The majority of studies regarding surgical treatment of parenchymal lesions are case series. Only one prospective clinical trial of treatment using surgical versus nonsurgical management has been published (61). The majority of evidence indicates that the development of parenchymal mass lesions, which are associated with progressive neurological dysfunction, medically refractory intracranial hypertension, or radiological signs of mass effect, are associated with a poor outcome if treated nonsurgically. Specific surgical criteria, however, have not been firmly established. Evidence also suggests that decompressive craniectomy may be the procedure of choice in patients with posttraumatic edema, hemispheric swelling, or diffuse injury, given the appropriate clinical context. This context has yet to be defined.