Keywords
REM Sleep Behavior Disorder - Sleep Apnea, Obstructive
INTRODUCTION
Parasomnias are defined as undesirable verbal events, and/or motor movements, and/or
experiences that emerge during or around sleep, which are classified into three groups
depending on the sleep stage they arise as: non-rapid eye movement (NREM)-related
parasomnias, rapid eye movement (REM)-related parasomnias, and other parasomnias (emerging
irrespective of the sleep stage).[1]
Rapid eye movement sleep behavior disorder (RBD) is one of the subtypes of REM-related
parasomnias, which are characterized by recurrent dream enactment behaviors (DEBs)
such as sleep-related vocalization and/or complex motor behaviors, which are documented
or presumed to occur during REM sleep either through polysomnography (PSG) or clinical
history. For a definitive RBD diagnosis, REM sleep without atonia (RSWA) should be
demonstrated in PSG recordings. Lastly, the diagnosis of RBD can only be established
if these disturbances are not better explained by another sleep disorder, mental disorder,
or medication or substance use.[1] Idiopathic RBD (iRBD) and/or isolated RSWA is now accepted as one of the earliest
prodromal biomarker of alpha-synucleinopathies, which comprise a set of neurodegenerative
disorders including Parkinson's disease (PD), multiple system atrophy (MSA), and dementia
with Lewy bodies (DLB).[2]
[3]
[4] Therefore, it is of crucial importance to differentiate iRBD/RSWA from secondary
etiologies, associated conditions, and mimics.
The relationship between RBD and obstructive sleep apnea (OSA) is controversial, as
some studies[5] suggest that the presence of RSWA in RBD may play as a protective role against OSA,
while others[6] state that the presence of RBD may worsen OSA through anatomical interconnections
in neural circuits of the lower brain stem and through alterations in neurotransmitters.
On the other side, OSA contributes to the accumulation of abnormal misfolded proteins,
alpha-synuclein, via sleep fragmentation and intermittent hypoxia, and results in
acceleration of neurodegenerative diseases in the long term.[7] Moreover, arousal reactions associated with apneas and hypopneas in OSA may induce
vivid dreaming and postarousal DEBs during REM sleep, which mimic RBD due to locomotion
and agitated and violent behaviors.[8]
[9] These pseudo-RBD symptoms, termed OSA-induced, hypnopompic, REM sleep-related parasomnias, may represent a different type of confusional arousal that occurs in REM sleep following
intense episodes of apneas and hypopneas associated with arousal reactions. The differential
diagnosis of these attacks from isolated RBD requires a detailed evaluation and PSG
investigation.
Parasomnias related to NREM sleep may also be easily misdiagnosed as iRBD. Especially
in the pediatric age group, or in patients with narcolepsy, psychological distress
and anxiety, DEBs may occur in NREM sleep rather than in REM sleep periods.[10] Alternative behaviors may also be confused with DEBs, as many sleepwalkers, or certain
patients with sleep terrors have reported[11] vague contents of dreams with less elaborate content and less vivid experiences.
Moreover, NREM and REM parasomnias may coexist, which is called parasomnia overlap disorder (POD). Overall, abnormal nocturnal behaviors (NBs) may result from different types
of parasomnias, or they may originate from arousal reactions triggered by the apneas
and hypopneas in OSA, or from periodic limb movements (PLMs), or present as part of
other diseases such as nocturnal seizures or movement disorders. These similarities
in clinical symptomatology and reciprocal interaction among sleep disorders, together
with other mimicking conditions, emphasize the importance of a detailed and comprehensive
clinical evaluation of these patients. There are questionnaires validated for screening
for RBD, such as The Mayo Sleep Questionnaire, the RBD Screening Questionnaire (RBDSQ),
the RBD Single Question Questionnaire (RBD-1Q), and the 9-Item Innsbruck REM Sleep
Behavior Disorder Inventory (IRBD-9), but their usefulness is debatable.[12]
[13] Nevertheless, video-PSG for the definitive diagnosis of RBD is a time-consuming
intensive method, and machine-learning techniques such as actigraphy require assisting
with other clinical data, as in questionnaires. In the present study, we investigated
the discriminative role of the validated Turkish version of the IRBD-9 (IRBD-9-Turkish)
for iRBD regarding patients with OSA and those with OSA-related abnormal NBs (OSA-NBs).
