Abstract: Therapy delivery to a patient may be controlled based on a determined sleep stage of the patient. In examples, the sleep stage may be determined based on a frequency characteristic of a biosignal indicative of brain activity of the patient. A frequency characteristic may include, for example, a power level within one or more frequency bands of the biosignal, a ratio of the power level in two or more frequency bands, or a pattern in the power level of one or more frequency bands over time. A therapy program may be selected or modified based on the sleep stage determination. Therapy may be delivered during the sleep stage according to the selected or modified therapy program. In some examples, therapy delivery may be controlled after making separate determinations of a sleep stage based on the biosignal and another physiological parameter, and confirming that the sleep stage determinations are consistent.

Abstract: Various embodiments concern delivering electrical stimulation to the brain at a plurality of different levels of a stimulation parameter and sensing a bioelectrical response of the brain to delivery of the electrical stimulation for each of the plurality of different levels of the stimulation parameter. A suppression window of the stimulation parameter can be identified as having a suppression threshold as a lower boundary and an after-discharge threshold as an upper boundary based on the sensed bioelectrical responses. A therapy level of the stimulation parameter can be set for therapy delivery based on the suppression window. The therapy level of the stimulation parameter may be set closer to the suppression threshold than the after-discharge threshold within the suppression window. Data for hippocampal stimulation demonstrating a suppression window is presented.

Abstract: Posture-responsive therapy is delivered by the medical system based on posture state input from only one of multiple posture sensors at any given time. An example implantable medical system includes a first posture sensor and a second sensor. A processor controls therapy delivery to the patient based on at least one of a patient posture state or a patient activity level determined based on input from only one of the first or second posture sensors. In some examples, one of multiple posture sensors of an implantable posture-responsive medical system is used to automatically reorient another posture sensor (of the system), which has become disoriented. The disoriented posture sensor may be automatically reoriented for one or more posture states at a time.

Abstract: Seizure prediction systems and methods include measuring impedance within a brain of a patient to determine whether the brain is in a state indicative of a possibility of an onset of a seizure. In some embodiments, the measured impedance is compared to a predetermined threshold in order to determine whether the brain is in a state indicative of a possibility of a seizure. In other embodiments, a trend of the impedance measurements is correlated to a template. In other embodiments, a frequency component of a waveform of the impedance measurement amplitudes over time is correlated to frequency components of a template waveform. Upon detecting a state in which a seizure is likely to occur, a seizure indicator may be generated, which, in some embodiments, may be used to activate therapy delivery to the patient or, in other embodiments, activate an alarm.

Abstract: The disclosure is directed to a pressure sensor of an implantable medical device. The pressure sensor may utilize detect fluid pressure based on a changing capacitance between two capacitive elements. The pressure sensor may define at least a portion of a fluid enclosure of the IMD. In one example, the pressure sensor has a self-aligning housing shape that occludes an opening in the pump bulkhead of the IMD. An operative surface of the pressure and the portion of the fluid enclosure may be formed of a corrosion resistant and/or biocompatible material. A first capacitive element of the pressure sensor may be a metal alloy diaphragm that deflects in response to external fluid pressure. A second capacitive element of the pressure sensor may be a metal coating on a rigid insulator sealed from the fluid by the diaphragm and a housing of the sensor.

Abstract: Various embodiments concern delivering electrical stimulation to the brain at a plurality of different levels of a stimulation parameter and sensing a bioelectrical response of the brain to delivery of the electrical stimulation for each of the plurality of different levels of the stimulation parameter. A suppression window of the stimulation parameter can be identified as having a suppression threshold as a lower boundary and an after-discharge threshold as an upper boundary based on the sensed bioelectrical responses. A therapy level of the stimulation parameter can be set for therapy delivery based on the suppression window. The therapy level of the stimulation parameter may be set closer to the suppression threshold than the after-discharge threshold within the suppression window. Data for hippocampal stimulation demonstrating a suppression window is presented.

