Abstract Details

Title Atypical Sleep-related Rhythmic Movement Disorder

Topic Sleep

Presentation(s) P1 - Poster Session 1 (9:00 AM-5:00 PM)

Poster/Presentation
Number 472

Objective This is a rare case report describing fast rhythmic movements associated with sleep.

Background Rhythmic movements have been described in sleep as hypnagogic foot tremors (HFT) and sleep-related rhythmic movement disorder (RMD). HFT is characterized by at least 4 lower extremity electromyographic (EMG) bursts occurring at a frequency of 0.3 – 4 Hz for a duration of 250-1000 milliseconds; RMD are repetitive, stereotypical, rhythmic movements of large muscle groups with at least four movements occurring at a frequency of 0.5 – 2 Hz with an amplitude twice that of the background EMG and usually occurring in kids. We present a unique case of an adult female with obvious sleep-related rhythmic movements noted on EMG and video monitoring during overnight polysomnogram (PSG) that were significantly faster than RMD and HFT.

Design/Methods A 42-year-old obese woman with a past medical history of anxiety and depression presented with excessive daytime sleepiness, sleep onset and sleep maintenance insomnia, frequent nightmares, snoring, occasional sleepwalking, and movements in sleep.

Results An in-lab overnight polysomnogram showed obstructive sleep apnea, with an Apnea-Hypopnea Index (AHI) of 22 and oxygen desaturation to a nadir of 87%. In addition, multiple rapid, rhythmic flexion-extension movements of the right foot at a frequency of 4-6 Hz were seen, mostly during wake-to-sleep transitions, continuing for 6-7 seconds. Foot movements recorded on the PSG video were time-locked with EMG bursts and had no ictal correlation on the electroencephalogram. Frequent periodic limb movements were also noted during sleep but were independent of these rhythmic movements.

Conclusions To our knowledge, this is the first report of a case of sleep-related rhythmic movements occurring at a frequency higher than the 2-4 Hz seen in HFT or RMD. Sleep specialists should be aware of this faster variant of sleep-related rhythmic movements.

Authors/Disclosures
Subhendu Rath, MBBS (Virginia Commonwealth University) PRESENTER	Dr. Rath has nothing to disclose.
	No disclosure on file

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