**2. Prevalence of REM sleep behavior disorder**

The overall prevalence of RBD remains largely unknown. A large telephone survey using the Sleep-EVAL system for assessing violent behaviors during sleep in the general

Screening Methods for REM Sleep Behavior Disorder 183

RBD is a relatively rare condition and is largely unknown to most physicians (see above 2),

The differential diagnosis of recurrent dream enactment behavior includes NREM parasomnia, nocturnal panic attacks, nocturnal seizures, nightmares, nocturnal wandering associated with dementia, and OSAS (Boeve, 2010a). A complaint of nocturnal disruptive behaviors is the major clinical feature of several other conditions, such as primary and

Primary arousal disorders from NREM sleep include confusional arousals, sleepwalking, and sleep terrors. In contrast to RBD, sleepwalking and sleep terrors are more frequent in children and rarely appear *de novo* in middle-aged or elderly individuals. They are also characterized by confusion and retrograde amnesia upon awakening at the time of nocturnal episodes; these phenomena are not seen in patients with RBD. In general, RBD involves attempted enactment of altered dreams and rapid awakening from an episode that usually occurs two or more

Table 2. Diagnostic criteria for REM sleep behavior disorder in ICSD-2

secondary disorders of arousal, dreaming, and panic disorders (Table 3). Primary disorders of arousal (from NREM sleep)

Obstructive sleep apnea syndrome (pseudo RBD)

**4. Differential diagnosis of REM sleep behavior disorder** 

therefore it is often misdiagnosed and mistreated.

Confusional arousals

Sleep-related epilepsy Psychiatric diseases

Secondary arousal disorders

Sleep-related dissociative disorder

Posttraumatic stress syndrome

 Sleepwalking Sleep terrors

Panic disorder

Table 3. Differential diagnosis of RBD

population (4972 individuals aged 15-100 years) in the United Kingdom suggested an estimated prevalence of RBD of about 0.5% (Ohayon et al., 1997). A study of 1034 elderly subjects aged 70 years or above in the Hong Kong area found an estimated prevalence of polysomnography (PSG)-confirmed RBD of 0.38% (Chiu et al., 2000). There is a male predominance (87%) with primarily men over the age of 50 being affected (Schenck & Mahowald, 2002). Boeve summarized the demographics and clinical phenomenology of RBD (Table 1) (Boeve, 2010a).

Table 1. Demographics and clinical phenomenology of RBD (Modified from Boeve, 2010a)

### **3. Diagnosis for REM sleep behavior disorder**

Until recently, the diagnosis of RBD was based on clinical manifestations, namely the presence of limb or body movements associated with dream mentation and at least one of the following: (1) harmful or potentially harmful sleep behaviors during sleep; (2) dreams that appear to be acted out; and (3) sleep behaviors that disrupt sleep continuity. Polysomnographic observations of patients were not necessary for diagnosis according to the International Classification of Sleep Disorders-1 (ICSD-1).

Eisensehr et al. and Gagnon et al. pointed out the limitations of these criteria because one half of the cases of RBD with PD would have been undetected based clinical interviews alone (Eisensehr et al., 2001; Gagnon et al., 2002). RBD-like features can occur with other sleep conditions such as obstructive sleep apnea syndrome (OSAS), sleepwalking, night terrors, and sleep-related seizures (see below 4). In the second version of the ICSD (ICSD-2), PSG findings were required to establish the diagnosis. The first essential criterion is the presence of REM sleep without atonia. The second criterion is the presence of either sleeprelated injurious or disruptive behaviors revealed by history or abnormal REM sleep behaviors documented during PSG recording. Time-synchronized video recording is essential for helping to establish the diagnosis of RBD during PSG. The last two criteria are exclusion criteria, which are the absence of epileptiform activity during sleep and the presence of other sleep disorders or medical or neurological disorders that could better explain the sleep disturbance. The diagnostic criteria are listed in Table 2.


population (4972 individuals aged 15-100 years) in the United Kingdom suggested an estimated prevalence of RBD of about 0.5% (Ohayon et al., 1997). A study of 1034 elderly subjects aged 70 years or above in the Hong Kong area found an estimated prevalence of polysomnography (PSG)-confirmed RBD of 0.38% (Chiu et al., 2000). There is a male predominance (87%) with primarily men over the age of 50 being affected (Schenck & Mahowald, 2002). Boeve summarized the demographics and clinical phenomenology of

Table 1. Demographics and clinical phenomenology of RBD (Modified from Boeve, 2010a)

Until recently, the diagnosis of RBD was based on clinical manifestations, namely the presence of limb or body movements associated with dream mentation and at least one of the following: (1) harmful or potentially harmful sleep behaviors during sleep; (2) dreams that appear to be acted out; and (3) sleep behaviors that disrupt sleep continuity. Polysomnographic observations of patients were not necessary for diagnosis according to

