Temporal recovery and delayed decline of cognitive functions in patients with hypoxic encephalopathy after cardiac arrest

Abstract

Abstract Background Neuropsychological recovery is important for survivors’ quality of life after cardiac arrest. However, most studies on cognitive symptoms after cardiac arrest examined cognitive functions within one year after onset. Aim To investigate long‐term changes in cognitive functions in individuals with hypoxic encephalopathy after cardiac arrest. Methods We retrospectively recruited survivors of cardiac arrest who demonstrated cognitive dysfunction at the chronic stage. The inclusion criteria were follow‐up period of more than 3 years with multiple neuropsychological examinations and brain MRI/CT within 1 year after onset. Results Five patients showed various cognitive dysfunctions 1 year after onset, and the follow‐up periods were 3 to 13 years. Four patients showed temporal recovery of cognitive functions over a period of a few years followed by gradual deterioration afterward. The youngest patient, 48 years of age at the final assessment, demonstrated gradual improvement without clear evidence of deterioration for 4 years. Brain magnetic resonance imaging (MRI) revealed hyperintense areas at the acute stage in 2 patients, and mild cortical atrophy and cerebral hypoperfusion were observed in 3 patients. Delayed cognitive decline in our cases differs in length of the course from that in previously reported “delayed” postanoxic encephalopathy, which appears several days to weeks after onset. Conclusions Cognitive functions in survivors of cardiac arrest recovered for a few years and then gradually deteriorated, which suggests hypoxic changes induce long‐term impact on cerebral functions.