METHODS
Sample selection
The present multicenter study was prospectively conducted in 10 different cities in
Türkiye by the contributions of 13 sleep centers accredited by the Turkish Sleep Medicine
Society (TSMS). Upon obtaining approval for the validation study for the IRBD-9-Turkish
(developed by Frauscher et al.[13]) and after the validation of the version,[14] we applied the IRBD-9-Turkish to our study sample. The current study was approved
by the institutional Ethics Committee (MULA Reference: Turkish Sleep Study Group_TR_431114_MULA_20220608_FE),
and the guidelines of the Strengthening the Reporting of Observational Studies in
Epidemiology (STROBE) statement were followed. All participants provided written informed
consent, and the study complied with the principles of the Declaration of Helsinki.
The sample size was calculated based on statistical guidelines,[15] and the patients admitted to the outpatient sleep clinics of 13 different sleep
centers in 10 different cities were prospectively and consecutively investigated to
be enrolled into the study during the study protocol.
Clinical and video-PSG analysis
The demographic and clinical history of the participants was recorded through a preformed
questionnaire, and the presence of abnormal verbal and/or motor activities during
sleep were specifically recorded in detail in all patients. Moreover, NREM parasomnias
were interrogated in all participants.
All participants underwent full-night video-PSG recordings in accredited sleep laboratories
that were recorded and scored by the sleep experts based on the most recent version
of the American Academy of Sleep Medicine (AASM) Manual for the Scoring of Sleep and
Associated Events.[16] A mandatory PSG characteristic of RBD, RSWA was accordingly scored in the electromyographic
(EMG) recordings of chin and extremity electrodes (tibialis anterior muscle). The
recording of EMG activity was performed in accordance with AASM criteria as follows:
an amplification of 5 μV/mm, a low-frequency filter of 10 Hz, a high-frequency filter
of 100 Hz, and a sampling frequency of 500 Hz. The presence of RSWA was defined as
sustained (tonic) and phasic EMG activity scored from the chin and/or from the tibialis
anterior muscle EMG channels. Tonic EMG activity was defined as an increase in the
amplitude of the EMG electrode greater than the minimum amplitude demonstrated in
NREM sleep and lasting for at least 50% of the duration of an epoch. Phasic EMG muscle
activity was defined as bursts of transient muscle activity in at least 5 out of 10
(50%) 3-second mini-epochs, with each burst lasting for 0.1 to 5.0 seconds and at
least 4 times as high in amplitude compared to the background EMG activity.[16] In addition, the total duration of phasic and tonic activity in the chin EMG channel
and phasic activity in the extremity EMG channels were semiautomatically calculated
for all REM sleep periods per night. Patients with a clinical history of repetitive
complex motor movements and/or vocalization related to dream content during sleep,
as well as those with proven RSWA in video-PSG recordings, were diagnosed as having
RBD, based on the third edition (the most current version at the time of the study)
of the International Classification of Sleep Disorders (ICSD-3).[17]
Respiratory events were also recorded, scored, and analyzed in accordance with international
guidelines,[16] and the apnea-hypopnea index (AHI) was calculated. The diagnosis of OSA was made
based on the ICSD-3[17] criteria as follows: at least 1 relevant clinical symptomatology and AHI ≥ 5 events/hour,
or AHI ≥ 15 events/hour with or without clinical symptomatology. Patients with OSA
were divided into two groups, those with and without abnormal nocturnal movements,
to be analyzed separately. The abnormal behaviors related to OSA are different from
normal sleep behaviors (such as shifting body position or limb stretching, often described
as “comfort movements”), but more complex behaviors like exploring the environment,
defense behaviors, manipulative motor patterns or food-carrying behaviors.[18]
The video-PSG parameters included the following: total recording time, total sleep
time, sleep efficiency, sleep latency, REM sleep latency, wakefulness after sleep
onset, the percentages of wakefulness and sleep stages (N1, N2, N3, and REM sleep),
AHI, mean and minimum oxygen saturation, and the index of periodic limb movements
in sleep (Supplementary Material available at https://www.arquivosdeneuropsiquiatria.org/wp-content/uploads/2025/04/ANP-2024.0257-Supplementary-Material.docx - Supplementary Material Table S1).
