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

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 longterm impact on cerebral functions.