Heart rate change and clinical characteristics in patients with neck myoclonus: An observational study.

OBJECTIVE

This study was conducted to evaluate heart rate (HR) change and clinical characteristics in patients with neck myoclonus (NM), a physiological motor phenomenon occurring during sleep.

METHODS

For 18 consecutive patients in whom NM was confirmed from video-polysomnography, we analyzed 576 NMs. Change rate of HR at each 1 sec point towards the averaged HR in prior 5 sec period was calculated before and after all NM events.

RESULTS

Findings show NM events as more prevalent during REM sleep than during NREM sleep (83.9% vs. 16.1%). For NM without cortical arousal in REM and NREM sleep, the respective HR increased 20 s before NM (p < 0.05); the change rate was up to 13%. For NM with cortical arousal in REM sleep, the HR increased 50 s before NM (p < 0.05); the change rate reached 18%. Three NM subjects showed abnormal vocalization or shouting during REM. Six NM subjects had excessive daytime sleepiness without sleep disorder.

CONCLUSION

HR increased before NM events, which may be associated with pathophysiology of NM. NM may possibly be associated with excessive daytime sleepiness or abnormal behaviors during REM sleep.

SIGNIFICANCE: HR increase is associated with pathophysiology of NM and clinical symptoms.