PARASOMNIA - Overview Parasomnia REM

One of the 6 main diagnostic entities in ICSM-3 is Parasomnia, which are strange behaviours during sleep. Diagnoses that could explain strange behaviour during sleep in any other way should be excluded, like epilepsy or psychiatric disease. The diagnosis is depending on typical history from patient, parents and or bed partner. Often there is a positive family history. NonREM parasomnia have typical features, which comprise of a spectrum of appearances of scary images occurring simultaneously with confusional arousals or violent behaviour. Sleep- or night terror (pavor nocturnus) often occur during the first hours of sleep, less violent are confusional arousals and somnambulism (sleepwalking). More common are sleep talking (somniloqui) and teeth grinding (bruxism). NonREM parasomnia classically start in young age and end during puberty. In 3-4% of the population parasomnia can persist during adulthood. Since parasomnia only occur during sleep, sleep should be measured during the attacks. Sleep deprivation, alcohol, stress and drugs are known to provoke parasomnia attacks, thus should be included in history taking. To distinguish between parasomnia and epilepsy one can use questionnaires like the FLEP (Frontal Lobe Epilepsy or Parasomnia) scale designed by Derry (Derry et al, Arch Neurol. 2006;63:705-709). Sometimes NR parasomnia can lead to forensic implications. The main features of Parasomnia are their complex behaviour, often with vocalization and occurring in the beginning of the night during 3N. Epilepsy during the night results in more stereotype, simple movements, generally without vocalization and occurring throughout the night during all sleep stages. REM parasomnia occur as the name indicates only during REMsleep. One can distinguish 2 types: a. Nightmares, bad dreams that causes a person to wake up and b. motor signs that normally do not occur during the normal muscle atonia of REMsleep. The latest type is called REM behaviour disorder or RBD. Classically NR parasomnia occur in the young and RBD occur in the elderly, over 55 years of age. The history taking indicates nightmares or motor behaviour, generally in the second half of the night and during dreams. REM parasomnia are classically dream enacting behaviours. During normal REMsleep a “switch” in the brainstem switches off voluntary movement, in REMparasomnia this switch is not, or partially operated. For the diagnosis RBD a video-polysomnography is mandatory. RBD can be caused by medication or an underlying neuro-degenerative disorder. If the cause is not clear it is called iRBD, the i for idiopathic. iRBD can be the first sign of a neurodegenerative disorder that can occur 8-10 years before the appearance of a neurological disease is clinically apparent. Most iRBD’s will therefore convert to RBD over time. The diagnoses involved in RBD are Parkinsons disease (PD), Lewy Body type Dementia (LBD) and Multy System Atrophy (MSA). The conversion rate after 10 years is 75% for PD, 95% for LBD and MSA. In some cases PET or SPECT scans will show the markers of the above-mentioned diagnoses. NR parasomnia can easily be treated with avoidance of provoking factors and cognitive behavioural therapy. In contrast RBD can only be treated with medication. One starts in general with melatonin 3-5 mg just before bedtime and if not successful even in higher dosages, combined with clonazepam 0,5mg. Follow-up neurological and clinical geriatric examination is advisable.