Methods and Systems for Measuring a Subject's Susceptibility to a Seizure

Abstract

Systems and methods for monitoring physiological signals from a subject to determine the subject's susceptibility for having a seizure. Also includes are systems and methods for activating an alert when there is a communication error between an implanted device and the external assembly. Additionally included are systems and method for long-term substantially continuous physiological signal data collection. At least a portion of the systems of the present invention may be implanted within the subject. In some embodiments, brain activity signals are sampled from the subject with implanted electrodes and are communicated to an external assembly where the brain activity signals are analyzed to determine the subject's susceptibility for having a seizure.

1 . A system for monitoring a subject's susceptibility for having a seizure:
 a sensor adapted to detect a brain activity signal;   an implanted communication assembly in communication with the sensor, the implanted communication assembly configured to sample the brain activity signal with the sensor;   an external assembly that is positioned outside the subject's body that is configured to receive a data signal from the implanted communication assembly and indicate a subject's susceptibility to a seizure; and   an alert that is configured to indicate that there is a communication error between the implanted assembly and the external assembly.   
     
     
         2 . The system of  claim 1  wherein the alert is disposed in the external assembly. 
     
     
         3 . The system of  claim 1  wherein the alert is a vibratory alert. 
     
     
         4 . The system of  claim 1  wherein the alert is an audible alert. 
     
     
         5 . The system of  claim 1  wherein the alert is a visible alert. 
     
     
         6 . The system of  claim 1  wherein the alert is disposed in the implanted communication assembly. 
     
     
         7 . The system of  claim 6  wherein the alert is a vibratory alert. 
     
     
         8 . The system of  claim 1  wherein the communication error comprises the external assembly is out of communication range with the implanted assembly. 
     
     
         9 . The system of  claim 1  wherein the communication error comprises the external assembly is out of communication range with the implanted assembly for a predetermined amount of time. 
     
     
         10 . The system of  claim 1  wherein the communication error comprises the external assembly not receiving the data signal at an expected time or within an expected period of time. 
     
     
         11 . The system of  claim 10  wherein the external assembly is adapted to expect the data signal on a substantially continuous basis. 
     
     
         12 . The system of  claim 10  wherein the external assembly is adapted to expect the data signal periodically. 
     
     
         13 . The system of  claim 1  further comprising a memory device disposed in the implanted assembly configured to buffer the data signal when there is a communication error between the implanted assembly and the external assembly. 
     
     
         14 . The system of  claim 1  wherein the communication error comprises an unexpected gap in the data signal communication stream. 
     
     
         15 . The system of  claim 14  wherein the gap comprises missing packets of data in a numbered sequence of packets. 
     
     
         16 . The system of  claim 1  wherein the communication error comprises a data formatting error. 
     
     
         17 . The system of  claim 16  wherein the data formatting error comprises an invalid cyclic redundancy check. 
     
     
         18 . The system of  claim 1  further comprising a processing assembly comprising at least one algorithm that estimates the subject's susceptibility for having a seizure based on the sampled brain activity signal. 
     
     
         19 . A method of activating an alert when there is a communication error between an implantable device and a device external to a subject, the method comprising:
 sampling a brain activity signal from the subject;   transmitting a data signal indicative of the sampled brain activity signal from an implanted assembly to an external assembly outside of the ; and   activating an alert when there is a communication error between the implanted assembly and the external assembly.   
     
     
         20 . The method of  claim 19  wherein the communication error comprises the external assembly not receiving the data signal from the implanted assembly. 
     
     
         21 . The method of  claim 19  wherein the communication error comprises the external assembly not receiving the data signal from the implanted assembly for a predetermined time period. 
     
     
         22 . The method of  claim 19  wherein the communication error comprises the external assembly being out of communication range with the implanted assembly. 
     
     
         23 . The method of  claim 19  wherein the communication error comprises the external assembly not receiving the transmitted data signal at an expected time or within an expected period of time. 
     
