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[A marked decrease of orexin in the cerebrospinal fluid in a patient with myotonic dystrophy type 1 showing an
Tomoaki Iwata1, Naoki Suzuki, Hideki Mizuno
1Department of Neurology, Tohoku University School of Medicine.
Rinsho Shinkeigaku = Clinical Neurology
|September 1, 2009
Summary
Myotonic dystrophy type 1 can cause narcolepsy, characterized by low orexin/hypocretin levels and sleep disturbances like sleep apnea. This highlights the need for proper evaluation of sleep disorders in myotonic dystrophy patients.
Area of Science:
- Neurology
- Genetics
- Sleep Medicine
Background:
- Myotonic dystrophy type 1 (DM1) is a multisystem disorder.
- Excessive daytime somnolence is a frequent complaint in DM1 patients.
Observation:
- A 60-year-old female DM1 patient presented with narcolepsy.
- Genetic analysis revealed 1,800-2,400 CTG repeats in the DMPK gene.
- Brain MRI was normal, but polysomnography showed sleep apnea and chronic alveolar hypoventilation.
Findings:
- Multiple sleep latency tests showed normal sleep latencies without sleep onset REM.
- Cerebrospinal fluid orexin/hypocretin levels were markedly decreased to undetectable levels.
Implications:
- Narcolepsy associated with DM1 may significantly impair quality of life.
- Undiagnosed sleep disorders in DM1 could potentially increase mortality risk.
- Appropriate evaluation and management of narcolepsy in DM1 are crucial.
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