Hippocampal damage in the human brain after cardiac arrest

Background and Purpose: Very few reports are available on changes in the hu man hippocampus after cardiac arrest. The objective of this study was to in vestigate if specific hippocampal volume losses can be demonstrated in the human brain following reperfusion after cardiac arrest. Methods: We assesse d the volumes of the hippocampal formation (HF) and temporal lobe excluding HF (TL) as the contrast using magnetic resonance (MR)-imaging-based volume try in 11 vegetative patients after cardiac arrest and in 22 healthy contro ls of similar age, sex and body size distribution. The measured volumes wer e normalized for differences in the head size among subjects by dividing by the total intracranial volume (TICV). The MR images of the 11 patients wer e obtained between days 8 and 21 after cardiac arrest. Results: The observe d volumes of HFs and TLs of both patient and control groups were as follows : right HF volume (HFV): 2.67 +/- 0.19 (mean +/- SD, cm(3)) in patients ver sus 3.89 +/- 0.44 in controls; left HFV: 2.72 +/- 0.17 versus 3.74 +/- 0.35 ; right TL volume (TLV): 73.37 +/- 6.54 versus 80.08 +/- 7.62, and left TLV : 72.45 +/- 6.77 versus 78.59 +/- 6.68. The normalized indic;es (HFV/TICV a nd TLV/TICV) were as follows: right HF: 0.0021 +/- 0.0002 (mean +/- SD) in patients versus 0.0031 +/- 0.0001 in controls, p < 0.0001, left HF: 0.0022 +/- 0.0002 versus 0.0030 +/- 0.0001, p < 0.0001, right TL: 0.058 +/- 0.002 versus 0.064 +/- 0.004, p = 0.0007, and left TL: 0.058 +/- 0.002 versus 0.0 62 +/- 0.004, p = 0.0014. The HFV-TLV ratios (HFV/TICV divided by TLV/TICV) of both groups were: right HFV-TLV ratio: 0.037 +/- 0.004 in patients vers us 0.049 +/- 0.004 in controls, p < 0.0001, left HFV-TLV ratio: 0.038 +/- 0 .004 versus 0.048 +/- 0.004, p < 0.0001. Conclusions: The patient group had HFs that were 26.8-30.6% smaller than those of the control group, but in t he patient group, the TLs slightly decreased in size by only 7.8-8.2% of th e volume of those in the control group within 21 days after cardiac arrest. The volume reductions in the bilateral HFs of patients after cardiac arres t were significantly larger than those in the bilateral TLs. We speculate t hat this specific rapid hippocampal shrinkage reflects its greater vulnerab ility to global brain ischemia. Copyright (C) 2000 S. Karger AG, Basel.