Patient selection
After the detailed collection of clinical and PSG data, patients were enrolled into
the study based on the inclusion and exclusion criteria. The inclusion criteria were
volunteer patients aged ≥ 18 years, submitted to 1 night of video-PSG in a sleep laboratory
accredited by the TSMS, with definitive diagnoses of iRBD and RSWA as demonstrated
by video-PSG, and a definitive diagnosis of OSA.
On the other hand, patients with RBD secondary to narcolepsy or use of drugs such
as antidepressant medications, other psychiatric and/or neurological conditions such
as epilepsy and neurodegenerative disorders, deteriorated clinical condition such
as severe medical condition or presenting cancer and/or alcohol or substance abuse
were excluded.
The IRBD-9-Turkish was then applied to all participants, and the calculation of the
item scores was carried out as it in the validation study.[14] The total RBD symptom score was calculated by dividing the total number of “yes”
answers (that is, symptoms present) by the total number of questions. In the second
section, the frequency scores of all items were added and divided by the total number
of questions to obtain the RBD frequency score. The English and Turkish versions of
the IRBD-9 are presented in Supplementary Material Table S2.
Statistical analysis
Statistical analyses were performed using the IBM SPSS Statistics for Windows (IBM
Corp.) software, version 20.0. Data were expressed as mean ± standard deviation or
median and interquartile range (IQR) values. The Kruskal-Wallis test was used to compare
more than two groups when the data was not normally distributed, and Pearson's correlation
analysis was used to assess correlations between two normally-distributed variables.
The reliability of the IRBD-9-Turkish was evaluated using the internal consistency
(calculated through the Cronbach's alpha coefficient). The sensitivity and specificity
of various cut-off values were determined and shown using a receiver operating characteristic
(ROC) curve. The Cronbach's alpha coefficient was determined to assess the questionnaire's
reliability. An area under curve (AUC) greater than 0.70 was deemed sufficient, and
a Cronbach's alpha coefficient greater than 0.7 was regarded as satisfactory.[19] The scale's structural validity was evaluated using exploratory factor analysis
(EFA). Construct validity of the IRBD-9-Turkish was investigated through EFA (as described
in detail in the validation study[14]), which showed a 2-factor solution for the IRBD-9-Turkish with the rotated factor
loadings ranging from 0.61 to 0.92. Therefore, the 2-factor model explained a significant
portion of the scale variation: five items (questions 1, 2, 3, 6, and 8) were loaded
on factor I, and the other items (questions 4, 5, 7, and 9) were loaded on factor
II. Values of p ≤ 0.05 were considered statistically significant.
RESULTS
Study population
Current study involved 105 participants with a mean age of 58.3 ± 11.6 years and 68.6%
of males subjects. The mean symptom score on the IRBD-9-Turkish of the total sample
was of 0.36 ± 0.25 points. In total, 51 patients presented iRBD, and 54, OSA. The
mean symptom score was significantly higher in iRBD patients compared with OSA patients
([Table 1]).
