Aug 15 2008

Persistent Vegetative State – From Schiavo to Egnor

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Last week I wrote an entry about the Terri Schiavo case, discussing a new published study criticizing the news reporting of this controversial case. The case involved the right to life of a woman in a persistent vegetative state (PVS) and the relative rights of her husband vs her parents to decide her care. Michael Egnor, a neurosurgeon who writes for the Evolution News & Views blog, and with whom I have had a long blog debate, mostly about dualism and the nature of consciousness, has responded to my post on Schiavo. Not surprisingly he has taken a different view of the case. He writes:

In my view, the political efforts to save Ms. Schiavo’s life were well-intentioned and completely justified. I believe that many of the medical opinions offered publicly by physicians who favored withdrawal of Ms. Schiavo’s hydration and nourishment were rank pseudoscience. What was done to Ms. Schiavo was an atrocity.

He also offers to have a blog discussion about the topic with me, writing:

A detailed and thoughtful public exchange of views about the Terri Schiavo case by two experts in neurological medicine—an academic neurologist and an academic neurosurgeon who have quite different opinions on this matter—would be very informative. The discussion could take the form of detailed exchanges between Dr. Novella and me on specific aspects of the case, such as the autopsy report, the neurological exams, the nature and reliability of the diagnosis of persistent vegetative state, and the ethical and political issues involved. This discussion extends to many of the issues involving the materialist inference in neuroscience that Dr. Novella and I have debated over the past year.

So here is my first installment. I will focus on the nature of persistent vegetative state and respond to some of the comments of Dr. Egnor.

Persistent Vegetative State

Dr. Egnor defines PVS thusly:

“Persistent vegetative state,” defined succinctly but accurately, is the denial of subjective experience in a brain-damaged human being. PVS is the medical assertion that a human being is an object, but not a subject.

I disagree. The first assertion, that PVS is defined as the lack of subjective experience, is misleading, and the second assertion, that the diagnosis of PVS is a statement that a person is an object, is wrong. The latter comment is more straightforward to deal with. A person diagnosed as being in a PVS is still, legally, medically, ethically, a person. They are most certainly not an object and are not treated as such. All of the medical ethics of a living person are still in play.

By contrast, the diagnosis of brain death does render a person an object – specifically a corpse. Once legally declared brain dead a person is dead. They can now legally and ethically be treated as a corpse. You can harvest their organs, perform an autopsy, and bury them.

In what sense does Dr. Egnor claim a person in a PVS is an object? Demonstrably – in no practical sense. He needs to clarify this statement. He may be referring to the fact that life-sustaining care can be withdrawn. However, living people have the right to refuse medical treatment, even if that treatment is necessary to maintain life. People who, for whatever reason, are unable to make their wishes known or who are not mentally competent to make decisions for themselves will have someone to make health care decisions for them. This defaults to the next of kin, or anyone can appoint a health care power of attorney if in the future they are in a position where they cannot make decisions for themselves, or the court may appoint a health care proxy. Such a person has the right to refuse treatment on behalf of the patient – including refusing life-saving interventions.

The point is that conscious or unconscious, competent or not, the rights of a person in a PVS are the same as anyone. The only difference is that they cannot communicate their wishes (regardless of why they cannot). It is even possible, through a living will, for someone to make a decision for themselves – in advance.

Dr. Egnor’s other assertion – that PVS is defined as the lack of subjective experience, is misleading because it is incomplete. That is the inference that is made, but it is not operationally how the diagnosis is made. Here is one definition, published in the New England Journal of Medicine:

The vegetative state is a clinical condition of complete unawareness of the self and the environment, accompanied by sleep-wake cycles, with either complete or partial preservation of hypothalamic and brain-stem autonomic functions. In addition, patients in a vegetative state show no evidence of sustained, reproducible, purposeful, or voluntary behavioral responses to visual, auditory, tactile, or noxious stimuli; show no evidence of language comprehension or expression; have bowel and bladder incontinence; and have variably preserved cranial-nerve and spinal reflexes.

