Dreaming furiously? A sleep laboratory study on the dream content of people with Parkinson's disease and with or without rapid eye movement sleep behavior disorder.

OBJECTIVE: Rapid eye movement (REM) sleep behavior disorder (RBD) has been related to altered, action-filled, vivid, and aggressive dream content, but research comparing the possible differences in dreams of Parkinson's disease (PD) patients with and without RBD is scarce. The dream content of PD patients with and without RBD was analyzed with specific focus on action-filledness, vividness, emotional valence, and threats. METHODS: A total of 69 REM and NREM dream reports were collected in the sleep laboratory, 37 from nine PD patients with RBD and 32 from six PD patients without RBD. A content analysis of (1) action-filledness (actions and environmental events); (2) vividness (emotions and cognitive activity); (3) intensity of actions, events and emotions; (4) emotional valence, and (5) threatening events was performed on the transcripts. RESULTS: Altogether 563 dream elements expressing action-filledness and vividness were found. There were no significant between-group differences in the number or distribution of elements reflecting action-filledness or vividness, emotional valence or threats. In within-group analyses, PD patients with RBD had significantly more negative compared to positive dreams (p = 0.012) and compared to PD patients without RBD, a tendency to have more intense actions in their dreams (p = 0.066). CONCLUSIONS: Based on the results of this study, there are no major between-group differences in the action-filledness, vividness, or threat content of dreams of PD patients with and without RBD. However, within-group analyses revealed that dreams were more often negatively than positively toned in PD patients with RBD.

Olfactory dysfunction predicts early transition to a Lewy body disease in idiopathic RBD.

OBJECTIVE: The aim of the present study was to determine the predictive value of olfactory dysfunction for the early development of a synuclein-mediated neurodegenerative disease in subjects with idiopathic REM sleep behavior disorder (iRBD) over an observational period of 5 years. METHODS: Thirty-four patients with polysomnography-confirmed iRBD underwent olfactory testing using the entire Sniffin' Sticks test assessing odor identification, odor discrimination, and olfactory threshold. Patients with iRBD were prospectively followed up over a period of 4.9 ± 0.3 years (mean ± SD). The diagnosis of neurodegenerative diseases was based on current clinical diagnostic criteria. RESULTS: After 2.4 ± 1.7 years (mean ± SD), 9 patients (26.5%) with iRBD developed a Lewy body disease (6 Parkinson disease and 3 dementia with Lewy bodies). The entire Sniffin' Sticks test and the identification subtest had the same overall diagnostic accuracy of 82.4% (95% confidence interval: 66.1%-92.0%) in predicting conversion. The relative risk for a Lewy body disease in the lowest tertile of olfactory function was 7.3 (95% confidence interval: 1.8-29.6) compared with the top 2 tertiles. CONCLUSIONS: Assessment of olfactory function, particularly odor identification, may help to predict the development of a Lewy body disease in patients with iRBD over a relatively short time period and thus to identify patients suitable for future disease modification trials.

Is there a polysomnographic signature of augmentation in restless legs syndrome?

OBJECTIVE: Augmentation of restless legs syndrome (RLS) is a potentially severe side-effect of dopaminergic treatment. Data on objective motor characteristics in augmentation are scarce. The aim of this study was to investigate in detail different variables of leg movements (LM) in untreated, treated, and augmented RLS patients. METHODS: Forty-five patients with idiopathic RLS [15 untreated, 15 treated (non-augmented), 15 augmented] underwent RLS severity assessment, one night of video-polysomnography with extended electromyographic montage, and a suggested immobilization test (SIT). RESULTS: Standard LM parameters as well as periodicity index (PI) and muscle recruitment pattern did not differ between the three groups. The ultradian distribution of periodic leg movements (PLM) in sleep during the night revealed significant differences only during the second hour of sleep (P <0.05). However, augmented patients scored highest on RLS severity scales (P <0.05) and were the only group with a substantial number of PLM during the SIT. CONCLUSION: This study demonstrates that polysomnography is of limited usefulness for the diagnosis and evaluation of RLS augmentation. In contrast, the SIT showed borderline differences in PLM, and differences on subjective scales were marked. According to these results, augmentation of RLS is a phenomenon that predominantly manifests in wakefulness.

Delayed diagnosis, range of severity, and multiple sleep comorbidities: a clinical and polysomnographic analysis of 100 patients of the innsbruck narcolepsy cohort.

