Cerebral perfusion pressure and intracranial pressure in relation to neuropsychological outcome

Objective: The study attempted to examine the relationship between neuropsychological functioning and reduced cerebral perfusion pressure (CPP), raised intracranial pressure (ICP), and reduced mean arterial pressure (MAP), monitored during intensive care treatment. Design: This prospective follow-up study included consecutive patients and evaluated outcome at 6 months postinjury by the administration of a neuropsychological test battery. Setting: The study was conducted at the University Hospital of Gent, Belgium. Patients and participants: Over a 30-month period, 43 patients were included. Inclusion criteria were the following: hospital admission following closed head injury, ICP monitoring, no medical history of central nervous system disease or mental retardation, survival for at least 6 months, and informed consent for participation. Interventions: All patients received the hospital's standard treatment for head injury, which remained unchanged during the study period. Measurements and results: Reduced CPP was analyzed using the number of observed values below 70 mmHg, raised ICP using the number of values above 20 mmHg, and MAP using the number of values below 80 mmHg. The neuropsychological test battery included 11 measures of attention, information processing, motor reaction time, memory, learning, visuoconstruction, verbal fluency, and mental flexibility. No linear relationships were found between overall neuropsychological impairment and episodes of reduced CPP, raised ICP, or reduced MAP. Conclusions: Although reduced CPP and raised ICP are frequent, often fatal, complications of head injury, in survivors they do not seem to be related to later neuropsychological functioning.