Orexin/hypocretin levels in the cerebrospinal fluid and characteristics of patients with myotonic dystrophy type 1 with excessive daytime sleepiness
Received 2 December 2017
Accepted for publication 3 January 2018
Published 8 February 2018 Volume 2018:14 Pages 451—457
Checked for plagiarism Yes
Review by Single-blind
Peer reviewers approved by Prof. Dr. Roumen Kirov
Peer reviewer comments 2
Editor who approved publication: Dr Taro Kishi
Yuki Omori,1 Takashi Kanbayashi,1,2 Aya Imanishi,1 Ko Tsutsui,1 Yohei Sagawa,1 Yuka S Kikuchi,1 Masahiro Takeshima,1 Kazuhisa Yoshizawa,1 Sachiko Uemura,3 Tetsuo Shimizu1,2
1Department of Neuropsychiatry, Akita University Graduate School of Medicine, Akita, Japan; 2International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Japan; 3Department of Physical Therapy, Akita University Graduate School of Health Sciences, Akita, Japan
Purpose: Myotonic dystrophy type 1 (DM1) is often characterized by excessive daytime sleepiness (EDS) and sleep-onset rapid eye movement periods caused by muscleblind-like protein 2. The EDS tends to persist even after treatment of sleep apnea. We measured the cerebrospinal fluid (CSF) orexin levels in DM1 patients with EDS and compared the clinical characteristics with narcolepsy type 1 and idiopathic hypersomnia (IHS) patients.
Patients and methods: We measured the CSF orexin levels in 17 DM1 patients with EDS and evaluated subjective sleepiness using the Epworth Sleepiness Scale (ESS), objective sleepiness using mean sleep latency (MSL), and sleep apnea using apnea-hypopnea index (AHI). We compared the ESS scores and MSL between decreased (≤200 pg/mL) and normal (>200 pg/mL) CSF orexin group in DM1 patients. Furthermore, we compared the CSF orexin levels, ESS scores, MSL, and AHI among patients with DM1, narcolepsy type 1 (n=46), and IHS (n=30).
Results: Seven DM1 patients showed decreased CSF orexin levels. There were significant differences in the ESS scores and MSL between decreased and normal CSF orexin groups in DM1 patients. The ESS scores showed no significant difference among patients with DM1, narcolepsy type 1, and IHS. The MSL in DM1 and IHS patients were significantly higher than narcolepsy type 1 patients (p=0.01, p<0.001). The AHI in DM1 patients was significantly higher than narcolepsy type 1 patients (p=0.042) and was insignificantly different from IHS patients. The CSF orexin levels in DM1 patients were significantly lower than IHS patients and higher than narcolepsy type 1 patients (p<0.001, p<0.001).
Conclusion: The CSF orexin levels of DM1 patients moderately decreased compared to those of IHS patients as the control group. However, the EDS of DM1 patients may not be explained by only orexin deficiency.
Keywords: myotonic dystrophy type 1, orexin, narcolepsy, sleep-onset rapid eye movement periods, muscleblind-like protein
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