ELEMENTS OF NORMAL SLEEP ACTIVITY - K COMPLEXES

SYNONYM = K WAVE
Shape
Consist of an initial sharp component, followed by a slow component that fuses with a superimposed fast component. It may or may not be followed by sleep spindles. It is easily differentiated from vertex waves by longer duration and greater complexity and variation.

Amplitude
More than 200 µv in monopolar

Duration
More than 500 ms

Distribution
Frontal and vertex region

Persistence
They are seen at irregular intervals in stages 2, 3 and 4 of NREM sleep.

Synchrony
Bisynchronous

Miscellaneous

1. V waves and K complexes appear in well developed from for the first time at the age of 5-6 months.


2. They can be elicited during sleep by sensory stimulation (particularly auditory). The positive component usually occurs 0.75 seconds after the stimulus.

Reference:

1. Fisch BJ. Spehlmann’s EEG primer, Amsterdam: Elsevier, 3rd edition


2. Niedermeyer E, Lopes da Silva F. Electroencephalography: basic principles, clinical applications and related fields, Baltimore, Maryland: Williams and Wilkins, 4th edition


3. Stern JM, Engel J. Atlas of EEG patterns, Philadelphia: Lippicott Willams & Wilkins