LETTERS:
PUBLISHED
Rapid Eye Movement Atonia Is Not Rapid Eye Movement Sleep Behavior Disorder We have read with interest the paper by Bolitho et al.1 recently published in Movement Disorders, assessing the ability of four screening questionnaires to correctly identify rapid eye movement (REM) sleep without atonia (RSWA) in patients with Parkinson disease (PD). We also agree with Dr. Postuma’s editorial2 about the importance of comparing different screening tools “head to head.” However, we believe that the validity of the study results might be significantly limited by some problematic aspects. RSWA is a crucial feature of REM sleep behavior disorder (RBD); however, it only represents one of the diagnostic criteria,3 and its exact extent has not yet been defined, especially in patients with RBD and PD. Nevertheless, authors implicitly assume equivalence between RSWA and RBD, and surprisingly enough, do not provide any data about the diagnosis of RBD according to standard criteria (eg, International Classification of Sleep Disorders, 2nd edition4 at the time of the study). Given these premises, measures of sensitivity and specificity of the different screening questionnaires could not be obtained. But even assuming “equivalence” between RSWA and RBD, the study found an unexpectedly high rate of falsepositive RBD diagnosed by questionnaire (eg, subjects who scored positively on the questionnaire but did not have RSWA), and a virtual absence of false-negative (subjects who are unaware of their RBD but who exhibit RWSA). This is very surprising, in light of studies showing that 18% of PD patients without a history of dream-enacting behaviors actually have RSWA or video-behavioral RBD manifestations5 or reporting a sensitivity of only 33% for the clinical interview for RBD in PD patients.6 According to our and others’ experience, detection of RSWA in unaware PD patients, especially those without a bed partner, is not uncommon. This raises some concerns about the methodology used to assess sleep in these patients. First, Bolitho et al.1 do not mention how they scored REM sleep stage in this population (eg, allowing the presence of muscle tone during REM sleep in all subjects). Second, but even more
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*Correspondence to: Maria Livia Fantini, MD, MSc, Neurology Service, CHU Clermont-Ferrand, EA 7280 – UFR Medicine, University Clermont 1, 58, rue Montalembert, 63003 Clermont-Ferrand, France, E-mail: [email protected] Relevant conflicts of interest/financial disclosures: Nothing to report. Full financial disclosures and author roles may be found in the online version of this article. Received: 8 April 2014; Revised: 24 April 2014; Accepted: 17 August 2014 Published online 16 September 2014 in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/mds.26033
ARTICLE
critical, they provide no data about video-recorded behaviors during nocturnal polysomnography, which are an essential part of the diagnostic criteria according to the ICSD-2.4 Actually, the authors stated that sleep was assessed with ambulatory polysomnography without mention of concomitant video-recording. If this is true, the calculation of RSWA appears to be at least problematic. Indeed, authors need to explain how they could correctly assess REM sleep epochs in RBD patients, and especially how they differentiated EMG changes related to RBD episodes from those attributable to normal arousals during REM sleep, body position changes, cough, wakefulness, and so forth. To what extent was EMG activity related to RBD episodes included or excluded from their calculation of RSWA? Conversely, if video-recording was performed and carefully inspected, the authors should give details of RBD episodes observed in questionnaire-positive and -negative RBD patients. In conclusion, we believe that the mere comparison of results of two sets of parameters (questionnaires and RSWA), both of which are not perfect indicators of a disorder (RBD), cannot be performed without a clear and sound clinical diagnosis of the disorder itself, following established standard criteria. The evident lack of information and the probable impossibility of establishing such a firm diagnosis (with the data available in the paper) make these results not conclusive. Maria Livia Fantini, MD, MSc,1 Michela Figorilli, MD,1,2 and Raffaele Ferri, MD3 1
Neurology Service, CHU Clermont-Ferrand, UFR Medicine, Clermont-Ferrand, France 2 Sleep Disorders Center, University of Cagliari, Italy 3 Department of Neurology IC, Oasi Institute for Research on Mental Retardation and Brain Aging (IRCCS), Troina, Italy
References 1.
Bolitho SJ, Naismith SL, Terpening Z, et al. Investigating rapid eye movement sleep without atonia in Parkinson’s disease using the rapid eye movement sleep behavior disorder screening questionnaire. Mov Disord 2014;29:736–742.
2.
Postuma RB. Diagnosing REM sleep behavior disorder in Parkinson’s disease: can we avoid the polysomnogram? Mov Disord 2014;29:713–714.
3.
American Academy of Sleep Medicine, eds. International Classification of Sleep Disorders, 3rd ed. Darien, IL: American Academy of Sleep Medicine, 2014.
4.
American Academy of Sleep Medicine, eds. International Classification of Sleep Disorders, 2nd ed. Diagnostic and Coding Manual. Westchester, IL: American Academy of Sleep Medicine, 2005.
5.
Gagnon JF, Bedard MA, Fantini ML, et al. REM sleep behavior disorder and REM sleep without atonia in Parkinson’s disease. Neurology 2002;59:585–589.
6.
Eisensehr I, Lindeiner H, Jager M, Noachtar S. REM sleep behavior disorder in sleep-disordered patients with versus without Parkinson’s disease: is there a need for polysomnography? J Neurol Sci 2001;186:7–11.
