Introduction: The behavior disorder occurring during REM (Rapid Eye Movement) sleep is a parasomnia characterized by absence of atonia typical of this phase of sleep, although the other characteristics are maintained, namely rapid eye movements and desynchronization of cortical electrical activity. Clinically it is accompanied by abrupt, often violent movements, which may involve a limb or the trunk in relation to dreams typical of this phase of sleep, and which may interrupt sleep. Many pathological processes have been described, including: the Shy-Dragger syndrome, Parkinson's disease, olivopontocerebellar atrophy, multisystemic atrophy, in relation to certain antidepressant drugs, and most frequently the idiopathic form.
Clinical cases: We present two cases, one diagnosed as olivopontocerebellar atrophy and another in which there were no pathological findings. Both were referred to our department for the study of possible sleep disorders. In both cases neurophysiological studies, basically polysomnography with monitorization of various muscle groups and video, led to the diagnosis.
Conclusions: We discuss the diagnostic and physiological criteria, and physiopathological explanations of each case, with special reference to N-Methyl-D-Aspartate (NMDA) and non-N-Methyl-D-Aspartate (non-NMDA) receptors. Finally we consider the pharmacological treatment of this disorder.