From physiological neck myoclonus to sleep related head jerk

Evaluation of movement and brain activity

Clinical neurophysiology studies can contribute important information about the physiology of human movement and the pathophysiology and diagnosis of different movement disorders. Some techniques can be accomplished in a routine clinical neurophysiology laboratory and others require some special equipment. This review, initiating a series of articles on this topic, focuses on the methods and techniques. The methods reviewed include EMG, EEG, MEG, evoked potentials, coherence, accelerometry, posturography (balance), gait, and sleep studies. Functional MRI (fMRI) is also reviewed as a physiological method that can be used independently or together with other methods. A few applications to patients with movement disorders are discussed as examples, but the detailed applications will be the subject of other articles.

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

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Heart rates increased with neck myoclonus events.

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The rate of increase was higher for neck myoclonus with cortical arousal than for those without.

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Neck myoclonus may be associated with excessive daytime sleepiness or abnormal behaviors during REM sleep.

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.

REM sleep behavior disorder: Mimics and variants

Rapid eye movement (REM) sleep behavior disorder (RBD) is a parasomnia with dream-enactment behaviors occurring during REM sleep and associated with the lack of the physiological REM sleep muscle atonia. It can be isolated and secondary to other neurological or medical conditions. Isolated RBD heralds in most cases a neurodegenerative condition due to an underlying synucleinopathy and consequently its recognition is crucial for prognostic implications. REM sleep without atonia on polysomnography is a mandatory diagnostic criterion. Different conditions may mimic RBD, the most frequent being obstructive sleep apnea during sleep, non-REM parasomnia, and sleep-related hypermotor epilepsy. These diseases might also be comorbid with RBD, challenging the evaluation of disease severity, the treatment choices and the response to treatment evaluation. Video-PSG is the gold standard for a correct diagnosis and will distinguish between different or comorbid sleep disorders. Careful history taking together with actigraphy may give important clues for the differential diagnosis. The extreme boundaries of RBD might also be seen in more severe and complex conditions like status dissociatus or in the sleep disorders' scenario of anti IgLON5 disease, but in the latter both clinical and neurophysiological features will differ. A step-by-step approach is suggested to guide the differential diagnosis.

Sleep-related head jerks: toward a new movement disorder

STUDY OBJECTIVES

Sleep-related head jerks (SRHJ) are often considered as a physiological motor phenomenon, occurring mainly during rapid eye movement (REM) sleep. Their clinical relevance and links with other sleep parameters are unclear. We characterized the clinical and polysomnographic features of patients with excessive SRHJ and compare them with healthy controls and patients with isolated REM sleep behavior disorder (iRBD).

METHODS

A total of 30 patients (19 males, 27.5 y.o., 16.0-51.0) with a REM-HJ index >30/h were identified over a period of 5 years. All had a video-polysomnographic (PSG) recording to characterize the SRHJ, to assess associations with other sleep parameters and to quantify phasic and tonic electromyographic activity during REM sleep, compared with 30 healthy controls and 30 patients with iRBD.

RESULTS

Five among the 30 patients had a primary complaint of involuntary nighttime head movements associated with sleepiness or non-restorative sleep. The mean REM-HJ index was 57.22/h ± 24.42, a nonperiodic pattern, stable across the sleep cycles, and with a low between-test variability (for the nine patients with two PSG assessments in untreated condition). REM-HJs were often associated with arousals (65.2%) and leg movements (38.1%) and less with respiratory events (9.6%), without association with increased phasic and tonic electromyographic activities. SRHJ were also found in 36.7% of controls and 56.7% of iRBD patients, but with a lower index in REM sleep (0.79/h ± 1.59 and 2.76/h ± 4.57).

CONCLUSIONS

Although SRHJ are frequent in the general population and with uncertain clinical significance, rare severe symptomatic forms should be individualized and eventually be categorized as a new sleep-related movement disorder, distinct from RBD and periodic leg movements.

