The Normal Adult EEG in Sleep

Practice vocabulary flashcards covering the characteristics and transients of normal adult EEG during drowsiness and sleep stages.

EEG Stage I and Stage II Sleep

Stages where regional epileptiform discharges and regional slowing often first appear or are increased.

Drowsiness Clues

Identified by the absence of eye blinks, presence of slow lateral eye movements, slowing or dropout of the PDR, increased theta, frontal beta, and bursting hypersynchronous delta.

PDR

Posterior Dominant Rhythm; its slowing, fragmentation, and ultimate disappearance occurs during drowsiness and Stage 1 sleep.

Stage 1 Sleep

A sleep stage characterized by diffuse theta activity and the appearance of vertex waves and Positive Occipital Sharp Transients of sleep (POSTs).

Vertex waves (V waves)

Episodic, sharply contoured potentials less than $200\,ms$ in duration, maximal over the central regions, which may be spike-like or occur in rhythmic runs.

POSTs

Positive Occipital Sharp Transients of sleep; these are electropositive sharp waves located in the occipital region and may be mono- or biphasic.

Stage 2 sleep

Defined by the appearance of well-defined sleep spindles and K-complexes.

Sleep spindles

Sinusoidal waves occurring at $12\text{--}14\,(\pm 2)\,Hz$ in the central regions; brief or fragmentary spindles suggest the patient is not yet firmly in Stage II.

K-complexes

High-voltage, synchronous bi- or triphasic slow potentials greater than $500\,ms$ in duration, usually with central or bifrontal preponderance; they can be evoked by sudden auditory stimuli.

Slow Wave Sleep (SWS)

Sleep characterized by increasing amounts of diffuse delta activity and the progressive disappearance of sleep spindles.

REM sleep

Rapid eye movement sleep characterized by loss of muscle tone, low-voltage theta activity, and irregular vertical and horizontal eye movements.