Nerve fiber stimulation using plural equally active electrodes

• US 4,803,988 A
• Filed: 02/02/1987
• Issued: 02/14/1989
• Est. Priority Date: 11/02/1984
• Status: Expired due to Term

• Current Assignee: Encore Medical Asset Corporation (Enovis Corp.)
• Original Assignee: Staodynamics, Inc.
• Inventors: Thomson, Thomas H.
• Primary Examiner(s): Smith, Ruth S.
• Application Number:
  US07/009,927
• Time in Patent Office: 743 Days
• Field of Search: 128/419 PG, 128/421-423
• US Class Current: 607/70
• CPC Class Codes: A61N 1/36021 for treatment of pain

Abstract

Nerve fiber stimulation is disclosed to substantially increase the activity of the then selected nerve fibers, with optimization being achieved through utilization of electrical pulses that are caused to occur in a predetermined pattern with respect to polarity, spacing, frequency and duration so as to interact with the electroneurophysiological characteristics of the particular nerve fibers then to be electrically stimulated. Bi-phased pulse pairs are repeatedly generated and applied to the nerve fibers to be stimulated through plural active electrodes with the first pulse of each applied pulse pair being a positive polarity pulse causing the nerve to be set into the refractory period, while the second pulse of each applied pulse pair is a negative polarity pulse that is made to occur substantially at the end of the refractory period for the particular nerve fibers then being stimulated to thereby excite those nerve fibers, and the pulse pairs are repeated at a rate based upon the timewise occurrence of the enhanced excitability condition of the nerve fibers then being stimulated. By stimulation of each of a plurality of electrodes using positive/negative pulse pairs, all electrodes can be made substantially equally active. Since additional pulses occurring during the period closely following occurrence of a pulse pair do not normally adversely affect performance, additional pulses can be added to form additional pulse pairs such that a plurality of electrodes can be made substantially equally active to thereby enhance overall achievement of optimum stimulation.

Claims

1. A device for providing optimized electrical stimulation through plural active electrodes to preselected nerve fibers having known refractory periods and enhanced excitability conditions that occur during known periods following the occurrence of an action potential, said device comprising:

generating means for generating a series of output pulse groups with each said group including at least first and second pulses of positive and negative polarity, respectively, and with said first pulse occurring timewise before said second pulse, said first and second pulses of each said pulse group being spaced from one another a distance, in time, substantially equal to that of the known refractory period of said preselected nerve fibers to be stimulated, each said pulse group of said series of pulse groups occurring so as to be timewise spaced from each adjacent pulse group a distance not substantially greater than the timewise occurrence of said enhanced excitability condition of said preselected nerve fibers to be stimulated and having a pulse of negative polarity that occurs timewise prior to the first pulse of the immediately succeeding pulse group with a timewise spacing therebetween substantially equal to that of the known refractory period of said preselected nerve fibers to be stimulated;

first and second electrodes; and

coupling means connected with said generating means and said first and second electrodes to apply said series of output pulse groups to said preselected nerve fibers through said first electrode and to apply said series of output pulse groups in inverted polarity to said preselected nerve fibers through said second electrode, whereby an applied pulse of positive polarity of each said pulse group sets said preselected nerve fibers, and so that a later occurring applied pulse of negative polarity of said pulse groups occurs substantially at the end of said refractory period to excite said preselected nerve fibers, with said first and second electrodes thereby both being made active to optimize stimulation of said preselected nerve fibers and thereby substantially increase the activity thereof.

2. The device of claim 1 wherein said generating means generates a second negative pulse, which second negative pulse occurs timewise after said first named negative pulse in each said output pulse group.

3. The device of claim 2 wherein said second negative pulse is spaced from said first negative pulse a distance such that said second negative pulse is spaced from the positive pulse in the immediately next occurring pulse group a distance substantially equal to that of the known refractory period of said preselected nerve fibers to be stimulated.

4. The device of claim 1 wherein said preselected nerve fibers have a maximum hyperexcitability condition, and wherein said generating means includes means to provide said pulses of said series of pulse groups such that each corresponding pulse of each said output pulse group occurs with a timewise spacing therebetween substantially equal to that of the known time between said action potential and said maximum hyperexcitability condition of said preselected nerve fibers to be stimulated.

5. The device of claim 1 wherein said generating means includes means providing for stimulation of at least one class of sensory, motor, pain control and autonomic nerve fibers, and wherein first and second electrodes are made substantially equally active to stimulate the nerve fibers then selected for stimulation.

6. The device of claim 1 wherein said generating means includes means providing for stimulation of sensory neurons by causing a pulse spacing to occur between preselected pulses between about 550 and 650 microseconds, and wherein said coupling means causes application of a negative pulse to each of said first and second electrodes at a time between about 550 and 650 microseconds after occurrence of a positive pulse.

7. The device of claim 6 wherein said generating means includes means for causing each said pulse group to be repeated at time intervals such that corresponding pulses are spaced between about 2200 to 2800 microseconds.

