Brain Imaging Could Predict Recovery from a Vegetative State

Patient getting an MRI scanNearly a decade ago, the case of Terri Schiavo, a Florida woman in a vegetative state, sparked a national debate. Schiavo’s husband believed that she would never recover consciousness and that she would not want to live in such a state, but her parents believed she still retained some consciousness and that recovery was possible.

After a protracted legal battle, Schiavo’s husband was allowed to remove her life support, and she died. Brain imaging through positron emission tomography, however, could render cases such as Schiavo’s obsolete by shedding light on which people in a vegetative state are likely to recover.

What Is a Vegetative State?

A vegetative state is different from a coma and other forms of consciousness loss. The condition is typically caused by a brain injury, such as a blow to the head. In a vegetative state, the person is awake but does not show any signs of conscious awareness. He or she may blink, display basic reflexes, and maintain a regular heartbeat without assistance.

People in vegetative states also sleep and wake at regular intervals. Scientists can’t be fully certain of what it feels like to be in a vegetative state, but they believe that people in such states are unaware of the world around them. If, like Schiavo, a person remains in a vegetative state for more than six months, they are diagnosed as being in a permanent vegetative state.

The label of persistent vegetative state is somewhat controversial, since people can—but rarely do—awaken from such a state. It can also be challenging to properly diagnose someone, and some people diagnosed as vegetative may actually be experiencing a different type of consciousness loss.

Perhaps most troubling to the loved ones of those in vegetative states, there’s no way to know what these patients’ subjective experience is actually like. No one knows whether they are capable of any rudimentary thoughts or awareness.

PET Scans for Vegetative Patients

Doctors have historically used bedside consciousness tests on patients who have lost consciousness. The estimated error rate of these tests, however, is 40%. An error in such a test could provoke family members to remove life support because they believe a loved one has no hope of recovery.

Positron emission tomography (PET) scans may help to end the uncertainty surrounding vegetative states. A new study compared the results of PET scans with those of functional MRI (fMRI) imaging to assess patients who had lost consciousness. The results were promising. PET scans could accurately predict the degree of recovery within one year in 74% of those in a vegetative state.

The study also compared the results of PET scans to those of bedside consciousness tests, and it was here that PET scans looked the most promising. Of 36 people diagnosed as completely unconscious via behavioral tests, PET scans showed signs of consciousness in one third, suggesting that there could be more hope for patients in vegetative states than was previously thought.


  1. Disorders of consciousness . (n.d.). Retrieved from
  1. Functional brain imaging reliably predicts which vegetative patients have potential to recover consciousness. (2014, April 15). Retrieved from
  1. Matsuda, W. (2003). Awakenings from persistent vegetative state: Report of three cases with parkinsonism and brain stem lesions on MRI. Journal of Neurology, Neurosurgery & Psychiatry, 74(11), 1571-1573. doi: 10.1136/jnnp.74.11.1571
  1. Terri Schiavo has died. (2005, March 31). Retrieved from

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  • Andrea


    April 22nd, 2014 at 3:53 PM

    There will be so many families who could benefit from this is this ever ended up being a reality. Think about the pain that you would feel having to take a loved one off of life support if you even thought that there was any hope that the person could recover.

    But if there was something that could tell you beyond a shadow of a doubt that there was no hope for recovery, then I am not saying that this would ever make the decision easier but you at least not feel like you are killing a loved one. This could offer families peace that they may not have had before.

  • ella


    April 23rd, 2014 at 7:17 AM

    Why hasn’t this been used more widely? Is it cost or just still the degree of uncertainty that there is surrounding the results?

  • Donette S

    Donette S

    April 23rd, 2014 at 11:02 AM

    I can tell you that no matter what a scan or a test says there will still be those families who hold out hope against hope that their family member can recover and they don’t want to hear anything that they will perceive as negative or without a glimmer of hope. I can’t say that I wouldn’t do the same if I had someone that I loved dearly who was hanging on to life by a thread. There will just be those families that no matter how much proof you give them they will always want something more and I think that for them this is not going to change very many minds.

  • dorothy


    April 24th, 2014 at 3:45 AM

    i would never want to live like this and if you don’t want the family to fight it out then you need to make your own wishes known by having a living will

  • Flynn


    April 26th, 2014 at 12:49 PM

    Having to make that decision to take someone off of life support is not one that I ever have to make again. I had to do that with my dad several years ago and believe me it was the worst day of my life with that kind of decision hanging in the balance. The rational side of me was battling it out with the selfish side of me and I didn’t have anyone who could help me make the decision. All I had to go by were conversations about this very thing that he and I had had a few years before and he had clearly made his wishes known. I am glad that I live in a state that allowed me to honor those wishes but it still was hard to do. I am not sure that any kind of test would have made it better but maybe it could have at least reassured me that there was no chance of him coming back the way he was. I don’t know, it’s never easy regardless of the info you have or don’t.

  • Cam


    April 28th, 2014 at 3:36 AM

    Do you think that this is necessarily a good thing? Will this simply prolong the grieving process for some families as they continue to wait for hop that may not actually be there?

  • Bart


    April 30th, 2014 at 7:33 AM

    Cam I hear what you are saying but the fact of the matter is that for these families they need something that shows them that there is either hope to be had or that it is time to let the family member go. I would never want to have to make that decision based on just what doctors are telling me that their feelings are aboutt he cause. I want some irrefutable proof one way or the other before I am faced with this kind of decision and I think that this is all the PET scans are offering. Just a little more comfort that you are making the right decision for your family member.

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