The preservation of muscle tone during REM phases is the single most important symptom of RBD. It entails involuntary myoclonic jerks throughout the body as well as movements of limbs and head, likely resembling motor dream enactment [6]. Affected individuals execute possibly aggressive or violent motions that may lead to self-injury, harm to third parties and damage to objects [7]. More complex presentations have also been described. Patients may gesture, punch, kick, sit up or leap from bed, grab somebody or something [8]. Their behavior is generally unintentional and not directed against a determined person or item. They may or may not wake up and recall their vivid dreams. Fatigue and excessive daytime sleepiness are a common consequence of RBD [9].

Ventilation is usually not affected.

• Nocturnal Awakening

  […] that fall down (6.4); items 7 and 8, nocturnal awakenings; item 9, general disturbances of sleep; and item 10, the presence of any neurological disorder. [bmcneurol.biomedcentral.com]

• Nocturia

  Sedating medications should be ceased and obstructive sleep apnea, primary sleep disorders, and nocturia should be ruled out. Caffeine is a useful treatment in those without periodic leg movement disorder of sleep or restless leg syndrome [ 95 ]. [doi.org]

• Somnambulism

  Somnambulism Sitting, walking, or other complex behaviors occur during sleep, usually with the eyes open but without evidence of recognition. [merckmanuals.com]

  Differential diagnosis Several sleep disorders causing behaviors in sleep can be considered in the differential diagnosis, such as sleep walking (somnambulism), sleep terrors, nocturnal seizures, nightmares, psychogenic dissociative states, post-traumatic [bjmp.org]

• Cerebellar Ataxia

  Spinocerebellar ataxia type 31 (SCA 31) is a slowly progressive neurodegenerative disorder characterized by pure cerebellar ataxia. Unlike other CAG repeat diseases, sleep-related problems have not been reported in patients with SCA 31 so far. [ncbi.nlm.nih.gov]

• Loss of Gait

  INTRODUCTION: Rapid eye movement (REM) sleep behavior disorder (RBD) in Parkinson's disease (PD) is associated with differences in clinical phenotype, including dementia, autonomic loss, and gait dysfunction. [ncbi.nlm.nih.gov]

Diagnostic criteria for RBD have been defined as follows by the American Academy of Sleep Medicine [10]:

• Involuntary movements are associated with dreams

As well as either one of the following:

• Harmful or potentially harmful behavior during sleep
• Motor dream enactment
• Disruption of sleep continuity

The diagnosis of RBD may be based on these minimal criteria, but is ideally supported by the following polysomnographic findings as obtained during REM sleep:

• Increased chin electromyography tone
• Enhanced chin or limb phasic electromyography twitching associated with excessive myoclonic jerks or complex, vigorous, or violent behavior or the absence of epileptiform activity

These criteria apply if mental disorders have been ruled out. In contrast, concomitant neurodegenerative disease or other neurological disorder are not to be considered at this point. In fact, a considerable subset of RBD patients suffers from additional pathologies like Parkinson's disease.

• Gliosis

  Histopathologic analysis showed Lewy body disease, but no significant neuronal loss or gliosis was present in the SN or LC. This case represents another example of Lewy body disease associated with RBD. [ncbi.nlm.nih.gov]

  In the brain, all six cases presented variable neuronal loss, gliosis and alpha-synuclein immunoreactive Lewy pathology (Lewy bodies and Lewy neurites) in vulnerable regions such as the olfactory bulb, dorsal motor nucleus vagal nerve, central raphe nucleus [journals.plos.org]

• Neurofibrillary Tangle

  After death, semiquantitative analyses were conducted for synuclein, amyloid, neurofibrillary tangles, and cerebrovascular lesions. RESULTS: Forty cases had probable RBD (PD+RBD), and 41 did not (PD-RBD). [ncbi.nlm.nih.gov]

A sound evidence basis for symptomatic treatment of RBD remains lacking, and randomized controlled treatment trials are needed. [ncbi.nlm.nih.gov]

The reduction in VAS frequency-severity rating fell was similar for the two treatments, dropping from 6.68 before treatment to 4.22 afterwards in melatonin-treated patients and from 6.53 to 4.15 in clonazepam-treated patients. [news-medical.net]

Prospective outcome and treatment studies of RBD are necessary to enable accurate prognosis and better evidence for symptomatic therapy and future neuroprotective strategies. [ncbi.nlm.nih.gov]

Our findings in this study were very similar to those seen in patients with Parkinson's disease-REM sleep behavior disorder (PD-RBD), consistent with a common mechanism and presumed underlying etiology of synucleinopathy in both groups. [ncbi.nlm.nih.gov]

The precise etiology and neural structures involved in RBD are unknown. [emedicine.medscape.com]

This review article considers the epidemiology of RBD, clinical and polysomnographic diagnostic standards for both RBD and RSWA, previously reported associations of RSWA and RBD with neurodegenerative disorders and other potential causes, the pathophysiology [ncbi.nlm.nih.gov]

Pathophysiologically, brainstem and supratentorial mechanisms involving glutamatergic, glycinergic, and GABA-ergic neurotransmission have been implicated. Recently, an animal model of RBD has been described. [ncbi.nlm.nih.gov]

The focus of this review is symptomatic treatment for injury prevention. [ncbi.nlm.nih.gov]

In healthy brains, muscles are temporarily paralyzed during sleep to prevent this from happening. [universityherald.com]

Specialized Alarm System To prevent injury during episodes of RBD an alarm system that gently awakens the patient has been devised. [multiplesystematrophy.org]

Authors of the study suggest that, to be considered effective, a neuroprotective drug should significantly prevent the dopamine concentration from dropping in these patients. [sciencedaily.com]

Physiologically, longer periods of non-REM sleep are interrupted by short REM phases. A complete sleep cycle comprising all four stages of non-REM sleep as well as a REM phase usually lasts about 100 minutes [1]. Both disturbances of non-REM or REM sleep and irregular cycling are related to sleep disorders.

Dreaming typically occurs during REM sleep. Accordingly, REM phases are characterized by bursts of rapid eye movement, increase of the brain and sympathetic nerve activity, heart rate, and blood pressure, as well as irregular respiration and the absence of muscle tone [2]. Enhanced brain activity is reflected in wake-like electroencephalograms, loss of muscle tone may be depicted by means of electromyography [1]. The preservation of muscle tone during REM phases is pathologic, and affected individuals are diagnosed with REM sleep behavior disorder (RBD), a type of parasomnia [3].

Although the majority of cases is deemed idiopathic, incidence rates are markedly increased among patients suffering from neurodegenerative disorders like Parkinson's disease, dementia with Lewy bodies and multiple system atrophy. In this context, RBD has been proposed as a risk factor for neurodegenerative diseases, and have been shown to precede the latter by decades [4]. This may have major implications for the diagnosis and early treatment of the respective entities. RBD may also be seen in individuals taking antidepressants and in those abusing or withdrawing from alcohol or drugs [5].

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