Orexin/hypocretin levels in the cerebrospinal fluid and characteristics of patients with myotonic dystrophy type 1 with excessive daytime sleepiness

Abstract

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

View correction statement:

Orexin/hypocretin levels in the cerebrospinal fluid and characteristics of patients with myotonic dystrophy type 1 with excessive daytime sleepiness [Corrigendum]

Acknowledgments

We would like to thank Dr Hiroaki Nozaki, Takayoshi Shimohata, Yumi Sekine, Kumiko Yasui, Naoki Suzuki, Daisuke Sato, Nobuyoshi Fukuhara, Yoshikazu Takayanagi, Ayumi Nishiyama, Genki Mizukoshi, Konomi Shimoda, Aiko Yasuniwa, Keisuke Suzuki, Kazusa Katanoda, Tsubasa Tei, and Ako Fujii for providing the patient samples and clinical data used in this study. This study was funded by a Special Coordination Fund from the Ministry of Education, Culture, Sports and Technology (MEXT). Additional support was provided by the International Institute for Integrative Sleep Medicine, sponsored by the World Premier International Research Center Initiative, from MEXT, Japan. We would like to thank Editage (www.editage.jp) for English language editing.

Author contributions

All authors contributed toward data analysis, drafting and revising of the paper, and agree to be accountable for all aspects of the work.

Disclosure

The authors report no conflicts of interest in this work.