Examination of EEG spectra to identify markers/predictors of apneic events in obstructive sleep apnea
BACKGROUND: Obstructive sleep apnea (OSA)is the most common sleep disorder, affecting 13% of men and 6% of women in the U.S. The incidence of OSA has increased 300% in last 20 years. OSA not only causes excessive daytime sleepiness, decreased work productivity, and reduced quality of life, but also increases patients’ risks for hypertension, stroke, heart failure and atrial fibrillation. Currently, the gold standard for OSA diagnosis is polysomnography (PSG), which requires patients to be monitored continuously throughout a single night of sleep. Due to the length of this monitoring process, undiagnosed patients have been forced to wait for 3-4 months to undergo PSG. Shortening this monitoring process would enable patients with OSA to be identified and treated earlier. SALIENT FINDINGS: The initiation of stage N3 sleep is measurably different in OSA patients before and after treatment, with significant differences primarily appearing in left-sided leads, but not right-sided leads. Treatment with CPAP corrects these differences, so that both healthy and CPAP-treated OSA patients do not show differences in either the left-sided or the right-sided leads. In untreated OSA patients vs. healthy patients, the changes in spectral power are marked by a decrease in theta band power concomitant with an increase in delta band power. Unlike the other left-sided leads, the F3 lead did not show significant differences in OSA patients. Therefore, although differences are exclusively left-sided, they are not found in all left-sided leads. No significant differences in alpha band power were seen in any leads.