Sunday, February 14, 2010

Descartes before the horse (Marin IJ)

“Physicians and society are not ready for ‘I have brain activation, therefore I am.’ That would seriously put Descartes before the horse.”

The above statement comes from a New England Journal of Medicine (NEJM) editorial by the esteemed neurologist Allan H. Ropper. Dr. Ropper was referring to an accompanying NEJM study of 54 brain injured patients in which four patients thought to be in a persistent vegetative state (PVS) actually demonstrated the ability to control brain activity – in one case enough to answer simple yes or no questions – via the “activation” images on a functional MRI (fMRI). The study follows on the heels of the story of Rom Houben – a 46-year-old Belgian man thought to have been in a PVS for over twenty years. Recently, doctors, with the help of fMRI, diagnosed Houben with locked-in-syndrome – a rare neurologic condition that prevents the brain’s impulses (intentions to act, speak, etc.) from reaching the rest of the body. With Houben’s case and the newly released NEJM study, we have fresh wrinkles in the centuries old debate of where the brain ends and the mind begins. The question of the moment – as posed by Dr. Ropper – is whether fMRI activation, in the absence of other signs of awareness, is evidence of “life” in the brain? And if it is, what does this mean for the estimated 15,000 Americans currently considered to be in a vegetative state?

To address these questions, let’s first make an important distinction. Research shows that that people who have become “vegetative” due to brain trauma have a greater chance of recovering than those who have ended up “vegetative” because their brains were deprived of oxygen (such deprivation is called an “anoxic” event). Current thinking is that patients in the anoxic group (patients like Terri Schiavo) will either improve in the first three months or, sadly, never. The recent NEJM study supports this thinking in that none of the study’s patients who had suffered anoxic brain injury showed any evidence of being able to modulate brain activity. Among the patients who had suffered traumatic brain injury, however, the evidence was clearly much different. While it was previously thought that patients with traumatic brain injury were not likely to improve after the first year post-injury, Rom Houben’s circumstances and the NEJM study seem to call that one-year-deadline into question.

It seems then that we can expect minimal benefit from using fMRI on PVS patients with a history anoxic brain injury. In cases of traumatic brain injury, on the other hand, fMRI may be useful. But we must keep in mind that fMRI has a critical weakness: its results can only be considered definitive if positive .If the result is negative (no evidence of conscious brain activity), the patient might be asleep. This means that a negative fMRI can, at best, be part of an integrated evaluation process – including history, clinical exam, CT scan, and Electroencephalogram (EEG).

Perhaps fMRI should be considered as part of the work-up of brain injured patients if they do not show obvious signs of improvement within a year of injury? In some cases, these patients may even be able to answer questions, via fMRI, about whether they are in pain or perhaps even communicate their wishes about life-sustaining treatment. This sounds like a beneficial use of fMRI but must be measured against dollars and cents (a single fMRI scan costs approximately $700) and practicality (currently fMRI units are scarce and located primarily at research centers). The experts I contacted agreed that fMRI is not ready for widespread use in the PVS population. Dr. Geoffrey K. Aguirre, an assistant professor of neurology and an fMRI researcher at the University of Pennsylvania, emphasized, “The gold standard has been, and remains EEG. It does a great job of detecting sleep/wake cycles and distinguishing (for example) coma from locked-in syndrome from something in between. The fMRI work is focused upon the particular question of if you can give prognostic information for recovery from vegetative to minimally conscious state.” Dr. Art Caplan, from the University of Pennsylvania Center for Bioethics, also urged caution: “The real challenge is, as better scanning appears, when do we define it as the standard of care for determining PVS, minimal consciousness and death? I think that day is drawing closer but the cost and practicality are very real concerns.”

What are we to make of this? For me, the lesson is similar to that of the Terri Schiavo case; as uncomfortable as it may be, it is best to think about and communicate your wishes and beliefs about life in a PVS ahead of time. You can do so by preparing an advanced directive (living will) that identifies those people who will be responsible for making medical decisions for you (if you are incapacitated) and spells out specific wishes. For example, my living will says: “under no circumstances do I want to be portrayed on television if I am a coma or vegetative state.” I think this is like knocking on wood – if you take care of it ahead of time, it won’t happen. So, make your wishes clear. Talk about PVS with your family and your doctor now; don’t wait until the horse is out of the barn.

For more information on advanced directives go to: For most, the California Probate Code Sample Form will suffice.