Devices And Methods For Nerve Mapping

• US 20110270119A1
• Filed: 04/30/2010
• Published: 11/03/2011
• Est. Priority Date: 04/30/2010
• Status: Active Grant

• Current Assignee: J3G Spine LLC
• Original Assignee: J3G Spine LLC
• Inventors: Rasmussen, Jann
• Granted Patent: US 9,743,884 B2
• Time in Patent Office: Days
• US Class Current: 600/554
• CPC Class Codes: A61B 5/4029 for evaluating the peripheral nervous systems A61B5/24 takes precedence
• CPC Class Codes: A61B 5/4893 Nerves

Abstract

One embodiment includes a method for monitoring nerve tissue which includes inserting a dilator into muscle, the dilator including first and second electrodes at the distal tip. While the dilator is in muscle, a system may communicate (a) a first series of unequal current amplitude applications (e.g., a serious including 0.5, 7, 3, 5 mA applications) to the first electrode to produce at least a first evoked potential (e.g., a MAP or NAP), and (b) a second series of unequal current amplitude applications to the second electrode to produce at least a second evoked potential. The method further includes sensing the first and second evoked potentials and determining a relative location of a nerve based on the sensing of at least one of the first and second evoked potentials.

Claims

1. A method for monitoring nerve tissue during a lateral interbody fusion (LIF) comprising:

inserting a dilator into patient psoas muscle to perform a LIF, the dilator including a distal end portion including first and second electrodes;

while the dilator is in psoas muscle, communicating (a) a first series of unequal current amplitude applications to the first electrode to produce at least a first evoked potential, and (b) a second series of unequal current amplitude applications to the second electrode to produce at least a second evoked potential;

sensing the first and second evoked potentials; and

determining a relative location of a nerve based on the sensing of at least one of the first and second evoked potentials.

2. The method of claim 1 including determining the relative location of the nerve in relation to the dilator based on comparing (a) the lowest current amplitude level, communicated to the first electrode, needed to produce an evoked potential, with (b) the lowest current amplitude level, communicated to the second electrode, needed to produce an evoked potential.

3. The method of claim 1, wherein sensing the first and second evoked potentials includes sensing muscle action potentials (MAPs).

4. The method of claim 1, wherein sensing the first and second evoked potentials includes sensing first and second nerve action potentials (NAPs).

5. The method of claim 4 including administering a first amount of muscle relaxant to the patient such that the first and second evoked potentials cannot be sensed by sensing muscle action potentials (MAPs).

6. The method of claim 4, wherein the first NAP emanates from a nerve innervating muscle temporarily paralyzed due to the patient receiving a paralytic drug.

7. The method of claim 1, the dilator distal end portion including third and fourth electrodes, including:

simultaneously communicating current to the first, second, third, and fourth electrodes;

simultaneously communicating additional current to the first and second electrodes, to produce an additional evoked potential, while communicating no current to the third and fourth electrodes;

sensing the additional evoked potential; and

communicating the first series of unequal current amplitude applications to the first electrode based on sensing the additional evoked potential.

8. The method of claim 1, wherein communicating the first series of unequal current amplitude applications to the first electrode includes titrating current to the first electrode to determine a current amplitude needed to produce the first evoked potential.

9. The method of claim 1 including inserting the dilator into the patient psoas muscle, the dilator including the first and second electrodes on a distal-most edge of the dilator.

10. The method of claim 1 including determining the relative location of the nerve based on comparing (a) a first current amplitude level communicated to the first electrode to produce the first evoked potential, with (b) a second current amplitude level communicated to the second electrode to produce the second evoked potential.

11. An article comprising a non-transitory medium storing instructions that enable a processor-based system to:

while a dilator including a distal end portion having first and second electrodes is located in muscle, communicate (a) a first series of unequal current amplitude applications to the first electrode to produce at least a first evoked potential, and (b) a second series of unequal current amplitude applications to the second electrode to produce at least a second evoked potential;

sense the first and second evoked potentials; and

determine a relative location of a nerve based on the sensing of at least one of the first and second evoked potentials.

12. The article of claim 11 storing instructions that enable the system to determine the relative location of the nerve in relation to the dilator based on comparing (a) the lowest current amplitude level, communicated to the first electrode, needed to produce an evoked potential, with (b) the lowest current amplitude level, communicated to the second electrode, needed to produce an evoked potential.

13. The article of claim 11 storing instructions that enable the system to sense the first and second evoked potentials which respectively include first and second nerve action potentials (NAPs).

14. The article of claim 11 storing instructions that enable the system to:

simultaneously communicate current to the first and second electrodes and to third and fourth electrodes, the third and fourth electrodes included in a distal end portion of the dilator;

simultaneously communicate additional current to the first and second electrodes, to produce an additional evoked potential, while communicating no current to the third and fourth electrodes;

sense the additional evoked potential; and

communicate the first series of unequal current amplitude applications to the first electrode based on sensing the additional evoked potential.

15. The article of claim 11 storing instructions that enable the system to titrate current to the first electrode to determine a current amplitude needed to produce the first evoked potential.

16. The article of claim 11 storing instructions that enable the system to determine the relative location of the nerve based on comparing (a) a first current amplitude level communicated to the first electrode to produce the first evoked potential, with (b) a second current amplitude level communicated to the second electrode to produce the second evoked potential.

17. A method including:

inserting a dilator into patient muscle, the dilator including a distal end portion including first and second electrodes;

communicating current to a sub-dermal electrode implanted in the patient to produce a nerve action potential (NAP);

sensing the NAP by detecting a first potential on the first electrode and a second potential on the second electrode; and

determining a location of a nerve based on comparing amplitudes of the first and second potentials.

18. The method of claim 17 including inserting the dilator into psoas muscle, the dilator including the first and second electrodes on a distal-most edge of the dilator.

19. The method of claim 17 including administering a first amount of muscle relaxant to the patient such that the first and second evoked potentials cannot be sensed by sensing muscle action potentials (MAPS).

20. The method of claim 17, wherein the NAP emanates from a nerve innervating muscle temporarily paralyzed due to the patient receiving a paralytic drug.