Multi-channel brain or cortical activity monitoring and method

Abstract

The present invention relates to a quantitative electroencephalogram (QEEG) monitor and system capable of monitoring and displaying simultaneously neuropathological characteristic and activity of both sides of a subject's brain. The methods include various indices and examination of differences in these indices by which neurophysiological conditions or problems can be identified and treated. These methods, and the systems and devices using these methods preferably can be used for identifying these neurophysiological conditions or brain dysfunction with monitors and methods for seizure detection, for sedation monitoring, for anesthesia monitoring, and the like. These bilateral brain monitoring methods and systems, and the devices using these methods can be used by individuals or clinicians with little or no training in signal analysis or processing. These bilateral monitoring methods can also be used in a range of applications.

1 - 20 . (canceled) 
     
     
         21 . A method of detecting a change in subject status with a device for quantifying brain or cortical activity in the subject as a function of depth of sedation or anesthesia comprising the steps of:
 a. anesthetizing or sedating a subject;   b. monitoring the subject with a brain having a left hemisphere and a right hemisphere, the subject under anesthesia or sedation and being monitored with a device for quantifying brain or cortical activity as a function of depth of sedation or anesthesia, the device with at least two measurement electrodes, and at least one reference electrode, the at least two measurement electrodes comprising at least one electroencephalogram (EEG) electrode, having a signal, positioned to monitor left hemisphere brain or cortical activity and at least one EEG electrode, having a signal, positioned to monitor right hemisphere brain or cortical activity of the subject's brain, the reference electrode comprising at least one EEG electrode, each electrode providing an EEG analog signal which is subsequently converted to a digital signal;   c. measuring the brain or cortical activity of both the subject's left and right brain hemispheres essentially simultaneously over a period of time part of the period of time over which the subject is under sedation or anesthesia;   d. calculating based in part on the digital signals with the processor at least one numerical quantitative electroencephalogram (QEEG) time-series index corresponding to the brain or cortical activity as a function of depth of anesthesia or sedation of each of the left and right hemispheres of the subject's brain over the period of time part of which the subject is under sedation or anesthesia;   e. displaying the at least two numerical time-series indices, with at least one numerical time-series index corresponding to the brain or cortical activity of each of the left and the right hemispheres over the period of time part of the period of time which the subject is under sedation or anesthesia on a monitor simultaneously;   f. comparing the numerical time-series indices of each hemisphere's cortical activity as a function of depth of anesthesia or sedation; and   g. determining based on the calculated indices for each hemisphere whether differences between the brain or cortical activity of one hemisphere of the brain is indicative of a change in subject status when compared to the brain or cortical activity of the other hemisphere of the brain of the subject.   
     
     
         22 . The method of  claim 21  wherein the change in subject status corresponds to a reaction of the subject following noxious stimulation. 
     
     
         23 . The method of  claim 21  farther comprising an additional step, the additional step is comparing the calculated numerical brain or cortical activity indices for each of the subject's brain hemispheres and determining, based at least in part on the differences between the at least two numerical QEEG time-series indices, whether the signal of one or more of the EEG electrodes has poor signal quality. 
     
     
         24 . The method of  claim 21  further comprising an additional step, the additional step is comparing the calculated numerical brain or cortical activity time-series indices for each of the subject's brain hemispheres and determining whether the subject has suffered, or is suffering some neuropathological activity based on differences between the indices. 
     
     
         25 . The method of  claim 21  wherein the indices are calculated using a wavelet transform or a Fast Fourier transform. 
     
     
         26 . The method of  claim 21  further comprising an additional step, the additional step is treating the subject by administrating a drug or therapeutics to said subject based on a comparison by a processor, clinician or physician of at the least two quantitative electroencephalographic time-series indices corresponding to the brain activity as a function of depth of anesthesia or sedation of the brain region of the subject. 
     
     
         27 . A method for comparative electroencephalography in monitoring brain function as a function of anesthesia or sedation in a plurality of distinct brain regions of the same subject on a continuous and substantially concurrent basis, comprising the steps of:
 a. applying at least one electroencephalographic measurement electrode at each of said plurality of brain regions, and applying at least one reference electrode, and coupling each measurement and reference electrode to a control and processing system;   b. continuously acquiring an analog electroencephalographic signal from each of said electroencephalographic measurement electrodes;   c. converting the analog electroencephalographic signal from each of said electroencephalographic measurement electrodes to a digital signal;   d. separately and concurrently calculating for each said digital electroencephalographic signal at least one numerical quantitative electroencephalographic time-series index representative of the brain activity as a function of depth of anesthesia or sedation of the brain region corresponding to the measurement electrode;   e. concurrently visually displaying on a monitor at least one numerical quantitative electroencephalographic time-series index for each of at least two distinct brain regions; and   f. administrating a drug or therapeutics to said subject based on a comparison by a processor, clinician or physician of the at least two quantitative electroencephalographic time-series indices corresponding to the brain activity as a function of depth of anesthesia or sedation of the brain region.   
     
