Tonic Electromyogram Density in Multiple System Atrophy with Predominant Parkinsonism and Parkinson's Disease / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Both Parkinson's disease (PD) and multiple system atrophy (MSA) have associated sleep disorders related to the underlying neurodegenerative pathology. Clinically, MSA with predominant parkinsonism (MSA-P) resembles PD in the manifestation of prominent parkinsonism. Whether the amount of rapid eye movement (REM) sleep without atonia could be a potential marker for differentiating MSA-P from PD has not been thoroughly investigated. This study aimed to examine whether sleep parameters could provide a method for differentiating MSA-P from PD.</p><p><b>METHODS</b>This study comprised 24 MSA-P patients and 30 PD patients, and they were of similar age, gender, and REM sleep behavior disorder (RBD) prevalence. All patients underwent clinical evaluation and one night of video-polysomnography recording. The tonic and phasic chin electromyogram (EMG) activity was manually quantified during REM sleep of each patient. We divided both groups in terms of whether they had RBD to make subgroup analysis.</p><p><b>RESULTS</b>No significant difference between MSA-P group and PD group had been found in clinical characteristics and sleep architecture. However, MSA-P patients had higher apnea-hypopnea index (AHI; 1.15 [0.00, 8.73]/h vs. 0.00 [0.00, 0.55]/h, P = 0.024) and higher tonic chin EMG density (34.02 [18.48, 57.18]% vs. 8.40 [3.11, 13.06]%, P < 0.001) as compared to PD patients. Subgroup analysis found that tonic EMG density in MSA + RBD subgroup was higher than that in PD + RBD subgroup (55.04 [26.81, 69.62]% vs. 11.40 [8.51, 20.41]%, P < 0.001). Furthermore, no evidence of any difference in tonic EMG density emerged between PD + RBD and MSA - RBD subgroups (P > 0.05). Both disease duration (P = 0.056) and AHI (P = 0.051) showed no significant differences during subgroup analysis although there was a trend toward longer disease duration in PD + RBD subgroup and higher AHI in MSA - RBD subgroup. Stepwise multiple linear regression analysis identified the presence of MSA-P (β = 0.552, P < 0.001) and RBD (β = 0.433, P < 0.001) as predictors of higher tonic EMG density.</p><p><b>CONCLUSION</b>Tonic chin EMG density could be a potential marker for differentiating MSA-P from PD.</p>

Rapid Eye Movement Sleep Behavior Disorder Symptoms Correlate with Domains of Cognitive Impairment in Parkinson's Disease / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Rapid eye movement (REM) sleep behavior disorder (RBD) may be a risk factor for cognitive impairment in patients with Parkinson's disease (PD). However, little is known regarding the relation between the severity of RBD and the different domains of cognitive impairment. The aim of this study was: (1) to investigate the domains of cognitive impairment in patients with PD and RBD, and (2) to explore risk factors for PD-mild cognitive impairment (PD-MCI) and the relationship between RBD severity and impairment in different cognitive domains in PD.</p><p><b>METHODS</b>The participants were grouped as follows: PD without RBD (PD-RBD; n = 42), PD with RBD (PD + RBD; n = 32), idiopathic RBD (iRBD; n = 15), and healthy controls (HCs; n = 36). All participants completed a battery of neuropsychological assessment of attention and working memory, executive function, language, memory, and visuospatial function. The information of basic demographics, diseases and medication history, and motor and nonmotor manifestations was obtained and compared between PD-RBD and PD + RBD groups. Particular attention was paid to the severity of RBD assessed by the RBD Questionnaire-Hong Kong (RBDQ-HK) and the RBD Screening Questionnaire (RBDSQ), then we further examined associations between the severity of RBD symptoms and cognitive levels via correlation analysis.</p><p><b>RESULTS</b>Compared to PD-RBD subjects, PD + RBD patients were more likely to have olfactory dysfunction and their Epworth Sleepiness Scale scores were higher (P < 0.05). During neuropsychological testing, PD + RBD patients performed worse than PD-RBD patients, including delayed memory function, especially. The MCI rates were 33%, 63%, 33%, and 8% for PD-RBD, PD + RBD, iRBD, and HC groups, respectively. RBD was an important factor for the PD-MCI variance (odds ratio = 5.204, P = 0.018). During correlation analysis, higher RBDSQ and RBDQ-HK scores were significantly associated with poorer performance on the Trail Making Test-B (errors) and Auditory Verbal Learning Test (delayed recall) and higher RBD-HK scores were also associated with Rey-Osterrieth complex figure (copy) results.</p><p><b>CONCLUSIONS</b>When PD-RBD and PD + RBD patients have equivalent motor symptoms, PD + RBD patients still have more olfactory dysfunction and worse daytime somnolence. RBD is an important risk factor for MCI, including delayed memory. Deficits in executive function, verbal delayed memory, and visuospatial function were consistently associated with more severe RBD symptoms.</p>