Abstract: In some examples, one or more processors determine characteristics of frequency components of a sensed bioelectrical signal. In response to determining the characteristics, the one or more processors determine therapy parameters for frequency components of a stimulation signal. The one or more processors may determine the therapy parameters based on the characteristics of the frequency components of the sensed bioelectrical signal. As another example, the one or more processors may determine the therapy parameters based on received information after the characteristics of the frequency components of the sensed bioelectrical signal are displayed to a user.

Abstract: Posture-responsive therapy is delivered by the medical system based on posture state input from only one of multiple posture sensors at any given time. An example implantable medical system includes a first posture sensor and a second sensor. A processor controls therapy delivery to the patient based on at least one of a patient posture state or a patient activity level determined based on input from only one of the first or second posture sensors. In some examples, one of multiple posture sensors of an implantable posture-responsive medical system is used to automatically reorient another posture sensor (of the system), which has become disoriented. The disoriented posture sensor may be automatically reoriented for one or more posture states at a time.

Abstract: The temporal correlation between a bioelectrical brain signal of a patient and patient motion data, such as a signal indicative of patient motion or a patient posture indicator, is displayed by a display device. In some examples, the patient posture indicator comprises a graphical representation of at least a portion of a body of the patient. In some examples, the temporal correlation between a bioelectrical brain signal, a signal indicative of patient motion, and a signal indicative of cardiac activity of the patient is displayed by the display device.

Abstract: Devices and methods provide for the sensing of physiological signals during stimulation therapy by preventing stimulation waveform artifacts from being passed through to the amplification of the sensed physiological signal. Thus, the sensing amplifier is not adversely affected by the stimulation waveform and can provide for successful sensing of physiological signals. A common mode voltage is applied to the stimulation electrodes while sensing during a recharge period where the common mode voltage approximates the stimulation pulse being received at the sensing electrodes. This common mode voltage is determined based on measuring a common mode signal for at least one of the inputs of the amplifier or by deriving the proper common mode from monitoring the output signal of the amplifier to observe the elimination of artifacts during stimulation. Blanking switches may be used to blank the sensing of the peak of the recharge period should that peak be relatively large.

Abstract: Therapy delivery to a patient may be controlled based on a determined sleep stage of the patient. In examples, the sleep stage may be determined based on a frequency characteristic of a biosignal indicative of brain activity of the patient. A frequency characteristic may include, for example, a power level within one or more frequency bands of the biosignal, a ratio of the power level in two or more frequency bands, or a pattern in the power level of one or more frequency bands over time. A therapy program may be selected or modified based on the sleep stage determination. Therapy may be delivered during the sleep stage according to the selected or modified therapy program. In some examples, therapy delivery may be controlled after making separate determinations of a sleep stage based on the biosignal and another physiological parameter, and confirming that the sleep stage determinations are consistent.

Abstract: In general, this disclosure is directed to a mixer amplifier that can be utilized within a chopper stabilized instrumentation amplifier. The chopper stabilized instrumentation amplifier may be used for physiological signal sensing, impedance sensing, telemetry or other test and measurement applications. In some examples, the mixer amplifier may include a current source configured to generate a modulated current at a modulation frequency for application to a load to produce an input signal, an amplifier configured to amplify the input signal to produce an amplified signal, and a demodulator configured to demodulate the amplified signal at the modulation frequency to produce an output signal indicating an impedance of the load.

Abstract: A characteristic of a washout period following the delivery of therapy to a patient according to a therapy program may be determined based on a physiological parameter of the patient. A washout period includes the period of time during which a carryover effect from the therapy dissipates. The washout period characteristic may include, for example, a duration of the washout period, an amplitude or a trend in a physiological signal during the washout period or a power level or a ratio of power levels in frequency bands of the physiological signal. In some embodiments, washout period characteristics associated with a plurality of therapy programs may be used to compare the programs. In other embodiments, a washout period characteristic may be used to determine a mood state of the patient and, in some cases, modify a therapy program. Monitoring a washout period may also be useful for timing therapy program trials.

