Magnetic nerve stimulator for exciting peripheral nerves

• US 5,725,471 A
• Filed: 11/28/1994
• Issued: 03/10/1998
• Est. Priority Date: 11/28/1994
• Status: Expired due to Term

• Current Assignee: Emory University, Magic Rack LLC
• Original Assignee: Neotonus, Inc. (Neuronetics, Inc.)
• Inventors: Epstein, Charles, Davey, Kent R.
• Primary Examiner(s): Lacyk, John P.
• Application Number:
  US08/345,572
• Time in Patent Office: 1,198 Days
• Field of Search: 600/9-15, 607/48-52
• US Class Current: 600/13
• 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

A magnetic nerve stimulator system is comprise of a core of highly saturable material with a coil winding. A thyrister capacitive discharge circuit pulses the device. A rapidly changing magnetic field is guided by the core, preferably vanadium permendur. For task specific excitation of various nerve groups, specially constructed cores allow for excitation of nerves at deeper levels with higher efficiency than is possible with air-core stimulators. Among the applications possible with this invention are treatment of incontinence, rehabilitation of large muscle groups in the leg and arm, and excitation of abdominal wall muscle groups to aid in weight loss and metabolic rate increase. A C-shape is employed for focussing the stimulation as desired.

Claims

1. A magnetic nerve stimulator comprising:

(a) an arc shaped core spanning an angle of less than three hundred sixty degrees (360°

), said arc shaped core comprising vanadium permendur;

(b) a stimulator coil, said coil at least partially wrapped around said core; and

(c) electric current means connected to said stimulator coil to create a current flow in said stimulator coil that causes said stimulator coil and said core to generate a magnetic field.

2. A magnetic nerve stimulator as claimed in claim 1, wherein said arc shaped core spans an angle of approximately 210 degrees thereby defining an opening of approximately 150 degrees, wherein said magnetic field is focussed beyond said opening.

3. A magnetic nerve stimulator as claimed in claim 1, wherein said core is approximately C shaped.

4. A magnetic nerve stimulator as claimed in claim 1, wherein the shape of said core focuses and/or concentrates the magnetic field produced by said coil and said core.

5. A magnetic nerve stimulator as claimed in claim 1 wherein said core is substantially tubular.

6. A magnetic nerve stimulator as claimed in claim 5, wherein said core comprises at least one recess for holding said coil.

7. A magnetic nerve stimulator as claimed in claim 1 wherein said electric current means comprises:

(a) a power supply;

(b) a transformer connected to said power supply;

(c) a full wave rectifier bridge connected to said transformer;

(d) a diode connected to said full wave rectifier bridge;

(e) capacitor means connected to said diode;

(f) a thyristor connected to said capacitor means, said thyristor connected to said stimulator coil; and

(g) a second diode connected to said capacitor means, said second diode also being connected to said stimulator coil.

8. A magnetic nerve stimulator as claimed in claim 7, wherein said capacitor means comprises a single capacitor.

9. A magnetic nerve stimulator as claimed in claim 1, wherein the decay time of said coil is about one hundred (100) microseconds.

10. A magnetic nerve stimulator as claimed in claim 1, wherein said coil generates a magnetic field at least about fifteen (15) times per second.

11. A magnetic nerve stimulator as claimed in claim 1, wherein said core defines an arc of approximately two hundred ten (210) degrees.

12. A magnetic nerve stimulator as claimed in claim 1, wherein said core comprises a ribbon of said saturable material coated with a thin insulative coating.

13. A magnetic nerve stimulator as claimed in claim 12, wherein said ribbon is further provided with an epoxy coating.

14. A magnetic nerve stimulator as claimed in claim 3, wherein the ends of said core are smoothly ground.

15. A magnetic nerve stimulator as claimed in claim 1, further comprising at least two approximately C shaped cores, said two C-shaped cores being held closely together to form a common leg, and wherein said coil is wrapped around a portion of said common leg.

16. A magnetic nerve stimulator as claimed in claim 1, wherein two of said cores are provided, said cores being C-shaped, and wherein said magnetic nerve stimulator further comprises a seat for a user to sit upon, said cores being located underneath said seat yet the magnetic field produced by said magnetic nerve stimulator being above said seat.

17. A magnetic nerve stimulator as claimed in claim 16, wherein said cores produce a magnetic field during operation of said stimulator, said magnetic field being focused in the direction of a user'"'"'s bladder muscles when the user sits on said seat.

18. A magnetic nerve stimulator as claimed in claim 1, where said stimulator comprises at least a section which wraps around a portion of a patient'"'"'s abdomen.

19. A method for magnetically stimulating the nerves of an organism comprising the steps of:

(a) charging a capacitor with an electric charge;

(b) discharging said capacitor through a stimulator coil, said stimulator coil at least partially surrounding a core comprising vanadium permendur; and

(c) stimulating the nerves of said organism using the magnetic field generated by said stimulator coil and said core.

