Programmable signal analysis device for detecting neurological signals in an implantable device

#The present invention is generally directed to circuitry for use within implantable medical devices and in particular to such circuitry which senses neurological signals, e.g., from nerves or muscles, to detect intended or actual muscle stimulation.

#The present invention relates to devices and systems of such devices for monitoring and/or affecting parameters of a patient's body for the purpose of medical diagnosis and/or treatment. More particularly, such devices, preferably battery powered, are configured for implanting within a patient's body, each device being configured to sense a body parameter, e.g., temperature, O2 content, physical position, electrical potential, etc., and/or to affect a parameter, e.g., via nerve and/or muscle stimulation.

#Commonly owned U.S. Pat. Nos. 6,164,284; 6,208,894; and 6,315,721; each entitled “System of Implantable Devices For Monitoring and/or Affecting Body Parameters” and U.S. Pat. No. 6,185,452 entitled “Battery Powered Patient Implantable Device”, each incorporated herein by reference in their entirety, describe devices configured for implantation within a patient's body, i.e., beneath a patient's skin, for performing various functions including: (1) stimulation of body tissue and/or sensing of body parameters, and (2) communicating between implanted devices and devices external to a patient's body. In an exemplary use, the implanted device is used to electrically stimulate a neural pathway and/or muscle and the same (and/or another) implanted device senses an evoked response from the intended muscle tissue and uses the detected signal to confirm that stimulation did occur and/or to achieve closed loop control. In general, the detected signal may exhibit a frequency component that corresponds to the intensity of the intended or actual muscle response and amplitude components that correspond to its proximity to the desired source tissue and/or other signal generating tissue. Depending on the application, there are various techniques that may be used to interpret the neurological signal. Such implantable devices are preferably powered using rechargeable batteries and it is desired that the time between rechargings be maximized by minimizing the power dissipation of such circuitry within these implantable devices. Accordingly, what is needed is a programmable signal analysis circuit that can be configured to interpret neurological signals using a plurality of analysis modes. Furthermore, such a circuit should minimize its power dissipation to thus enhance the battery life of the implantable devices.

#FIG. 1 is a simplified block diagram of an exemplary system suitable for practicing the present invention, the system being comprised of implanted devices, e.g., microstimulators, microsensors and microtransponders, under control of an implanted system control unit (SCU).

#FIG. 2 comprises a block diagram of the system of FIG. 1 showing the functional elements that form the system control unit and implanted microstimulators, microsensors and microtransponders.

#FIG. 3A comprises a block diagram of an exemplary implantable device, as shown in U.S. Pat. No. 6,164,284, including a battery for powering the device for a period of time in excess of one hour in response to a command from the system control unit.

#The following description is of the best mode presently contemplated for carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of describing the general principles of the invention. The scope of the invention should be determined with reference to the claims.

#The present invention is generally directed to circuitry for use within implantable medical devices and in particular to such circuits which sense neurological signals, e.g., from nerves or muscles, to detect intended or actual muscle stimulation. In an exemplary application for the present invention, such circuits may be used within implanted devices configured similarly to the devices described in the commonly owned U.S. Pat. No. 6,164,284. Such implanted devices typically comprise a sealed housing suitable for injection into the patient's body and preferably contain a power source, e.g., a battery, having a capacity of at least 1 microwaft-hour and power consuming circuitry preferably including a data signal transmitter and receiver and sensor/stimulator circuitry for driving an input/output transducer. In a typical application, such devices are used to stimulate a neural pathway or muscle and/or to block a neural pathway to alleviate pain or block stimulation of a muscle. The present invention is thus specifically directed to an implementation of the sensor circuitry for use in such an implantable device.

#In an exemplary system of devices which use the signal analysis device of the present invention, a system control unit (SCU) comprises a programmable unit capable of (1) transmitting commands to at least some of a plurality of implantable devices and (2) receiving data signals from at least some of those implantable devices. Such a system preferably operates, at least in part, in closed loop fashion whereby the commands transmitted by the SCU are dependent, in part, on the content of the data signals received by the SCU.