The diagnosis of PVS is made on the basis of the absence of evidence for conscious awareness, while retaining some brain reflexes. It is generally understood that we cannot know what is actually going on in the “mind” of the patient. We can only infer from the exam and from other lines of evidence, such as the exam findings outlined in the quote above.

But also a complete neurological assessment will also involve imaging of the anatomy of the brain. If the cortex is clearly severely and diffusely damaged by MRI scanning, that supports the clinical diagnosis of PVS. In addition we can use EEG to look at the degree of electrical activity of the cortex. If a patient displays no signs of conscious awareness, has diffuse damage on MRI, and has reduced electrical activity on EEG, those are three independent lines of evidence leading to the same conclusion – severe brain damage.

It is important to distinguish the methods of assessing a patient and making a diagnosis from the inferences that are drawn from that evidence. In conflating the two Dr. Egnor makes it seem as if we are pretending to read the minds of comatose patients.

There are two aspects of the PVS diagnosis that are important to treatment decisions. The first is an estimate of the level of consciousness that a person currently has. This is an important piece of information in assessing their current quality of life. The second issue is their prognosis – what is the probability that they will improve in the future. These are the two factors that people always want to know in making decisions for their loved ones – what are they experiencing now, and what is their chance for improvement?

I always emphasize to families in such situations that we can never be completely certain. We can only make evidence-based judgments. I am usually also careful to say, for example, “there is no evidence from my exam that there is any conscious awareness,” rather than a more definitive statement that there is no awareness. I will then give the family a sense of my confidence. This depends on many variable – the age of the patient, the time since the injury, the severity of the exam, and the extent of damage seen on imaging and EEG.

My job is not to make the decision for the family, but to give them the best medical facts we have available so that they can make an informed decision. It is up to them to weigh issues of quality of life, their religious or metaphysical beliefs, and their assessment of what their loved-one would have wanted. I do not get directly involved with such considerations – nor should I. The role of science is to inform such decisions, not make them.

Prognosis is an easier question to answer than assessing current quality of life. In patients who have been in a PVS for more than 6 months recovery is extremely rare. There are cases of recovery, which garner great media attention, but they are the rare exception.

Current Difficulties

From Dr. Egnor’s initial post on this topic I imagine he is going to review all of the difficulties in diagnosing a patient with PVS. I am going, to an extent, preempt him by acknowledging up front that there are many difficulties with the diagnosis of PVS and the inferences that we draw from it. The neurological exam is a very poor tool for examining cortical function in a patient that cannot follow commands or communicate. I tell this to students all the time – all we can say is that there is an absence of evidence for cortical activity, but we must acknowledge the limitations of the exam. That is why we must combine that information with MRI, EEG, and other tools.

Of note, as new tools for looking at brain activity are coming into use, such as function MRI scanning, we are learning more about the possible conscious state of patients in PVS and related conditions. Not surprisingly, as more accurate tools come into use we are discovering the inaccuracies of our prior tools. This is a common and expected experience. I certainly hope that as our technology advances we will be able to make more precise and reliable diagnoses of patients in various types of coma – so as to better inform those who must make care decisions.

It is also true that our statements are largely statistical, and we can be wrong in an individual case. Although sometimes the statistics can be overwhelming (the chance of waking up from a PVS that has persisted for more than 6 months is truly vanishingly small), they are still just statistical – not predictions of the future.

But, I would argue that this is no different than all of medicine. Medicine is an applied science. It is the practice of making the best inferences we can from the data we are able to obtain. It involves making statistical statements about probable outcomes in order to make treatment decisions. I am sure that Dr. Egnor does not give his patients absolute certainties about the outcomes of their surgery. A surgeon can only advise a patient as to the likely outcome of operating – or not operating, on their condition.