Table 1
Comparison of the descriptive statistics of iRBD and OSA patients
|
Patients with iRBD (n = 51)
|
Patients with OSA (n = 54)
|
pvalue
|
|
Sex: n (%)
|
Male (n = 131)
|
32 (62.7)
|
40 (74.1)
|
0.299
|
|
Female (n = 107)
|
19 (37.3)
|
14 (25.9)
|
|
Mean age (years)
|
64.90 ± 7.69
|
51.96 ± 11.19
|
< 0.001
|
|
Mean IRBD-9-Turkish total score (symptom)
|
0.56 ± 0.20
|
0.17 ± 0.13
|
< 0.001
|
|
Mean RBDSQ-T total score
|
8.67 ± 1.87
|
2.69 ± 2.45
|
<0.001
|
|
Mean RBD duration (months)
|
50.18 ± 69.90
|
NA
|
–
|
|
Mean PLMSI
|
15.97 ± 20.36
|
10.35 ± 16.21
|
0.123
|
|
RSWA fulfilling the AASM criteria: n (%)
|
None
|
0 (0.0)
|
53 (98.1)
|
< 0.001
|
|
Chin alone
|
0 (0.0)
|
0 (0.0)
|
|
Extremity alone
|
2 (3.9)
|
1 (1.9)
|
|
Chin and extremity
|
49 (96.1)
|
0 (0.0)
|
|
Mean duration of increased phasic/tonic activity in the chin EMG channel
|
156.26 ± 482.56
|
0.15 ± 0.31
|
< 0.001
|
|
Mean duration of increased phasic activity in the extremity EMG channels
|
61.58 ± 220.90
|
0.18 ± 0.51
|
< 0.001
|
Abbreviations: AASM, American Academy of Sleep Medicine; EMG, electromyography; iRBD,
idiopathic rapid eye movement sleep behavior disorder; IRBD-9-Turkish, Turkish version
of the 9-item Innsbruck Rapid Eye Movement Sleep Behavior Disorder Inventory; NA,
not applicable; OSA, obstructive sleep apnea; PMLSI, Periodic Limb Movements in Sleep
Index; RBDSQ-T, Turkish Version of the Rapid Eye Movement Sleep Behavior Disorder
Questionnaire; RSWA, rapid eye movement sleep without atonia.
Validation of the IRBD-9-Turkish inventory
Construct validity analysis for the symptom score section showed a 2-factor model
for the IRBD-9-Turkish, with questions 1, 2, 3, 6, and 8 loaded onto factor I, and
questions 4, 5, 7, and 9 loaded onto factor II (as described in the validation study[14]). The mean scores on factors I and II showed that iRBD patients scored significantly
higher on factor I than the OSA patients ([Table 2]). The mean scores on factor II were also higher in iRBD patients, which was not
statistically significant.
Table 2
Comparison of the mean scores on factors I and II of the exploratory factor analysis
between iRBD and OSA patients
|
Mean symptom score
|
Patients with iRBD (n = 51)
|
Patients with OSA (n = 54)
|
p-value
|
|
Factor I (questions 1,2,3,6,8 of the IRBD-9-Turkish)
|
0.78 ± 0.21
|
0.13 ± 0.17
|
< 0.001
|
|
Factor II (questions 4,5,7,9 of the IRBD-9-Turkish)
|
0.29 ± 0.28
|
0.23 ± 0.18
|
0.522
|
Abbreviations: iRBD, idiopathic rapid eye movement sleep behavior disorder; IRBD-9-Turkish,
Turkish version of the 9-item Innsbruck Rapid Eye Movement Sleep Behavior Disorder
Inventory; OSA, obstructive sleep apnea.
Criterion validity analysis showed that the optimal cut-off value of the IRBD-9-Turkish
was of 0.28 for healthy individuals compared with the iRBD patients, with a sensitivity
of 0.941 and a specificity of 0.947, resulting in correct diagnosis in 94.4% of the
patients (as shown in the validation study[14]). Patients with OSA also displayed a significantly lower cut-off value, of 0.278,
with a sensitivity of 0.941 and a specificity of 0.889, resulting in correct diagnosis
in 91.2% of the patients ([Table 3]).
Table 3
Diagnostic performance of the IRBD-9-Turkish symptom section in OSA patients compared
to iRBD patients
|
Diagnostic performance of the IRBD-9-Turkish inventory symptom section
|
|
In comparison to iRBD
|
Cut-off
|
Sensitivity (%)
|
Specificity (%)
|
PPV (%)
|
NPV (%)
|
LR (+)
|
LR (-)
|
AUC
|
pvalue
|
|
OSA
|
0.278
|
94.1
|
88.9
|
88.9
|
94.1
|
8.47
|
0.07
|
0.95
|
< 0.001
|
|
Diagnostic performance of the IRBD-9-Turkish inventory symptom section for factors
I and II
|
|
Patients with iRBD and OSA
|
Cut-off
|
Sensitivity (%)
|
Specificity (%)
|
PPV (%)
|
NPV (%)
|
LR (+)
|
LR (-)
|
AUC
|
pvalue
|
|
Factor I
|
0.300
|
96.1
|
90.7
|
90.7
|
96.1
|
10.4
|
0.04
|
0.973
|
< 0.001
|
|
Factor II
|
0.375
|
29.4
|
88.9
|
71.4
|
57.1
|
2.65
|
0.79
|
0.533
|
0.557
|
Abbreviations: AUC, area under the curve; iRBD, idiopathic rapid eye movement sleep
behavior disorder; IRBD-9-Turkish, Turkish version of the 9-item Innsbruck Rapid Eye
Movement Sleep Behavior Disorder Inventory; LR(+), positive likelihood ratio; LR(-),
negative likelihood ratio; NPV, negative predictive value; OSA, obstructive sleep
apnea; PPV, positive predictive value.
