phase reversal
EEG pattern where a signal changes polarity across adjacent electrodes, indicating the location of electrical activity.
Full Definition
Phase reversal is an EEG phenomenon that occurs when an electrical field generated by brain activity causes the voltage to be positive at one electrode and negative at an adjacent electrode, creating a polarity reversal in the recorded signal. This pattern appears as a characteristic "phase reversal" or "polarity inversion" when viewing EEG tracings in a referential montage. Phase reversals are crucial for localizing the source of electrical activity, particularly epileptiform discharges, as they indicate that the generator is located between or near the electrodes showing the reversal. Accurate identification of phase reversals requires understanding of electrode placement and montage configuration.
Usage
Usage note: Hyphenate when used as compound adjective; separate when used as noun phrase.
In Context
- "The spike showed clear phase reversal between F7 and F8 electrodes." — EEG interpretation report
- "Phase reversal analysis localized the seizure onset to the right temporal region." — Epilepsy monitoring unit report