Criteria's of Low-Voltage EEG and Electrocerebral Inactivity

The criteria for low-voltage EEG and electrocerebral inactivity (ECI) are essential for accurate diagnosis and interpretation in clinical settings. Here are the key criteria for each:

Low-Voltage EEG Criteria

1. Definition: Low-voltage EEG is characterized by the persistent absence of any cerebrally generated waves greater than 20 µV 33.

2. Clinical Context: Low-voltage activity can occur in various contexts and may not be specific to any particular condition. It can be a normal variant, especially in older adults, but may also indicate pathological conditions 34.

3. Common Causes: Low-voltage EEG may be associated with degenerative diseases (e.g., Alzheimer's, Huntington's disease), metabolic disturbances, or extrinsic factors like scalp edema 34, 34.

Electrocerebral Inactivity (ECI) Criteria

4. Definition: ECI is defined as the absence of any detectable electrical activity in the brain, with no potentials greater than 2 µV when reviewed at a sensitivity of 2 µV/mm 33.

5. Recording Standards: To confirm ECI, the following criteria must be met:

§ Electrode Coverage: At least eight scalp electrodes must be used, covering midline and at least one ear.

§ Impedance: Electrode impedances should be between 0.1 and 10 kΩ.

§ Interelectrode Distance: Distances between electrodes should be at least 10 cm.

§ Sensitivity: The sensitivity of the EEG recording should be set to 2 µV/mm.

§ Filters: Low-frequency filter should be set to 1 Hz or less, and high-frequency filter should be set to 30 Hz or greater.

§ Technologist Testing: Each electrode must be tested by physical manipulation to ensure proper function.

§ Stimulation: The patient should undergo somatosensory, auditory, and visual stimulation during the recording.

§ Duration: The EEG must be recorded and reviewed for at least 30 minutes.

§ Additional Electrodes: Electrodes on extracerebral sites, including the chest for ECG, should be included.

§ Qualified Personnel: The recording must be conducted by a qualified EEG technologist 33.

Summary

Both low-voltage EEG and ECI have specific criteria that must be adhered to for accurate diagnosis. Low-voltage EEG indicates reduced brain activity, while ECI signifies a complete absence of detectable brain activity. Understanding these criteria is crucial for clinicians in assessing neurological function and determining prognosis.

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