STUDY OBJECTIVES: Narcolepsy is reported to affect 26-56/100,000 in the general population. We aimed to describe clinical and polysomnographic features of a large narcolepsy cohort in order to comprehensively characterize the narcoleptic spectrum. METHODS: We performed a chart- and polysomnographybased review of all narcolepsy patients of the Innsbruck narcolepsy cohort. RESULTS: A total of 100 consecutive narcolepsy patients (87 with cataplexy [NC], 13 without cataplexy [N]) were included in the analysis. All subjects had either excessive daytime sleepiness or cataplexy as their initial presenting clinical feature. Age at symptom onset was 20 (6-69) years. Diagnostic delay was 6.5 (0-39) years. The complete narcolepsy tetrad was present in 36/100 patients; 28/100 patients had three cardinal symptoms; 29/100 had two; and 7/100 had only excessive daytime sleepiness. Severity varied broadly with respect to excessive daytime sleepiness (median Epworth Sleepiness Scale score: 18, range 10-24), cataplexy (8-point Likert scale: median 4.5, range 1-8), hypnagogic hallucinations (median 4.5, range 1-7), and sleep paralysis (median 3, range 1-7). Sleep comorbidity was highly prevalent and ranged from sleeprelated movement disorders (n = 55/100), parasomnias (n = 34/100), and sleeprelated breathing disorders (n = 24/100), to insomnia (n = 28/100). REM sleep without atonia or a periodic limb movement in sleep index > 5/h were present in most patients (90/100 and 75/100). A high percentage of narcoleptic patients in the present study had high frequency leg movements (35%) and excessive fragmentary myoclonus (22%). Of the narcolepsy patients with clinical features of REM sleep behavior disorder (RBD), 76.5% had EMG evidence for RBD on the multiple sleep latency test (MSLT), based on a standard cutoff of a minimum of 18% of 3-sec miniepochs. CONCLUSION: This study is one of the largest monocentric polysomnographic studies to date of patients with narcolepsy and confirms the frequent comorbidity of narcolepsy with many other sleep disorders. Our study is the first to evaluate the percentage of patients with high frequency leg movements and excessive fragmentary myoclonus in narcolepsy and is the first to demonstrate EMG evidence of RBD in the MSLT. These findings add to the growing body of literature suggesting that motor instability is a key feature of narcolepsy.

Is a diagnosis of ancillary restless legs syndrome reproducible over time? Experience with the Wayne Hening telephone diagnostic interview.

OBJECTIVE: The Hening telephone diagnostic interview (HTDI) is a validated structured diagnostic instrument for restless legs syndrome (RLS). A diagnosis of ancillary RLS is defined as RLS with non bothering or only sporadic occurrence of RLS symptoms. The aim of our study was to test the reproducibility of a previously received diagnosis of ancillary RLS with the HTDI in a telephone follow-up examination. METHODS: Patients with a diagnosis of ancillary RLS underwent a telephone follow-up after an interval of 6 or more months from their entry into the RLS database. The interview included the HTDI, the International RLS Study Group severity rating scale (IRLS) and questions on current RLS medication. RESULTS: Sixty patients with ancillary RLS were eligible for this study, 50 participated. Thirty-six patients were assigned to definite RLS, 11 to probable RLS, one to possible RLS, and two patients were rated as not RLS. Median IRLS score of those with RLS was 10 (0-30). CONCLUSIONS: This is the first study to report results of the German version of the HTDI. We demonstrate a high reproducibility of a diagnosis of ancillary RLS over time and that the HTDI is an excellent diagnostic tool for RLS even in ancillary cases.

Normative EMG values during REM sleep for the diagnosis of REM sleep behavior disorder.

