Method and apparatus for measurement of evoked neural response

• US 20060089561A1
• Filed: 09/04/2003
• Published: 04/27/2006
• Est. Priority Date: 09/04/2002
• Status: Active Grant

• Current Assignee: Cochlear Limited
• Original Assignee: Cochlear Limited
• Inventors: Eder, Helmut Christian, Hurley, Padraig Joseph, Money, David Kerry, Nygard, Tony Mikeal
• Granted Patent: US 7,809,445 B2
• Time in Patent Office: Days
• US Class Current: 600/546
• CPC Class Codes: A61B 5/24 Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
• CPC Class Codes: A61B 5/377 using evoked responses
• CPC Class Codes: A61B 5/388 Nerve conduction study, e.g. detecting action potential of peripheral nerves
• CPC Class Codes: A61B 5/7217 of noise originating from a therapeutic or surgical apparatus, e.g. from a pacemaker
• CPC Class Codes: A61N 1/36039 fitting procedures
• CPC Class Codes: H04R 25/606 acting directly on the eardrum, the ossicles or the skull, e.g. mastoid, tooth, maxillary or mandibular bone, or mechanically stimulating the cochlea, e.g. at the oval window

Abstract

A method and device for measuring an evoked neural response comprising a sensor (25) for obtaining a sensed signal representing the evoked neural response, a high gain amplifier (30) having a signal input (31) for receiving the sensed signal and having a reference input (32), and means for altering or setting a reference voltage at the reference input (32) to prevent the amplifier (30) saturating with variations of the sensed signal.

Claims

1. A method of measurement of an evoked neural response comprising the steps of:

obtaining a sensed signal representing the evoked neural response from a sensor;

passing the obtained sensed signal to a signal input of a high gain amplifier; and

altering a reference voltage of the high gain amplifier in order to prevent the high gain amplifier saturating with variations of the sensed signal.

2. The method according to claim 1 wherein the step of altering the reference voltage is performed during the measurement of the evoked neural response.

3. The method according to claim 1 wherein the step of altering the reference voltage is performed by setting the reference voltage equal to a present value of the sensed signal.

4. The method according to claim 3 wherein the setting of the reference voltage equal to a present value of the sensed signal is undertaken by a sample-and-hold circuit having an input from the sensed signal.

5. The method according to claim 3 further comprising the step of setting the reference voltage of the high gain amplifier equal to the present value of the sensed signal at the commencement of every sample period.

7. The method according to claim 1 wherein the step of obtaining the sensed signal comprises obtaining a sensed signal of the neural response of an auditory nerve.

8. The method according to claim 7 wherein the step of obtaining the sensed signal of the neural response of the auditory nerve uses one or more electrodes of an electrode array of a cochlear implant.

6. The method according to claim 6 further comprising the step of integrating samples derived at the output of the high gain amplifier to obtain a continuous waveform representing the amplified sensed signal.

9. A device for measuring an evoked neural response, the device comprising:

a sensor for obtaining a sensed signal representing the evoked neural response;

a high gain amplifier having a signal input for receiving the sensed signal, and having a reference input; and

means for altering a reference voltage at the reference input of the high gain amplifier in order to prevent the high gain amplifier saturating with variations of the sensed signal.

10. The device according to claim 9 wherein the reference voltage is altered during the measurement of the evoked neural response.

11. The device according to claim 10 wherein the reference voltage is altered by setting the reference voltage equal to a present value of the sensed signal.

12. The device according to claim 11 further comprising a sample-and-hold circuit having an input from the sensed signal, said sample-and-hold circuit setting of the reference voltage equal to a present value of the sensed signal.

13. The device according to claim 12 wherein the reference voltage of the high gain amplifier is set equal to the present value of the sensed signal at the commencement of every sample period.

14. The device according to claim 13 wherein samples derived at the output of the high gain amplifier are integrated to obtain a continuous waveform representing the amplified sensed signal.

15. The device according to claim 9 wherein the obtained sensed signal is of the neural response of an auditory nerve.

16. The device according to claim 15 wherein the sensor comprising one or more electrodes of an electrode array of an implanted portion of a cochlear implant for obtaining the sensed signal.

17. The device according to claim 9 comprising a cochlear implant.

18. A method of measurement of an evoked neural response comprising the steps of:

obtaining a sensed signal representing the evoked neural response from a sensor;

passing the obtained sensed signal to a signal input of a high gain amplifier; and

setting a reference voltage of the high gain amplifier equal to a present value of the sensed signal in order to prevent the high gain amplifier saturating with variations of the sensed signal.

19. A device for measuring an evoked neural response, the device comprising:

a sensor for obtaining a sensed signal representing the evoked neural response;

a high gain amplifier having a signal input for receiving the sensed signal, and having a reference input; and

means for setting a reference voltage at the reference input of the high gain amplifier equal to a present value of the sensed signal in order to prevent the high gain amplifier saturating with variations of the sensed signal.