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Excessive Fragmentary Myoclonus: What Do We Know?
1Centre for Sleep and Wake Disorders, Department of Neurology, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic. jiri.nepozitek@lf1.cuni.cz.
Prague Medical Report
|April 2, 2017
Summary
Excessive fragmentary myoclonus (EFM) is a sleep polysomnography finding of brief muscle twitches. Its clinical significance remains unclear, and it may represent a normal variant rather than a specific disorder.
Area of Science:
- Neurology
- Sleep Medicine
- Neurophysiology
Background:
- Excessive fragmentary myoclonus (EFM) is a polysomnographic finding characterized by brief, isolated muscle twitches.
- Defined by specific criteria in The International Classification of Sleep Disorders, 3rd edition, EFM occurs across all sleep stages.
- The clinical significance and specific diagnostic value of EFM are not well understood.
Purpose of the Study:
- To review the characteristics and clinical associations of Excessive Fragmentary Myoclonus (EFM).
- To discuss the diagnostic implications and potential classifications of EFM within sleep medicine.
Main Methods:
- Analysis of polysomnographic data, specifically surface electromyography (EMG) findings.
- Review of existing literature and diagnostic criteria for sleep disorders.
- Examination of EFM's co-occurrence with various neurological and sleep-related conditions.
Main Results:
- EFM presents as sudden, arrhythmic, asynchronous, and asymmetric brief muscle twitches.
- It has been observed alongside conditions like sleep apnea, narcolepsy, periodic limb movements, insomnia, and neurodegenerative disorders.
- The wide range of associated conditions suggests EFM is not a specific disorder or sign.
Conclusions:
- The clinical significance of Excessive Fragmentary Myoclonus (EFM) is currently unclear.
- EFM's association with diverse conditions indicates it may not be a specific sleep disorder or polysomnographic sign.
- The possibility of EFM being a normal sleep variant remains under consideration.