Discordant Observation of Brain Injury by MRI and Malignant Electroencephalography Patterns in Comatose Survivors of Cardiac Arrest following Therapeutic Hypothermia

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Fig 1.
Selected examples of patterns of DWI, ADC, and T2-FLAIR abnormalities in subjects without (A) and with (B–D) malignant EEG patterns (longitudinal bipolar montage [low-frequency filter, 1 Hz; high-frequency filter, 70 Hz; 60-Hz notch on; sensitivity, 7 uV/mm]). All of these subjects had bad outcomes (death, coma, or persistent vegetative state at discharge). A, Diffuse gyral edema and restricted diffusion, wbADC = 666 × 10⁻⁶ mm²/s. EEG (nonmalignant) pattern of diffuse background slowing. B, Focal diffusion abnormality involves the sensorimotor cortices, wbADC = 835 × 10⁻⁶ mm²/s. EEG demonstrates a (malignant) suppression burst pattern. Bursts are associated with clinical jerks. C, Essentially normal MR imaging appearance of the brain, wbADC = 782 × 10⁻⁶ mm²/s. EEG demonstrates a (malignant) pattern of generalized periodic discharges. D, Posterior (parietal) diffusion abnormality with little gyral edema, wbADC = 824 × 10⁻⁶ mm²/s. EEG (malignant) pattern of GPDs.
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Fig 2.
Whole-brain median ADC values compared among groups based on a pattern of EEG and outcome (median ± interquartile ratio). A, Whole-brain ADC × 10⁻⁶ mm²/s. B, Percentage of brain voxels with ADC < 700 × 10⁻⁶ mm²/s. There were no subjects with a malignant pattern and good outcome. Mal indicates malignant EEG; NonMal, nonmalignant EEG.

Table 1:

Demographics of groups based on EEG pattern and outcome^{^a}

	Malignant EEG (n = 0)	Malignant EEG (n = 9)	Nonmalignant EEG (n = 12)	Nonmalignant EEG (n = 12)	P Value
Outcome	Good	Bad	Good	Bad
Age (median) (IQR)	NA	50 (42.5–59.5)	53.5 (43.5–63.0)	58.5 (43–66.0)	.252
Female (No.) (%)	NA	8 (89)	4 (33)	6 (50)	.051
Arrest to MRI (median days) (IQR)	NA	3 (2.5–5.0)	5 (4.3–10.3)	4 (3–4)	.065
Length of stay (median days) (IQR)	NA	9 (5–18)	23 (13–27)	13.5 (6–24.5)	.077
GCS at time of MRI (median score) (IQR)		4 (3–6)	10^{^b} (8.5–14)	6 (3.5–8)	.0014
Rhythm of arrest (No.)
Asystole	NA	2	3	3	.71
PEA	NA	2	1	4
VF/VT	NA	4	6	5
Unknown	NA	1	2	0
Location of arrest (No.)
In hospital	NA	2	1	3	.53
Out of hospital	NA	7	11	9

Note:—IQR indicates interquartile range; PEA, pulseless electrical activity; VF/VT, ventricular fibrillation/ventricular tachycardia; NA, not applicable; GCS, Glasgow Coma Scale.
↵a There were no individuals with malignant EEG and good outcome in this cohort. There were no significant differences by groupings using Kruskal-Wallis and Fisher exact tests for nonparametric analysis of continuous and categoric variables, respectively; sex and days from arrest to MRI were nearly significant with P = .051 and .065, respectively.
↵b P < .01 for comparison with the bad outcome groups; nonsignificant difference between the bad outcome groups.

Table 2:

Patterns of brain injury evident on MRI with groupings based on EEG and outcome with the Fisher exact test

	Malignant EEG (n = 0)	Malignant EEG (n = 9)	Nonmalignant EEG (n = 12)	Nonmalignant EEG (n = 12)	P Value
Outcome	Good	Bad	Good	Bad
No. with diffuse pattern of restricted diffusion (%)	NA	0 (0)	1 (8.3)	5 (41.7)	.05
No. with diffuse pattern of gyral edema (%)	NA	3 (33)	1 (17)	6 (50)	.25
No. with restricted diffusion in basal ganglia (any) (%)	NA	4 (44)	1 (17)	10 (83)	.005
No. with restricted diffusion in the hippocampi (%)	NA	1 (11)	0 (0)	5 (50)	.009