NEUROPHYSIOLOGICAL APPARATUS AND PROCEDURES

• US 20090138050A1
• Filed: 01/23/2009
• Published: 05/28/2009
• Est. Priority Date: 05/08/2003
• Status: Active Grant

• Current Assignee: Nuvasive Incorporated
• Original Assignee: Nuvasive Incorporated
• Inventors: Ferree, Bret A.
• Granted Patent: US 9,131,947 B2
• Time in Patent Office: Days
• US Class Current: 606/279
• CPC Class Codes: A61B 17/1626 Control means; Display units
• CPC Class Codes: A61B 17/1671 for the spine
• CPC Class Codes: A61B 17/7092 for checking pedicle hole has correct depth or has an intact wall pedicle drill depth limiters A61B17/1626
• CPC Class Codes: A61B 2017/00039 Electric or electromagnetic phenomena other than conductivity, e.g. capacity, inductivity, Hall effect
• CPC Class Codes: A61B 5/388 Nerve conduction study, e.g. detecting action potential of peripheral nerves
• CPC Class Codes: A61B 5/395 Details of stimulation, e.g. nerve stimulation to elicit EMG response
• CPC Class Codes: A61B 5/4566 Evaluating the spine A61B5/4561 takes precedence
• CPC Class Codes: A61B 5/4893 Nerves

Abstract

Neurophysiological instruments and techniques are improved through various enhancements. Stimulation of an instrument is possible while it is advancing into the spine or elsewhere, alerting the surgeon to the first sign the instrument or device (screw) may be too near a nerve. A directional probe helps surgeons determine the location of the hole in the pedicle. Electrically insulating sleeves prevent shunting into the soft tissues. According to a different improvement, the same probe to be used to stimulate different devices, such as screws and wires. Electrical impulses may be recorded from non-muscle regions of the body, including the spine and other portions of the central nervous system as opposed to just the extremities.

Claims

1. A method for determining the direction of a pedicle breach during hole formation, comprising the steps of:

forming an access corridor to a pedicle in a patient;

forming a hole in the pedicle by advancing an instrument into the pedicle;

rotating said instrument about a longitudinal axis during hole formation while applying a stimulation signal to said instrument; and

determining the direction of said breach by monitoring neuromuscular responses to successive stimulation signals during the rotation of said instrument.

2. The method of claim 1, wherein said instrument is configured to transmit an electric stimulation signal to said pedicle from a neurophysiology monitoring system communicatively linked to said instrument.

3. The method of claim 2, wherein said neurophysiology monitoring system detects the presence of said breach by determining a stimulation threshold at which muscles innervated by a nerve adjacent to said pedicle respond to said stimulation signals.

4. The method of claim 3, wherein said instrument comprises a probe member, said probe member including an electrode region formed along at least one side of a distal end of said probe member for emitting said stimulation signal, and comprising the additional step of:

determining the position of said electrode region about said longitudinal axis when said stimulation threshold is lowest to indicate the direction of said breach.

5. The method of claim 4, wherein said probe member is insulated to prevent shunting of said stimulation signal along the length of said probe member.

6. The method of claim 5, wherein said probe member includes a first uninsulated portion forming said electrode region.

7. A method for determining directionality during surgery, comprising the steps of:

forming an access corridor to a pedicle target site in a patient;

advancing an instrument into said pedicle; and

rotating said instrument about a longitudinal axis to determine the direction of a breach detected in said pedicle at least one of during and after hole formation.

8. The method of claim 7, wherein said instrument is configured to transmit an electric stimulation signal to a nerve adjacent said pedicle from a neurophysiology monitoring system communicatively linked to said instrument.

9. The method of claim 8, wherein said neurophysiology monitoring system detects said breach by determining a threshold stimulation level at which muscles innervated by said nerve respond to said stimulation signal.

10. The method of claim 9, wherein said instrument comprises a probe member, said probe member including an electrode region formed along one side of a distal end of said probe member for emitting said stimulation signal, and comprising the additional step of:

determining the position of said electrode region about said longitudinal axis when said stimulation threshold is lowest to indicate the direction of said breach.

11. The method of claim 10, wherein said probe member is insulated to prevent shunting of said stimulation signal along the length of said probe member.

12. The method of claim 11, wherein said probe member is insulated and said electrode region is by a non-insulated portion.

13. An instrument for determining directionality during surgery, comprising:

a probe member having a circumferentially insulated distal end configured for advancement into a pedicle and an electrode region situated about only a portion of said circumference, said electrode configured to transmit an electric stimulation signal to a pedicle from a neurophysiology monitoring system communicatively linked to said instrument.

14. The instrument of claim 13, wherein said neurophysiology monitoring system determines the location of a pedicle breach by determining a threshold stimulation level at which muscles innervated by a nerve proximate said pedicle respond to said stimulation signal.

15. The instrument of claim 14, wherein said instrument indicates the location of said pedicle breach by determining the position of said electrode region about a longitudinal axis of said probe member when said stimulation threshold is lowest.

16. The instrument of claim 13, wherein a non-insulated area forms said electrode region.

17. The instrument of claim 13, wherein said probe member is insulated to prevent shunting of said stimulation signal along the length of said probe member.

18. The instrument of claim 13, wherein said probe member is electrically linked to said neurophysiology monitoring system via a connector attached to said probe member.

19. The instrument of claim 18, wherein said connector is a clip around at least a portion of said probe member.