For example, if someone has a ateriovenous malformation (AVM) we can tell them what the probability is that the AVM will cause a major bleed in the future, and compare this to the risk of surgery and the probable benefit of surgery. These are all statistical statements. No one knows what will actually happen to an individual patient with or without surgery.

This is exactly the same situation with PVS. We can tell families, to the best current available medical knowledge, what the likely condition of their loved-one is and what their likely prognosis is.

Conclusion

In a future post I will discuss the Terri Schiavo case specifically, in light of the above discussion.

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18 responses so far

18 Responses to “Persistent Vegetative State – From Schiavo to Egnor”

  1. deciuson 15 Aug 2008 at 11:39 am

    Egnoramus.

  2. deciuson 15 Aug 2008 at 12:42 pm

    Oh, and the abject irony pertaining an affiliated to the Disco ‘Tute preoccupied by some perceived “rank pseudoscience”.
    You can’t make this stuff up.

  3. Reviving Shiavo « Skepacabraon 15 Aug 2008 at 12:43 pm

    [...] Reviving Shiavo Neurosurgeon Michael Egnor has started up another debate with Neurologist Steven Novella. The first time was over dualism. This time it’s over Persistent Vegetative State with a specific emphasize on the infamous Terry Schiavo case from years ago. Here’s Novella’s first response to the challenge. [...]

  4. Blake Staceyon 15 Aug 2008 at 1:34 pm

    If the cortex is clearly severely and diffusely damaged by MRI scanning, that supports the clinical diagnosis of PVS.

    That’s one potent MRI scan.

  5. DevilsAdvocateon 15 Aug 2008 at 3:04 pm

    My cortex was once badly scratched by a CAT scan. Bah-dah-boom.

    I’m not even a medico, but I took great offense on their part to read Egnor’s words:

    “PVS is the medical assertion that a human being is an object, but not a subject.”

    What an ugly thing to say, as if medical professionals all of a sudden begin referring to a patient as an “it” when the patient is or goes PVS. What a backhanded way of issuing an ad hominem comment, and a clearcut signal of Egnor’s anti-materialist bias, however he perceives materialism and materialists.

  6. Freddy the Pigon 15 Aug 2008 at 5:52 pm

    Egonr did not say a PVS was a lack of subjective experience – he used a much more loaded word “denial of subjective experience in a brain-damaged human being” – implying that the evil materialists are denying the existance of something the Egnor “knows” exists.

  7. Dave S.on 15 Aug 2008 at 6:48 pm

    Of course she was still a person and not an object. In the legal sense for example, the judge had ordered a guardian ad litem to look after her interests. That would not be needed if she were just a mere object with no rights. And she did communicate her wishes, orally, which was the over-riding factor, given that she had rights.

  8. neuroboy6on 16 Aug 2008 at 10:30 am

    Steve,

    Thanks for such a clear and concise treatment of this very complex issue. I have had many of these same discussions with family members of similarly afflicted loved ones.

    It is obvious that your skills as a caring, informative, clinician match your considerable skills as an academician.

    Greg

  9. massimoon 16 Aug 2008 at 10:40 am

    oh man, this again? from enors post,

    “If the mind is entirely caused by the brain, the inference that a severe degree of brain damage could eliminate the mind is unexceptional. If mental causation is in part immaterial, one would approach the inference that brain damage would render a human being an object-but-not-a-subject with great caution.”

    how does this immaterial thing work with the material part? does the immaterial, um, ghosty-thing work alone also, when the material part doesn’t do its part? i would ask ol’ doc egnor, but his blog isn’t open to dialogue apparently.

  10. daedalus2uon 16 Aug 2008 at 11:10 am

    Egnor’s problem is that his thinking is completely muddled. Whether a particular arrangement of matter is an object or a person is not a scientific decision, it is a legal one. From a scientific position, a human being is an object, a human object. There is no scientific controversy over labeling a person an object, so long as the definitions used are consistent and unambiguous. What one does with that scientific observation, with that scientific label is a legal issue, not a scientific one.

