Fisch EEG Primer Chapter 5 Flashcards
The product of the recording: the clinical EEG record
Guidelines used in obtaining EEGs are established by
The American Clinical Neurophysiology Society
What is the minimum number of electrodes to be placed according to the international 10-20 system
21, electrodes should be silver chloride, gold, or equivalent and should ALL be composed of same material to avoid electrical interference from mismatch
What is the accepted range of electrical contact impedence at each electrode
100 - 5000 ohms tested at approximately 10Hz
The EEG recording should have what minimum number of channels?
8, but preferably more than 16, correctly localizing increases with number of channels
Amplifier sensitivity should usually be set between…
5-10 microV/mm and then adjusted as necessary - typically 7microV/mm
Low frequncy filters should initally be set to…
1Hz
High frequency filters should initally be set to…
70Hz
Routine calibration should be performed at what phase of recording?
Beginning and end by calibration pulses (square wave pulses), an electrode test, and from cerebral activity (biocalibration) of same elctrode pair tested in all channels.
Paper speed is routinely set to what speed?
3cm/s (30mm/s)
The required duration of artifact-free wakefulness that should be obtained…
20 minutes (each montage minimum of 2 minutes) - wakefulness should be demostrated by asking alerting questions (date, calculation, etc) and recording answers in corresponding record.
Activating procedures such as hyperventilation, photic stimulation and sleep should be performed in every case where…
seizure is suspected
All EEG recordings need to include which pertinent demographic data/record data?
name, age, date and time of recording, gestational/conceptional age (children), meds, cranial defects, instrument settings, any patient behavior that may influence recording!!
Newborn recordings typically require…
1 hours of recording to include quiet and active sleep, fewer number of elctrodes, adjusted sensitivity and filter setting for higher amplitude and slower potentials
Electrocerebral Inactivity (ECI)/Electrocerbral Silence (ECS) - standards for suspected cerebral brain death ()
- no EEG activity over 2microV with scalp electrodes 10cm apart for at least 30 minutes, filters 1Hz/>30Hz, impendences 100 to <10,000 ohms
- absent drugs/sedatives, hypothermia, or ciruclatory shock
EEG transmission by telephone requires…
-1 fully trained technician and1 fully equipped EEG instrument at both the transmitting and receiving sites