BACKGROUND: Correct diagnosis of rapid eye movement sleep behavior disorder (RBD) is important because it can be the first manifestation of a neurodegenerative disease, it may lead to serious injury, and it is a well-treatable disorder. We evaluated the electromyographic (EMG) activity in the Sleep Innsbruck Barcelona (SINBAR) montage (mentalis, flexor digitorum superficialis, extensor digitorum brevis) and other muscles to obtain normative values for the correct diagnosis of RBD for clinical practice. SETTING: Two university hospital sleep disorder centers. PARTICIPANTS: Thirty RBD patients (15 idiopathic [iRBD], 15 with Parkinson disease [PD]) and 30 matched controls recruited from patients with effectively treated sleep related breathing disorders. INTERVENTIONS: Not applicable. METHODS AND RESULTS: Participants underwent video-polysomnography, including registration of 11 body muscles. Tonic, phasic, and "any" (any type of EMG activity, irrespective of whether it consisted of tonic, phasic or a combination of both) EMG activity was blindly quantified for each muscle. When choosing a specificity of 100%, the 3-sec miniepoch cutoff for a diagnosis of RBD was 18% for "any" EMG activity in the mentalis muscle (area under the curve [AUC] 0.990). Discriminative power was higher in upper limb (100% specificity, AUC 0.987-9.997) than in lower limb muscles (100% specificity, AUC 0.813-0.852). The combination of "any" EMG activity in the mentalis muscle with both phasic flexor digitorum superficialis muscles yielded a cutoff of 32% (AUC 0.998) for patients with iRBD and with PD-RBD. CONCLUSION: For the diagnosis of iRBD and RBD associated with PD, we recommend a polysomnographic montage quantifying "any" (any type of EMG activity, irrespective of whether it consisted of tonic, phasic or a combination of both) EMG activity in the mentalis muscle and phasic EMG activity in the right and left flexor digitorum superficialis muscles in the upper limbs with a cutoff of 32%, when using 3-sec miniepochs.

Narcolepsy-cataplexy: deficient prepulse inhibition of blink reflex suggests pedunculopontine involvement.

Hypocretin (orexin) deficiency plays a major role in the pathophysiology of narcolepsy-cataplexy. In animal models, hypocretinergic projections to the pedunculopontine nucleus are directly involved in muscle tone regulation mediating muscle atonia - a hallmark of cataplexy. We hypothesized that pedunculopontine nucleus function, tested with prepulse inhibition of the blink reflex, is altered in human narcolepsy-cataplexy. Twenty patients with narcolepsy-cataplexy and 20 healthy controls underwent a neurophysiological study of pedunculopontine nucleus function. Blink reflex, prepulse inhibition of the blink reflex and blink reflex excitability recovery were measured. Blink reflex characteristics (R1 latency and amplitude, and R2 and R2c latency and area under the curve) did not differ between patients and controls (P > 0.05). Prepulse stimulation significantly increased R2 and R2c latencies and reduced R2 and R2c areas in patients and controls. However, the R2 and R2c area suppression was significantly less in patients than in controls (to 69.8 ± 14.4 and 74.9 ± 12.6%, respectively, versus 34.5 ± 28.6 and 43.3 ± 29.5%, respectively; each P < 0.001). Blink reflex excitability recovery, as measured by paired-pulse stimulation, which is not mediated via the pedunculopontine nucleus, did not differ between patients and controls (P > 0.05). Our data showed that prepulse inhibition is reduced in narcolepsy-cataplexy, whereas unconditioned blink reflex and its excitability recovery are normal. Because the pedunculopontine nucleus is important for prepulse inhibition, these results suggest its functional involvement in narcolepsy-cataplexy.

Decision making and executive functions in REM sleep behavior disorder.

STUDY OBJECTIVES: This study was designed to assess decision making and executive functions in patients with idiopathic REM sleep behavior disorder (iRBD). IRBD is often seen as an early sign of later evolving neurodegenerative disease, most importantly Parkinson disease (PD) and Lewy body dementia (DLB). It has been proposed that iRBD patients show a cognitive profile similar to patients with PD. DESIGN: All participants performed an extensive test battery tapping executive functions as well as the IOWA gambling task, which measures decision making under ambiguity. SETTING: University hospital sleep disorders center. PARTICIPANTS: 16 iRBD patients and 45 age- and education-matched controls. INTERVENTION: N.A. MEASUREMENTS AND RESULTS: Compared with controls, iRBD patients showed disadvantageous decision making under ambiguity and did not learn by feedback over the task. IRBD patients' decision pattern was characterized by the lack of a consistent strategy, as indicated by frequent shifts between the single choices. A high proportion of iRBD patients (75%) showed random performance or worse even at the end of the task. No group differences were found in tasks assessing information sampling, flexibility and categorization, problem solving, and impulsivity. CONCLUSIONS: As suggested by the present investigation, iRBD patients may show difficulties in decision making under ambiguity in a stage when other cognitive functions are relatively well preserved. Whether this is driven by subgroups of patients prone to develop PD or DLB has to be assessed by follow-up investigations.

White and gray matter abnormalities in narcolepsy with cataplexy.