8. The device of claim 1 wherein said generating means includes means providing for stimulation of pain reduction neurons by causing a pulse spacing between preselected pulses between about 1500 and 2100 microseconds, and wherein said coupling means causes application of a negative pulse to each of said first and second electrodes at a time between about 1500 and 2100 microseconds after occurrence of a positive pulse.

9. The device of claim 8 wherein said generating means includes means for causing each said pulse group to be repeated at time intervals such that corresponding pulses are spaced between about 4200 to 4800 microseconds.

10. The device of claim 1 wherein said generating means includes means providing for stimulation of fast

twitch motor nerves by causing a pulse spacing to occur between preselected pulses between 100 microseconds and 140 microseconds, and wherein said coupling means causes application of a negative pulse to each of said first and second electrodes at a time between about 100 and 140 microseconds after occurrence of a positive pulse.

11. The device of claim 10 whrein said generating means includes means for causing each said pulse group to be repeated at time intervals such that corresponding pulses are spaced between about 1700 to 2300 microseconds.

12. A device for providing optimized electrical stimulation through plural active electrodes to preselected nerve fibers having known refractory periods and enhanced excitability conditions that occur following the occurrence of an action potential, said device comprising:

generating means for generating a series of output pulse groups each having first, second and third pulses with said first pulse of each said pulse group being a positive polarity pulse and said second and third pulses of each said pulse group being negative polarity pulses, said first and second pulses of each said pulse group being spaced, in time, from one another a distance substantially equal to the known refractory period of said preselected nerver fibers to be stimulated, said second and third pulses of each said pulse group being also spaced, in time, from one another, and each said third pulse being spaced from said first pulse of the immediately subsequently occurring pulse group a distance, in time, substantially equal to the known refractory period of said preselected nerve fibers to be stimulated, with each pulse group also occurring so as to be timewise spaced from each adjacent pulse group a distance based upon the occurrence of said enhanced excitability condition of said preselected nerve fibers to be stimulated;

first and second electrodes; and

coupling means connecting with said generating means and said first and second electrodes to receive said pulses from said generating means and to apply said pulses through said first electrode to said preselected nerve fibers and to apply said pulses in inverted polarity through said second electrode to said preselected nerve fibers so that said first pulse of each said pulse group coupled through said first electrode sets said preselected nerve fibers with said second pulse of each said pulse group occurring substantially at the end of said refractory period for said preselected nerve fibers to excite said preselected nerve fibers, and so that said inverted third pulse of each said pulse group coupled through said second electrode sets said preselected nerve fibers with said inverted first pulse of each said exceeding pulse group occurring substantially at the end of said refractory period for said preselected nerve fibers to excite said nerve fibers, whereby said first and second electrodes are both made active to optimize stimulation of said preselected nerve fibers to increase the activity thereof.

13. A method for optimizing electrical stimulation through plural active electrodes of nerve fibers having predetermined refractory periods and enhanced excitability conditions that occur during known periods following the occurrence of an action potential, said method comprising:

generating a first pulse of positive polarity and applying said first pulse through a first electrode to nerve fibers to be electrically stimulated to thereby set said fibers;

generating a second pulse of negative polarity and applying said second pulse through said first electrode to said nerve fibers to be electrically stimulated to cause excitation thereof, with said second pulse being generated at a time subsequent to said first pulse that is substantially equal to that of the refractory period for said nerve fibers then to be stimulated;

repeatedly generating said first and second pulses with each occurrence of each of said first and second pulses being timewise spaced from each adjacent corresponding first and second pulses a distance not substantially greater than the timewise occurrence of said enhanced excitability condition of said preselected nerve fibers to be stimulated;

inverting a pulse of negative polarity to positive polarity and applying said resulting positive pulse through a second electrode to said nerve fibers to be electrally stimulated to thereby set said fibers;

inverting the positive pulse next occurring after said inverted pulse of negative polarity and applying the resulting negative pulse through said second electrode to said nerve fibers to be electrally stimulated to cause excitation thereof, with said resulting negative pulse being applied at a time subsequent to that of said resulting positive pulse applied through said second electrode with said time being substantially equal to that of said refractory period for said nerve fibers then to be stimulated.

14. The method of claim 13 wherein said method includes repeatedly generating a third pulse in addition to generating said first and second pulses, with said third pulse being of negative polarity and occurring after said second pulses, and with said third pulse being inverted and said resulting positive pulse being applied through said second electrode to set said nerve fibers then to be stimulated.

15. The method of claim 14 wherein said nerve fibers then to be stimulated have a maximum hyperexcitability condition, and wherein said first, second, and third pulses are repeatedly generated so that each corresponding pulse occurs with a timewise spacing therebetween substantially equal to that of the known time between said action potential and said maximum hyperexcitability condition of said nerve fibers then to be stimulated.

16. The method of claim 13 wherein said pulses applied through said first and second electrodes stimulate at least one of sensory, motor, pain control, and automatic fibers.