the magnetic coil such that the induced current density in the magnetic coil is sufficient to cause a seizure in the patient;

a monitoring device for monitoring the patient; and

a control device for preventing further stimulation when a seizure is in progress.

2. The system of claim 1, wherein the monitoring device includes at least one of an EEG monitor, an ECG monitor, a blood pressure monitor, and a heart rate monitor.

3. The system of claim 1, wherein the control device prevents further stimulation by interrupting the flow of current to the magnetic coil.

4. The system of claim 1, wherein the control device prevents further stimulation by shielding the patient from the magnetic field.

5. The system of claim 1, wherein the control device prevents further stimulation by moving the coil a sufficient distance away from the patient to prevent stimulation.

6. The system of claim 1, wherein the pulse is part of a burst applied over a range of about 2 to about 8 seconds.

7. The system of claim 6, wherein the burst is applied with a pulse repetition rate of about 40 to about 60 Hertz.

8. The system of claim 6, wherein the burst is applied with a pulse repetition rate of over 100 Hertz.

9. The system of claim 6, further comprising a second burst separated from the burst by a waiting period of less than one minute.

10. The system of claim 1, further comprising a device for recording parameters of the therapy.

11. The system of claim 1, wherein the control device provides a signal for indicating the occurrence of a seizure.

12. The system of claim 1, wherein the magnetic coil is an approximately hemispherical magnetic core having a magnetic saturation of at least 0.5 Tesla.

13. The system of claim 1, further comprising a feedback circuit that adjusts a magnetic field created by the magnetic coil.

14. The system of claim 13, wherein the feedback circuit adjusts a pulse repetition rate.

15. The system of claim 13, wherein the feedback circuit adjusts a burst length.

16. The system of claim 13, wherein the feedback circuit adjusts a flux density.

17. The system of claim 1, further comprising a computer processing device for analyzing a signal provided by the monitoring device.

18. The system of claim 17, wherein the processing device compares a measured cortical excitability of a patient with a cortical excitability reflective of a seizure. The system of claim 18, wherein the measured cortical excitability of a patient is a function of EEG signals.

19. The system of claim 18, wherein the cortical excitability reflective of a seizure is a predetermined EEG signal.

20. The system of claim 17, wherein the processing device provides a signal to a feedback circuit that adjusts a magnetic field created by the magnetic coil.

21. The system of claim 17, wherein the processing device provides a signal to a display device to allow a magnetic field created by the magnetic coil to be manually adjusted.

22. A method for treating a patient, comprising:

applying a magnetic field to the patient;

producing a seizure in the patient as a function of a strength of the magnetic field; and

preventing further stimulation from the magnetic field when the seizure is in progress.

23. The method of claim 22, further comprising determining if the patient is in a resting state, a pre-seizure state, in seizure, or a post-seizure state.

24. The method of claim 22, further comprising anesthetizing the patient.

25. The method of claim 22, further comprising monitoring the patient.

26. The method of claim 25, wherein monitoring includes at least one of EEG monitoring, ECG monitoring, blood pressure monitoring, and heart rate monitoring.

27. The method of claim 25, further comprising analyzing a signal provided by the monitoring.

28. The method of claim 27, wherein the analyzing comprises comparing a measured cortical excitability of a patient with a cortical excitability reflective of a seizure.

29. The method of claim 28, wherein the measured cortical excitability of a patient is a function of EEG signals.

30. The method of claim 28, wherein the cortical excitability reflective of a seizure is a predetermined EEG signal.

31. The method of claim 27, further comprising adjusting a magnetic field created by the magnetic coil as a function of the analyzing.

32. The method of claim 27, further comprising displaying an indication of the analyzing to allow a magnetic field created by the magnetic coil to be adjusted.

33. The method of claim 22, further comprising recording parameters of the therapy.

34. The method of claim 33, wherein the parameters include at least one of settings to induce seizure, seizure duration, heart rate, blood pressure, ECG data and EEG data.

35. The method of claim 22, further comprising adjusting a pulse of electrical current to a magnetic coil.

36. The method of claim 35, wherein the induced current density as a result of the pulse creates a magnetic field sufficient to cause a seizure in the patient.