Movement Disorders, Vol. 29, No. 14, 2014
1835
PUBLISHED
Rapid Eye Movement Atonia Is Not Rapid Eye Movement Sleep Behavior Disorder We have read with interest the paper by Bolitho et al.1 recently published in Movement Disorders, assessing the ability of four screening questionnaires to correctly identify rapid eye movement (REM) sleep without atonia (RSWA) in patients with Parkinson disease (PD). We also agree with Dr. Postuma’s editorial2 about the importance of comparing different screening tools “head to head.” However, we believe that the validity of the study results might be significantly limited by some problematic aspects. RSWA is a crucial feature of REM sleep behavior disorder (RBD); however, it only represents one of the diagnostic criteria,3 and its exact extent has not yet been defined, especially in patients with RBD and PD. Nevertheless, authors implicitly assume equivalence between RSWA and RBD, and surprisingly enough, do not provide any data about the diagnosis of RBD according to standard criteria (eg, International Classification of Sleep Disorders, 2nd edition4 at the time of the study). Given these premises, measures of sensitivity and specificity of the different screening questionnaires could not be obtained. But even assuming “equivalence” between RSWA and RBD, the study found an unexpectedly high rate of falsepositive RBD diagnosed by questionnaire (eg, subjects who scored positively on the questionnaire but did not have RSWA), and a virtual absence of false-negative (subjects who are unaware of their RBD but who exhibit RWSA). This is very surprising, in light of studies showing that 18% of PD patients without a history of dream-enacting behaviors actually have RSWA or video-behavioral RBD manifestations5 or reporting a sensitivity of only 33% for the clinical interview for RBD in PD patients.6 According to our and others’ experience, detection of RSWA in unaware PD patients, especially those without a bed partner, is not uncommon. This raises some concerns about the methodology used to assess sleep in these patients. First, Bolitho et al.1 do not mention how they scored REM sleep stage in this population (eg, allowing the presence of muscle tone during REM sleep in all subjects). Second, but even more
------------------------------------------------------------
*Correspondence to: Maria Livia Fantini, MD, MSc, Neurology Service, CHU Clermont-Ferrand, EA 7280 – UFR Medicine, University Clermont 1, 58, rue Montalembert, 63003 Clermont-Ferrand, France, E-mail: [email protected] Relevant conflicts of interest/financial disclosures: Nothing to report. Full financial disclosures and author roles may be found in the online version of this article. Received: 8 April 2014; Revised: 24 April 2014; Accepted: 17 August 2014 Published online 16 September 2014 in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/mds.26033
ARTICLE
critical, they provide no data about video-recorded behaviors during nocturnal polysomnography, which are an essential part of the diagnostic criteria according to the ICSD-2.4 Actually, the authors stated that sleep was assessed with ambulatory polysomnography without mention of concomitant video-recording. If this is true, the calculation of RSWA appears to be at least problematic. Indeed, authors need to explain how they could correctly assess REM sleep epochs in RBD patients, and especially how they differentiated EMG changes related to RBD episodes from those attributable to normal arousals during REM sleep, body position changes, cough, wakefulness, and so forth. To what extent was EMG activity related to RBD episodes included or excluded from their calculation of RSWA? Conversely, if video-recording was performed and carefully inspected, the authors should give details of RBD episodes observed in questionnaire-positive and -negative RBD patients. In conclusion, we believe that the mere comparison of results of two sets of parameters (questionnaires and RSWA), both of which are not perfect indicators of a disorder (RBD), cannot be performed without a clear and sound clinical diagnosis of the disorder itself, following established standard criteria. The evident lack of information and the probable impossibility of establishing such a firm diagnosis (with the data available in the paper) make these results not conclusive. Maria Livia Fantini, MD, MSc,1 Michela Figorilli, MD,1,2 and Raffaele Ferri, MD3 1
Neurology Service, CHU Clermont-Ferrand, UFR Medicine, Clermont-Ferrand, France 2 Sleep Disorders Center, University of Cagliari, Italy 3 Department of Neurology IC, Oasi Institute for Research on Mental Retardation and Brain Aging (IRCCS), Troina, Italy
References 1.
Bolitho SJ, Naismith SL, Terpening Z, et al. Investigating rapid eye movement sleep without atonia in Parkinson’s disease using the rapid eye movement sleep behavior disorder screening questionnaire. Mov Disord 2014;29:736–742.
2.
Postuma RB. Diagnosing REM sleep behavior disorder in Parkinson’s disease: can we avoid the polysomnogram? Mov Disord 2014;29:713–714.
3.
American Academy of Sleep Medicine, eds. International Classification of Sleep Disorders, 3rd ed. Darien, IL: American Academy of Sleep Medicine, 2014.
4.
American Academy of Sleep Medicine, eds. International Classification of Sleep Disorders, 2nd ed. Diagnostic and Coding Manual. Westchester, IL: American Academy of Sleep Medicine, 2005.
5.
Gagnon JF, Bedard MA, Fantini ML, et al. REM sleep behavior disorder and REM sleep without atonia in Parkinson’s disease. Neurology 2002;59:585–589.
6.
Eisensehr I, Lindeiner H, Jager M, Noachtar S. REM sleep behavior disorder in sleep-disordered patients with versus without Parkinson’s disease: is there a need for polysomnography? J Neurol Sci 2001;186:7–11.
Movement Disorders, Vol. 29, No. 14, 2014
1835
