FOCAL CEREBRAL HYPEREMIA AFTER FOCAL HEAD-INJURY IN HUMANS - A BENIGNPHENOMENON

To assess the relationship between posttraumatic cerebral hyperemia an d focal cerebral damage, the authors performed cerebral blood flow map ping studies by single-photon emission computerized tomography (SPECT) ) in 53 patients within 3 weeks of brain injury. Focal zones of hypere mia were present in 38% of patients. Hyperemia was correlated with cli nical features and early computerized tomography (CT) and magnetic res onance (MR) imaging performed within 48 hours of the SPECT study and l ate CT and MR studies at 3 months. The hyperemia was observed primaril y in structurally normal brain tissue (both gray and white matter), as revealed by CT and MR imaging, immediately adjacent to intraparenchym al or extracerebral focal lesions; it persisted for up to 10 days, but was never seen within the edematous pericontusional zones. The percen tage of patients in the hyperemic group having brief (< 30 minutes) or no loss of consciousness was significantly higher than in the nonhype remic group (twice as high, p < 0.05). Other clinical parameters were not significantly more common in the hyperemic group. The mortality of patients with focal hyperemia was lower than that of individuals with out it, and the outcome of survivors with hyperemia was slightly bette r than patients without hyperemia. These results differ from the liter ature, which suggests that global post traumatic hyperemia is primaril y an acute, malignant phenomenon associated with increased intracrania l pressure, profound unconsciousness, and poor outcome. The current re sults agree with more recent studies which show that post traumatic hy peremia may occur across a wide spectrum of head injury severity and m ay be associated with favorable outcome.