Supplemental Methods e-1
Evaluation of daytime sleepiness and sleep-related breathing disorders. In addition to lumbar puncture, 13 URMC patients underwent overnight polysomnography (PSG) followed by a multiple Sleep Latency Test (MSLT). The PSG recordings were made utilizing a Grass model 8 amplifier and Stellate Harmonie software. The base PSG montage included 2 EOGs referenced to a single mastoid (LOC & ROC), 6 EEGs referenced to linked mastoids (F3, F4, C3, C4, O1 and O2), a bipolar mentalis EMG, and an EKG. Respiratory parameters were measured by1 channel of nasal/oral airflow (obtained with a pressure transducer), 2 channels for the piezo-electric sensors for the detection of thoracic and abdominal excursions (respiratory effort) and one channel dedicated to the measure of blood oxygen saturation (via oximetry). The airflow, effort, and O2 saturation were used to detect and quantify respiratory events (apnea and/or hypopnea). Two channels of leg-related motor activity (right & left tibial EMG) were used to evaluate and quantify periodic limb movements (PLMs).
Sleep Scoring.PSGs were scored in 30-second epochs according to Rechtschaffen and Kales (1968) criteria.1Scoring procedures deviated slightly from Rechtschaffen and Kales methods and standards in two ways. First, both a duration and amplitude criteria were used to define K-complexes. Based on the work of Bastien et al.2the minimum amplitude for K-complexes was 50 V. Second, based on early work by Dement et al,3an epoch was scored as Stage 2 sleep, in the absence of spindles and K-complexes for 3 or more minutes, if between 5-19% Delta activity was identified. 1 These are to allow more reliable and precise sleep scoring between scorers as these areas can be a source of inter-rater differences. PSG scorers identified apnea/hypopnea and PLMs events based on standard criteria (American Academy of Sleep Medicine guidelines)4 These events were tabulated to form an apnea/hypopnea index (AHI) and PLM index.
MSLT.This procedure was performed on the day following the PSG utilizing a 4 nap protocol beginning no later than 10AM and interspersed by 2 hours intervals. Standard procedures were used as specified by Carskadon and colleagues.5,6A mean sleep latency (MSL) value from the 4 sessions was calculated for each patient. The number of sleep-onset rapid eye movement (REM) periods during the study was determined.
1. Rechtschaffen A, Kales A. A Manual of Standardized Terminology, Techniques and Scoring System for Sleep Stages of Human Subjects. U.S. Government Printing Office, Washington, D.C.; 1968
2.Bastien C, Campbell K. The Evoked K-Complex: All-or-None Phenomenon? Sleep1992; 15:236-245.
3. Dement WC, Kleitman N. Cyclic variations in EEG during sleep and their relation to eye movements, body motility and dreaming. Neurophysiology 1957; 9:673-690.
4.AmericanAcademy of Sleep Medicine Task Force. Sleep-related breathing disorders in adults: recommendations for syndrome definition and measurement techniques in clinical research. Sleep 1999; 22: 667-689.
5.Carskadon MA, Kryger MH, Roth T, Dement W.C. Measuring daytime sleepiness in Principles and Practice of Sleep Medicine. W.B. Saunders Company, Philadelphia, PA. 1989; 684-688.
6.Carskadon MA, Dement WC, Mitler MM. Guidelines for the multiple sleep latency test (MSLT): A standard measure of sleepiness. Sleep 1986; 9:519-524.