Recognition and diagnosis of sleep disorders in Parkinson’s disease

Maartje Louter 0 1 Willemijn C. C. A. Aarden 0 1 Joy Lion 0 1 Bastiaan R. Bloem 0 1 Sebastiaan Overeem 0 1 0 M. Louter W. C. C. A. Aarden J. Lion B. R. Bloem S. Overeem (&) Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen Medical Centre , PO Box 9101, 6500 HB Nijmegen, The Netherlands 1 M. Louter W. C. C. A. Aarden S. Overeem Sleep Medicine Centre 'Kempenhaeghe' , Heeze, The Netherlands Sleep disturbances are among the most frequent and incapacitating non-motor symptoms of Parkinson's disease (PD), and are increasingly recognized as an important determinant of impaired quality of life. Here we review several recent developments regarding the recognition and diagnosis of sleep disorders in PD. In addition, we provide a practical and easily applicable approach to the diagnostic process as a basis for tailored therapeutic interventions. This includes a stepwise scheme that guides the clinical interview and subsequent ancillary investigations. In this scheme, the various possible sleep disorders are arranged not in order of prevalence, but in a 'differential diagnostic' order. We also provide recommendations for the use of sleep registrations such as polysomnography. Furthermore, we point out when a sleep specialist could be consulted to provide additional diagnostic and therapeutic input. This structured approach facilitates early detection of sleep disturbances in PD, so treatment can be initiated promptly. - Sleep disorders are among the most common non-motor symptoms in Parkinsons disease (PD), with an estimated prevalence of 65 % to more than 95 % [19, 41, 46, 63]. Sleep disorders negatively affect the quality of life [54, 55, 58]. Fortunately, specific treatment options are available, but adequate treatment requires a precise and timely diagnosis of the specific sleep disorder at hand. This recognition and diagnosis remain challenging in everyday clinical practice because of the wide variety and intricate combinations of sleep disorders in PD. The whole gamut of sleep disorders may occur in PD, including excessive daytime sleepiness, insomnia, nocturnal motor symptoms and sleep-related breathing disorders. Three main groups of causes can be identified. Sleep problems can be a primary disease symptom caused by neuronal degeneration in sleep-regulating brain regions. An example is EDS in patients with cognitive decline [64]. Second, sleep may be disrupted by other symptoms of PD, such as nocturnal motor symptoms (e.g., difficulty turning in bed) or autonomic dysfunction (e.g., nocturia). Third, many drugs used in the treatment of PD can affect sleep [18, 29, 46, 48, 53]. For example, selegilinewhich is metabolized to methamphetamine and amphetaminemay cause insomnia [12]. Most sleep disturbances can be diagnosed and treated by a movement disorders specialist. However, the diversity and complex origin of sleep disorders in PD may complicate the diagnostic trajectory. Ancillary investigations are needed occasionally, including polysomnographic recordings. In specific cases, the diagnostic and therapeutic help of a sleep medicine specialist can be useful. To adequately treat sleep disorders in PD, an accurate diagnosis is crucial. Treatment options are diverse and depend on the specific sleep disorder(s) that are present. In Table 1, some of the most common sleep disorders are highlighted, together with specifically tailored treatment options. For more elaborate details on the treatment of sleep disorders in PD, we refer to previously published reviews [4, 44]. The purpose of this article is twofold. We highlight the most important recent developments that have clinical relevance for the (differential) diagnosis of sleep disorders in PD. In additionand based on this new knowledgewe provide a practical, easily applicable approach to the recognition and diagnosis of sleep disorders in PD and atypical parkinsonian syndromes. The sleep history The clinical interview remains the single most important diagnostic instrument. Although sleep disorders are common in PD, they are not always mentioned spontaneously by the patient, as was recently shown [11]. A few quick screening questions, probing both nocturnal sleep and daytime sleepiness (see Table 2), should be asked on a Table 1 Therapeutic options of the most common sleep disorders in PD Improve nocturnal sleep regular basis in every PD patient. When these questions raise suspicion of a relevant sleep disorder, a structured history is the essential starting point of the diagnostic trajectory. Table 2 describes the various topics that should be covered in such a comprehensive sleep history. Sleep questionnaires Sleep questionnaires can help to collect data in a standard fashion, although they are no substitute for a personal Table 2 Key elements of the sleep history for PD patients clinical interview. In the past years, several sleep questionnaires have been developed to indentify sleep disorders in PD. A recent study of The Sleep Scale Task Force reviewed these scales and made recommendations for their use [31]. The Pittsburgh Sleep Quality Index (PSQI) is a well-validated measure of nocturnal sleep quality and severity of nighttime sleep disturbances [8]. The Parkinsons Disease Sleep Scale (PDSS) is a more general scale that specifically rates sleep problems in PD [10]. The Epworth Sleepiness Scale (ESS) is recommended to screen for excessive daytime sleepiness and to rate its severity [38]. A specific screening for sleep attacks is provided by The Inappropriate Sleep Composite Score (ISCS) [30]. Nighttime sleep problems and excessive daytime sleepiness are both part of the Scales for Outcomes in Parkinsons Disease Sleep (SCOPA-SLEEP), but this scale has not yet been validated against otherobjectivesleep measures [43]. The Sleep Scale Task Force has also commented on the fact that many available sleep questionnaires offer an overall rating of the severity of night- or daytime sleep problems, but are not intended to diagnose a specific sleep disorder. Recently, the PDSS has been revised and updated to tackle this issue. The PDSS-2 now screens for sleep disorders that are common in PD, such as restless legs syndrome, nocturnal akinesia, and/or pain and sleep apnea [66]. The PDSS-2 was validated using a semi-structured interview, but a validation against objective measurements such as polysomnography has not yet been performed. A number of neurophysiological studies allow for the assessment of sleep architecture and the detection of nocturnal sleep disorders as well as excessive daytime sleepiness, but these sleep registrations should always be interpreted carefully and in combination with the clinical interview. The mainstay technique is polysomnography (PSG): the simultaneous recording of multiple signals to measure both sleep itself and associated physiological parameters such as breathing. Additional audiovisual recording can be very useful, especially for (...truncated)