Abstract: This disclosure describes techniques for controlling spectral aggressors in a sensing device that uses a chopper amplifier to amplify an input signal prior to sampling the signal. In some examples, the techniques for controlling spectral aggressors may include generating a chopper-stabilized amplified version of an input signal based on a chopper frequency, sampling the chopper-stabilized amplified version of the input signal at a sampling rate to generate a sampled signal, and analyzing a target frequency band of the sampled signal. The chopper frequency and the sampling rate may cause spectral interference that is generated due to the chopper frequency to occur in the sampled signal at one or more frequencies that are outside of the target frequency band of the sampled signal. The techniques for controlling spectral aggressors may reduce the noise caused by the chopper frequency in the resulting sampled signal, thereby improving the quality of the signal.

Abstract: Systems and method may be used for interfacing with a patient. Systems may include a plurality of electrodes in electrical communication with a processor. The processor may be configured to receive sense signals from electrodes and to determine the reliability of the received signal. A test tone signal comprising a test tone frequency may be applied, and the magnitude of the test tone frequency may be analyzed in the received signal. If it is determined that the magnitude of the test tone frequency is below a threshold, the system may take action, such as lowering the gain on an amplifier. Stimulation signals may be applied to the patient at a stimulation frequency simultaneously with one or both of receiving sense signals and providing the test tone signal.

Abstract: Systems and method may be used for interfacing with a patient. Systems may include a plurality of electrodes in electrical communication with a processor. The processor may determine a relative impedance difference between a first electrode and a second electrode, and apply a sub-therapeutic stimulation pulse to one of the first and second electrodes to adjust the relative impedance difference therebetween. Systems may include a processor capable of one or both of providing therapeutic stimulation to a patient via at least one electrode, and receiving electrical signals indicative of the patient's physiological activity. In some examples, the processor may simultaneously provide therapeutic stimulation to a patient and receive electrical signals from the patient indicative of the patient's physiological activity.

Abstract: In some examples, one or more processors determine characteristics of frequency components of a sensed bioelectrical signal. In response to determining the characteristics, the one or more processors determine therapy parameters for frequency components of a stimulation signal. The one or more processors may determine the therapy parameters based on the characteristics of the frequency components of the sensed bioelectrical signal. As another example, the one or more processors may determine the therapy parameters based on received information after the characteristics of the frequency components of the sensed bioelectrical signal are displayed to a user.

Abstract: In some examples, a phase locked loop (PLL) circuit outputs a timing signal having a frequency and phase that is the same as a patient signal that is an input to the PLL circuit. The PLL circuit includes or is coupled to a storage circuit that stores information needed to cause the PLL circuit to maintain the frequency of the timing signal to the same frequency even after the patient signal is not available as an input.

Abstract: This disclosure describes a chopper mixer telemetry circuit for use in a wireless receiver. The receiver may be located in an implantable medical device (IMD) or external programmer. The chopper mixer telemetry circuit may include a mixer amplifier that operates as a synchronous demodulator to provide selective extraction of wireless signals received from a transmitter while suppressing out-of-band noise that can undermine the reliability of the telemetry link between an IMD or programmer and another device. The mixer amplifier may utilize parallel signal paths to convert the received telemetry signal into an in-phase (I) signal component and a quadrature (Q) signal component and recombine the I and Q signal components to reconstruct the total signal independently of the phase mismatch between the transmitter and receiver. Each signal path may include a chopper-stabilized mixer amplifier that amplifies telemetry signals within a desired band while suppressing out-of-band noise.

Abstract: This disclosure describes techniques for controlling spectral aggressors in a sensing device that uses a low power sleep mode to manage the power consumed by the device. In some examples, the techniques for controlling spectral aggressors may include configuring one or more of an algorithm processing rate for a processor, a buffering rate for the processor, a sampling rate for an analog-to-digital converter, an execution unit processing rate for the processor, and an algorithm subdivision factor for the processor such that spectral interference caused by a sleep cycle rate of the processor occurs outside of one or more target frequency bands of a sampled signal. The techniques of this disclosure may be used to reduce noise in a sensing system that uses a low power sleep mode to manage the power consumed by the device.