NEUROSURGERY VOLUME 64 | NUMBER 4 | APRIL 2009 | 705 CLINICAL STUDIES Arturo Chieregato, M.D. Neurosurgical and Trauma Intensive Care Unit, Maurizio Bufalini Hospital, Cesena, Italy Alberto Noto, M.D. Cardiovascular and Thoracic Unit, G. Martino Hospital, University of Messina, Messina, Italy Alessandra Tanfani, M.D. Neurosurgical and Trauma Intensive Care Unit, Maurizio Bufalini Hospital, Cesena, Italy Giovanni Bini, M.D. Neurosurgical and Trauma Intensive Care Unit, Maurizio Bufalini Hospital, Cesena, Italy Costanza Martino, M.D. Neurosurgical and Trauma Intensive Care Unit, Maurizio Bufalini Hospital, Cesena, Italy Enrico Fainardi, M.D., Ph.D. Neuroradiological Unit, S. Anna Hospital, Ferrara, Italy Reprint requests: Arturo Chieregato, M.D., Rianimazione per la Traumatologia e le Neuroscience, Ospedale Maurizio Bufalini, viale Ghirotti 286, 47023 Cesena, Italy. Email: achiere@ausl-cesena.emr.it Received, March 7, 2008. Accepted, November 6, 2008. Copyright © 2009 by the Congress of Neurological Surgeons A cute subdural hematoma (SDH) is one of the leading causes of death and disability in severe traumatic brain injury (TBI). The physiological findings in the hyperacute phase before evacuation have been described at various times and seem to be affected by low ABBREVIATIONS: ΔrCBFmax, side-to-side differences in rCBF max; ΔrCBFmean, side-to-side differences in rCBF mean; ΔrCBFmin, side-to-side differences in rCBF min; CBF, cerebral blood flow; CMR, cerebral metabolic rate; CPP, cerebral perfusion pressure; CT, computed tomographic; EDH, extradural hematoma; GCS, Glasgow Coma Scale; GOS, Glasgow Outcome Scale; Ht, hematocrit; ICP, intracranial pressure; PET, positron emission tomographic; rCBF, regional cerebral blood flow; rCBFmax, maximum of all rCBF levels below the evacuated subdural hematoma; rCBFmean, mean of all rCBF levels below the evacuated sub- dural hematoma; rCBFmin, minimum of all rCBF levels below the evacuated subdural hematoma; ROI, region of interest; SD, standard deviation; SDH, subdural hematoma; TBI, traumatic brain injury; Xe-CT, Xe-computed tomography HYPEREMIA BENEATH EVACUATED ACUTE SUBDURAL HEMATOMA IS FREQUENT AND PROLONGED IN PATIENTS WITH AN UNFAVORABLE OUTCOME: A XE-COMPUTED TOMOGRAPHIC STUDY OBJECTIVE: To verify the values and the time course of regional cerebral blood flow (rCBF) in the cortex located beneath an evacuated acute subdural hematoma (SDH) and their relationship with neurological outcome. METHODS: rCBF levels were measured in multiple regions of interest, by means of a Xe-computed tomographic technique, in the cortex underlying an evacuated SDH and contralaterally in 20 patients with moderate or severe traumatic brain injury and an evacuated acute SDH. Twenty-three patients with moderate or severe traumatic brain injury and an evacuated extradural hematoma or diffuse injury served as the control group. Outcome was evaluated by means of the Glasgow Outcome Scale at 12 months. RESULTS: Values for the maximum (rCBFmax) and the mean of all rCBF levels in the cortex beneath the evacuated SDH were more frequently consistent with hyperemia. The side-to-side differences in the mean of all rCBF and rCBFmax levels between lesioned and nonlesioned hemispheres were greater in patients with evacuated SDH than in controls (P  0.0013 and P  0.0018, respectively). The side-to-side difference in the maximum rCBF value was higher in SDH patients with unfavorable outcomes than in controls at 24 to 96 hours and at 4 to 7 days and higher than in patients with favorable outcomes at 4 to 7 days. The widest side-to-side difference in rCBFmax value was more elevated in patients with an evacuated SDH with unfavorable outcome than in patients with a favorable outcome (P  0.047), whereas no differences were found in controls. The SDH thickness and the associated midline shift were greater in patients with unfa- vorable outcomes than in those with favorable outcomes. CONCLUSION: On average, hyperemic long-lasting rCBF values frequently occur in the cortex located beneath an evacuated SDH and seem to be associated with unfavorable outcome. KEY WORDS: Brain hyperemia, Brain ischemia, Cerebral blood flow, Computed tomography, Head injury, Regional blood flow, Subdural hematoma, Traumatic brain injury, Xenon Neurosurgery 64:705–718, 2009 DOI: 10.1227/01.NEU.0000341872.17024.44 www.neurosurgery-online.com