STUDY OBJECTIVES: The authors applied diffusion-tensor imaging including measurements of mean diffusivity (MD), which is a parameter of brain tissue integrity, fractional anisotropy (FA), which is a parameter of neuronal fiber integrity, and voxel-based morphometry, which is a measure of gray and white matter volume, to detect brain tissue changes in patients with narcolepsy-cataplexy. DESIGN: N/A. PATIENTS: Patients with narcolepsy-cataplexy (n = 16) and age-matched healthy control subjects (n = 12) were studied. INTERVENTIONS: Whole cerebral MD, FA measures, and the volumes of the gray and white matter compartments were analyzed using statistical parametric mapping. MEASUREMENT AND RESULTS: Significant MD increases and concomitant FA decreases were localized in the fronto-orbital cortex (P < 0.001) and the anterior cingulate (FA, P < 0.001; MD, P = 0.03) in narcolepsy-cataplexy. Additional MD increases without FA changes were detected in the ventral tegmental area, the dorsal raphe nuclei (P < 0.001), and the hypothalamus (P < 0.01). FA signal decreases were observed in the white matter tracts of the inferior frontal and inferior temporal cortices of narcolepsy-cataplexy patients (P < 0.001). Brain volume loss was evident in focal areas of the inferior and superior temporal cortices (P < 0.001) and the cingulate (P = 0.038). CONCLUSIONS: Areas of increased diffusivity in the hypothalamus appear consistent with hypocretinergic cell loss reported in narcolepsy-cataplexy. Signal abnormalities in the ventral tegmental area and the dorsal raphe nuclei correspond to major synaptic targets of hypocretin neurons that were associated with the regulation of the sleep-wake cycle. Brain tissue alterations identified in the frontal cortex and cingulate are crucial in the maintenance of attention and reward-dependent decision making, both known to be impaired in narcolepsy-cataplexy.

Can observers link dream content to behaviours in rapid eye movement sleep behaviour disorder? A cross-sectional experimental pilot study.

Motor activity in rapid eye movement (REM) sleep behaviour disorder (RBD) has been linked to dream content. Systematic and controlled sleep laboratory studies directly assessing the relation between RBD behaviours and experienced dream content are, however, largely lacking. We aimed to investigate whether a link can be established between RBD behaviours and dream content when both are systematically sampled in a controlled setting. We investigated six patients with Parkinson syndrome and RBD who underwent 2-3 nights of video-polysomnographic recording during which they were awakened from REM sleep (10 min after the onset of the second and successive REM periods). Spontaneous free-worded dream reports and a structured dream questionnaire were obtained. Video recordings of motor manifestations were each combined with four dream reports, and seven judges had to match the video clip with the correctly reported dream content from a choice of four possibilities. Of the 35 REM sleep awakenings performed, a total of 17 (48.6%) motor-behavioural episodes with recalled dream content were obtained. The mean of correctly identified video-dream pairs was 39.5% (range 0-100%). Our data showed that reported dream content can be linked to motor behaviours above chance level. Matching accuracy was affected mainly by the clarity of dream reports and the specific nature of movements manifest in video recordings.

Investigation of autonomic function in idiopathic REM sleep behavior disorder.

Idiopathic REM sleep behavior disorder (iRBD) has been suggested as an early "pre-motor" stage of Parkinson's disease (PD) in a significant proportion of cases. We investigated autonomic function in 15 consecutive iRBD patients and compared these findings to PD patients and healthy controls. All participants underwent cardiovascular autonomic function testing, and were rated on the COMPASS scale. Symptomatic orthostatic hypotension was present in two iRBD patients, two PD patients and none of the healthy controls. In the tilt table examination, blood pressure changes were similar between iRBD patients and healthy controls. In the PD group, blood pressure drops were more pronounced. In the orthostatic standing test, iRBD patients had higher blood pressure changes than healthy controls. Highest drops were found in PD. Valsalva ratio was lower in iRBD and PD compared to healthy controls. Total COMPASS score was higher in iRBD compared to healthy controls. Highest scores were found in PD. These results support the presence of autonomic dysfunction in iRBD. On several measures, dysfunction was intermediate between healthy controls and PD consistent with the concept that iRBD can be manifestation of synuclein-associated neurodegenerative disorders. Follow-up studies are needed to determine whether iRBD patients with dysfunction on several autonomic domains are at particular risk for developing one of these diseases.

Genome-wide association study identifies novel restless legs syndrome susceptibility loci on 2p14 and 16q12.1.

