Implantable Seizure Monitor

• US 20110004116A1
• Filed: 04/29/2010
• Published: 01/06/2011
• Est. Priority Date: 03/08/2006
• Status: Active Grant

• Current Assignee: Neuropace Inc.
• Original Assignee: Neuropace Inc.
• Inventors: Greene, David
• Granted Patent: US 8,140,151 B2
• Time in Patent Office: Days
• US Class Current: 600/544
• CPC Class Codes: A61B 5/291 for electroencephalography [EEG]
• CPC Class Codes: A61B 5/4094 Diagnosing or monitoring seizure diseases, e.g. epilepsy

Abstract

An implantable seizure monitor can include at least one sensing electrode and an electronics module configured to detect, record and/or log neurological events. For example, the electronics module can be configured to detect brainwaves indicative of seizures, such as, for example, epileptic seizures, and to create a log indicating when such seizures occur. The implantable seizure monitor can include a cushioning member made of a soft material and configured to be implantable between the epidermis and cranium of a patient.

Claims

1. A method for detecting neurological events comprising:

sensing brainwaves of a patient;

generating a signal indicative of the sensed brainwaves;

amplifying the signal in an amplifier, the amplifier having a gain adjustable to predetermine an amplitude of the signal that will place the amplifier in saturation, and

determining if a neurological event has occurred based on occurrences of saturation of the amplifier.

2. The method according to claim 1, wherein determining if the neurological event has occurred includes determining if the neurological event has occurred based on the frequency at which the amplifier saturates.

3. The method according to claim 1, wherein determining if the neurological event has occurred includes determining if the neurological event has occurred based on the number of times the amplifier saturates in a predetermined number of time windows.

4. The method according to claim 1, wherein determining if the neurological event has occurred includes:

determining, for each time window in a plurality of contiguous time windows, whether the amplifier is saturated;

determining whether a ratio of a number of time windows in which the amplifier is saturated and the number of contiguous time windows exceeds a predetermined ratio.

5. A method for calibrating an implantable device including an adjustable gain amplifier, the method comprising:

setting an initial gain of the amplifier;

sensing brainwaves of a patient using the implantable device;

generating a signal indicative of the sensed brainwaves using the implantable device;

amplifying the signal in an amplifier, the amplifier having a gain adjustable to predetermine an amplitude of the signal that will place the amplifier in saturation, and

determining occurrences of saturation of the amplifier during normal brain activity;

determining whether the occurrences of saturation of the amplifier during normal brain activity exceed a threshold;

adjusting the gain of the amplifier if the occurrences of saturation of the amplifier during normal brain activity exceeds the threshold;

repeating determining occurrences of saturation of the amplifier during normal brain activity, determining whether the occurrences of saturation of the amplifier during normal brain activity exceed the threshold, and adjusting the gain, until the occurrences of saturation of the amplifier during normal brain activity do not exceed the threshold;

if the occurrences of saturation of the amplifier during normal brain activity do not exceed the threshold, determining if a neurological event has occurred based on occurrences of saturation of the amplifier.

6. The method of claim 5, wherein determining whether the occurrences of saturation of the amplifier during normal brain activity exceed a threshold includes determining whether a number of saturations of the amplifier exceeds a threshold number of times during a time interval.

7. The method of claim 5, wherein the initial gain is a maximum gain value of the amplifier.

8. The method of claim 7, wherein adjusting the gain of the amplifier includes reducing the gain of the amplifier.

9. The method of claim 5, further comprising storing the occurrences of saturation of the amplifier during normal brain activity.

10. The method of claim 9, wherein determining whether the occurrences of saturation of the amplifier during normal brain activity exceed a threshold includes determining whether the stored occurrences of saturation of the amplifier during normal brain activity exceed the threshold.

11. The method of claim 5, further comprising determining whether the occurrences of saturation of the amplifier during normal brain activity does not exceed a minimum value;

and

increasing the gain of the amplifier if the occurrences of saturation of the amplifier during normal brain activity does not exceed the minimum value, wherein the repeating includes determining whether the occurrences of saturation of the amplifier during normal brain activity does not exceed a minimum value and increasing the gain of the amplifier.