Method and apparatus for detection of nervous system disorders
First Claim
1. A method of detecting a precursor to a neurological event, the method comprising:
- sampling an electroencephalograph (EEG) signal to obtain a stream of data values, each data value having an amplitude within one of at least a first amplitude range and a second amplitude range;
generating a stream of change signal values based on the stream of data values, a change signal value having a first value if a current data value is within a different amplitude range from an immediately preceding data value, and having a second value if the current data value is within a same amplitude range as the immediately preceding output value;
detecting a precursor to a neurological event using a processor when a count of the first values exceeds a predetermined precursor threshold.
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Accused Products
Abstract
Systems and methods for detecting and/or treating nervous system disorders, such as seizures, are disclosed. Certain embodiments of the invention relate generally to implantable medical devices (IMDs) adapted to detect and treat nervous system disorders in patients with an IMD. Certain embodiments of the invention include detection of seizures based upon comparisons of long-term and short-term representations of physiological signals. Other embodiments include prediction of seizure activity based upon analysis of physiological signal levels. An embodiment of the invention monitors the quality of physiological signals, and may be able to compensate for signals of low signal quality. A further embodiment of the invention includes detection of seizure activity following the delivery of therapy.
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Citations
24 Claims
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1. A method of detecting a precursor to a neurological event, the method comprising:
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sampling an electroencephalograph (EEG) signal to obtain a stream of data values, each data value having an amplitude within one of at least a first amplitude range and a second amplitude range; generating a stream of change signal values based on the stream of data values, a change signal value having a first value if a current data value is within a different amplitude range from an immediately preceding data value, and having a second value if the current data value is within a same amplitude range as the immediately preceding output value; detecting a precursor to a neurological event using a processor when a count of the first values exceeds a predetermined precursor threshold. - View Dependent Claims (2, 3)
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4. A method of detecting a precursor to a neurological event, the method comprising:
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sampling an electroencephalograph (EEG) signal to obtain a stream of data values; applying the data values to a level transform having a level threshold defining two amplitude ranges, the level transform adapted to produce a stream of output values, each output value identifying the amplitude range corresponding to each data value; applying the stream of output values to a change detector, the change detector adapted to produce a stream of change signal values, a change signal value, having a first value if a current output value is different from an immediately preceding output value, and having a second value if the current value is the same as the immediately preceding value; counting the first values that occur in a predefined window; and detecting a precursor to a neurological event using a processor when the count of first values exceeds a predetermined precursor threshold. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A computer-readable medium programmed with instructions for performing a method of detecting a precursor to a neurological event, the medium comprising instructions for causing a programmable processor to:
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sample an electroencephalograph (EEG) signal to obtain a stream of data values, each data value having an amplitude within one of at least a first amplitude range and a second amplitude range, the amplitude ranges being chosen to differentiate between normal EEG signal amplitudes and epileptiform discharges; generate a stream of change signal values based on the stream of data values, a change signal value having a first value if a current data value is within a different amplitude range from an immediately preceding data value, and having a second value if the current data value is within a same amplitude range as the immediately preceding output value; and detect a precursor to a neurological event when a count of the first values exceeds a predetermined precursor threshold.
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18. A computer-readable medium programmed with instructions for performing a method of detecting a precursor to a neurological event, the medium comprising instructions for causing a programmable processor to:
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sample an electroencephalograph (EEG) signal to obtain a stream of data values; apply the data values to a level transform having a level threshold, the level threshold defining two amplitude ranges, the level transform adapted to produce a stream of output values, each output value identifying the amplitude range corresponding to each data value; apply the stream of output values to a change detector, the change detector adapted to produce a stream of change signal values, a change signal value having a first value if a current output value is different from an immediately preceding output value, and having a second value if the current value is the same as the immediately preceding value; count the first values that occur in a predefined window; and detect a precursor to a neurological event when the count of first values exceeds a predetermined precursor threshold. - View Dependent Claims (19, 20)
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21. A system for detecting a precursor to a neurological event, comprising:
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an implantable lead adapted to sense EEG signals from a brain of a patient; and an implantable medical device (IMD) in communication with the implantable lead and adapted to receive EEG signals, the IMD having a power source, memory, and electronic circuitry adapted to sample an electroencephalograph (EEG) signal to obtain a stream of data values; apply the data values to a level transform having a level threshold, the level threshold defining two amplitude ranges, the level transform adapted to produce a stream of output values, each output value identifying the amplitude range corresponding to each data value; apply the stream of output values to a change detector, the change detector adapted to produce a stream of change signal values, a change signal value having a first value if a current output value is different from an immediately preceding output value, and having a second value if the current value is the same as the immediately preceding value; count the first values that occur in a predefined window; and detect a precursor to a neurological event when the count of first values exceeds a predetermined precursor threshold. - View Dependent Claims (22, 23, 24)
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Specification