20. A method as in claim 19, wherein said highly saturable material comprises vanadium permendur.

21. A method as in claim 19, wherein said nerves are part of the peripheral nervous system of said organism.

22. A method as in claim 19, further comprising the step of stimulating said nerves for the treatment of incontinence.

23. A method as in claim 19, further comprising the step of stimulating said nerves for the purpose of weight control.

24. A method as in claim 19, further comprising the step of stimulating said nerves for the purpose of muscle rehabilitation.

25. A method as in claim 19, further comprising the step of stimulating said nerves in cycles, said cycles comprising periods of stimulation of said nerves and periods of rest of said nerves.

26. A method as in claim 19, further comprising the step of focusing and/or concentrating said magnetic field into a desired region.

27. A magnetic nerve stimulator comprising:

(a) a core of highly saturable material;

(b) a stimulator coil, said coil having its longitudinal axis located within the geometric outer boundaries defined by said core; and

(c) electric current means connected to said stimulator coil to create a current flow in said stimulator coil that causes said stimulator coil and said core to generate a magnetic field, said electric current means comprising;

(i) a power supply;

(ii) a transformer connected to said power supply;

(iii) a full wave rectifier bridge connected to said transformer;

(iv) a diode connected to said full wave rectifier bridge;

(v) capacitor means connected to said diode;

(vi) a thyristor connected to said capacitor means, said thyristor connected to said stimulator coil; and

(vii) a second diode connected to said capacitor means, said second diode also being connected to said stimulator coil.

28. A magnetic nerve stimulator as claimed in claim 27, wherein said highly saturable material is a material capable of maintaining a magnetic field of approximately two (2) Tesla within said core.

29. A magnetic nerve stimulator as claimed in claim 27, wherein said core comprised vanadium permendur.

30. A magnetic nerve stimulator as claimed in claim 27, wherein said core defines an arc of approximately two hundred ten (210) degrees.

31. A magnetic nerve stimulator as claimed in claim 30, wherein said highly saturable material comprises vanadium permendur.

32. A magnetic nerve stimulator comprising:

(a) an arc shaped core spanning an angle of approximately two hundred ten (210) degrees and having an opening of approximately one hundred fifty (150) degrees, said core comprising a highly saturable material;

(b) a stimulator coil wrapped around at least a portion of said core; and

,

(c) electric current means connected to said stimulator coil to create a current flow in said stimulator coil that causes said stimulator coil and said core to generate a magnetic field, said magnetic field being focussed beyond said opening.

33. A magnetic nerve stimulator as claimed in claim 32, wherein said highly saturable material is a material capable of maintaining a magnetic field of approximately two (2) Tesla within said core.

34. A magnetic nerve stimulator as claimed in claim 32, wherein said highly saturable material comprises vanadium permendur.

35. A magnetic nerve stimulator comprising:

(a) a seat for a user;

(b) two C-shaped cores in proximity to one another to form a common leg portion, said cores comprising highly saturable material and located beneath said seat;

(c) a stimulator coil wrapped around at least a portion of said cores, including said common leg portion; and

,

(d) electric current means connected to said stimulator coil to create a current flow in said stimulator coil that causes said stimulator coil and said cores to generate a magnetic field.

36. A magnetic nerve stimulator as claimed in claim 35, wherein said highly saturable material is a material capable of maintaining a magnetic field of approximately two (2) Tesla within said core.

37. An apparatus as claimed in claim 35, wherein said electric current means comprises:

(i) a power supply;

(ii) a transformer connected to said power supply;

(iii) a full wave rectifier bridge connected to said transformer;

(iv) a diode connected to said full wave rectifier bridge;

(v) capacitor means connected to said diode;

(vi) a thyristor connected to said capacitor means, said thyristor connected to said stimulator coil; and

(vii) a second diode connected to said capacitor means, said second diode also being connected to said stimulator coil.

38. An apparatus as claimed in claim 37, wherein each of said C-shaped cores comprise vanadium permendur and comprise an angle of approximately 220 degrees.

39. An apparatus as claimed in claim 35, wherein each of said C-shaped cores comprise an angle of approximately 220 degrees.

40. An apparatus as claimed in claim 39, wherein said cores comprise vanadium permendur.

41. A method for treating incontinence in an organism by magnetically stimulating the nerves of the organism, comprising the steps of:

(a) providing a magnetic nerve stimulator, said stimulator comprising at least one core of highly saturable material, and a stimulator coil at least partially surrounding said core;

(b) passing an electric current through said coil to generate a magnetic field; and

,

(c) treating incontinence in said organism by stimulating the nerves of said organism using said magnetic field.

42. A magnetic nerve stimulator as claimed in claim 41, wherein said highly saturable material is a material capable of maintaining a magnetic field of approximately two (2) Tesla within said core.

43. A method as claimed in claim 41, wherein said core comprises an angle of approximately two hundred and ten (210) degrees, with an opening of approximately one hundred and fifty (150) degrees.

44. A method as claimed in claim 43, wherein said highly saturable material comprises vanadium permendur.