Scoring of large muscle group movements during sleep: An International Restless Legs Syndrome Study Group (IRLSSG) position statement

There is a gap in the manuals for scoring sleep-related movements because of the absence of rules for scoring large movements. A taskforce of the International Restless Legs Syndrome Study Group elaborated rules that define the detection and quantification of movements involving large muscle groups. Consensus on each of the criteria in this paper was reached by testing the presence of consensus on a first proposal; if no consensus was achieved, the concerns were considered and used to modify the proposal. This process was iterated until consensus was reached. A preliminary analysis of the duration of movements involving large muscle groups was also carried out on data from two previous studies, which, however, used a visual analysis of video-polysomnographic recordings obtained from children or adults. Technical specifications and scoring rules were designed for the detection and quantification of large muscle group movements during sleep with a duration between 3 and 45 s in adults or 3 and 30 s in children, characterized by an increase in electromyographic activity and/or the occurrence of movement artifact in any combination of at least two recommended channels and not meeting the criteria for any other type of movement. Large muscle group movements are often accompanied by sleep stage changes, arousals, awakenings, and heart rate rises. The absence of clear and detailed rules defining them has likely impeded the development of studies that might disclose their clinical relevance; these new rules fill this gap.

Electroclinical Features of Sleep-Related Head Jerk

STUDY OBJECTIVES

To evaluate clinical and electrophysiological features of sleep-related head jerk (SRHJ) and electromyographic activity of superficial neck muscles during head jerk.

METHODS

Totally, 850 cases with video-polysomnography recording were collected, among which 50 presented with SRHJ. In these 50 patients, 15 underwent electromyography (EMG) check on bilateral sternocleidomastoid (SCM) and trapezius muscles as well as chin, while 35 had only chin EMG check. Further, the sensitivity and specificity of the both EMGs were calculated and compared.

RESULTS

Six among the 50 SRHJ patients had a primary complaint of involuntary head jerks associated with impaired sleep. Approximately 76.1% of head jerks occurred during REM sleep with the median head jerk index of 5.9/h, 64.5% of which were associated with electroencephalogram arousals and 66.4% with body movements. One patient showed SRHJ predominantly in NREM sleep but also in wakefulness. Surface EMG of SCM/trapezius muscles showed a sensitivity of 92% and a specificity of 97.8%, whereas chin EMG had a sensitivity of 14.5% and a specificity of 98.8%.

CONCLUSION

SRHJ was associated with electroencephalogram arousals and might interfere with sleep. Surface EMG of SCM/trapezius muscles exhibited a good accuracy in the revelation of SRHJ.

Parasomnias, sleep-related movement disorders and physiological sleep variants in focal epilepsy: A polysomnographic study

PURPOSE

The link existing between epilepsy and sleep is widely recognized. However, little is known about the prevalence and the clinical consequences of the comorbidity between focal epilepsy and sleep disorders, especially those sleep phenomena classified as isolated symptoms or normal variants. Objective of the study was to evaluate the frequency of sleep disorders and physiological sleep variants in a group of adult patients with focal epilepsy as compared to healthy controls by means of nocturnal polysomnography.

METHODS

We performed a retrospective observational study in the Neurological Clinic of the University of Catania in adult patients with a diagnosis of focal epilepsy and in a group of control subjects. All subjects underwent an overnight polysomnography. The following sleep disorders were considered: NREM-related parasomnias; REM-related parasomnias; sleep-related movement disorders; isolated symptoms or normal variants.

RESULTS

100 patients [mean age 30.3 ± 14.7 years, 40 men] and 62 controls [mean age 36.4 ± 15.9, 20 men] were studied. A significant higher percentage of sleep disorders was recorded in patients as compared to controls (73 % vs 48.4 %; p = 0.002). In particular, we found a higher frequency of periodic limb movements (PLM) (20 % vs 4.8 %; p = 0.007), bruxism (20 % vs 4.8 %; p = 0.007) and neck myoclonus (22 % vs 4.8 %; p = 0.003). Moreover, alternating limb muscle activation was associated with sleep-related hypermotor epilepsy (OR = 7.9; p = 0.01).

CONCLUSION

Sleep disorders and physiological sleep variants are common in adult patients with focal epilepsy.

Impaired glycinergic transmission in hyperekplexia: a model of parasomnia overlap disorder

We report sleep phenotypes and polysomnographic findings in two siblings with a novel homozygous variant of the GLRA1 gene causing hereditary hyperekplexia (HH). Both sisters had startles during wakefulness and sleep, sleep terrors, and one had symptoms of REM sleep behavior disorder (RBD). Frequent startles were found in NREM sleep associated with NREM parasomnias in deep sleep. In REM sleep, both had motor behaviors and increased phasic/tonic muscle activities confirming RBD. Clonazepam improved startles, motor behaviors, and muscle activities in REM sleep. Impaired glycinergic transmission in human HH could be involved in the pathophysiology of RBD and NREM parasomnias.