    Scientific labels have nothing to do with legal rights and obligations. Neither do labels of pseudoscience.

    The ultimate problems of the Schiavo case was that the politicians involved delved into pseudolegalities. If pseudoscience is beliefs with the trappings of science but which are based not on facts and logic but on the beliefs of those pushing them, then pseudolegalities are beliefs and actions with the trappings of legality but which are based not laws but on the beliefs of those pushing them.

    The problem is that there were politicians who allowed their personal (usually religious) beliefs to influence their judgment as to what was “legal” or not. The legislature doesn’t have the legal authority to over rule a legally binding judicial ruling. Neither does the governor. That they did this (breaking their vows to uphold the rule of law) and were allowed to do this, and as Egnor seems to be doing, praised for doing so, is very unfortunate and really shows how far from wanting to uphold the actual “rule of law” many politicians and the public actually are.

  11. John Piereton 16 Aug 2008 at 2:20 pm

    I expanded a bit on the legal side of the issue here:

    http://dododreams.blogspot.com/2008/08/object-lesson.html

    At least Egnor is an equal opportunity fool. He brings his ignorance equally to bear on medicine, science and law.

  12. Badon 16 Aug 2008 at 10:53 pm

    What an incredibly bombastic ass. He, like many other liars who simply lie about the core issues of this case, actually has the nerve to accuse other people of treating her like an object, when in fact the whole point of the case was defending the right of a PERSON to refuse medical treatment: i.e. to NOT be treated like an object for some doctor or anyone else to keep alive indefinitely and play around with because they have some new theory of something neat to try on a non-complaining body.

  13. clgoodon 17 Aug 2008 at 7:09 pm

    Dr. Novella:

    I’m very grateful for this series of posts. I was deeply moved by the Schiavo case and now recognize how incompletely informed I was. I truly appreciate the education. If my brain ever assumes a PVS (or, perhaps worse, a PEC State) I hope that you or someone like you is my physician.

  14. tooth fairyon 17 Aug 2008 at 7:58 pm

    I think all families or anyone directly involved with a case like this would be so commforted knowing that their doctor refers to them as an object. Great P.R Egnor. Nice joke on the CAT scan Devils

  15. Dave S.on 17 Aug 2008 at 8:57 pm

    Florida statute (Chapter 765, HEALTH CARE ADVANCE DIRECTIVES) defines PVS as follow:

    (12) “Persistent vegetative state” means a permanent and irreversible condition of unconsciousness in which there is:

    (a) The absence of voluntary action or cognitive behavior of any kind.

    (b) An inability to communicate or interact purposefully with the environment.

  16. [...] on this issue), offering to discuss the relevant issues in our respective blogs. I wrote the first part of my response Friday, and here is part [...]

  17. ncbillon 29 Aug 2008 at 5:18 pm

    In the future, whether or not someone is in a PVS is unlikely to matter.

    Currently, Florida state law requires that the individual be in PVS or have certain other “qualifying” conditions before a feeding tube (or respirator, etc.) can be removed.

    However, federal decisions (e.g. Quinlan, Cruzan) have firmly come down on the side of the individual to refuse ANY medical care.

    Justice O’Connor even talks about the “burden” of a feeding tube.

    Because of those rulings I am deeply skeptical any state restrictions (must be in a PVS, etc.) on discontinuing “life support” medical treatments would survive a federal court appeal.

  18. Anwer Pashaon 24 Jan 2009 at 11:22 pm

    Actually it is very hard to understand about a persistent vegetative state.He/she needs more care than a new born baby. They can not cry,they can not weep but most of can see to some extend and can listen all what we are saying about them. They are afraid of every happening arround them. I asked my son ( a PVS now some conscious but wihout motor function) that I have read that evey one locked in Syndrome or PVS when asked about his first wish , They replied that they want to die,”Do you?” He replied by blinking eyes for yes but smiled to show that he is joking.I do not know yet what he meant. If you want to know more you can search about Jawad Pasha of Pakistan.

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