Misdiagnosing the Persistent Vegetative State
An apparently high rate of misdiagnosis demands critical review and action
BMJ 1996;313:5-6 (6 July)
Editorials
Diagnosing the persistent vegetative state is important and sometimes difficult. Patients who retain some degree of awareness must be recognised if their quality of life is to be maximised and inappropriate withdrawal of tube feeding prevented. On p 13 Keith Andrews and colleagues present a retrospective study of the clinical records of 40 patients admitted over three years to a single unit specialising in the rehabilitation of patients with profound brain damage. (http://www.bmj.com/cgi/content/full/313/7048/5#R1"1) The authors conclude that 17 of these patients were misdiagnosed. Patients in the persistent vegetative state seem to be awake with their eyes open but show no evidence of awareness, but the 17 misdiagnosed patients were able to communicate consistently using eye pointing or a touch sensitive buzzer. Such an apparently high rate of misdiagnosis raises important concerns about the accuracy of the diagnosis of the vegetative state and related syndromes of severe brain damage. (http://www.bmj.com/cgi/content/full/313/7048/5#R1"1) It also demands a critical review of the study's methods.
One important question is whether the sample of patients is representative. This seems unlikely since, as the authors point out, their unit is the only one in Britain specialising in the management of this group of patients. It is also important to distinguish late recovery from late discovery of consciousness. Patients who start regaining consciousness several months after the injury (late recoveries) should not be confused with patients who may have been conscious for some time before the discovery (late discoveries). The authors state that none of the misdiagnosed patients were vegetative at the time of admission, but it is not clear how such a conclusion can be reached with certainty, especially when 10 of the 17 misdiagnosed patients were admitted to the unit less then 12 months after injury.
Another question is whether the methods used to identify awareness were valid. In my experience rehabilitation units often develop "unique" ways of communicating with patients that only they can master. If the "touch sensitive buzzer switch system" is as useful and reproducible as this article suggests, it should be made available to other rehabilitation units, which in turn should be able to reproduce these authors' results. Videotapes of the buzzer in operation would help to demonstrate to others the usefulness and reproducibility of this system. Until such validation occurs, I must view the buzzer system with some scepticism.
Diagnosing the persistent vegetative state can be aided by neurodiagnostic tests such as computed tomography, magnetic resonance imaging, electroencephalography, and positron emission tomography. These could have helped to explain why some patients had such severe motor impairment as to appear unconscious. In particular, they could help to distinguish the persistent vegetative state from the locked in syndrome, in which patients are severely motor impaired but have relatively normal consciousness. Such patients would be likely to have minimal cerebral cortical atrophy on computed tomography and magnetic resonance imaging, and positron emission tomography would show nearly normal cerebral cortical metabolism of glucose and oxygen (or at least much higher than in patients in a vegetative state). Both the multi-society task force on the vegetative state in the United States (http://www.bmj.com/cgi/content/full/313/7048/5#R2"2) (http://www.bmj.com/cgi/content/full/313/7048/5#R3"3) and the working group of the Royal College of Physicians in Britain (http://www.bmj.com/cgi/content/full/313/7048/5#R4"4) stated that these neurodiagnostic studies have some use in the diagnosis. It is unfortunate that Andrews et al did not make use of them.
The authors emphasise the importance of getting the diagnosis right, and few would argue with them. But it is interesting to note that all 17 patients who were found to be conscious were severely disabled; all were severely paralysed and anarthric, most were either blind or severely visually impaired, some were substantially cognitively impaired, and all were presumably dependent on feeding tubes. Reasonable people may differ in their views of the quality of life of these conscious individuals, but I would speculate that most people would find this condition far more horrifying than the vegetative state itself, and some might think it an even stronger reason for stopping treatment than complete unconsciousness.
But whether being in the vegetative state is viewed as preferable to being just outside it, and whatever your views on withdrawal of tube feeding in such patients, careful examination of every patient is essential to determine their consciousness and ability to suffer. It would be dreadful indeed to stop treatment in patients who were thought to be unconscious but who could in fact experience thirst and hunger when treatment, including artificial nutrition and hydration, was stopped. Equally important is the need to maximise quality of life for those who are capable of communicating. Some may even be able to contribute to decisions about their medical treatment.
Professor Andrews and his colleagues should be congratulated on their detailed and careful evaluation of patients with severe brain damage. Their work will help us to unravel the mysteries of the vegetative state for the welfare of patients, their families, and society. With more experience, we may develop a better sense of the value of the buzzer switch system, and if the rate of misdiagnosis of vegetative state is as high as this article suggests, others should be able to duplicate their results.
Associate physician in neurology Hennepin County Medical Center, Minneapolis, MN 55415, USA
Ronald Cranford
Andrews K, Murphy L, Munday R, Littlewood C. Misdiagnosis of the vegetative state: retrospective study in a rehabilitation unit. BMJ 1996;313:13-6. (http://www.bmj.com/cgi/ijlink?linkType=ABST&journalCode=bmj&resid=313/7048/13) [Abstract/Free Full Text]
Multi-Society Task Force on PVS. Medical aspects of the persistent vegetative state (first part). N Engl J Med 1994;330:1499-508. (http://www.bmj.com/cgi/ijlink?linkType=ABST&journalCode=nejm&resid=330/21/1499) [Abstract/Free Full Text]
Multi-Society Task Force on PVS. Medical aspects of the persistent vegetative state (second part). N Engl J Med 1994;330:1572-9. (http://www.bmj.com/cgi/ijlink?linkType=FULL&journalCode=nejm&resid=330/22/1572) [Free Full Text]
Royal College of Physicians Working Group. The permanent vegetative state. Review by a working group convened by the Royal College of Physicians and endorsed by the Conference of Medical Royal Colleges and their faculties of the United Kingdom. Journal of the Royal College of Physicians of London 1996;30:119-121. (http://www.bmj.com/cgi/external_ref?access_num=8709056&link_type=MED) [Medline]
This article can be found at http://www.bmj.com/cgi/content/full/313/7048/5
