Novel aspects of the neuropathology of the vegetative state after blunt head injury.

A detailed neuropathological study was undertaken of the brains of patients who had been assessed clinically as vegetative after blunt head injury. There were 35 cases, (33 male; median age 38 years) with a survival of 6.5-19 months (median 9): 17 were injured in a road traffic accident, 9 after assault and 6 after a fall; 3 were recorded as having had a lucid interval. There was an intracranial hematoma in 9 and the median contusion index was 4; raised intracranial pressure was identified in 25, grades 2 and 3 diffuse traumatic axonal injury was present in 25, ischemic damage in 15 and hydrocephalus in 27. Thalamic and hippocampal damage was present in 28 and stereological studies revealed a differential loss of neurons in three principal nuclei of the thalamus and in different sectors of the hippocampus. Immunohistochemistry provided evidence of an inflammatory reaction and in situ DNA fragmentation, features that are strongly indicative of a continuing neuronal loss in subcortical gray matter. These findings provide evidence for the importance of diffuse brain damage to white matter as the structural basis of the vegetative state after blunt head injury with contributions from neuronal loss in the thalami and the hippocampus. Although amyloid plaques and tau inclusions were identified in some, their contribution did not seem important in the ultimate clinical outcome.

Neuropathological findings in disabled survivors of a head injury.

We investigated how the occurrence and severity of the main neuropathological types of traumatic brain injury (TBI) influenced the severity of disability after a head injury. Eighty-five victims, each of whom had lived at least a month after a head injury but then died, were studied. Judged by the Glasgow Outcome Scale (GOS), before death 35 were vegetative, 30 were severely and 20 were moderately disabled. Neuropathological assessment showed that 71 (84%) victims had sustained cerebral contusions, 49 (58%) had diffuse axonal injury (DAI), 57 (67%), had ischemic brain damage (IBD), 58 (68%) had symmetrical ventricular enlargement, and in 47 (55%) intracranial pressure (ICP) had been increased. Thirty-five (41%) had undergone evacuation of an intracranial hematoma. Brainstem damage was seen in only 11 (13%). Analysis (χ(2) test for trends) of the relationship between these features and outcome showed that findings of DAI, raised ICP, thalamic damage, or ventricular enlargement (all p<0.005), and IBD (p=0.04) were associated with an increasingly worse outcome. Conversely, moderate or severe contusions (p=0.001) were increasingly associated with better outcomes, and evacuation of a hematoma was associated (p=0.001) with outcomes likely to be better than vegetative. We conclude that diffuse or multifocal neuropathological patterns of TBI from primary axonal injury or secondary ischemic damage are most likely to be associated with the most severely impaired outcomes after a head injury.