     
         28 . The method of  claim 27  further comprising an additional step, the additional step is comparing the at least two quantitative electroencephalographic time-series indices corresponding to the brain activity as a function of depth of anesthesia or sedation of each brain region and determining, based at least in part on the differences between the at least two quantitative electroencephalographic time-series indices, whether the signal of one or more of the EEG electrodes has poor signal quality. 
     
     
         29 . The method of  claim 27  further comprising an additional step, the additional step is comparing the at least two quantitative electroencephalographic time-series indices corresponding to the brain activity as a function of depth of anesthesia or sedation of each brain region and determining, based at least in part on the differences between the at least two quantitative electroencephalographic time-series indices, whether the subject has suffered, or is suffering some neuropathological activity based on differences between the indices. 
     
     
         30 . The method of  claim 27  wherein the indices are calculated using a wavelet transform, a spectral process or a Fast Fourier transform. 
     
     
         31 . A method for quantifying brain or cortical activity in the subject as a function of depth of anesthesia comprising the steps of:
 a. anesthetizing a subject;   b. monitoring the subject having a brain with a left hemisphere and a right hemisphere, the subject under anesthesia, and the monitoring with a device having at least two measurement electrodes, and at least one reference electrode, the at least two measurement electrodes comprising at least one electroencephalogram (EEG) electrode, having a signal, positioned to monitor left hemisphere brain or cortical activity and at least one EEG electrode, having a signal, positioned to monitor right hemisphere brain or cortical activity of the subject's brain, the reference electrode comprising at least one EEG electrode, each electrode providing an analog EEG signal which is subsequently converted to a digital signal;   c. measuring the brain or cortical activity of both the subject's left and right brain hemispheres essentially simultaneously over a period of time part of the period of time over which the subject is under anesthesia;   d. calculating based in part on the digital signals with the processor at least one numerical quantitative electroencephalogram (QEEG) time-series index using a wavelet transform or a Fast Fourier transform, and corresponding to the brain or cortical activity as a function of depth of anesthesia of each of the left and right hemispheres of the subject's brain, over the period of time part of period of time which the subject is under anesthesia; and   e. displaying simultaneously at least one numerical time-series index corresponding to the brain or cortical activity of each of the left and right hemispheres over the period of time on a monitor.   
     
     
         32 . The method of  claim 31 , further including an additional step of treating the subject by administrating a drug or therapeutics to said subject based on a comparison by a processor, clinician or physician of at the least two quantitative electroencephalographic time-series indices corresponding to the brain activity as a function of depth of anesthesia or sedation of the brain region of the subject. 
     
     
         33 . The method of  claim 32 , wherein the treating of the subject is done by the administration of the drug using the processor, which is a closed loop processor. 
     
     
         34 . The method of  claim 33 , wherein the closed loop processor utilizes a least risk approach based on the calculated QEEG indices corresponding to each and both the right and left hemispheres of the subject's brain. 
     
     
         35 . The method of  claim 31 , further comprising an additional step, the additional step comparing the calculated numerical brain or cortical activity indices for each of the subject's brain hemispheres and determining, based at least in part on the differences between the at least two numerical QEEG time-series indices, whether the signal of one or more of the EEG electrodes has poor signal quality. 
     
     
         36 . The method of  claim 31 , further comprising an additional step, the additional step comparing the calculated numerical brain or cortical activity time-series indices for each of the subject's brain hemispheres and determining whether the subject has suffered, or is suffering some neuropathological activity based on differences between the indices. 
     
     
         37 . The method of  claim 31 , wherein the indices are calculated using a wavelet transform or a Fast Fourier transform. 
     
     
         38 . The method of  claim 37 , wherein a bispectral index is calculated utilizing a Fast Fourier transform. 
     
     
         39 . The method of  claim 31 , further including notifying a caregiver to identify when the subject requires attention or there is a potential problem with the device. 
     
     
         40 . The method of  claim 39 , wherein the caregiver is notified by a message, a signal or a combination.