MRI in the Chronic Vegetative State
ABSTRACT & COMMENTARY
Source: Kampfl A, et al. Prediction of recovery from post-traumatic vegetative state with cerebral magnetic-resonance imaging. Lancet 1998;351:1763-1767.
In this clearly written study, kampfl and colleagues describe the abnormalities found on a single MRI evaluation of 80 patients who had been in a persistent vegetative state (PVS) for more than than 6-8 weeks. The precipitating cause of PVS was brain trauma, and subsequent patient outcome was carried to 12 months. Seventy percent of the patients were males. Mean age per patient was 25.8 ± 7.3 years. Admission Glasgow Coma scales in patients remaining PVS were not significantly lower than persons with severe injuries who became non-PVS (NPVS) (i.e., interactively conscious by the end of the year). Sources of trauma were motor vehicle accidents (70%), followed by accidents during skiing, cycling, and other unidentified circumstances.
MRI films were obtained on a 1.5 T unit operating at a high level of mechanical efficiency and were reviewed by a well-trained imaging staff. All patients remained vegetative at the time of the 6-8 week MRI study.
At the end of one year, 42 patients remained PVS, and 38 labeled NPVS had regained consciousness: 24 at three months, 12 more by six months, and two between six and the end of 12 months. Of the recoverers, six were said to have good outcomes, 19 reached a level of moderate disability, and 13 remained severely disabled. The total number of MRI-detected lesions per patient averaged the same in both PVS and NPVS. (See Table.)
Regions not selectively predictive of outcome included: Lobar white matter, internal capsules, scattered frontal, temporal, and parietal lobes, basal ganglia, hippocampus, ventral brain stem, medulla, and cerebellum. The degree of brain atrophy, however, was predictive: ventricular enlargement PVS = 24 (57%); NPVS, 14 (37%); P = 0.08. Not selectively predictive: cortical or brain stem atrophy.
COMMENTARY
This valuable study cannot fail to have an effect on future patterns of planning rehabilitative care and of making appraisals for future social needs for patients early diagnosed as having post-traumatic PVS. All of the subjects were studied once by MRI while still being PVS 6-8 weeks following the brain injury. Surgical treatment, when necessary, was performed in equal numbers of patients who regained consciousness and those who remained PVS at one year. The fact that only one MRI evaluation was performed on each patient may or may not have altered any later changes in ultimate management. The delay of 6-8 weeks before giving odds for recovery, however, would not have influenced day-to-day nursing and physical therapy. What is important is that delayed MRI films should greatly enable physicians to begin to formulate reasonable estimates of ultimate outcome and associated financial concerns.
Table
Prognostic differences or trends by MR images that related to individual one-year outcomes
| Structures |
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| Corpus callosum |
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| Corona radiata |
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| Dorso lateral-medial mesencephalo |
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Your editor, reviewing our own MRI films on a small number of patients with callosal damage in PVS, has similarly noted the disastrous association of posterior corpus callosum damage with poor outcome in head injury patients. Our numbers have been too few to carry specific prognostic meaning, although, like the present study, posterior callosal damage to the splenium and adjacent cuneus were most frequent. Normally, these posterior areas are known to increase their physiologic activity during periods of cognitive activity and REM sleep.1 The failure to identify any odds ratios for patients having ophthalmologic abnormalities is a bit surprising, but circumstances surrounding early diagnosis and treatment of study signs are not included here.
A supplementary Lancet editorial is provided by Dr. Keith Andrews, head of the Royal Neurorehabilitation Hospital of England.2 He discussed errors in diagnosing patients remaining PVS long after the initiating accident, but putatively overlooked by previous physicians. His diagnoses appear to depend considerably on findings of his non-medical staff and were not validated by either qualified neurologists or any kind of laboratory data. These include an absence of either EEG records or any form of brain imaging. -fp
References
1. Maquet P, et al. Functional neuroanatomy of human rapid-eye-movement sleep and dreaming. Nature 1996;383:163-166.
2. Andrews K. Prediction of recovery from post-traumatic vegetative state. Lancet 1998;351:1751.
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