Classification of Parasomnias

Curr Sleep Medicine Rep (2016) 2:45–52 DOI 10.1007/s40675-016-0039-y PARASOMNIAS (A AVIDAN, SECTION EDITOR) Classification of Parasomnias Louis Kazaglis 1,2 & Michel A. Cramer Bornemann 3,4 Published online: 30 March 2016 # Springer International Publishing AG 2016 Abstract Parasomnias, or undesirable events accompanying sleep, encompass a broad spectrum of behaviors and experiences. Classification of parasomnias has undergone a significant transformation in the International Classification of Sleep Disorders Third Edition. Underlying this new classification is the understanding that Wake, NREM sleep, and REM sleep are not mutually exclusive states. Recent advances in neuroscience support the State Dissociation paradigm which would allow for an unstable admixture of components of these states to coexist. Parasomnias are the clinical manifestation of this state instability. This article briefly reviews the characteristics, demographics, and pathophysiology of the core parasomnias and associated disorders, with emphasis on disorders of arousal and diagnosis and prognostic significance of REM sleep behavior disorder. Keywords Confusional arousals . Disorders of arousal . Parasomnia . REM sleep behavior disorder . Sleep terrors . State dissociation Introduction Parasomnias, or undesirable events accompanying sleep, encompass a broad spectrum of behaviors and experiences. Classification of parasomnias has undergone a significant transformation in the most recent iteration of the International Classification of Sleep Disorders (ICSD). Parasomnias can be best understood using the State Dissociation paradigm. This article briefly reviews the characteristics, demographics, and pathophysiology of the core parasomnias and associated disorders, with emphasis on Disorders of Arousal and REM sleep behavior disorder. This article is part of the Topical Collection on Parasomnias Background * Michel A. Cramer Bornemann The word parasomnia derives from the Greek prefix para, meaning alongside of, combined with the Latin noun somnus for sleep, to account for the dictionary definition of events that accompany sleep. In the clinical setting, the term thereby relates to undesirable events that accompany sleep. Accordingly, parasomnias encompass a broad spectrum including dreaming, misperceptions, dysphoric emotions, abnormal sleep-related movements as well as behaviors, and dysregulated autonomic nervous system functioning. Parasomnias become clinical disorders as they may result in sleep fragmentation, adverse health effects, troublesome psychosocial effects, and even injuries. The latter may have potential forensics implications. Consequently, addressing safety is often an initial goal as the clinical impact may involve more Louis Kazaglis 1 Minnesota Regional Sleep Disorders Center, Hennepin County Medical Center, 701 Park Avenue, G8.320, Minneapolis, MN 55415, USA 2 Department of Medicine, School of Medicine, University of Minnesota, Twin Cities, MN, USA 3 Olmsted Medical Center, Rochester Northwest, 5067 55th Street NW, Rochester, MN 55901, USA 4 Sleep Medicine Fellowship, Minnesota Regional Sleep Disorders Center, Hennepin County Medical Center, Minneapolis, MN, USA 46 than just the patient, depending upon the complexity and duration of the sleep-related behaviors. Parasomnias have long been defined in the International Classification of Sleep Disorders (ICSD) as undesirable physical events or experiences that occur during entry into sleep, within sleep, or during arousals from sleep. Furthermore, parasomnias may occur during non-rapid eye movement sleep (NREM), rapid eye movement sleep (REM), and during transitions to and from sleep. However, such a definition, though technically correct, is overly simplistic, open for misinterpretation, and vulnerable for misapplication. In an age in which an inquisitive mind may almost immediately satiate their thirst for knowledge with the stroke of a few keypads when interacting with an internet search engine, healthcare providers must remain vigilant concerning web-based information that are often uncritically accepted by patients. The general public and popular media continue to be captivated by the belief that the unconscious mind, in either a state of hypnosis or sleep, may reveal itself in words, mental images, or behaviors though its meaning is kept at a distance from the conscious mind through a barrier of repression. Various avenues for the interpretation into dreams have evolved based upon the premise that behaviors and/or experiences which arise from the platform of sleep are the result of a breakdown of psychic censorship and may thereby provide insight into the machinations of the unconscious mind. Such BDream Theory,^ including that developed by Sigmund Freud, which may masquerade in subtle forms including that as Bwish fulfillment,^ especially when applied to parasomnias has been supplanted by modern neuroscientific constructs that are driven by rigorous methodology that require hypotheses that are both testable and verifiable. As such, the human condition is now understood to be comprised of three essential states: Wake, NREM sleep, and REM sleep. It is the dynamic interplay of these three states which can account for previously difficult to explain human experiences. Nevertheless, the pseudoscience of certain aspects of BDream Theory^ continues to hold sway over the general public as supported by the everlasting success of dream interpretation manuals and the belief in the metaphorical significance of dream symbolism. Particularly in cases with legal implications, it is important to recognize when older, now discredited, paradigms for understanding human behavior remain in play. Recent advances in neuroscience coupled with refined neurodiagnostic imaging modalities now reveal that the three states are modulated by a host of physiologic influences including the degree of aminergic and cholinergic neurochemical bias, CNS activation, and the degree of endogenous vs. exogenous input. Directly influenced by regularly recurring physiologic conditions including homeostatic drive and circadian rhythmicity, the process of state declaration is most often maintained in a stable and predictable fashion throughout a 24-h period. However, as the components of sleep frequently Curr Sleep Medicine Rep (2016) 2:45–52 oscillate, it is not unexpected that the brain with its estimated 85-100 billion neurons [1] may experience brief episodic electrochemical switching errors. In such situations, sleep and wake may be abruptly rendered into a state that is not yet fully declared and in a temporary unstable state of dissociation. Thus, sleep and wake, as well as its associated consciousness and unconsciousness, are not dichotomous states as they occur on a spectrum and are evanescent [2]. The most current version of the International Classification of Sleep Disorders (ICSD third Edition) now recognizes State Dissociation as the (...truncated)