Letters

Misdiagnosis certainly occurs

Aside from the implication that physicians who provide rehabilitative care are scientifically suspect, Cranford shows his inexperience in the neurorehabilitation of brain injured patients when he doubts the veracity of the buzzer communication system.³ Prosthetic communication and environmental control systems, including simple on-off switching devices like the buzzer, are commonly used in rehabilitation.⁴ Obviously, the patients in Andrews and colleagues' study were showing the responsiveness required to negate a diagnosis of vegetative state before they could use a communication device with 90% consistency.

Cranford--a member of the Multi-Society Task Force on Persistent Vegetative State--says that neurodiagnostic tests have "some use in the diagnosis" of vegetative state; we find this perplexing. While the task force stated that structural and functional neuroimaging "may provide useful information when used in conjunction with clinical evaluation," it also said that "neurodiagnostic tests alone can neither confirm the diagnosis of vegetative state nor predict the potential for recovery of awareness."⁵ Contradictory statements such as these need to be reconciled. In addition, if these tests are diagnostic, as Cranford suggests, then it was the referring physicians who were remiss not Andrews and colleagues. Whether neurodiagnostic tests were used has little relevance to Andrews and colleagues since their purpose was to validate or invalidate the preadmission diagnoses.

Cranford zealously promotes the concept of "permanent vegetative state" in the face of concern that this implies unquantified finality. Yet he suggests that some patients recovered awareness under the observation and care of Andrews and colleagues. Thus the patients were not misdiagnosed: their diagnosis changed. On the basis of the Multi-Society Task Force's criteria,⁵ 70% of these patients were "permanently" vegetative. How amazing that most patients suddenly emerged from this state, and their diagnosis changed, 16 days after their admission to the Royal Hospital for Neurodisability.

Despite Cranford's scepticism we continue to encounter misdiagnosis of the vegetative state in our practice. Further study of patients diagnosed as being in this state, dissemination of current diagnostic criteria, and education of doctors about the difficulties of evaluation are sorely needed.

NANCY L CHILDS Medical director, inpatient brain injury programme

WALT N MERCER Director of research, psychology department

Healthcare Rehabilitation Center, 1106 West Dittmar Road, Austin, TX 78745, USA

Nancy L Childs, Walt N Mercer 

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 by R Smith.] [Abstract/Free Full Text]
2. Childs NL, Mercer WN, Childs HW. Accuracy of diagnosis of persistent vegetative state. Neurology 1993;43:1465-7. [Abstract/Free Full Text]
3. Cranford R. Misdiagnosing the persistent vegetative state. BMJ 1996;313:5-6. (6 July.) [Free Full Text]
4. Miller RM, Groher ME, Yorkston KM, Rees TS. Speech, language, swallowing, and auditory rehabilitation. In: DeLisa JA, ed. Rehabilitation medicine: principles and practice. Philadelphia: Lippincott, 1988.
5. Multi-Society Task Force on PVS. Medical aspects of the persistent vegetative state. N Engl J Med 1994;330:1499-508. [Abstract/Free Full Text]