Table 3

Median spindle frequency distribution across AHI groups, scalp locations and night sections
Non-OSA (7) Mild OSA (11) Mod OSA (10) KW H df
Location Night Period
Frontal total∗∗∗ 12.6 (1.6) 12.4 (1.5) 12.1 (1.3)c,f 51.704 2
I 12.4 (1.6) 12.3 (1.6) 12.1 (1.3)a,d 8.135 2
II∗∗ 12.3 (1.5) 12.3 (1.4) 12.1 (1.3)b 12.339 2
III∗∗∗ 12.8 (1.4) 12.5 (1.6)c 12.0 (1.2)c,f 48.252 2
Central total∗∗∗ 13.5 (1.4) 13.1 (1.7)c 12.5 (2.1)c,f 180.116 2
I∗∗∗ 13.3 (1.9) 13.0 (2.2) 12.5 (1.9)c,f 51.716 2
II∗∗∗ 13.6 (1.2) 13.3 (1.8)a 12.7 (2.1)c,f 46.849 2
III∗∗∗ 13.5 (1.3) 13.1 (1.4)c 12.3 (2.3)c,f 85.931 2
Parietal total∗∗∗ 13.7 (0.9) 13.6 (1.6) 12.9 (2.3)c,f 194.36 2
I∗∗∗ 13.6 (1.0) 13.7 (2.0) 12.6 (2.1)c,f 66.639 2
II∗∗∗ 13.7 (0.9) 13.8 (1.5) 13.3 (1.8)c,f 82.901 2
III∗∗∗ 13.8 (0.9) 13.4 (1.4)c 12.5 (2.4)c,f 73.002 2

AHI, Apnea-Hypopnea Index; Mod, moderate OSA; Location, scalp EEG topography; total, (I+II+III) sample; I, II and III, initial, middle and final night sections, respectively. Data presented as median (interquartile range). KW H, Kruskal-Wallis statistic; df, degrees of freedom. P-value significance as follows: <0.05, ∗∗<0.01, ∗∗∗<0.001. Dunn’s post-hoc multiple comparisons tests as follows: a<0.05, b<0.01, c<0.001 for contiguous comparisons; d<0.05, e<0.01, f<0.001 for non-contiguous comparisons. Compared to non-OSA subjects, moderate OSA patients had significantly lower median spindle frequency in all locations and night sections under study. It should be noticed that frequency distributions were, in the large majority, non-unimodal, indicating that variations in frequency medians were only partially informative, and resulted from variability in the proportions of at least two spindle populations.

Schönwald et al.

Schönwald et al. BMC Neuroscience 2012 13:89   doi:10.1186/1471-2202-13-89

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