IRBD-9-Turkish inventory in patients with OSA and OSA-NB
The diagnostic performance of the symptom section of the IRBD-9-Turkish was also observed
to be significant for factor I, but not for factor II ([Table 3]). The ROC curves were able to separate patients with iRBD from patients with OSA
through an analysis of factors I and II ([Figure 1]). Of the 54 OSA patients, 19 (35.2%) presented OSA-NB, demonstrated by both clinical
and video-PSG findings, which were associated with the arousal reactions secondary
to apneas and hypopneas; while 39 patients (64.8%) had no symptoms nor signs of NBs.
Descriptive statistics of these two groups are shown in [Table 4].
Figure 1 Graph illustrating the receiver operating characteristic (ROC) curves: area under
the curve (AUC) for factor I = 0.973 (95%CI: 0.946–1.000; p < 0.001); and for factor II = 0.533 (95%CI: 0.419–0.647; p = 0.557).
Table 4
Descriptive statistics of OSA and OSA-NBs patients
|
Patients with OSA-NBs (n = 19)
|
Patients with OSA (n = 39)
|
pvalue
|
|
Sex: n (%)
|
Male (n = 40)
|
11 (61.1)
|
29 (74.4)
|
0.326
|
|
Female (n = 17)
|
7 (38.9)
|
10 (25.6)
|
|
Mean age (years)
|
50.5 ± 11.01
|
52.56 ± 10.92
|
0.264
|
|
Mean IRBD-9-Turkish total score (symptom)
|
0.35 ± 0.19
|
0.13 ± 0.08
|
< 0.001
|
|
Mean RBDSQ-T total score
|
4.39 ± 2.83
|
2.28 ± 2.32
|
0.001
|
|
Mean duration of increased phasic/tonic activity in chin EMG channel
|
0.06 ± 0.24
|
0.18 ± 0.34
|
< 0.001
|
|
Mean duration of increased phasic activity in extremity EMG channels
|
0.07 ± 0.31
|
0.22 ± 0.57
|
< 0.001
|
Abbreviations: EMG, electromyography; IRBD-9-Turkish, Turkish version of the 9-item
Innsbruck Rapid Eye Movement Sleep Behavior Disorder Inventory; NBs, abnormal nocturnal
behaviors; OSA, obstructive sleep apnea; RBDSQ-T, Turkish Version of the Rapid Eye
Movement Sleep Behavior Disorder Questionnaire.
The analysis of the subgroups of patients with OSA and OSA-NBs through a stratified
analysis of the symptom section of the IRBD-9-Turkish revealed that the cut-off value
was significantly higher in patients with OSA-NBs (0.39 versus 0.278 for those with
OSA; p < 0.001), with a sensitivity of 0.765 and a specificity of 0.667, resulting in a
correct diagnosis of BNs in 75% of the patients with OSA ([Table 5]). The ROC curve using the IRBD-9-Turkish symptom score was able to distinguish patients
with iRBD from patients with OSA-NBs ([Figure 2]).
