Shortly after Terri Schiavo's autopsy was released, Not Dead Yet, a disability advocacy group, issued a press release asserting that the autopsy results "leave the central issues in her life and death unanswered." Not Dead Yet contested the view that the autopsy bolstered the diagnosis of a persistent vegetative state. It supported its contention by calling attention to comments by Stephen J. Nelson, the neuropathologist who examined Schiavo's brain during the autopsy.
Nelson rightly noted that "The persistent vegetative state, and minimally conscious state, are clinical diagnoses, not pathologic ones," and that "Neuropathologic examination alone of the decedent's brain—or any brain, for that matter—cannot prove or disprove a diagnosis of persistent vegetative state or minimally conscious state."
Nonetheless, the findings are consistent with the Multi-Society Task Force report on PVS published in 1994 in the New England Journal of Medicine and with Bryan Jennett's review of PVS pathology in his authoritative 2002 text, The Vegetative State: Medical Facts, Ethical and Legal Dilemmas. Jennett and Fred Plum coined the term "persistent vegetative state" in 1972 in an article in the Lancet.
The autopsy reported that at her death, Terri Schiavo had a brain weight of 615 grams, half that of a normal brain and significantly less than Karen Ann Quinlan's, which weighed 835 grams. She had developed hydrocephalus ex vacuo, a condition marked by enlarged ventricles filled with cerebrospinal fluid, because of this profound loss of cortical volume. Her brain also revealed microscopic changes that would be expected in hypoxic-ischemic cases of PVS—cases, that is, in which the brain is damaged by oxygen deprivation. Schiavo sustained changes that were "striking in their appearance, and global in their distribution." Laminar necrosis—death in a midcortical level—had a patchy distribution in most cortical sections, with border zones between arterial blood supply especially affected. There was a "readily discernible noteworthy gradient loss when moving from anterior to posterior regions," with the occipital lobes in the back of the head responsible for vision being most severely affected. Remarkably, her brain showed a total loss of basal ganglia neurons, and her thalamus was "similarly affected."
These observations are consistent with Jennett's research on the pathology of the vegetative state. He has noted that in nontraumatic cases of PVS, "the damage is usually extensive necrosis in the cerebral cortex, almost always associated with thalamic damage." In such cases, the most common abnormality was "laminar necrosis with the damage increasing in intensity from the frontal to the occipital cortex." Less frequently, "cortical damage was restricted to arterial boundary zones."
Not Dead Yet has made Nelson's regard for diagnostic methodology appear contentious by focusing on his careful explanation that nothing in the autopsy was "inconsistent" with a diagnosis of PVS. In point of fact, there is no inconsistency between the examinations of Ms. Schiavo after her death and while she was alive, when the Florida Supreme Court found clear and convincing evidence that she was vegetative.
The autopsy results are inconsistent, however, with some of the claims made by those who questioned the diagnosis. Some people offered video snippets as proof that Ms. Schiavo possessed visual awareness as a refutation of the neurologic diagnosis. The autopsy confirms that Ms. Schiavo couldn't see her mother. Extensive laminar necrosis in her occipital lobe coupled with the extensive damage of the thalamic relay between the retina and visual cortex would have produced blindness.
Ironically, diagnostic skeptics placed their faith in neuroimaging, an experimental technology that would have been contraindicated in Ms. Schiavo, according to Nelson, because she had a thalamic stimulator. Ms. Schiavo's parents, the Schindlers, had requested a neuroimaging study, perhaps prompted by studies done on traumatic brain injury patients who were minimally conscious and near the level of functional communication. Those studies were also not diagnostic. They were an element of a study to investigate neuronal network response to spoken language in patients whose diagnoses were clinically distinct from Schiavo's.
Neuroimaging remains incapable of distinguishing disorders of consciousness. When such diagnostic studies are developed, will scientific skeptics accept them? The comments of...