28 Decisions in Persistent Vegetative State
A 17-year-old teenager remained comatose 2 weeks after a severe traumatic brain injury. During the first days following the accident, he was treated for refractory increased intracranial pressure associated with multiple frontal and temporal lobe contusions. A frontal decompressive craniectomy was needed at some point. His clinical course was complicated by seizures, pulmonary infection, and bacteriemia. Early decubital redness appeared. After resolution of the intracranial hypertension no change in his neurologic examination was noted, and he has stayed comatose. He has not developed sleep and wake cycles. On examination, he has his eyes open at times, but is not tracking a finger, nor fixating on his parents when they are in the room. A loud handclap does not produce any reaction. He grinds his teeth. There is spontaneous extensor posturing. He may sweat profusely occasionally.
All clinical indicators point toward the development of a persistent vegetative state. The nursing staff has not noticed any signs of awareness, but the family is not so sure. Long-term support is desired. There are questions by the family members whether improvement can occur and at what level the patient might be able to function.
Outcome prediction in young patients after severe traumatic brain injury is a necessary task for neurosurgeons and neurologists. When patients display clinical signs of a persistent vegetative state and also have neuroimaging documentation of severe brain injury, the need for long-term care will come up and decisions will have to be made.
There are multiple prediction models in head injury. The largest database of traumatic head injury (IMPACT; International Mission for Prognosis and Analysis of Clinical trials in Traumatic brain injury) uses admission characteristics to calculate a prognosis estimate. These are age, motor response, pupil responses, presence of hypoxia and hypotension, CT categorization into severity of lesions and presence of a mass lesion, presence of traumatic subarachnoid hemorrhage, epidural mass, and also serum glucose and hemoglobin values (calculator at www.tbi-impact.org). In our patient example, the predicted 6 months mortality is 64% and predicted 6 months unfavorable outcome (death, vegetative state, and severe disability) is 83%. Hopeful parents will be encouraged by these numbers. Physicians will express serious doubt. Every physician involved with long-term care of traumatic brain injury will know that we can never be certain and prediction in young comatose patients with intact brainstem reflexes has serious limitations.
The general guide is that if the clinical findings of persistent vegetative state are still present after 3 months in nontraumatic coma (i.e., anoxic-ischemic encephalopathy, hypoglycemia, CNS infections, status epilepticus) substantial recovery of awareness is not anticipated. In traumatic brain injury, 12 months are needed for reasonable certainty, but recovery to a minimally conscious state may occur beyond this time limit.
There has been renewed interest in persistent vegetative state and the accuracy of the clinical diagnosis. The diagnosis of persistent vegetative state is well defined (Table 28.1). The common questions have been: Is persistent vegetative state truly persistent? Is our neurologic examination reliable? Do we have better ways to assess “consciousness?” Can functional MRI scans predict recovery? Can functional MRI scans find evidence of some awareness not detected clinically? The reliability of neurological examination has withstood the test of time, although errors by non-neurologists are still considerable. Some of the above questions cannot be answered yet with certainty. Functional MRI scan remains a research tool, but brain activation on a functional MRI does not mean consciousness.
TABLE 28.1 Clinical Signs of Persistent Vegetative State
| Breathing regular (with tracheostomy in place) |
| Bronchial hypersecretion |
| Blood pressure stable |
| Immobile |
| Flexion-extension contractures |
| Eyes closed or open |
| No evidence of focus or holding attention |
| No eye movements to examiner (except briefly when suddenly confronting) |
| Eyes roving, nystagmoid, gaze preference changing, no eye contact for more than 5 seconds |
| Eyes may move upward or downward or assume lateral gaze for 1–2 minutes |
| No sound (if not made impossible with tracheostomy) |
| Spontaneous teeth grinding |
| Spontaneous clonus, or shivering |
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