EEG Reporting Guidelines and Structure

EEG Reporting Guidelines

• These guidelines are not rigid rules but a general guide for reporting EEGs.
• Guidelines apply to standard EEG recordings, not specialized procedures.
• For specialized procedures (e.g., neonatal records, electrocerebral silence), detailed technical descriptions are needed.
• If the technique used is the one recommended in other ACNS guidelines, a simple statement referencing those guidelines is sufficient.
• The printed form should include minimal patient information, which can be copied from the Basic Data Sheet.
• The report should include the patient’s name and EEG identification number.

EEG Report Structure

• The report consists of three main sections: Introduction, Description, and Interpretation.
• The Introduction should include information about patient preparation, medication, and state of consciousness at the onset of the recording.
• Any medication that could influence the EEG should be included.
• If the number of electrodes is not the standard 21, or if other physiologic parameters are monitored, this should be mentioned.
• The total recording time should be reported if it deviates significantly from the ACNS recommendations.

Describing the EEG

• The Description section should objectively present all characteristics of the record, both normal and abnormal.
• The description should be comprehensive enough for another electroencephalographer to determine the normality or degree of abnormality of the record without viewing the EEG.
• The Description should begin with the background activity, including dominant frequency, quantity, location, amplitude, symmetry, and rhythmicity.
• Use Hertz (Hz) or cycles per second for frequency.
• Amplitude should be determined using adjacent scalp electrodes placed according to the 10-20 System.
• It’s desirable to estimate the mean amplitude in microvolts.
• Enumerate non-dominant activities with their frequency, quantity, amplitude, location, symmetry, and rhythmicity.
• Describe the response to opening and closing eyes and movements of the extremities, noting symmetry, completeness, and duration.
• If no dominant frequency is present (e.g., in abnormal, infant, or sleep recordings), describe all different activities.
• When there’s marked inter-hemispheric asymmetry, describe each hemisphere separately.
• Following the background activity description, describe abnormalities that don’t form part of the background activity.
• Describe the type, distribution, topography, symmetry, synchrony, amplitude, timing, and quantity of abnormal patterns.
• Quantity should be expressed subjectively.
• For episodic abnormalities, describe periodicity, rhythmicity, and duration.
• In the activation procedures section, state the quality of hyperventilation and sleep, and the type and range of frequencies used for photic stimulation.
• Describe the effects of hyperventilation and photic stimulation, including both normal and abnormal responses.
• If these procedures are not done, state the reason.
• Do not include the absence of certain characteristics in the description unless it's the lack of normal features (e.g., low-voltage fast frequencies, sleep spindles).
• Only mention artifacts when they are questionable and could represent cerebral activity, when they are unusual or excessive, or when they provide valuable diagnostic information.

Interpretation

• The Impression section is the interpreter's subjective statement about the normality or abnormality of the record.
• The Impression is written primarily for the referring clinician and should be concise.
• When the record is considered abnormal, grade the abnormality to facilitate comparison between successive records.
• Briefly list the reasons for the conclusion, focusing on the two or three most characteristic abnormalities.
• If previous EEGs are available, make a comparison with previous tracings.
• The Clinical Correlation section should explain how the EEG findings fit (or don't fit) the total clinical picture.
• If abnormalities are present but could be due to medication or other interventions, state this.
• The electroencephalographer should not suggest changes in medication or other clinical approaches.
• The Clinical Correlation section can include recommendations for further EEGs with different activation procedures.
• A normal record generally doesn't require further explanation.
• If clinical information suggests a serious question between conditions (e.g., hysteria and epilepsy), include a clarifying statement.
• Digital recording, reporting, and transmission allow incorporating brief samples of the actual recording, so including examples of abnormalities is desirable.