Surgery – Truss – Pad
Patent
1990-08-02
1993-01-26
Kamm, William E.
Surgery
Truss
Pad
36441305, A61B 50476
Patent
active
051815206
DESCRIPTION:
BRIEF SUMMARY
This invention relates to the analysis of an electro-encephalogram (EEG). The invention enables a computer to be used for part of the analysis.
The EEG is a long-established technique for recording spontaneous electrical brain activity using electrodes attached to the scalp of the subject. Its use in connection with monitoring the development of, for example, new born infants and especially premature new born infants has enabled the brain development of the infants to be monitored during the neonatal period. In recent years, small magnetic tape cassette recorders, such as the Oxford Medical Ltd.'s Medilog 4-24, have been used to record up to 24 hours of EEG data on two channels from very small sick babies, because the small size of the recorder has enabled it to be placed in a neonatal intensive care unit without interfering with the other apparatus used in such units. Such recorders provide enormous amounts of data for retrospective analysis, at present performed by replaying a tape on to a visual display unit at, for example, 20 or 60 times its recorded speed. This enables a 24 hour recording to be reviewed in a minimum of 24 minutes and can enable a specialist to detect abnormalities in the EEG and to take necessary remedial action. The EEG can also be printed while it is being displayed to enable the specialist to return to parts of the EEG which he suspects reveal abnormalities. An obvious disadvantage of this system is its retrospective nature, but it also suffers the disadvantage that the specialist is occupied for long periods of time reviewing the EEG traces.
Although gross abnormalities in an EEG, such as convulsions or periods of substantially no activity can be quickly detected by the specialist observing the visual display, the EEG can also reveal more subtle, though still very important, information after longer and expert analysis of the printed trace of the EEG. The visual analysis is based on several well recognized features such as the frequency and amplitude of the waveforms, the symmetry and synchrony of discharges from the right and left sides of the brain, and the presence of abnormal discharges such as convulsions.
In contrast to the normal adult EEG which shows continuous electrical activity, the EEG of premature infants is characterized by short bursts of activity, sometimes of less than 5 seconds duration, interspersed with intervals of very reduced or apparently absent electrical activity. The intervals between the bursts, which may last for 60 seconds or more, are of significance in that they can show the increasing maturity of the infant brain as the activity becomes more continuous with longer bursts and shorter intervals. Prolonged intervals relative to the age of the infant can be associated with intracranial hemorrhage or hypoxic brain damage. Obviously the more rapidly that the EEG can be analyzed, the sooner remedial action can be taken when required and possibly the severity of damage to the brain reduced.
The EEGs of older children and adults may also display intervals of reduced or apparently absent electrical activity due to the effects of drugs, anesthetics or injury.
It is an object of the present invention to provide an improved method and apparatus for the analysis of EEGs.
According to one aspect of the present invention there is provided apparatus for analyzing an electro-encephalogram (EEG) including input terminals for at least one electrical signal derived from the EEG, comparator means for comparing a representation of the magnitude of the electrical signal with a threshold level and producing an indication whenever the representation of the electrical signal reaches the threshold level, timing means for measuring the time intervals between successive indications produced by the comparator means, and producing output values representing the time intervals, selecting means for selecting only those of the output values that represent time intervals longer than a predetermined minimum time period, adding means for accumulating the selected output values represe
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Brydon John W. E.
Connell John A.
Dubowitz Victor
Oozeer Rowena C.
Wertheim David F. P.
Kamm William E.
Pontius Kevin
Royal Postgraduate Medical School
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