Clinical assessment of nocturnal disability in Parkinson’s disease

Abstract

Research by our group and by others suggests that sleep disturbances are common in Parkinson’s disease (PD) and can occur at all stages of PD, and that virtually all PD patients suffer from varying levels of nocturnal disability causing sleep disruption.1–4⇓⇓⇓ The etiology is likely to be diverse, and includes degeneration of central sleep regulatory centers and the effect(s) of dopaminergic drugs.2,5⇓ The problem of nocturnal symptoms in PD is compounded by the fact that such symptoms arise from a multitude of causes, categorized as insomnia, motor, urinary, and neuropsychiatric symptoms, often with secondary daytime somnolence, and occasionally in the form of “sleep attacks,” although this remains controversial.6,7⇓ Conventional sleep assessment is based on anamnesis, caregiver or spouse reports, patients’ diaries, the usual PD rating scales, polysomnography, or video recordings.8 Currently available scales for measuring disability, such as the Unified Parkinson’s Disease Rating Scale (UPDRS),9 do not allow a formal clinimetric approach or do not provide a holistic assessment of sleep-related problems in PD. The newly developed and validated Parkinson’s Disease Sleep Scale (PDSS),10,11⇓ the first specific instrument designed to measure sleep disturbances in PD, aims to provide a bedside/clinical holistic measure of the nocturnal symptom complex of PD in a semi-quantitative manner. The gold standards for physiologic measurement of sleep and sleep parameters are polysomnography (PSG) and multiple sleep latency tests (MSLT). However, these tests measure sleep architecture, require measurements in specialized sleep laboratories, and are relatively expensive. Furthermore, they may not provide information on causes of sleep disabilities such as nocturnal tremor, nocturia, or akinesia. The Epworth Sleepiness Scale (ESS) has been widely used but is not specific to PD and measures only daytime somnolence.12 Problems with the use of ESS in PD include intercultural …