Quantitative analysis of the loss of distinction between gray and white matter in comatose patients after cardiac arrest

• Published in: Stroke (1970) Vol. 31; no. 9; pp. 2163 - 2167
• Main Authors: TORBEY, M. T, SELIM, M, KNORR, J, BIGELOW, C, RECHT, L
• Format: Journal Article
• Language: English
• Published: Hagerstown, MD Lippincott Williams & Wilkins 01.09.2000; American Heart Association, Inc
• Subjects: Adult; Aged; Aged, 80 and over; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Basal Ganglia - diagnostic imaging; Biological and medical sciences; Brain - diagnostic imaging; Coma - diagnostic imaging; Emergency and intensive cardiocirculatory care. Cardiogenic shock. Coronary intensive care; Female; Heart Arrest - diagnostic imaging; Heart Arrest - mortality; Humans; Intensive care medicine; Male; Medical sciences; Middle Aged; Prognosis; Reproducibility of Results; Retrospective Studies; ROC Curve; Tomography, X-Ray Computed; Coma; Human; Nervous system diseases; Cardiocirculatory arrest; Prognosis; Radiodiagnosis; Consciousness impairment; Grey matter; Cardiovascular disease; White matter; Medical imagery; Complication; Computerized axial tomography; Neurological disorder; Predictive factor; Quantitative analysis
• ISSN: 0039-2499; 1524-4628
• DOI: 10.1161/01.str.31.9.2163

Anecdotal reports suggest that a loss of distinction between gray (GM) and white matter (WM) as adjudged by CT scan predicts poor outcome in comatose patients after cardiac arrest. To address this, we quantitatively assessed GM and WM intensities at various brain levels in comatose patients after cardiac arrest. Patients for whom consultation was requested within 24 hours of a cardiac arrest were identified with the use of a computerized database that tracks neurological consultations at our institution. Twenty-five comatose patients were identified for whom complete medical records and CT scans were available for review. Twenty-five consecutive patients for whom a CT scan was interpreted as normal served as controls. Hounsfield units (HUs) were measured in small defined areas obtained from axial images at the levels of the basal ganglia, centrum semiovale, and high convexity area. At each level tested, lower GM intensity and higher WM intensity were noted in comatose patients compared with normal controls. The GM/WM ratio was significantly lower among comatose patients compared with controls (P:<0.0001, rank sum test). There was essentially no overlap in GM/WM ratios between control and study patients. The difference was greatest at the basal ganglia level. We also observed a marginally significant difference in the GM/WM ratio at the basal ganglia level between those patients who died and those who survived cardiac arrest (P:=0. 035, 1-tailed t test). Using receiver operating characteristic curve analysis, we determined that a difference in GM/WM ratio of <1.18 at the basal ganglia level was 100% predictive of death. At the basal ganglia level, none of 12 patients below this threshold survived, whereas the survival rate was 46% among patients in whom the ratio was >1.18. The empirical risk of death was 21.67 for comatose patients with a value below threshold. The ratio in HUs of GM to WM provides a reproducible measure of the distinction between gray and white matter. A lower GM/WM ratio is observed in comatose patients immediately after cardiac arrest. The basal ganglia level seems to be the most sensitive location on CT for measuring this relationship. Although a GM/WM ratio <1.18 at this level predicted death in this retrospective study, the difference in this study is not robust enough to recommend that management decisions be dictated by CT results. The results, however, do warrant consideration of a prospective study to determine the reliability of CT scanning in predicting outcome for comatose patients after cardiac arrest.