Positive Occipital Sharp Transients of Sleep (POSTS) and cone waves are both EEG patterns observed during sleep, but they have distinct characteristics, clinical significance, and implications.
Positive
Occipital Sharp Transients of Sleep (POSTS)
1.
Definition:
§ POSTS are
sharp waveforms that occur predominantly in the occipital region during sleep, particularly
in non-rapid eye movement (NREM) sleep.
2.
Waveform Characteristics:
§ They
typically exhibit a triangular shape and can be monophasic or diphasic. The
positive peak is prominent, followed by a negative potential of lower
amplitude.
3.
Location:
§ Recorded
primarily from the occipital leads (O1 and O2) of the EEG. They may also show
phase reversals at these electrodes.
4.
Duration and Frequency:
§ Each
transient lasts about 80 to 200 milliseconds and can occur as individual events
or in trains of up to six per second. The trains usually last about 1 to 2
seconds.
5.
Clinical Significance:
§ Generally
considered a normal variant in healthy individuals, especially in children and
adolescents. They are not associated with any pathological conditions and are
common in the EEGs of healthy adults.
6.
Age-Related Variability:
§ More
prevalent in younger populations and become less common with age. Rarely
observed in individuals over 70 years old.
Cone
Waves
7.
Definition:
§ Cone
waves are a type of EEG pattern that can be observed during sleep,
characterized by a specific morphology that resembles a cone or a pointed
shape.
8.
Waveform Characteristics:
§ Cone
waves typically have a more pronounced peak and a rapid return to the baseline,
creating a sharp, pointed appearance. They may not have the same triangular
shape as POSTS.
9.
Location:
§ Cone
waves can be recorded from various regions of the scalp, not limited to the
occipital area. Their distribution may vary depending on the underlying
condition or the specific context in which they are observed.
10.
Duration and Frequency:
§ The
duration and frequency of cone waves can vary, and they may not follow the same
patterns of occurrence as POSTS. They can appear in bursts or as isolated
events.
11. Clinical
Significance:
§ Cone
waves may be associated with specific neurological conditions or sleep
disorders, and their presence can indicate underlying pathology. Unlike POSTS,
they may not be considered a normal variant and could warrant further
investigation.
12. Age-Related
Variability:
§ The
occurrence of cone waves may not have the same age-related patterns as POSTS,
and their clinical significance can vary widely based on the context in which
they are observed.
Summary
In
summary, while both Positive Occipital Sharp Transients of Sleep and cone waves
are EEG patterns observed during sleep, they differ significantly in their
characteristics, clinical implications, and associations with neurological
conditions. POSTS are generally benign and common in healthy individuals, while
cone waves may indicate underlying pathology and require careful interpretation
in the context of the patient's clinical picture.
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