ACUTE POSTTRAUMATIC SUBDURAL HEMATOMAS - INTRADURAL COMPUTED TOMOGRAPHIC APPEARANCE AS A FAVORABLE PROGNOSTIC FACTOR

OBJECTIVE: Posttraumatic acute subdural hematoma carries a high postop erative mortality rate. Preservation of subarachnoid spaces in preoper ative computed tomographic (CT) scans may be interpreted as a favorabl e prognostic factor. METHODS: Thirty-one cases of posttraumatic acute subdural hematoma operated on consecutively, with an interval from tra uma to surgery of less than 4 hours and a Glasgow Coma Scale score of less than 8, were reviewed. The immediate and long-term results were e valuated with reference to preoperative CT images, distinguishing case s with preserved subarachnoid spaces from the others. RESULTS: In 5 of the 31 cases, preoperative CT scans showed intact subarachnoid spaces and the absence of blood in the cerebrospinal fluid. These cases pres ented a much better postoperative course than did the others. CONCLUSI ON: The presence of intact subarachnoid spaces in CT scans for patient s with acute subdural hematomas may be interpreted as an extremely fav orable prognostic factor; this may be attributed to the protective eff ect of the integral visceral membrane of the hematoma, which prevents the diffusion of neurotoxic and vasoactive substances into the subarac hnoid spaces. This group of hematomas was classified as ''intradural,' ' with reference to the concept of the ''subdural compartment'' descri bed in studies conducted using an electron microscope.