In all of these patients, following the initial period of stabilization, the matter of interest is the clinical and imaging assessment, with the purpose of uncovering a surgically remediable lesion, namely a subdural or epidural hematoma or a treatable, well-defined, intraparenchymal hematoma that is not simply a contusion. In most cases, the discovery of such a mass lesion leads to surgical removal. But unless it is the only lesion, the procedure often proves to be insufficient and coma is likely to persist because of the associated cerebral damage. The recognition and management of these hematomas are described further on.
In the Traumatic Coma Data Bank, which included 1,030 gravely injured patients with Glasgow Coma Scale scores of 8 or less, 21 percent had subdural hematomas, 11 percent had intracerebral clots, and 5 percent had epidural hematomas. Notable, however, half the patients had no mass lesions on the CT scan. On this basis, these patients were thought to have diffuse axonal injury. However, in 50 consecutive autopsies of severely injured patients, summarized in an earlier era by Rowbotham, all but 2 showed macroscopic changes, suggesting the relative unreliability of CT analysis. The lesions in these cases consisted of surface contusions (48 percent), lacerations of the cerebral cortex (28 percent), subarachnoid hemorrhage (72 percent), subdural hematoma (15 percent), extradural hemorrhage (20 percent), and skull fractures (72 percent). As these figures indicate, several pathologic entities were found in the same patient.
There is that relatively small, distressing group of severely brain-injured patients in whom the vital signs become normal but who never regain full consciousness. As the weeks pass, the prospects become bleaker. Such a patient, especially if a child, may still emerge from coma after 6 to 12 weeks or longer and make a relatively good, although usually incomplete, recovery. Some of those who survive for long periods open their eyes and move their heads and eyes from side to side but betray no evidence of seeing or recognizing even the closest members of their families. They do not speak and are capable of only primitive postural or reflex withdrawal movements. Jennett and Plum referred to this as the “persistent vegetative state” (see Chap. 16 for a full discussion of this subject). Fourteen percent of the patients in the Traumatic Coma Data Bank remained in this state. Hemiplegia or quadriplegia with varying degrees of decerebrate or decorticate posturing are usually present. Life is sometimes terminated after several months or years by some medical complication but may patients have survived for decades. Our colleague R.D. Adams examined the brains of 14 patients who remained in coma and in vegetative states from 1 to 14 years. All showed extensive zones of necrosis and hemorrhage in the upper brainstem. Among patients who survived and remained vegetative until death, J.H. Adams and colleagues (2000) found that 80 percent had thalamic damage and 71 percent had findings of diffuse axonal injury. Moreover, trauma of extracranial organs and tissues is frequent and obviously contributes to the fatal outcome. Recent functional studies have shown that a limited proportion of patients who are in a vegetative or minimally conscious state can be trained to purposefully engage parts of the cerebrum.