October 8, 2007   •   VOL. 45, NO. 17   •   Oakland, CA

Diagnosing persistent vegetative state not exact

By Nancy Frazier O’Brien
Catholic News Service

WASHINGTON (CNS) — Although the medical community is developing a standardized definition of what constitutes a persistent vegetative state, no one knows precisely how many patients fall into that category.

The National Institute of Neurological Disorders and Stroke at the National Institutes of Health says patients in a persistent vegetative state “have lost their thinking abilities and awareness of their surroundings but retain noncognitive function and normal sleep patterns.”

“Some patients may regain a degree of awareness after persistent vegetative state,” according to the institute’s information page on coma and persistent vegetative state. “Others may remain in that state for years or even decades.”

CNS graphic/Emily Thompson

A spokesman for the institute said it does not keep statistics on how many patients are in a persistent vegetative state in the United States at any given time. Estimates from other sources, however, put the number somewhere between 10,000 and 40,000.

Dr. John Collins Harvey, a physician and moral theologian who is a senior research scholar at Georgetown University’s Center for Clinical Bioethics, puts the figure at the upper end of that range.

Diagnosis of persistent vegetative state is far from an exact science. Some patients considered to be in a persistent vegetative state have recovered cognitive function, although most in the medical community would attribute those cases to an initial misdiagnosis.

“There is no test to specifically diagnose vegetative state,” says the Brain Injury Association of America on its Web site. “The diagnosis is made only by repetitive neurobehavioral assessments.”

The first use of the term “persistent vegetative state” is credited to Bryan Jennett of Scotland and Fred Plum of the United States in a 1972 article in the British medical journal Lancet; they defined it as a state of “wakefulness without awareness.”

Over the years, various people in the medical community have expressed a preference for other terms — “continuing vegetative state,” “permanent vegetative state” or simply “vegetative state,” with no modifier.

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