A Case of Pseudo-RBD with OSA
RBD (REM behavior disorder) is a type of parasomnia in which voluntary muscle atonia is abolished during REM sleep and is associated with complex motor behavior and/or sleep-related vocalization while dreaming. RBD can also be due to other sleep disorders including OSA (obstructive sleep apnea) and this scenario is termed as pseudo-RBD. We are hereby presenting a case of pseudo-RBD in association with severe OSA which was resolved with optimal CPAP pressure.
KeywordsObstructive sleep apnea Medical education CPAP
RBD (REM behavior disorder) is a type of parasomnia in which voluntary muscle atonia is abolished during REM sleep and is associated with complex motor behavior and/or sleep-related vocalization while dreaming. RBD can also be due to other sleep disorders including OSA (obstructive sleep apnea) and this scenario is termed as pseudo-RBD . We are hereby presenting a case of pseudo-RBD in association with severe OSA which was resolved with optimal CPAP pressure.
2 Case History
A 60-year-old nonsmoker, nonalcoholic, hypertensive gentleman came with complaints of loud snoring and excessive fatigability for past few years. He used to sleep for around 6 h. He preferred to sleep in lateral position. On detailed questioning, patient gave history of frequent aggressive dream content and sudden limb movement while sleeping. His RBD sleep questionnaire score was 2 out of 13. His STOP BANG score was 5 and Epworth sleepiness scale was 5. On examination, his modified Mallampatti score was 4, tonsil grade was 1 and BMI was 23.8 kg/m2. There was no other craniofacial abnormality and neurological examination was within normal limits. There was no history of diabetes, narcolepsy, neurological or psychiatric disorder. He was on antihypertensive medications and there was no history of addiction. His hematological, biochemical and ABG parameters were within normal limits. With possibility of OSA, patient underwent Level I polysomnography (PSG).
While evaluating patient with symptoms of OSA, if patients give history of abnormal movements/behavior during sleep , possibility of RBD and pseudo-RBD should be kept in mind. OSA and RBD are different in terms of pathophysiology, complications and treatment . It is necessary to differentiate true RBD from pseudo-RBD (in association with OSA) as true RBD has been postulated to be a predictor for neurodegenerative diseases like parkinsonism . If a patient with pseudo-RBD is wrongly diagnosed as true RBD and treated with clonazepam (drug of choice for RBD), it may increase severity of OSA.
In our patient with suspected history of RBD, RWA was present, although abnormal movement was not seen during diagnostic vPSG. RWA gradually decreased while increasing CPAP pressure and finally disappeared on optimal CPAP pressure. Petrenko et al. also reported a similar case of pseudo-RBD with OSA and concluded that “RWA may be present in cases with pseudo-RBD. Hence RWA may not be specific for the diagnosis of true RBD” . In another study of 16 patients, it was shown that severe OSA may mimic RBD symptoms and vPSG is must for diagnosing RBD and also to evaluate other causes of dream-enacting behavior .
On follow-up, this patient did not buy CPAP due to financial constraints.
In conclusion, patients suspected of having OSA should be screened for RBD by asking about abnormal movements’ history during sleep. If RBD is suspected, level I PSG should be done as level III PSG will not pick up RWA. RWA is not pathognomonic of RBD, it is seen in OSA patients also.
- 4.Petrenko I, Gupta D. Can REM without atonia (RWA) be present in pseudo-REM sleep behavior disorder (pseudo-RBD) due to obstructive sleep apnea (OSA)? Neurology. 2016;86(16):4–290.Google Scholar