Eisensehr et al. and Gagnon et al. pointed out the limitations of these criteria because one half of the cases of RBD with PD would have been undetected based clinical interviews alone (Eisensehr et al., 2001; Gagnon et al., 2002). RBD-like features can occur with other sleep conditions such as obstructive sleep apnea syndrome (OSAS), sleepwalking, night terrors, and sleep-related seizures (see below 4). In the second version of the ICSD (ICSD-2), PSG findings were required to establish the diagnosis. The first essential criterion is the presence of REM sleep without atonia. The second criterion is the presence of either sleeprelated injurious or disruptive behaviors revealed by history or abnormal REM sleep behaviors documented during PSG recording. Time-synchronized video recording is essential for helping to establish the diagnosis of RBD during PSG. The last two criteria are exclusion criteria, which are the absence of epileptiform activity during sleep and the presence of other sleep disorders or medical or neurological disorders that could better

**3. Diagnosis for REM sleep behavior disorder**

the International Classification of Sleep Disorders-1 (ICSD-1).

explain the sleep disturbance. The diagnostic criteria are listed in Table 2.

RBD (Table 1) (Boeve, 2010a).


Table 2. Diagnostic criteria for REM sleep behavior disorder in ICSD-2

#### **4. Differential diagnosis of REM sleep behavior disorder**

RBD is a relatively rare condition and is largely unknown to most physicians (see above 2), therefore it is often misdiagnosed and mistreated.

The differential diagnosis of recurrent dream enactment behavior includes NREM parasomnia, nocturnal panic attacks, nocturnal seizures, nightmares, nocturnal wandering associated with dementia, and OSAS (Boeve, 2010a). A complaint of nocturnal disruptive behaviors is the major clinical feature of several other conditions, such as primary and secondary disorders of arousal, dreaming, and panic disorders (Table 3).


Table 3. Differential diagnosis of RBD

Primary arousal disorders from NREM sleep include confusional arousals, sleepwalking, and sleep terrors. In contrast to RBD, sleepwalking and sleep terrors are more frequent in children and rarely appear *de novo* in middle-aged or elderly individuals. They are also characterized by confusion and retrograde amnesia upon awakening at the time of nocturnal episodes; these phenomena are not seen in patients with RBD. In general, RBD involves attempted enactment of altered dreams and rapid awakening from an episode that usually occurs two or more

Screening Methods for REM Sleep Behavior Disorder 185

developed the Mayo Sleep Questionnaire (MSQ), a 16-item measure to screen for the presence of RBD, periodic legs movement disorder (PLMD), restless legs syndrome (RLS), sleepwalking, OSAS and sleep-related leg cramps (Boeve, 2010a; Boeve et al., 2002a, 2002b, 2010b, 2011). The data presented herein refer to the primary question on RBD (Question 1); if the primary question is answered affirmatively, subquestions are asked (subquestions 1b-

Table 4. Primary question on RBD in the Mayo Sleep Questionnaire (MSQ) (from the website: http://www.mayoclinic.org/pdfs/MSQ-copyrightfinal.pdf.)

Among the community-dwelling elderly, the MSQ has high sensitivity (100%) and specificity (95%) for diagnosis of RBD and was particularly specific for RBD in the absence

Boeve et al. also assessed the validity of the MSQ by comparing the responses of patients' bed partners with the findings (REM sleep without atonia) on PSG. The study subjects were 176 individuals (150 males; median age 71 years (range 39-90)) with the following clinical diagnoses: normal (n=8), mild cognitive impairment (n=44), Alzheimer's disease (n=23), dementia with Lewy bodies (n=74), and other dementia and/or parkinsonian syndromes (n=27). Sensitivity and specificity for question 1 on the MSQ for PSG-proven RBD were 98% and 74%, respectively. They concluded that the MSQ has adequate sensitivity and specificity for the diagnosis of RBD among aged subjects with cognitive impairment and/or

Stiasny-Kolster et al. in 2007 developed the original German/English RBD Screening Questionnaire (RBDSQ) (Stiasny-Kolster et al., 2007). The RBDSQ is a 10-item patient selfrating instrument that assesses sleep behavior with short questions that have to be answered by either "yes" or "no" by the patient. Since patients do not always have a long-time companion, the bed partner's input was encouraged but not required. Items 1 to 4 address the frequency and content of dreams and their relationship to nocturnal movements and

e) as shown in Table 4.

of an OSA feature (Boeve, 2010b).

parkinsonism (Boeve et al, 2011).

**5.2 RBDSQ**

hours after sleep onset. In contrast, sleepwalking and sleep terror episodes often emerge within two hours after sleep onset, are not usually associated with rapid alertness, and are rarely associated with dreaming in children. Adults can have associated dreaming, but it is usually more fragmentary and more limited than RBD dreams.

Severe OSAS and nocturnal epilepsy may mimic the symptoms of RBD. Patients with severe OSAS may present with unpleasant dreams and dream-enacting behaviors (Iranzo & Santamaria, 2005). Continuous positive airway pressure (CPAP) therapy can eliminate abnormal nocturnal behaviors. Sleep-related seizures usually present with repetitive stereotypical behaviors.

When a diagnostic clarification is necessary, particularly when the risk for injury is high, the behaviors occur at any time of the night, other features suggesting an evolving neurodegenerative are present, or loud snoring and observed apnea suggestive of OSA are present, PSG with simultaneous video monitoring is warranted (Boeve, 2010a).
