J.H. van der Hoeven

Obstructive Sleep apnea Therapy

In clinical practice, oral appliances are used primarily for obstructive sleep apnea patients who do not respond to continuous positive airway pressure (CPAP) therapy. We hypothesized that an oral appliance is not inferior to CPAP in treating obstructive sleep apnea effectively. We randomly assigned 103 individuals to oral-appliance or CPAP therapy. Polysomnography after 8–12 weeks indicated that treatment was effective for 39 of 51 persons using the oral appliance (76.5%) and for 43 of 52 persons using CPAP (82.7%). For the difference in effectiveness, a 95% two-sided confidence interval was calculated. Non-inferiority of oral-appliance therapy was considered to be established when the lower boundary of this interval exceeded −25%. The lower boundary of the confidence interval was −21.7%, indicating that oral-appliance therapy was not inferior to CPAP for effective treatment of obstructive sleep apnea. However, subgroup analysis revealed that oral-appliance therapy was less effective in individuals with severe disease (apnea-hypopnea index > 30). Since these people could be at particular cardiovascular risk, primary oral-appliance therapy appears to be supported only for those with non-severe apnea.

Multichannel recording of median nerve somatosensory evoked potentials

OBJECTIVES Clinical applications of multichannel (>or=64 electrodes) electroencephalography (EEG) have been limited so far. Amplitude variability of evoked potentials in healthy subjects is large, which limits their diagnostic applicability. This amplitude variability may be partially due to spatial undersampling of anatomical variations in cortical generators. In the present study, we therefore investigated whether 128-channel recordings of somatosensory evoked potentials (SEPs) can reduce this amplitude variability in healthy subjects. Additionally, we explored the relation between amplitude and age. METHODS We recorded median nerve SEPs using a 128-channel EEG system in 50 healthy subjects (20-70 years) and compared N20, P27, and P45 amplitude as obtained with a 128-channel analysis method - based on butterfly plots and spatial topographies - and as obtained using a conventional one-cortical-channel configuration and analysis. Scalp and earlobe references were compared. RESULTS Although amplitude variability itself was not reduced, a reduced coefficient of variation was obtained with the 128-channel method due to higher SEP amplitudes, compared to the conventional one-channel method, independent of reference. CONCLUSION These results suggest that at the cost of some additional preparation time, the 128-channel method can measure SEP amplitude more accurately and might therefore be more sensitive to physiological and pathological changes. For optimal amplitude estimation, we recommend to increase the number of centroparietal electrodes or, preferably, to perform at least a 64-channel recording.