Video-polysomnography (v-PSG) is essential for diagnosing rapid eye movement (REM) sleep behavior disorder (RBD). Although there are current American Academy of Sleep Medicine standards to diagnose RBD, several aspects need to be addressed to achieve harmonization across sleep centers. Prodromal RBD is a stage in which symptoms and signs of evolving RBD are present, but do not yet meet established diagnostic criteria for RBD. However, the boundary between prodromal and definite RBD is still unclear. As a common effort of the Neurophysiology Working Group of the International RBD Study Group, this manuscript addresses the need for comprehensive and unambiguous v-PSG recommendations to diagnose RBD and identify prodromal RBD. These include: (1) standardized v-PSG technical settings; (2) specific considerations for REM sleep scoring; (3) harmonized methods for scoring REM sleep without atonia; (4) consistent methods to analyze video and audio recorded during v-PSGs and to classify movements and vocalizations; (5) clear v-PSG guidelines to diagnose RBD and identify prodromal RBD. Each section follows a common template: The current recommendations and methods are presented, their limitations are outlined, and new recommendations are described. Finally, future directions are presented. These v-PSG recommendations are intended for both practicing clinicians and researchers. Classification and quantification of motor events, RBD episodes, and vocalizations are however intended for research purposes only. These v-PSG guidelines will allow collection of homogeneous data, providing objective v-PSG measures and making future harmonized multicentric studies and clinical trials possible.

Deep brain stimulation (DBS) is an established treatment for Parkinson disease (PD). In patients carrying GBA1 variants (GBA-PD), concerns persist that DBS may accelerate cognitive decline. This study investigated the potential additive effects of GBA1 genotype and DBS on long-term motor and nonmotor outcomes. This multicenter retrospective, controlled, Italian study included 3 groups: DBS-treated PD patients either carrying or noncarrying GBA1 variants (DBS-nonGBA-PD and DBS-GBA-PD) and GBA-PD patients who fulfilled DBS criteria but eventually were not operated. As secondary aims, we assessed the clinical outcomes of DBS-GBA-PD stratified by GBA1 variant classes and by different DBS targets. Cognitive, motor, and other nonmotor features were collected at baseline and after 1, 3 and, when available, 5 years. Between-group comparisons used χ² and Kruskal-Wallis tests with Bonferroni correction. Longitudinal changes were analyzed with linear mixed-effects models. Subgroup analyses were performed by GBA1 variant class and DBS target. A total of 615 participants were included: 430 DBS-nonGBA-PD (age 57.4 ± 7.7 years, 32% female), 109 DBS-GBA-PD (age 53.5 ± 8.4 years, 38% female), and 76 nonDBS-GBA-PD (age 57.7 ± 8.1 years, 37% female). At baseline, groups were largely matched for clinical features. Longitudinally, both DBS groups showed marked motor improvement (dyskinesias, on-off phenomenon, and wearing-off, all p vs T0 < 0.001), a benefit which was absent in nonDBS-GBA-PD. At 5 years, dementia occurred more frequently in DBS-GBA-PD and nonDBS-GBA-PD compared with DBS-nonGBA-PD (25.5% vs 36.8% vs 10.8%, p < 0.001). Hallucinations and urinary problems increased in both GBA-PD groups than nonGBA-PD (p-between <0.001 and 0.02, respectively), regardless of DBS. No relevant differences emerged on stratification for variant classes or DBS targets, up to 3 years postsurgery. Despite its retrospective design, this study supports DBS as a valid therapeutic option for GBA-PD, providing prolonged benefits on motor symptoms and quality of life. The accelerated cognitive decline observed in GBA-PD, compared with non-mutated participants, was similarly present in both operated and non-operated groups, suggesting it is driven by the genotype rather than DBS itself. This study provides Class III evidence that DBS does not worsen cognitive function in patients with GBA1-associated PD.

Isolated REM sleep behavior disorder (iRBD) is a prodromal state of α-synucleinopathies, presenting years before overt neurodegenerative disorders. Autonomic nervous system (ANS) involvement, particularly cardiovascular autonomic failure, may indicate progression. However, its role as a (multidimensional) marker for disease progression and phenoconversion remains unclear. This study aimed to investigate whether cardiovascular autonomic failure and symptoms of autonomic dysfunction serve as multidimensional markers in patients with iRBD. We conducted a prospective cohort study of patients with iRBD (iRBDs) and controls. Participants underwent cardiovascular reflex tests (CRTs) with beat-to-beat monitoring of blood pressure (BP) and ANS symptom assessments at baseline and annually. Primary outcomes were prevalence and progression of cardiovascular autonomic failure and the risk factors of phenoconversion. Longitudinal changes were evaluated through mixed-effects regression, predictors associated with conversion with Cox regression analysis. Sixty-four iRBDs (mean age 68.89 ± 6.75 years, 75% male) and 67 controls (66.57 ± 7.91 years, 68% male) were recruited. At baseline, iRBDs exhibited a prevalent sympathetic cardiovascular dysfunction, with more frequent neurogenic orthostatic hypotension (nOH in 9 iRBDs) and abnormal BP responses to CRTs (pathologic Valsalva maneuver [VM] overshoot in 27 iRBDs). Longitudinal data demonstrated progressive deterioration of sympathetic baroreflex function, with increased prevalence of nOH (7 iRBDs with incident nOH; yearly odds ratio [OR] = 2.44) and deterioration of parasympathetic cardiovagal function. Thirteen patients (20.3%) phenoconverted to α-synucleinopathies. Neurogenic OH (hazard ratio [HR] = 5.05), altered sympathetic baroreflex function (pathologic VM HR = 3.49), and blunted parasympathetic cardiovagal responses (pathologic deep breathing heart rate ratio HR = 3.27) were significant risk factors for phenoconversion; their early appearance 5 years from iRBD onset increased the conversion risk, up to 4-fold. Symptoms of autonomic failure were more prevalent in iRBD and deteriorated over time but failed to predict conversion. Progressive deterioration of cardiovascular autonomic function is a feature of iRBDs and affects the risk of phenoconversion. Limitations include the relatively short follow-up period and small number of converters. This study highlights the importance of objective cardiovascular autonomic testing as a multidimensional marker for risk stratification in iRBD.

Background: Blood pressure control in Parkinson's disease (PD) under subthalamic deep brain stimulation (STN‐DBS) is influenced by several intertwined aspects, including autonomic failure and levodopa treatment. Objective: To evaluate the effect of chronic STN‐DBS, levodopa, and their combination on cardiovascular autonomic functions in PD. Methods: We performed cardiovascular reflex tests (CRTs) before and 6‐months after STN‐DBS surgery in 20 PD patients (pre‐DBS vs. post‐DBS). CRTs were executed without and with medication (med‐OFF vs. med‐ON). Results: CRT results and occurrence of neurogenic orthostatic hypotension (OH) did not differ between pre‐ and post‐DBS studies in med‐OFF condition. After levodopa intake, the BP decrease during HUTT was significantly greater compared to med‐OFF, both at pre‐DBS and post‐DBS evaluation. Levodopa‐induced OH was documented in 25% and 5% of patients in pre‐DBS/med‐ON and post‐DBS/med‐ON study. Conclusion: Chronic stimulation did not influence cardiovascular responses, while levodopa exerts a relevant hypotensive effect. The proportion of patients presenting levodopa‐induced OH decreases after STN‐DBS surgery.