Review Note

Last Update: 04/01/2024 02:30 AM

Current Deck: Neurology::Epilepsy::EEG

Published

Benign epileptiform transients of sleep (BETS):

Occur in stage {{c1::1 or 2 NREM}} sleep.
usually {{c2::monophasic::phase}}, occasionally {{c2::diphasic::phase}}.
{{c3::temporal}} with broad field of distribution
There is typically no disturbance of {{c5::the background}}, although there is sometimes a single aftergoing slow wave.
Typically less than 50 mV and less than {{c4::50::#}} milliseconds

Etiology: Benign finding in healthy individuals.
Mechanism: Unknown, may represent increased excitability of temporal cortex.
Progression: BETS are common incidental findings that do not require intervention.
Monophasic refers to a waveform that has a single phase or deflection from baseline. For example, a positive monophasic spike would show an initial deflection in the positive direction without a negative phase following it [2].
Diphasic refers to a waveform with two phases or deflections from baseline. A diphasic spike would have both a prominent positive and negative component, such as an initial positive spike followed by a negative phase [2].
On EEG, monophasic and diphasic can describe the morphology of epileptiform discharges, sleep patterns like vertex waves, or various waveforms encountered during routine EEG interpretation [2][5][6].
Determining if a waveform is monophasic or diphasic provides information about the underlying neurophysiological generators and assists in distinguishing normal versus abnormal patterns [2]. For example, the vertex waves of stage 1 sleep are classically described as "diphasic sharp transients" with an initial negative component followed by a positive phase [5].
In summary, the terms monophasic and diphasic indicate whether an EEG waveform has a single phase/peak or two distinct phases, which aids in identifying and characterizing EEG patterns [2][5][6].