title: Spreading depolarizations and late secondary insults after traumatic brain injury.
abstract: Here we investigated the incidence of cortical spreading depolarizations (spreading depression and peri-infarct depolarization) after traumatic brain injury (TBI) and their relationship to systemic physiologic values during neurointensive care. Subdural electrode strips were placed on peri-contusional cortex in 32 patients who underwent surgical treatment for TBI. Prospective electrocorticography was performed during neurointensive care with retrospective analysis of hourly nursing chart data. Recordings were 84 hr (median) per patient and 2,503 hr in total. In 17 patients (53%), 280 spreading depolarizations (spreading depressions and peri-infarct depolarizations) were observed. Depolarizations occurred in a bimodal pattern with peak incidence on days 1 and 7. The probability of a depolarization occurring increased significantly as a function of declining mean arterial pressure (MAP; R(2) = 0.78; p < 0.001) and cerebral perfusion pressure (R(2) = 0.85; p < 0.01), and increasing core temperature (R(2) = 0.44; p < 0.05). Depolarization probability was 7% for MAP values of >100 mm Hg but 33% for MAP of < or =70 mm Hg. Temperatures of < or =38.4 degrees C were associated with a 21% depolarization risk, compared to 63% for >38.4 degrees C. Intracranial pressures were higher in patients with depolarizations (18.3 +/- 9.3 vs. 13.5 +/- 6.7 mm Hg; p < 0.001). We conclude that depolarization phenomena are a common cortical pathology in TBI. Their association with lower perfusion levels and higher temperatures suggests that the labile balance of energy supply and demand is an important determinant of their occurrence. Monitoring of depolarizations might serve as a functional measure to guide therapeutic efforts and their blockade may provide an additional line of defense against the effects of secondary insults.
authors.affiliation: UC Neuroscience Institute, Department of Neurosurgery, University of Cincinnati, Cincinnati, Ohio 45219, USA. jed.hartings@uc.edu
authors.forename: Jed A
authors.initials: JA
authors.lastname: Hartings
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Strong
authors.forename: Martin
authors.initials: M
authors.lastname: Fabricius
authors.forename: Andrew
authors.initials: A
authors.lastname: Manning
authors.forename: Robin
authors.initials: R
authors.lastname: Bhatia
authors.forename: Jens P
authors.initials: JP
authors.lastname: Dreier
authors.forename: Anna Teresa
authors.initials: AT
authors.lastname: Mazzeo
authors.forename: Frank C
authors.initials: FC
authors.lastname: Tortella
authors.forename: M Ross
authors.initials: MR
authors.lastname: Bullock
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001794:Blood Pressure / Q000502:physiology; D001831:Body Temperature / Q000502:physiology; D001930:Brain Injuries / Q000503:physiopathology*; D002560:Cerebrovascular Circulation / Q000502:physiology; D013181:Cortical Spreading Depression / Q000502:physiology*; D004594:Electrophysiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D055815:Young Adult