Influence of cerebral oxygenation following severe head injury on neuropsychological testing

Despite recent advances in the management of severe head injury the mortality and morbidity remains high. Intracranial pressure (ICP) and cerebral perfusion pressure (CPP) are crucial parameters for the correct management at the intensive care unit, due to their therapeutic and prognostic importance. In addition, regional brain tissue oxygenation (ptiO2) seems to be of importance. While different studies demonstrated the impact of cerebral hypoxia on outcome (mortality), no data are available focusing on morbidity (neuropsychological deficits). Therefore, our study is carried out to demonstrate a possible relationship between amount of cerebral oxygenation during acute stage after severe head injury and neuropsychological outcome. Besides ICP and CPP, ptiO2 was monitored in 40 severely head injured patients during the ICU stay from the day of admission until day 10. Monitoring data were stored and amount of hypoxic episodes were calculated. Besides outcome using the Glasgow Outcome Scale neuropsychological testing was performed 2-3 years after injury. Analysing the quality of brain tissue oxygenation, a relationship to the performance in neuropsychological tests could be found. Patients with low brain tissue oxygenation had a worse outcome in neuropsychological testing, especially concerning intelligence and memory. Associated with these deficits patients showed a reduced performance in their profession. Our data suggest a possible predictive value of brain tissue oxygen on morbidity analysing neurocognitive function after head injury. This may implicate monitoring and treatment of cerebral hypoxia.