CT prediction of contusion evolution after closed head injury: the role of pericontusional edema.
BACKGROUND
Cerebral contusions have a 51% incidence of evolution in the first hours after injury. Evolution is associated with clinical deterioration and is the reason for ICP monitoring or surgical intervention. We sought to define CT features that predict cerebral contusion evolution.


METHODS
Patients treated for cerebral contusion who had 2 CT scans within 24 hours after injury were evaluated (n = 21). CT scans were analyzed for area of contusion, hemorrhagic components, and edema. Increase (%) in contusion size was recorded. Contusion evolution was defined as > 5% size increase. Ratios of hemorrhagic components to surrounding edema were calculated.


RESULTS
Ten patients (47.6%) showed contusion evolution and 11 (52.4%) did not. Age, sex ratio, or injury severity between the 2 groups did not differ. Eight of 10 patients with evolving contusions had minimal or no perilesional edema on first CT; only 2 of 11 nonevolution patients had perilesional edema (p < 0.005). Mean ratio of area of surrounding edema to area of hemorrhagic products on first CT was 0.770 in evolution group versus 2.22 in non-evolution group (p = 0.055).


CONCLUSIONS
A higher proportion of patients without contusion evolution had perilesional edema present on first CT scan. The absence of pericontusional edema on early CT may be a useful marker to predict contusion evolution.