Table 2 Comparison between 30-min EEG and 2-h EEG
Characteristics | 30-min EEG | 2-h EEG | p value |
|---|---|---|---|
Symmetry | |||
 Mild asymmetrical | 1 (2.2%) | 1 (2.2%) |  |
 Symmetrical | 44 (97.8%) | 44 (97.8%) | 1.000 |
Predominant background Frequency | |||
 Beta | 5 (11.1%) | 1 (2.2%) |  |
 Alpha | 3 (6.7%) | 3 (6.7%) |  |
 Theta | 34 (75.6%) | 30 (66.7%) |  |
 Delta | 3 (6.7%) | 11 (24.4%) | 0.036* |
Posterior dominant alpha with eye closure | |||
 Absent | 41 (91.1%) | 42 (93.3%) |  |
 Present | 4 (8.9%) | 3 (6.7%) | 1.000 |
Continuity | |||
 Continuous | 43 (95.6%) | 42 (93.3%) |  |
 Suppression | 2 (4.4%) | 1 (2.2%) |  |
 Burst attenuation | – | 1 (2.2%) |  |
 Attenuation | – | 1 (2.2%) | – |
Reactivity | |||
 Unclear | – | 10 (22.2%) |  |
 Reactive | – | 9 (20%) |  |
 Unreactive | – | 9 (20%) |  |
 Unknown | – | 17 (37.8%) | – |
State change | |||
 Absent | 40 (88.9%) | 30 (66.7%) |  |
 Present with normal stage N2 sleep transients | 1 (2.2%) | 3 (6.7%) |  |
 Present without stage N2 sleep | 4 (8.9%) | 12 (26.7%) | 0.037* |
Cyclic alternating patterns of encephalopathy | |||
 Absent | 45 (100%) | 45 (100%) | – |
EEG Voltage | |||
 Normal | 39 (86.7%) | 37 (82.2%) |  |
 Low | 4 (8.9%) | 7 (15.6%) |  |
 Suppressed | 2 (4.4%) | 1 (2.2%) | 0.233 |
AP gradient | |||
 Absent | 38 (84.4%) | 35 (77.8%) |  |
 Present | 7 (15.6%) | 10 (22.2%) | 0.607 |
Breach effect | |||
 Absent | 45 (100%) | 45 (100%) | – |