Table 5
Group-by-group stratified analysis of the symptom section of the IRBD-9-Turkish inventory
|
In comparison to RBD
|
Cut-off
|
Sensitivity (%)
|
Specificity (%)
|
PPV (%)
|
NPV (%)
|
LR (+)
|
LR (-)
|
AUC
|
p-value
|
|
OSA
|
0.28
|
94.1
|
100.0
|
100.0
|
92.9
|
–
|
0.06
|
0.99
|
< 0.001
|
|
OSA-NB
|
0.39
|
76.5
|
66.7
|
86.7
|
50.0
|
2.29
|
0.35
|
0.79
|
< 0.001
|
Abbreviations: AUC, area under the curve; IRBD-9-Turkish, Turkish version of the 9-item
Innsbruck Rapid Eye Movement Sleep Behavior Disorder Inventory; LR(+), positive likelihood
ratio; LR(-), negative likelihood ratio; NBs, abnormal nocturnal behaviors; NPV, negative
predictive value; OSA, obstructive sleep apnea; PPV, positive predictive value; RBD,
rapid eye movement sleep behavior disorder.
Figure 2 Graph showing the ROC curve using the symptom score of the Turkish version of the
9-Item Innsbruck REM Sleep Behavior Disorder Inventory (IRBD-9-Turkish) to distinguish
patients with idiopathic rapid eye movement sleep behavior disorder (iRBD) from the
those with obstructive sleep apnea-related abnormal nocturnal behaviors (OSA-NBs)
(AUC = 0.791; 95%CI: 0.661–0.921; p < 0.001).
The analysis of ROC curves for factors I and II showed that the IRBD-9-Turkish symptom
score was able to distinguish patients with iRBD from patients with OSA ([Figure 3A]), and OSA-NBs ([Figure 3B]) only regarding factor I, but not factor II.
Figure 3 Graph showing the ROC curve using the IRBD-9-Turkish symptom score for factor I,
which distinguishes iRBD from OSA patients (AUC = 0.994; 95%CI: 0.983–1.000; p < 0.001); sensitivity = 0.961; specificity = 1.000; cut-off = 0.30) (A) and iRBD patients from those with OSA-NBs (AUC= 0.883; 95%CI: 0.797–0.970; p < 0.001); sensitivity = 0.922; specificity = 0.667; cut-off = 0.50).
DISCUSSION
The current study demonstrated a very high sensitivity and specificity of the IRBD-9-Turkish
in iRDB and OSA patients. The diagnostic performance, however, was observed to be
significant for factor I, but not for factor II. More intriguingly, our findings showed
that the IRBD-9-Turkish was also able to distinguish patients with iRBD from patients
with OSA-NBs in the factor I model. The cut-off value for the IRBD-9-Turkish inventory
was observed to be significantly higher for OSA-NBs patients (0.39) compared to those
with OSA (0.278) or iRBD (0.28). With a high sensitivity and specificity, the IRBD-9-Turkish
predicted the correct diagnosis of BNs in 75% of the OSA patients.
The IRBD-9 was developed and validated with a cutoff score of 0.25, showing an excellent
sensitivity and specificity (of 0.914 and 0.857 respectively).[13] Although it has been shown to differentiate patients with RBD from those without
it regardless of underlying etiology, no difference in scores were observed between
patients with idiopathic versus symptomatic RBD. On the other hand, BNs triggered
by apneas and hypopneas in OSA are very common and challenging in the differential
diagnosis of RBD in clinical practice. Considering that video-PSG is a time-consuming
and intensive method, the use of questionnaires to choose and prioritize patients
who will undergo later or and earlier investigations like such as and PSG would be
very helpful.[20] To the best of our knowledge, no questionnaire has been developed for the assessment
of OSA-NBs. Our results, noticeably, showed that the The IRBD-9 can also be used to
distinguish OSA-NBs from RBD-DEBS. While the definitive diagnosis of RBD requires
a detailed evaluation and video-PSG recordings, the use of the IRBD-9 as a screening
method in clinical practice, as well as in epidemiological population-based settings,
must be considered.
