Letters

Misdiagnosing the persistent vegetative state

EDITOR,--Keith Andrews and colleagues draw attention to an important issue--namely, the correct diagnosis of patients who remain apparently unaware months after sustaining acute brain damage.¹ Some caution is needed in interpreting their data.

The authors use the term "persistent vegetative state" loosely. Although a persistent vegetative state cannot be diagnosed until at least 12 months have passed from the onset of coma,² nine of the 16 patients whom the authors consider to have been misdiagnosed and whose details they give had been in a coma for less than 12 months. Therefore over half of the misdiagnoses in the study may simply reflect careless and incorrect use of the term persistent vegetative state by referring clinicians, with the patients' recovery coinciding with admission to the Royal Hospital for Neurodisability.

The security of the original diagnosis was not established in the remaining seven cases. One cannot assume that a neurologist is correct: in one case in which a persistent vegetative state had been diagnosed by an eminent neurologist, simple perusal of the notes showed recorded evidence of awareness and responsiveness (confirmed by my examination).

The first message from this study is that the clinician making the diagnosis of a persistent vegetative state must approach the task thoroughly and be experienced in assessing a patient's level of consciousness and awareness. Every clinician confronted with this difficult task should always obtain data from at least four sources: reading the notes thoroughly, interviewing at least one nurse who knows the patient well, interviewing at least one relative who has been close to the patient, and undertaking examination and observation. Throughout this process the clinician should consider whether there is an acceptable cause for the patient's state, whether drugs have a substantial role, and whether there is or has been any evidence of a meaningful response to meaningful external stimuli. It is imperative to take seriously all observations made by staff and relatives, who are usually the best witnesses.

The second message of the study is that the term persistent vegetative state is widely misused, even in recent papers.³ No clinician should accept a diagnosis of such a state within 12 months of the onset of coma. I strongly recommend use of the term "continuing vegetative state," or even the simpler term "coma," for all patients who are comatose over the first 12 months after the onset of coma. In this way clinicians and relatives will avoid drawing premature or incorrect conclusions from loosely applied diagnostic labels.

DERICK T WADE Consultant in neurological disability

Rivermead Rehabilitation Centre, Oxford OX1 4XD

Derick T Wade 

1. Andrews K, Murphy L, Munday R, Littlewood C. Misdiagnosis of the vegetative state: retrospective study in a rehabilitation unit. BMJ 1996;313:13-6. (6 July.) [With commentary with R Smith.] [Abstract/Free Full Text]
2. The permanent vegetative state. J R Coll Physicians Lond 1996; 30:119-21.
3. Grubb A, Walsh P, Lambe N, Murrells T, Robinson S. Survey of British clinicians' views on management of patients in persistent vegetative state. Lancet 1996;348:35-40. [Medline]