Restless legs syndrome (RLS) is a sensorimotor disorder with an age-dependent prevalence of up to 10% in the general population above 65 years of age. Affected individuals suffer from uncomfortable sensations and an urge to move in the lower limbs that occurs mainly in resting situations during the evening or at night. Moving the legs or walking leads to an improvement of symptoms. Concomitantly, patients report sleep disturbances with consequences such as reduced daytime functioning. We conducted a genome-wide association study (GWA) for RLS in 922 cases and 1,526 controls (using 301,406 SNPs) followed by a replication of 76 candidate SNPs in 3,935 cases and 5,754 controls, all of European ancestry. Herein, we identified six RLS susceptibility loci of genome-wide significance, two of them novel: an intergenic region on chromosome 2p14 (rs6747972, P = 9.03 × 10(-11), OR = 1.23) and a locus on 16q12.1 (rs3104767, P = 9.4 × 10(-19), OR = 1.35) in a linkage disequilibrium block of 140 kb containing the 5'-end of TOX3 and the adjacent non-coding RNA BC034767.

Executive functions, information sampling, and decision making in narcolepsy with cataplexy.

OBJECTIVE: Narcolepsy with cataplexy (NC) affects neurotransmitter systems regulating emotions and cognitive functions. This study aimed to assess executive functions, information sampling, reward processing, and decision making in NC. METHOD: Twenty-one NC patients and 58 healthy participants performed an extensive neuropsychological test battery. RESULTS: NC patients scored as controls in executive function tasks assessing set shifting, reversal learning, working memory, and planning. Group differences appeared in a task measuring information sampling and reward sensitivity. NC patients gathered less information, tolerated a higher level of uncertainty, and were less influenced by reward contingencies than controls. NC patients also showed reduced learning in decision making and had significantly lower scores than controls in the fifth block of the IOWA gambling task. No correlations were found with measures of sleepiness. CONCLUSIONS: NC patients may achieve high performance in several neuropsychological domains, including executive functions. Specific differences between NC patients and controls highlight the importance of the hypocretin system in reward processing and decision making and are in line with previous neuroimaging and neurophysiological studies.

Restless legs syndrome in Friedreich ataxia: a polysomnographic study.

Friedreich ataxia (FA) is the most common type of hereditary ataxia. Frataxin deficiency due to a GAA expansion in the first intron of chromosome 9 results in intramitochondrial iron accumulation. On the basis of the patients' complaints about sleep disturbance and pathophysiological considerations, we systematically assessed sleep history and polysomnography in FA. We included 16 consecutive FA patients (11 men, 5 women; mean age, 35.4 ± 11.1 years) with a mean disease duration of 16.5 ± 7.0 years. All patients underwent a standardized protocol including a detailed sleep history and polysomnographic recordings. Eight out of 16 patients were diagnosed with restless legs syndrome (RLS). In seven patients, RLS onset was after the onset of FA. Interestingly, FA patients with RLS had significantly lower serum ferritin levels than FA patients without RLS (76.3 ± 56.0 µg/L vs. 176.3 ± 100.7 µg/L; P = 0.043 after correction for sex and age). Moreover, periodic leg movements in wakefulness (PLMW) indices were significantly higher in FA patients with RLS than FA patients without RLS (FA with RLS, 118.1 ± 50.7; FA without RLS, 65.6 ± 44.2; P = 0.028). There was an inverse correlation between serum ferritin levels and PLMW indices obtained in all FA patients (rho -0.538, P = 0.039). RLS is common in FA. Its frequency in this primarily spinal ataxia appears consistent with the concept of dysfunctional spinal sensorimotor integration in the pathophysiology of RLS. The finding that RLS is more frequent in the context of lower serum ferritin levels in FA is interesting, but requires further investigation in larger patient samples.

White and gray matter abnormalities in idiopathic rapid eye movement sleep behavior disorder: a diffusion-tensor imaging and voxel-based morphometry study.

OBJECTIVE: We applied diffusion-tensor imaging (DTI) including measurements of mean diffusivity (MD), a parameter of brain tissue integrity, fractional anisotropy (FA), a parameter of neuronal fiber integrity, as well as voxel-based morphometry (VBM), a measure of gray and white matter volume, to detect brain tissue changes in patients with idiopathic rapid eye movement (REM) sleep behavior disorder (iRBD). METHODS: Magnetic resonance imaging (MRI) was performed in 26 patients with iRBD (mean disease duration, 9.2 ± 6.4 years) and 14 age-matched healthy control subjects. Statistical parametric mapping (SPM) was applied to objectively identify focal changes of MRI parameters throughout the entire brain volume. RESULTS: SPM localized significant decreases of FA in the tegmentum of the midbrain and rostral pons and increases of MD within the pontine reticular formation overlapping with a cluster of decreased FA in the midbrain (p < 0.001). VBM revealed increases of gray matter densities in both hippocampi of iRBD patients (p < 0.001). INTERPRETATION: The observed changes in the pontomesencephalic brainstem localized 2 areas harboring key neuronal circuits believed to be involved in the regulation of REM sleep and overlap with areas of structural brainstem damage causing symptomatic RBD in humans. Bilateral increases in gray matter density of the hippocampus suggest functional neuronal reorganization in this brain area in iRBD. This study indicates that DTI detects distinct structural brainstem tissue abnormalities in iRBD in the regions where REM is modulated. Further studies should explore the relationship between MRI pathology and the risk of patients with iRBD of developing alpha-synuclein-related neurodegenerative diseases like Parkinson disease.