Indeed, there are some other instruments validated for the assessment of nocturnal
behaviors other than RBD. Spoormaker et al.[21] developed the SLEEP-50 questionnaire, which was designed to assess many sleep complaints
and/or disorders, such as apneas, insomnia, narcolepsy, sleep paralysis, restless
legs syndrome, sleep-related cramps, circadian rhythm sleep disorders, nightmares,
and sleepwalking, aiming to distinguish sleep complaints from sleep disorders. The
Global Sleep Assessment Questionnaire (GSAQ), developed by Roth et al.[22] to recognize many sleep disorders, including PLMs and parasomnias. Fulda et al.[23] developed the Munich Parasomnia Screening (MUPS) to evaluate the occurrence and
the frequency of different groups of patients with nocturnal behaviors, such as sleep-related
movement disorders, isolated symptoms and normal variants, and parasomnias. There
are also other questionnaires that screen for more than one sleep disorder at the
same time,[24] but, in all, the questionnaires are focused on a specific sleep disorder, and OSA-NBs
has not been contemplated in any of them. The evaluation of iRBD through actigraphy
or actigraphy and screening questionnaires was also analyzed in a study[20] that showed that actigraphy recordings for 7 to 10 nights were able to detect iRBD,
with a high sensitivity (95.2%) and specificity (90.5%), while the simultaneous use
of actigraphy and questionnaires presented 100% of precision, with a sensitivity of
88.1%. Statistical models incorporating clinical features (loss of smell, autonomic
dysfunction etc) and/or neurophysiological markers (such as a decrease in fast-frequency
activities in spectral electroencephalography) may improve the clinical diagnostic
procedure in iRBD patients.[20]
[25]
The current study has strengths and limitations. Our results demonstrated the use
of the IRBD-9y in a new field of sleep medicine: OSA-NBs. The sensitivity and specificity
of the IRBD-9-TR were very high to differentiate patients with OSA from those with
iRBD, as well as those with OSA-NBs, a condition that can mimic isolated RBD. On the
other hand, the study sample was small. In addition, NBs associated with apneas and
hypopneas were not further grouped into those arising during NREM sleep and those
arising during REM sleep.
Despite its limitations, the present study also has strengths. It is a prospective
multicenter study representative of sleep centers in tertiary neurology clinics. The
IRBD-9-TR was applied to subjects referred to the sleep laboratory for the first time.
All participants were able to fill it out by themselves, without the help of the clinicians,
which shows the user-friendly character of the questionnaire for screening purposes.
Considering that, video-PSG investigations are time-consuming and expensive procedures,
and the use of RBD screening questionnaires would be very useful for clinicians and
researchers. While the IRBD-9 was designed for the differentiation of RBD from other
sleep disorders, its discriminative role regarding patients with OSA and OSA-NBs was
supported and strengthened by the results of the current study. This additional characteristic
might further help the differential diagnosis of iRBD from its mimics, which can be
very challenging in the daily clinical practice. Nevertheless, the results of the
present study warrant the conduction of larger studies with a more detailed analysis
of OSA-NBs. On the other hand, the important ethical implications of the diagnosis
of iRBD as a prodromal feature of alpha-synucleinopathy[3]
[4] should emphasize the role of screening tests as an intermediate step in choosing
and prioritizing patients for further evaluations, including video-PSG.
Table S1
Polysomnographic data of the study sample
|
Parameters
|
Patients with iRBD (n = 51)
|
Patients with OSA (n = 54)
|
p-value
|
|
Mean total recording time (minutes)
|
433.0 ± 57.3
|
442.0 ± 46.0
|
0.789
|
|
Mean total sleep time (minutes)
|
361.7 ± 76.7
|
384.6 ± 62.2
|
0.250
|
|
Mean sleep efficiency (%)
|
79.8 ± 13.7
|
81.8 ± 20.2
|
0.075
|
|
Mean sleep latency (minutes)
|
24.5 ± 23.3
|
24.9 ± 30.9
|
0.353
|
|
Mean REM sleep latency (minutes)
|
129.2 ± 72.3
|
148.8 ± 92.1
|
0.436
|
|
Mean wakefulness after sleep onset (minutes)
|
56.0 ± 38.7
|
55.0 ± 51.5
|
0.454
|
|
Mean N1 sleep (%)
|
8.4 ± 6.3
|
12.7 ± 11.5
|
0.031
|
|
Mean N2 sleep (%)
|
44.6 ± 15.0
|
54.6 ± 12.5
|
0.001
|
|
Mean N3 sleep (%)
|
25.2 ± 11.0
|
16.1 ± 10.4
|
0.001
|
|
Mean REM sleep (%)
|
20.0 ± 9.4
|
15.3 ± 8.3
|
0.014
|
|
Mean apnea-hypopnea index (events per hour)
|
5.6 ± 4.8
|
46.1 ± 19.8
|
< 0.001
|
|
Mean minimum oxygen saturation (%)
|
93.8 ± 2.1
|
89.6 ± 11.1
|
< 0.001
|
|
Mean Index of Periodic Limb Movements in Sleep (per hour)
|
9.7 ± 18.7
|
11.0 ± 16.6
|
0.580
|
Abbreviations: iRBD, idiopathic rapid eye movement sleep behavior disorder; REM, rapid eye movement;
OSA, obstructive sleep apnea.
