The circadian intracranial pressure would be a prognostic factor in traumatic brain injury?

Traumatic brain injury (TBI) generally influences circadian rhythms and has been implicated changes in circadian rhythm. Whether TBI-induced changes in circadian rhythm may affect the prognosis or recovery from TBI remains to be investigated. Sixty-two patients with TBI were continuously monitored for intracranial pressure (ICP) during the first 24 hours after the implantation of ICP monitor. The data from each patient were analyzed using the least squares fit of a 24-h cosine function by single cosinor method. Parameters of circadian A (Amplitude)/M (MESOR) were used to evaluate the circadian rhythm of the patients. Student's t-test and Pearson's chi-squared test were utilized to analyze the differences between good prognosis group and poor prognosis. A linear regression analysis was then applied to calculate the correlation between circadian A/M of ICP and Glasgow Coma Scale (GCS) before discharge, the Extended Glasgow Outcome Scale (GOS-E), the dosage of mannitol, and time spent in the intensive care unit (ICU), respectively. The results demonstrated that circadian A/M of patients' ICP exhibited a positive correlation with GCS scores taken before discharge, GOS-E scores, and was negatively correlated with the amount of mannitol, and time spent in the ICU. We conclude that changes in the ICP circadian rhythm in TBI patients could reflect an internal signal of brain damage and, therefore, may be useful to predict a patient's prognosis and recovery from TBI.