A descriptive analysis of neck myoclonus during routine polysomnography.

STUDY OBJECTIVES: Although episodes of neck myoclonus (head jerks) in REM sleep have a characteristic appearance, they have so far not been described systematically in video-polysomnography. This study assesses the occurrence, frequency, and characteristics of neck myoclonus in REM sleep in a prospective sleep disorder cohort, and investigates clinical correlates and associations with medication. SETTING: University hospital sleep disorders center. PARTICIPANTS: Two-hundred twenty-eight mixed sleep disorder patients. INTERVENTIONS: Not applicable. MEASUREMENTS AND RESULTS: REM sleep was screened visually for short "stripe-shaped" movement-induced artifacts visible vertically over the EEG leads in polysomnographic registration. If such artifact was present, the synchronized video was inspected for the presence of neck myoclonus. Out of 205 patients, 54.6% (n = 112) had neck myoclonus during REM sleep. The mean neck myoclonus index was 1.0 +/- 2.7/h REM sleep. Younger patients had a higher neck myoclonus index than older patients (< 45 years versus 45-60 years versus > 60 years: 1.8 +/- 4.2 versus 0.6 +/- 1.1 versus 0.5 +/- 1.1; P = 0.004). Ninety-five percent of subjects < 45 years had a neck myoclonus index between 0 and 9.4/h; 95% of subjects > 45 years had a neck myoclonus index between 0 and 2.7/h. Patients on benzodiazepine treatment had no neck myoclonus (0/112 vs. 13/93; P < 0.001). In 23 patients, additional surface neck EMG was performed. EMG activation associated with neck myoclonus had a mean duration of 0.6 +/- 0.4 sec. Correlation between duration of neck EMG activation and movement-induced EEG artifact duration was very high (rho = 0.96; P < 0.001). CONCLUSIONS: Neck myoclonus is common during REM sleep and more frequent in younger individuals. This could indicate that neck myoclonus during REM sleep is a physiological phenomenon. If there is a cut-off distinguishing normal from excessive has to be investigated in further studies.

REM sleep behavior disorder in 703 sleep-disorder patients: the importance of eliciting a comprehensive sleep history.

OBJECTIVES: The aim of our study was to evaluate the frequency of REM sleep behavior disorder (RBD) in a mixed sleep laboratory population and to assess potential associations. Moreover, we investigated referral diagnoses of patients subsequently diagnosed with RBD and assessed the frequency of incidental RBD. METHODS: Charts and polysomnographic reports of 703 consecutive patients comprising the full spectrum of ICSD-2 sleep disorders [501 males, 202 females; mean age, 51.0+/-14.1 years (range: 10-82 years)] were carefully reviewed. The vast majority of patients were adults (98.7%). Patients were categorized into those with and without RBD. For associations, all concomitant sleep and neurological diagnoses and medications were evaluated. RESULTS: Thirty-four patients (4.8%) were diagnosed with RBD (27 men; 7 women, mean age, 57.7+/-12.3 years). RBD was idiopathic in 11 patients (1.6%; 9 men) and symptomatic in 23 patients (3.3%; 18 men) secondary to Parkinsonian syndromes (n=11), use of antidepressants (n=7), narcolepsy with cataplexy (n=4), and pontine infarction (n=1). Six out of 34 patients were referred for suspected RBD, 20 reported RBD symptoms only on specific questioning, and 8 patients had no history of RBD but showed typical RBD behavioral manifestations in the video-polysomnography. Logistic regression analysis revealed significant associations between RBD and the presence of Parkinsonian syndromes (odds ratio [OR] 16.8, 95%CI: 6.4-44.1; P<0.001), narcolepsy with cataplexy (OR 10.7, 95%CI: 2.9-40.2; P<0.001), SSRI use (OR 3.9, 95%CI: 1.6-9.8; P=0.003), and age (OR 1.5/10-year increase, 95%CI: 1.0-2.0; P=0.039). CONCLUSION: In this population of 703 consecutive sleep-disorder patients, RBD was uncommon. Its etiology was predominantly symptomatic. The majority of RBD patients reported RBD symptoms on specific questioning only, underlining the importance of eliciting a comprehensive sleep history for the diagnosis of RBD.