Table S2
Original English version and Turkish version of the 9-item Innsbruck Rapid Eye Movement
Sleep Behavior Disorder Inventory (IRBD-9)
|
ENGLISH
1. Do you dream of violent or aggressive situations (e.g., to have to defend yourself)?
2. Do you scream, insult, or curse during your sleep? (Note: this does not include
normal sleep talking.)
3. Do you move out of your sleep and occasionally perform ‘‘flailing’' or more extensive
movements?
4. Have you left your bed and have you gone out of the room during your sleep since
entering your adulthood?
5. Have you ever fallen out of bed while you were sleeping?
6. Have you ever injured or nearly injured yourself or your bed partner while you
were sleeping?
7. Have you ever found items that were placed on the bed table when falling asleep
lying on the floor when you awakened (eg, alarm clock, mobile phone, etc.)?
8. Are the above-described movements out of your sleep occasionally or always in line
with the content of your dreams? (items 2, 3, 6)
9. Do you snore loudly and irregularly, or do you know you have an irregular breathing
during your sleep?
TURKISH
1. Uykunuzda, şiddet veya saldırganlık içeren rüyalar görür müsünüz? (kendinizi korumak
zorunda kaldığınız rüyalar ve benzeri)
2. Uykunuzda çığlık atıp, hakaret ediyor veya küfür ediyor musunuz? (Not: normal uyku
konuşması dâhil değildir)
3. Uykunuzda hareket ediyor ve ara sıra “sıçrama-silkelenme” veya daha aşırı hareketler
yapıyor musunuz?
4. Erişkin olduğunuzdan beri, uykunuzda yatağınızı terk edip odadan çıktığınız oldu
mu?
5. Uyurken hiç yataktan düştünüz mü?
6. Uyurken kendinizi veya eşinizi yaraladınız mı? veya neredeyse yaralayacak oldunuz
mu? (örn: istem dışı vurdunuz mu?)
7. Uykuya dalarken komodinin üzerinde olan eşyaları uyandığınızda yerde bulduğunuz
oldu mu? (örneğin çalar saat, cep telefonu vb.)
8. Yukarıda tanımlanan uykudaki hareketler, ara sıra veya sürekli olarak gördüğünüz
rüyalarınızın içeriği ile aynı mı? (2, 3, 6 maddeler)
9. Yüksek sesle ve düzensiz bir şekilde horlar mısınız veya uyurken düzensiz nefes
aldığınızı biliyor musunuz?
|
Bibliographical Record
Gülçin Benbir Şenel, Ayşın Kısabay Ak, Ayşegül Şeyma Sarıtaş, Hikmet Yılmaz, Kübra
Mehel Metin, Burcu Gökçe Çokal, Kadriye Ağan, Murat Aksu, Utku Oğan Akyıldız, Aylin
Bican Demir, Betül Çevik, Ahmet Yusuf Ertürk, Derya Karadeniz, İbrahim Öztura, Gülin
Sünter, Selma Tekin, İrsel Tezer, Deniz Tuncel Berktaş, Nazlı Totik, Kezban Aslan-Kara.
Innsbruck REM Sleep Behavior Disorder Inventory may distinguish abnormal nocturnal
movements related to obstructive sleep apnea. Arq Neuropsiquiatr 2025; 83: s00451809543.
DOI: 10.1055/s-0045-1809543
