A comparison of extradural and intraparenchymatous intracranial pressures in head injured patients

The reliability of extradural pressure measurements for the measure of intracranial pressure (ICP) is still controversial. This study was undertaken to assess the limits of agreement between extradural and intraparenchymatous pressures using respectively the Plastimed extradural sensor and the Camino fiberoptic system. The study took place in a neurosurgical intensive care unit. Ten head injured patients were included in the study, leading to the comparison of 1032 pairs of hourly ICP values. Although the measures were significantly correlated, there was no agreement between the two methods of ICP monitoring. Extradural pressure was higher than intraparenchymatous pressure (bias 9 mmHg; 95% confidence interval of bias -9.8 to 27.8 mmHg). The lack of agreement between the two methods is probably due to the unreliability of extradural pressure for the measurement of ICP.