Method of rapid neural response measurement without amplitude attenuation

• US 20040158170A1
• Filed: 02/04/2004
• Published: 08/12/2004
• Est. Priority Date: 02/04/2003
• Status: Active Grant

• Current Assignee: Advanced Bionics AG (Sonova Holding AG)
• Original Assignee: Advanced Bionics LLC (Sonova Holding AG)
• Inventors: Hood, Kevin H., Calle, Guillermo A., Overstreet, Edward H.
• Granted Patent: US 7,277,759 B2
• Time in Patent Office: Days
• US Class Current: 600/554
• CPC Class Codes: A61B 5/389 Electromyography [EMG]
• CPC Class Codes: A61B 5/4041 Evaluating nerves condition

Abstract

A method of recording neural responses reduces the inaccuracy of the recordings caused by nerve adaptation to repeated exposure of stimuli. In one embodiment, a maximum set of X number of successive stimuli are delivered through an electrode and the resulting neural response recorded and, afterwards, the next stimulation must occur through another electrode. This stimulation sequence prevents the same set of nerves from being stimulated too often, which can result in stimulus adaptation and cause measurement inaccuracy. In one embodiment of the invention, a smart software can be employed to provide visual plots of “growth curves”, including real-time calculated datapoints and their confidence intervals, and automatically terminate the recording session upon reaching a pre-set trigger. Alternatively, a human operator can terminate a recording session, based on visual feedback of growth curves, including their real-time calculated datapoints and confidence intervals.

Claims

1. A method of obtaining neural responses with a stimulation system having an array of electrodes, E1 . . . EN, to generate growth curves, NR #1 to NR #Last, the method comprising:

(a) delivering, without causing a predetermined level of NR attenuation, a stimulus train having X stimuli through one electrode of the array E1 . . . EN and recording, X number of times, a first NR datapoint, which datapoint is part of growth curve NR #1;

(b) repeating the above process of stimulating through each selected ones of electrodes of the array E1 . . . EN and recording a datapoint corresponding to each selected electrode and each growth curve, NR #2 to NR #Last, wherein each datapoint is recorded at least once, without causing a predetermined level of NR attenuation; and

(c) repeating the above steps (a) and (b) as many times as necessary to generate additional, different datapoints on each selected growth curve NR#1 to NR #Last; and

wherein X is a variable, whole number 1 or greater, and X represents the number of stimuli in any stimulus train.

2. The method of claim 1, wherein the step (c) to generate additional, different datapoints on each NR growth curve from NR#1 to NR #Last is accomplished by varying the stimulus amplitude while keeping the stimulus pulsewidth constant.

3. The method of claim 1, further comprising:

(d) obtaining an averaged datapoint for each growth curve NR#1 to NR #Last by averaging all available recordings for each datapoint.

4. The method of claim 1, further comprising:

(d) computing real-time averages of each datapoint, its confidence intervals and curve fitting a growth curve for each NR #1 . . . NR #Last, based on available datapoints.

5. The method of claim 4, further comprising:

(e) automatically terminating the recording session according to pre-programmed triggers based on real-time calculated datapoint values and their confidence intervals.

6. The method of claim 4, further comprising:

(e) visually displaying fitted growth curves, NR #1 . . . NR #Last, real-time averages of each datapoint on each growth curve, and confidence intervals for each datapoint; and

(f) terminating the recording session by a program operator based on visual feedback of the real-time display of growth curves, their averaged datapoints and confidence intervals for each datapoint.

7. The method of claim 1, further comprising:

(d) automatically terminating the recording of a current datapoint by a software program based on pre-programmed triggers.

8. The method of claim 1, wherein the electrodes stimulate spinal cord nerves.

9. The method of claim 1, wherein the electrodes stimulate cochlear nerves.

10. The method of claim 9, wherein X is a variable, whole number between 1 and 50.

11. The method of claim 9, wherein the inter-stimulus time interval between the delivery of successive stimuli for successively recording one datapoint is between about 0.002 and 1 second.

12. The method of claim 1, wherein no two adjacent electrodes or electrode configurations deliver stimulation immediately, one after the other, in order to reduce channel cross-talk.

13. A method of obtaining neural responses to generate at least two growth curves with a stimulation system having an array of stimulating electrodes, E1 . . . EN, the method comprising:

(a) delivering a stimulus train having X stimuli, without causing a predetermined level of attenuation of NR, the stimulus train delivered through a selected first electrode in the electrode array E1 . . . EN, to generate a replication of a data point for the first growth curve selected among, NR #1 . . . NR #Last; and

(b) repeating step (a) for at least a second, selected electrode in the electrode array to generate a replication of a datapoint located on at least a second growth curve selected among, NR#1 . . . NR # Last,

wherein delivering a first stimulus train to obtain a first datapoint and delivering a second stimulus train to obtain a second datapoint, when the two datapoints are located on the same, first growth curve, are never performed immediately one after the other, without the occurrence of an intervening wait state or an intervening delivery of a third stimulus to obtain a datapoint on a different, second growth curve; and

wherein X is a variable, whole number 1 or greater.

14. The method of claim 13, wherein the predetermined level of attenuation of the NR is a decrease of the last NR, in response to the (X+1) th stimulus, by at least a predetermined percentage, P.

15. The method of claim 13, further comprising:

(c) repeating, multiple times, the steps (a) and (b), by applying stimuli having different magnitudes when applying a stimulus train through each selected electrode, to obtain additional replications of datapoints in order to generate selected growth curves, NR#1 . . . NR #Last.

16. The method of claim 13, wherein the growth curves are for cochlear nerves.

17. The method of claim 16, wherein each stimulus train has between 1 and 50 substantially identical stimulus pulses.

18. The method of claim 17, wherein the inter-stimulus time interval between successive stimuli in each stimulus train is between about 1 to 0.002 seconds.

19. The method of claim 13, wherein stimulation is accomplished with a monopolar electrode configuration.

20. The method of claim 13, wherein, when there are first and second adjacent electrodes having overlapping coverage of a subset of nerves and a first stimulus train is delivered through the first electrode, a second stimulus train is not immediately thereafter, delivered through the second, adjacent electrode, without an occurrence of an intervening wait time sufficient for nerve recovery of nerves stimulated by the first stimulus train or a delivery of a third stimulus train to a third electrode, which third electrode is not adjacent to the first electrode.