ACNS Guideline 1 Flashcards
What is the minimum number of EEG channels required for clinical recording?
Sixteen channels.
What EEG electrode system is officially recommended by the IFCN?
The 10–20 system.
What materials are best for EEG electrodes?
Silver-silver chloride or gold disk electrodes.
What is the acceptable impedance range for modern EEG equipment?
Up to 10 kOhms, but balanced impedances are optimal.
What is the recommended duration for a baseline EEG recording?
At least 20 minutes of artifact-free recording.
What should be included in an EEG patient data sheet?
Name, age, date/time, technologist initials, indication for EEG, last seizure, meds, skull defects, medical history.
What is the function of the 60 Hz (notch) filter?
To reduce electrical interference when other methods fail.
What are needle electrodes not recommended for?
Routine clinical use
Due to patient discomfort, risk of injuries, and higher impedances compared to cup electrodes.
What are subdermal needle electrodes (SNE) or wire electrodes (SWE) used for?
Prolonged recording of EEG in stuporous or comatose patients
In situations where cup electrodes are not feasible.
What system is officially recommended by the IFCN for EEG electrode placement?
The 10 to 20 System
It is the most commonly used system and should be used universally.
What is the undesired term used when head measurements have not been made in electrode placement?
Modified 10 to 20 System
The term ‘estimated 10 to 20 placement’ is more appropriate.
What should be placed and connected to the jackbox during EEG recording?
An isolated ground electrode
Prevents dangerous currents from passing.
What is the acceptable range for interelectrode impedances in modern digital EEG recording?
Up to 10 k Ohms
Optimal recording requires balanced impedances.
What should be checked as a routine pre-recording procedure?
Interelectrode impedances
To ensure proper recording conditions.
What is the minimum information that should be included in the EEG record?
Name and age of the patient, date of recording, identification number, name/initials of the technologist
Essential for accurate medical and legal documentation.
What should be done at the beginning of every EEG recording?
Appropriate calibrations
Includes square wave calibration for stability.
What should the sensitivity of the EEG equipment for routine recording be set at?
5 to 10 mV/mm of trace deflection
A common initial sensitivity is 7 mV/mm.
What can happen if the sensitivity is set less than 10 mV/mm?
Significant low-amplitude activity may become undetectable
High sensitivity can obscure normal EEG activity.
What is the role of filtering in digital recordings?
Filtering occurs at two levels: analog filters in the amplifier and digital filters before display
Proper use is crucial for recognizing EEG abnormalities.
What is the recommended low-frequency filter setting for standard recordings?
No higher than 1 Hz
Vital to prevent loss of pathologic activity information.
What should the display duration be for routine EEG recordings?
10 to 20 seconds/page
Corresponds to a paper speed of 30 mm/second.
What is the minimum duration for the baseline record in EEG?
At least 20 minutes of technically satisfactory recording
Longer recordings are encouraged for better detection of abnormalities.
What should the recordings include regarding the patient’s eyes?
Periods when the eyes are open and closed
This helps assess the effect of stimuli on the EEG.
What should be the distance of the lamp during photic stimulation?
At least 30 cm from the patient’s face
Performed in dimmed lighting.
What is the minimum duration for hyperventilation in EEG recordings?
Minimum of 3 minutes
Followed by continued recording for at least 1 minute.
What should be performed before hyperventilation or at least 3 minutes after?
Photic stimulation
Photic stimulation is important for accurate EEG assessment.
Under what conditions should hyperventilation be routinely used?
Unless contraindicated by medical reasons
Examples include recent intracranial hemorrhage, significant cardiopulmonary disease, and patient inability to cooperate.
For how long should hyperventilation be performed?
A minimum of 3 minutes
Recording should continue for at least 1 minute after cessation of overbreathing.
What must be recorded before hyperventilation begins?
At least 1 minute of recording with the same montage
This helps evaluate the effects of the activation technique.
What additional recording should be included on one EEG channel?
A single-channel electrocardiogram (ECG)
This is helpful for assessing spikes, sharp waves, or artifacts.
What are photic stimulation and hyperventilation intended to elicit?
Epileptiform discharges and potentially seizures
Patients should be informed about this possibility in advance.
When should sleep recordings be performed?
Whenever possible, but not to the exclusion of the waking record
Sleep recordings provide additional information about epileptiform discharges.
What effect does sleep deprivation have on EEG results in patients with epilepsy?
Increases the frequency of detection of epileptiform discharges
This can occur even during wakefulness.
What should the technologist note on the EEG recording?
The patient’s level of consciousness and any changes thereof
This includes commands, movements, and seizure activity.
What stimuli should be applied systematically during recordings for stuporous or comatose patients?
Visual, auditory, and somatosensory stimuli
Responses or failures to respond should be noted closely in time.
Who is responsible for recognizing patterns associated with different states of consciousness?
The electroencephalographer
Observations by the technologist can provide interpretative value.
What is essential for assessing awake background activity?
Ensuring the patient is maximally alert for part of the record
This facilitates better EEG assessment.
What should special procedures that are of some risk to the patient be carried out in?
The presence of a qualified physician and adequate resuscitation equipment
Informed consent is also required.
Who interprets the EEG after the recording is completed?
A neurophysiologist
This should be done in a timely manner.
What critical results should the technologist notify the interpreting physician about?
Presence of electrographic or clinical seizures and significant clinical events
Timely notification is crucial for patient care.
What do EEGs for the evaluation of cessation of cerebral function require?
Special procedures and extraordinary precautions
Refer to specific guidelines for these situations.
