However, some research indicates that the muscle atonia in cataplexy may not be related to the sudden onset of REM sleep.
Because the atonia of the cataplexy remained despite the cyclicity of the REM sleep state, Ninshino concluded that the onset of REM sleep was not associated with muscle atonia in cataplexy, and therefore the mechanisms that induce muscle atonia in cataplexy may differ from mechanisms that induce ationia with the onset of REM sleep.
Suppression of hypoglossal motoneurons during the carbachol-induced atonia
of REM sleep is not caused by fast synaptic inhibition.
1,2,22] The muscle atonia
in cataplexy and sleep paralysis is physiologically similar to the atonia
occurring normally during REM sleep.
These must be coupled with intermittent or persistent electromagnetic augmentation during REM sleep, signifying a loss of atonia, Dr Schenck said.
Forty-six patients had REM sleep without atonia on polysomnographic testing and of these, 45 had synucleinopathies.
REM sleep behaviour disorder is characterized by the intermittent loss of REM atonia
due to disinhibition of normally inhibitory mid-brain projections to spinal motor neurons.
With the generalized muscle atonia
associated with REM sleep, this accessory muscle activity is lost (45), resulting in reduced minute ventilation (2).
SSRIs are also associated with increased frequency of PLMS as well as REM sleep without atonia
Further, as early as day two postnatal, myoclonic twitching can be seen occurring exclusively in conjunction with muscle atonia, which indicates that electrophysiological parameters can be used to characterize different stages of sleep (35).
The tonic events associated with REM sleep includes desynchronization of the cortical EEG, theta rhythm in the hippocampus and muscle atonia.
The other hallmarks of REM sleep are EMG atonia
and the occurrence of rapid eye movements.