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Polysomnography (PSG) and Guidelines
Availability
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Classification
Supplemental - Highly Recommended: Parkinson's Disease (PD)
Recommendations for use: Indicated for the diagnosis of REM sleep behavior disorder (RBD), periodic leg movements in sleep (PLMS), and obstructive sleep apnea (OSA). It is considered the gold standard for RBD, PLMS and OSA.
Short Description of Instrument
Polysomnography (PSG) consists of the joint evaluation of brain activity (electroencephalogram, EEG), eye movements (electro-oculogram, EOG), and muscle tone (electromyography, EMG). By studying these three variables, wakefulness sleep and its different sleep stages (N1 or dozing, N2 or light sleep, N3 or deep sleep and REM sleep) can be distinguished.
 
PSG includes the recording of the following:
1) electrocardiogram
2) nasal and oral air pressure flow
3) frequency and amplitude of thoracic and abdominal movements
4) oxyhemoglobin saturation using a pulse oximeter
5)  posture (supine, lateral or prone) and
6) muscle activity of the mentalis and limbs.
 
It requires the subject to spend a night in the sleep laboratory.
 
PSG recordings are usually evaluated in 30-second periods called "epochs", where we evaluate the state (wakefulness or sleep phase) and the rest of the variables. The determination of nasal and buccal flow, thoraco-abdominal movements, oxyhemoglobin saturation and posture allow to detect, quantify and classify the characteristics of apneas during sleep. The recording of the anterior tibial muscles will allow periodic leg movements during sleep to be detected. In the study of patients in whom RBD is suspected, it is necessary to study sleep with an audiovisual recording simultaneous with PSG (Video-Polysomnography) in order to clinically identify these alterations and relate their appearance to the phase of sleep in which they occur. In these patients, the activity of the musculature of the upper extremities (flexor digitorum in the forearms) is also usually recorded in addition to that of the mentalis.
Comments/Special Instructions
The study is done at night where all variables are recorded and monitored. A credentialed technologist is required to stay overnight and place all electrodes and tools before the recording starts.
Scoring and Psychometric Properties
Scoring: Interpretation of the study requires an experienced technician and sleep expert to follow the scoring rules. The rules have been designed for the recognition of different sleep stages and to determine the presence of PLMS, respiratory events, and RBD. They have been established by the American Academy of Sleep Medicine in the Manual for the Scoring Sleep and Associated Events.
 
Psychometric Properties: Evaluates sleep time, sleep efficiency, wake time after sleep, time in bed, sleep stages percentages, sleep onset latency, REM sleep latency, respiratory events, PLMS, OSA, and oxyhemoglobin desaturations. Synchronized video allows to identify abnormal motor and vocal behaviors.
Rationale/Justification
Strengths: Provides objective data and accurate detection of sleep abnormalities including RBD, PLMS and OSA.
 
Weaknesses: It evaluates a single night. Requires experts in the field for interpretation of the data. Expensive. Not available in all centers. Scoring is usually manual and time-consuming. Bothersome for the patient. Medications change normal sleep structure (e.g., antidepressants reduce REM sleep quantity and increases REM sleep latency while benzodiazepines increase N2 stage and decreases N3 sleep stage). In advanced PD patients, sleep architecture becomes abnormal as sleep spindles and K complex tend to disappear and REM sleep is linked to increased EMG activity (RBD). In these cases, specific rules need to be developed for advanced PD.
References
Key Reference:
Berry RB, Quan SF, Abreu AR, et al. (2020) American Academy of Sleep Medicine. The AASM Manual for the Scoring of Sleep and Associated Events: Rules, Terminology and Technical Specifications (Ver 2.6 Darien II). American Academy of Sleep Medicine.
 
Additional References:
Cesari M, Heidbreder A, St Louis EK, Sixel-DÖring F, Bliwise DL, Baldelli L, Bes F, Fantini ML, Iranzo A, Knudsen-Heier S, Mayer G, McCarter S, Nepozitek J, Pavlova M, Provini F, Santamaria J, Sunwoo JS, Videnovic A, HÖgl B, Jennum P, Christensen JAE, Stefani A; International RBD Study Group. Video-polysomnography procedures for diagnosis of rapid eye movement sleep behavior disorder (RBD) and the identification of its prodromal stages: Guidelines from the International RBD Study Group. 2022 Mar 14;45(3):zsab257.
 
Ferri R, Fulda S, Allen RP, Zucconi M, Bruni O, Chokroverty S, Ferini-Strambi L, Frauscher B, Garcia-Borreguero D, Hirshkowitz M, HÖgl B, Inoue Y, Jahangir A, Manconi M, Marcus CL, Picchietti DL, Plazzi G, Winkelman JW, Zak RS; International and European Restless Legs Syndrome Study Groups (IRLSSG and EURLSSG). World Association of Sleep Medicine (WASM) 2016 standards for recording and scoring leg movements in polysomnograms developed by a joint task force from the International and the European Restless Legs Syndrome Study Groups (IRLSSG and EURLSSG). Sleep Med. 2016 Oct;26:86-95.
 
Document last updated August 2022