37. The method of claim 35, wherein the pulse is part of a burst.

38. The method of claim 37, wherein the burst is applied over a range of about 2 to about 8 seconds.

39. The method of claim 37, wherein the burst is applied with a pulse repetition rate of about 40 to about 60 Hertz.

40. The method of claim 37, wherein the burst is applied with a pulse repetition rate of over 100 Hertz.

41. The method of claim 37, wherein the burst is applied with a pulse repetition rate of 60 to 100 Hertz.

42. The method of claim 37, wherein a second burst is applied after a waiting period.

43. The method of claim 42, wherein the waiting period is less than one minute.

44. The method of claim 22, wherein current densities of 20-45 milli-amperes/cm² are induced.

45. The method of claim 42, further comprising setting the waiting period to a fixed interval of one minute to guarantee that conditions are appropriate before triggering a next pulse burst.

46. The method of claim 42, further comprising setting the waiting period to a fixed interval of 15-20 seconds to guarantee that conditions are appropriate before triggering a next pulse burst.

47. The method of claim 36, further comprising determining cortical excitability levels prior to the burst.

48. The method of claim 42, further comprising determining cortical excitability levels between bursts.

49. The method of claim 48, further comprising adjusting the power level for the next burst.

50. The method of claim 48, further comprising automatically controlling the power level for successive bursts.

51. The method of claim 22, wherein the magnetic field is adjusted as a function of a pulse repetition rate.

52. The method of claim 22, wherein the magnetic field is adjusted as a function of burst length.

53. The method of claim 22, wherein the magnetic field is adjusted as a function of a flux density.

54. A method for treating a patient, comprising:

applying a magnetic field to the patient;

adjusting the magnetic field until sufficient to produce a seizure in the patient; and

preventing further stimulation from the field when a seizure is in progress.

55. The method of claim 54, further comprising determining at least one of the following:

if the patient is in a resting state, a pre-seizure state, in seizure, and a post-seizure state.

56. The method of claim 54, further comprising monitoring the patient.

57. The method of claim 56, further comprising analyzing a signal provided by the monitoring.

58. The method of claim 57, wherein the analyzing comprises comparing a measured cortical excitability of a patient with a cortical excitability reflective of a seizure.

59. The method of claim 58, wherein the measured cortical excitability of a patient is a function of EEG signals.

60. The method of claim 58, wherein the cortical excitability reflective of a seizure is a predetermined EEG signal.

61. The method of claim 57, further comprising adjusting a magnetic field created by the magnetic coil as a function of the analyzing.

62. The method of claim 57, further comprising displaying an indication of the analyzing to allow a magnetic field created by the magnetic coil to be adjusted.

63. The method of claim 56, wherein monitoring includes at least one of EEG monitoring, ECG monitoring, blood pressure monitoring, and heart rate monitoring.

64. The method of claim 54, further comprising recording parameters of the therapy.

65. The method of claim 64, wherein the parameters include at least one of:

settings to induce seizure, seizure duration, heart rate, blood pressure, ECG data and EEG data.

66. The method of claim 54, further comprising adjusting a pulse of electrical current to a magnetic coil.

67. The method of claim 66, wherein the pulse is part of a burst.

68. The method of claim 67, wherein the burst is applied over a range of about 2 to about 8 seconds.

69. The method of claim 67, wherein the burst is applied with a pulse repetition rate of about 40 to about 60 Hertz.

70. The method of claim 67, wherein the burst is applied with a pulse repetition rate of over 100 Hertz.

71. The method of claim 67, further comprising a second burst separate from the burst by a waiting period.

72. The method of claim 71, wherein the waiting period is less than one minute.

73. The method of claim 71, further comprising setting the waiting period to a fixed interval.

74. The method of claim 67, further comprising determining cortical excitability levels prior to the burst.

75. The method of claim 67, further comprising determining cortical excitability levels between bursts.

76. The method of claim 75, further comprising adjusting the power level for the next burst.

77. The method of claim 71, further comprising automatically controlling the ramp up of power level for successive bursts.

78. The method of claim 55, further comprising recording parameters that induce a seizure in the patient.

79. The method of claim 55, further comprising providing a silicon controlled rectifier, insulated gate bi-polar transistor, and an insulated gate commutated thyristor for applying voltage.

80. The method of claim 66, wherein the induced current density as a result of the pulse creates a magnetic field sufficient to cause a seizure in the patient.

81. The method of claim 67, wherein the burst is applied with a pulse repetition rate of 60 to 100 Hertz.

82. The method of claim 54, wherein the magnetic field is adjusted as a function of a pulse repetition rate.

83. The method of claim 54, wherein the magnetic field is adjusted as a function of burst length.

84. The method of claim 54, wherein the magnetic field is adjusted as a function of a flux density.

85. A method for producing a seizure in a patient, comprising applying to the patient a magnetic field of strength sufficient to produce a seizure using an approximately hemispherical magnetic core having a magnetic saturation of at least 0.5 Tesla.