Usefulness of the SINBAR electromyographic montage to detect the motor and vocal manifestations occurring in REM sleep behavior disorder.

OBJECTIVE: In a previous study we showed that simultaneous electromyographic (EMG) recording of the mentalis, flexor digitorum superficialis and extensor digitorum brevis (SINBAR EMG montage) detected the highest rates of rapid eye movement (REM) sleep phasic EMG activity in subjects with REM sleep behavior disorder (RBD). As a next step, in the present study we evaluated the usefulness of the SINBAR EMG montage to detect the movements and vocalizations occurring in RBD. METHODS: Polysomnographic studies with synchronized audiovisual monitoring of 11 patients with idiopathic RBD were analyzed. Phasic EMG activity in REM sleep was scored and quantified in 3-s mini-epochs while the video was reviewed to detect motor events and vocalizations. RESULTS: A total of 64.8% (11,562 out of 17,848) of all mini-epochs contained phasic EMG activity, whereas 28.8% (5135 out of 17,848) contained movements or vocalizations. Using the SINBAR EMG montage, 94.4% of the mini-epochs containing behavioral events were linked to phasic EMG activity. The sensitivity of the SINBAR EMG montage was 94.4%, specificity was 47.2%, negative predictive value was 95.4% and positive predictive value was 41.9%. Isolated EMG recording of the mentalis did not show phasic EMG activity in 35.5% of the behavioral events seen in the video. CONCLUSIONS: The SINBAR EMG montage is a useful approach for the diagnosis of RBD showing that simultaneous EMG recording of the mentalis, flexor digitorum superficialis and extensor digitorum brevis muscles detected the majority (94.4%) of the motor and vocal manifestations occurring in RBD. For clinical purposes, this means that it is efficient to screen the video when increased phasic EMG activity is seen on the polysomnography.

Motor disturbances during non-REM and REM sleep in narcolepsy-cataplexy: a video-polysomnographic analysis.

Motor events during sleep can be frequently observed in patients with narcolepsy-cataplexy. We hypothesized that increased motor events and related arousals contribute to sleep fragmentation in this disease. We aimed to perform a detailed whole-night video-polysomnographic analysis of all motor events during non-rapid eye movement and rapid eye movement sleep in a group of narcolepsy-cataplexy patients and matched controls, and to assess the association with arousals. Video-polysomnographic registrations of six narcolepsy-cataplexy patients and six sex- and age-matched controls were analysed. Each motor event in the video was classified according to topography, number of involved body parts, duration and its association with arousals. The mean motor activity index was 59.9 ± 23.0 h(-1) in patients with narcolepsy-cataplexy compared with 15.4 ± 9.2 h(-1) in controls (P = 0.004). Distribution of motor events was similar in non-rapid eye movement and rapid eye movement sleep in the patient group (P = 0.219). In narcolepsy-cataplexy, motor events involved significantly more body parts (≥ 2 body regions: 38.2 ± 15.6 versus 14.9 ± 10.0; P = 0.011). In addition, the proportion of motor events lasting longer than 1 s was higher in patients than controls (88% versus 44.4%; P < 0.001). Both total and motor activity-related arousal indices were increased in narcolepsy-cataplexy (total arousal index: 21.6 ± 9.0 versus 8.7 ± 3.5; P = 0.004; motor activity-related arousal index: 17.6 ± 9.8 versus 5.9 ± 2.3; P = 0.002). Motor activity and motor activity-related arousal indices are increased in both non-rapid eye movement and rapid eye movement sleep in narcolepsy-cataplexy compared with controls. This supports the concept of a general sleep motor dysregulation in narcolepsy-cataplexy, which potentially contributes to or even underlies sleep fragmentation in this disease.

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.