Table 2.
EEG characteristics and outcomes. Data are presented as N (%). White rows display EEG variables using standardized critical care EEG variables from the American Clinical Neurophysiology Society. Gray rows display EEG variables using combined response categories created in this study.
| Totals | Neurobehavioral Outcome | Mortality | |||||
|---|---|---|---|---|---|---|---|
| Unfavorable | Favorable | p-value | Die | Survive | p-value | ||
| 89 | 46 (52%) | 43 (48%) | 30 (34%) | 59 (66%) | |||
| EEG Background Category (5-level) | 0.001 | 0.000 | |||||
| Normal | 9 (10%) | 1 (2%) | 8 (19%) | 1 (3%) | 8 (14%) | ||
| Slow-Disorganized | 44 (49%) | 19 (41%) | 25 (58%) | 7 (23%) | 37 (63%) | ||
| Discontinuous | 18 (20%) | 10 (21%) | 8 (19%) | 6 (20%) | 12 (20%) | ||
| Burst-Suppression | 4 (4%) | 4 (9%) | 0 (0%) | 4 (13%) | 0 (0%) | ||
| Attenuated-Featureless | 14 (16%) | 12 (26%) | 2 (5%) | 12 (40%) | 2 (3%) | ||
| EEG Background Category (4-level) | 0.001 | 0.000 | |||||
| Normal | 9 (10%) | 1 (2%) | 8 (19%) | 1 (3%) | 8 (14%) | ||
| Slow-Disorganized | 44 (49%) | 19 (41%) | 25 (58%) | 7 (23%) | 37 (63%) | ||
| Discontinuous or Burst Suppression | 22 (25) | 14 (30%) | 8 (19%) | 10 (33%) | 12 (20%) | ||
| Attenuated-Featureless | 14 (16%) | 12 (26%) | 2 (5%) | 12 (40%) | 2 (3%) | ||
| Electrographic Seizures | 0.678 | 0.248 | |||||
| None | 82 (92%) | 41 (89%) | 41 (95%) | 26 (87%) | 56 (95%) | ||
| Seizure(s) | 1 (1%) | 1 (2%) | 0 (0%) | 1 (3%) | 0 (0%) | ||
| Status Epilepticus | 6 (7%) | 4 (9%) | 2 (5%) | 3 (10%) | 3 (5%) | ||
| Symmetric | 88 (99%) | 46 (100%) | 42 (98%) | 0.483 | 30 (100%) | 58 (98%) | 1.000 |
| Fastest Frequency (4-level) | 0.078 | 0.001 | |||||
| Attenuated | 11 (12%) | 9 (20%) | 2 (5%) | 9 (30%) | 2 (3%) | ||
| Delta | 52 (58%) | 26 (57%) | 26 (60%) | 17 (57%) | 35 (59%) | ||
| Delta + Theta | 24 27%) | 11 (24%) | 13 (30%) | 4 (13%) | 20 (34%) | ||
| Delta + Theta + Alpha | 2 (2%) | 0 (0%) | 2 (5%) | 0 (0%) | 2 (3%) | ||
| Fastest Frequency (3-level) | 0.083 | 0.001 | |||||
| Attenuated | 11 (12%) | 9 (20%) | 2 (5%) | 9 (30%) | 2 (3%) | ||
| Delta | 52 (58%) | 26 (57%) | 26 (60%) | 17 (57%) | 35 (59%) | ||
| Delta + Theta and/or Alpha | 26 (29%) | 11 (24%) | 15 (35%) | 4 (13%) | 22 (37%) | ||
| Continuity (8-level) | 0.002 | 0.000 | |||||
| Continuous | 49 (55%) | 20 (43%) | 29 (67%) | 8 (27%) | 41 (69%) | ||
| Nearly continuous with attenuation | 4 (4%) | 0 (0%) | 4 (9%) | 0 (0%) | 4 (7%) | ||
| Nearly continuous with suppression | 1 (1%) | 1 (2%) | 0 (0%) | 1 (3%) | 0 (0%) | ||
| Discontinuous with attenuation | 5 (6%) | 3 (7%) | 2 (5%) | 1 (3%) | 4 (7%) | ||
| Discontinuous with suppression | 12 (13%) | 6 (13%) | 6 (14%) | 4 (13%) | 8 (14%) | ||
| Burst-attenuation | 0 (0%) | 0 (0%) | 0 (0%) | 0 (0%) | 0 (0%) | ||
| Burst-suppression | 4 (4%) | 4 (9%) | 0 (0%) | 4 (13%) | 0 (0%) | ||
| Suppression | 14 (16%) | 12 (26%) | 2 (5%) | 12 (40%) | 2 (3%) | ||
| Continuity (4-level) | 0.002 | 0.000 | |||||
| Continuous or Nearly Continuous | 54 (60%) | 21 (46%) | 33 (76%) | 9 (30%) | 45 (76%) | ||
| Discontinuous with attenuation/suppression | 17 (19%) | 9 (20%) | 8 (19%) | 5 (17%) | 12 (20%) | ||
| Burst-attenuation/suppression | 4 (4%) | 4 (9%) | 0 (0%) | 4 (13%) | 0 (0%) | ||
| Suppression | 14 (16%) | 12 (26%) | 2 (5%) | 12 (40%) | 2 (3%) | ||
| Voltage | 0.001 | 0.000 | |||||
| Normal | 44 (49%) | 18 (39%) | 26 (60%) | 10 (33%) | 34 (58%) | ||
| Low | 27 (30%) | 12 (26%) | 15 (35%) | 5 (17%) | 22 (37%) | ||
| Suppressed | 18 (20%) | 16 (35%) | 2 (5%) | 15 (50%) | 3 (5%) | ||
| Stage II Transients (4-level) | 0.000 | 0.001 | |||||
| Present and normal | 14 (16%) | 1 (2%) | 13 (30%) | 0 (0%) | 14 (24%) | ||
| Present but abnormal | 9 (10%) | 2 (4%) | 7 (16%) | 1 (3%) | 8 (14%) | ||
| Absent | 65 (73%) | 43 (93%) | 22 (51%) | 29 (97%) | 36 (61%) | ||
| Awake only | 1 (1%) | 0 (0%) | 1 (2%) | 0 (0%) | 1 (2%) | ||
| Stage II Transients (2-level) | 0.000 | 0.000 | |||||
| Present (normal or abnormal) | 23 (26%) | 3 (7%) | 20 (47%) | 1 (3%) | 22 (37%) | ||
| Absent | 66 (74%) | 43 (93%) | 23 (53%) | 29 (97%) | 37 (63%) | ||
| Reactivity Present | 35 (39%) | 11 (24%) | 24 (56%) | 0.003 | 6 (20%) | 29 (49%) | 0.011 |
| Variability Present | 38 (43%) | 13 (28%) | 25 (58%) | 0.006 | 7 (23%) | 31 (53%) | 0.012 |
| Variability or Reactivity Present | 41 (46%) | 14 (30%) | 27 (63%) | 0.003 | 7 (23%) | 34 (58%) | 0.003 |
| Sporadic Epileptiform Discharges Present | 8 (9%) | 6 (13%) | 2 (5%) | 0.268 | 4 (13%) | 4 (7%) | 0.435 |
| Ictal-Interictal Continuum Patterns Present | 6 (7%) | 5 (11%) | 1 (2%) | 0.204 | 3 (10%) | 3 (5%) | 0.401 |