MODULE VIII - 1: NORMAL EEG (ADULTS & PEDIATRICS) Flashcards
What are the four main stages of sleep?
The four main stages of sleep are Stage I, Stage II, Slow Wave Sleep (Stage III), and Rapid Eye Movement (REM) sleep.
What are the main characteristics of Stage I sleep?
Stage I sleep is characterized by vertex waves, positive occipital sharp transients of sleep (POSTS), slow rolling eye movements, and a gradual loss of posterior dominant rhythm (PDR) with diffuse attenuation.
What type of eye movements are seen in Stage I sleep?
Slow rolling eye movements are observed in Stage I sleep.
How can you identify POSTS on an EEG?
POSTS appear as positive deflections in the occipital leads with a characteristic “sail-like” shape. They are not epileptiform and can occur in singles or runs throughout sleep stages.
What key EEG features define Stage II sleep?
Stage II sleep is marked by the appearance of sleep spindles and K-complexes, along with the continued presence of vertex waves and POSTS from Stage I.
What are sleep spindles, and what do they indicate?
Sleep spindles are bursts of 12-14 Hz activity arising from the thalamus, indicating the onset of deeper sleep and helping to differentiate Stage II from Stage I sleep.
What is a K-complex and when does it appear?
A K-complex is a high-amplitude, biphasic waveform often followed by a sleep spindle. It appears in response to internal or external stimuli during Stage II sleep.
What EEG features are characteristic of Stage 3, also known as slow wave sleep?
Stage 3 is marked by high-amplitude, synchronized delta waves (0.5-2 Hz), with less organized presence of spindles, K-complexes, and POSTS from earlier stages.
What is the significance of Slow Wave Sleep?
Slow Wave Sleep is associated with physical restoration and recovery, and it is considered the deepest stage of non-REM sleep.
What are the main characteristics of REM sleep (often referred to as Stage 4)?
REM sleep is marked by low-amplitude, mixed-frequency brain activity, rapid eye movements, muscle atonia (loss of muscle tone), and irregularities in heart rate and breathing.
What physiological changes are common during REM sleep?
REM sleep is characterized by rapid eye movements, loss of muscle tone, mild cardiac irregularity, and fluctuations in breathing.
What role do the rapid eye movements play in identifying REM sleep on an EEG?
Rapid eye movements create opposing frontal waveforms on the EEG, with positive waves on the side of the gaze direction and negative waves on the opposite side, helping to confirm REM sleep.