     
         24 . The method of  claim 23  wherein the communication error comprises the external assembly not receiving the transmitted data signal substantially continuously. 
     
     
         25 . The method of  claim 23  wherein the communication error comprises the external assembly not receiving the transmitted data signal periodically. 
     
     
         26 . The method of  claim 19  wherein the communication error comprises an unexpected gap in the data signal. 
     
     
         27 . The method of  claim 19  wherein the communication error comprises a data formatting error. 
     
     
         28 . The method of  claim 19  further comprising storing the data signal in the implanted assembly when there is a communication error between the implanted assembly and the external assembly. 
     
     
         29 . The method of  claim 19  further comprising processing the data signal to determine the subject's susceptibility for having a seizure. 
     
     
         30 . The method of  claim 19  wherein activating an alert comprises activating a vibratory alert. 
     
     
         31 . The method of  claim 19  wherein activating an alert comprises activating an audible alert. 
     
     
         32 . The method of  claim 19  wherein activating an alert comprises activating an audible alert. 
     
     
         33 . The method of  claim 19  wherein activating an alert comprises activating an alert in the external assembly. 
     
     
         34 . The method of  claim 19  wherein activating an alert comprises activating an alert in the internal assembly. 
     
     
         35 . The method of  claim 19  further comprising retransmitting the data signal after there is an communication error in transmitting the data. 
     
     
         36 . A seizure advisory device, comprising:
 a user interface that comprises an indicator that indicates if the subject is at a low susceptibility to a seizure or a high susceptibility to a seizure; and   an alert that is configured to provide an indication to the subject if the seizure advisory device is out of communication range with an implantable telemetry unit and is unable to accurately communicate the subject's susceptibility to the seizure.   
     
     
         37 . The seizure advisory device of  claim 36  wherein the indication is an audible output. 
     
     
         38 . A method of informing a subject when a seizure advisory device is out of communication range with an implantable device, the method comprising:
 receiving a transcutaneously transmitted data signal indicative of the sampled brain activity signal from an implanted device; and   activating an alert when an expected data signal transmitted from the implanted device is not received by the seizure advisory device.   
     
     
         39 . The method of  claim 38  wherein the seizure advisory device is configured to analyze the data signal to estimate the subject's susceptibility to a seizure. 
     
     
         40 . The method of  claim 38  wherein the implanted device is configured to analyze the data signal to estimate the subject's susceptibility to a seizure and the seizure advisory device is configured to communicate the estimated susceptibility to the subject. 
     
     
         41 . The method of  claim 38  wherein the data signal is transmitted substantially continuously and comprises substantially real-time sampled brain activity signals. 
     
     
         42 . A system for monitoring a subject's susceptibility for having a seizure:
 a sensor adapted to detect a brain activity signal;   an implanted communication assembly in communication with the sensor, the implanted communication assembly configured to sample the brain activity signal with the sensor;   an external assembly that is positioned outside the subject's body that is configured to receive a data signal from the implanted communication assembly and indicate a subject's likelihood of transitioning into a seizure condition;   wherein the external assembly is further configured to alert the subject when there is a communication error between the implanted assembly and the external assembly; and   an input on the external assembly that allows the subject to deactivate an alert function when the subject has a low likelihood of transitioning into the seizure condition.   
     
     
         43 . The system of  claim 42  wherein an alarm deactivation period is less than a time period in which the subject is unlikely to transition into the seizure condition. 
     
     
         44 . The system of  claim 43  wherein the low likelihood of transitioning into the seizure condition comprises a contra-ictal condition. 
     
     
         45 . The system of  claim 44  wherein the deactivation period is 45 minutes and the time period in which the subject is unlikely to transition into the seizure condition is 60 minutes. 
     
     
         46 . The system of  claim 44  wherein the deactivation period is adjustable by the subject up to a maximum time period that does not exceed the time period in which the subject is unlikely to transition into the seizure condition.