Low Specificity of Rapid Eye Movement Sleep Behavior Disorder Questionnaires: Need for Better Screening Methods.

BACKGROUND: Correct diagnosis of rapid eye movement sleep behavior disorder (RBD) is critical due to its link to α-synucleinopathies and risk of injuries and requires video-polysomnography (V-PSG). Usefulness of screening questionnaires outside the context of validation studies is limited. OBJECTIVE: The aim was to assess the performance of three validated RBD screening questionnaires compared with gold-standard V-PSG. METHODS: In this bicentric prospective study, 400 consecutive subjects referred to a sleep center for the first time filled three RBD questionnaires (RBD Screening Questionnaire, RBD Single Question, and Innsbruck RBD Inventory) in random order before sleep experts' interview. Subjects positive for at least one questionnaire were invited to undergo V-PSG. Data from patients negative for all questionnaires undergoing V-PSG for other reasons were also evaluated. Questionnaire performances were compared to gold-standard V-PSG RBD diagnosis. RESULTS: Three hundred ninety-nine patients (median age: 51 [interquartile range: 37-64] years, 54.9% men) participated. Two hundred thirty-eight (59.6%) were positive for at least one questionnaire, and RBD was diagnosed using V-PSG in 30 patients (7.5%). Questionnaire specificity was 48.1% to 67.4%, sensitivity 80% to 92%, accuracy 51% to 68.3%, negative predictive value 94.2% to 98%, and positive predictive value 14.1% to 20.7%, with no relevant differences in performances among the evaluated questionnaires. CONCLUSIONS: RBD questionnaires have low specificity and low positive predictive value and should not be used as a standalone tool for the diagnosis of RBD. Further development of RBD screening methods is needed, particularly for upcoming neuroprotective trials. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Lack of Asymmetry of Nigrostriatal Dopaminergic Function in Healthy Subjects.

OBJECTIVE: In right-handed patients with Parkinson's disease (PD) or isolated rapid eye movement sleep behavior disorder, dopamine transporter (DAT) [(123)I]ß-carboxymethyoxy-3-ß-(4-iodophenyl) tropane single photon emission computed tomography (SPECT) shows predominant nigrostriatal deficit in the left striatum. This suggests that in PD patients, the nigrostriatal system of the dominant hemisphere is more susceptible to disease-related dysfunction. To confirm this hypothesis, we investigated whether the nigrostriatal function is symmetric in healthy controls and in patients with PD. METHODS: In 113 right-handed healthy controls and 279 right-handed early-PD patients, we examined the striatal dopaminergic terminals function in each hemisphere using DAT-SPECT. RESULTS: In the controls, DAT-SPECT showed symmetric specific binding ratios in the putamen and caudate nucleus of each hemisphere. In patients with PD, the specific binding ratio was lower in the left than in the right putamen. CONCLUSIONS: Right-handed healthy controls have symmetric nigrostriatal dopaminergic function. The left hemispheric predominance of nigrostriatal deficit seen in right-handed premotor and manifest PD represents an early pathological feature of the disease. © 2020 International Parkinson and Movement Disorder Society.