P wave: upright in leads I, aVF and V3 - V6. All the important intervals on this recording are within normal ranges. In REM sleep one can also see some mild cardiac irregularity and breathing fluctuations, and muscle activity should be absent throughout this stage. Note that the heart is beating in a regular sinus rhythm between 60 - 100 beats per minute (specifically 82 bpm). Thus, opposing frontal waveforms are seen: a positive wave on the side to which you're looking, and a negative wave on the opposite side. These waves arise because the cornea is positively charged, so when a patient looks to their right, the right eye cornea moves closer to the F8 electrode, leading to a positive charge seen at F8 at the same time on the left side, the left eye's cornea moves away from the F7 electrode, leading to a negative charge seen at F7. It derives its name from the rapid eye movements that arise and, on EEG, are seen as very sharply contoured, opposing waveforms (with the upslope usually faster than the downslope) in the left and right frontal regions. It is marked by a diffuse attenuation of amplitudes, with a range of frequencies amongst the background that can look similar to an awake state. If you have symptoms that are recurrent, despite having a normal EEG, you may benefit from a prolonged or ambulatory EEG. Rapid eye movement, or REM sleep, increases in frequency across the span of the night. In children, vertex waves can be scary looking but still remain normal, as discussed in the pediatric section. They can come alone or in runs of varying amplitude and morphology, but even when they appear very sharp or high amplitude they are not epileptiform. POSTS have a cousin in the awake state called lambda waves, which are discussed in the artifact section.Īlso found in stage I sleep are vertex waves, which are bilateral phase reversing discharges over the central regions.
1979) were made independent of EEG evaluations for 34 normal EEG and 39. They arise in stage I sleep, but can persist throughout the later stages of sleep. EEG studies of tardive dyskinesia (TD) have not been common and certainly they. Classically, they have a "sail-like" appearance, and can come in singles or runs. POSTS are a very descriptive waveform, as they are positive deflections seen in the occipital leads that look like sharps, but are not epileptiform, as seen below. Stage I sleep is somewhere along the spectrum from drowsiness to being fully asleep, and is marked most easily by the appearance of drowsiness (decreased eye blinks, slow roving eye movements as discussed in the awake section), then a gradual loss of the PDR with coinciding diffuse attenuation of the tracing, and finally the presence of positive occipital sharp transients of sleep (POSTS) and vertex waves.
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