Every now and then
you hear talks that astonish and fundamentally change the way you view some
issue or disease state. I heard one of these at this year’s Society for Neurosurgical Anesthesia and Critical Care (http://www.snacc.org/)
Dr Adrian M Owen of the
Well Dr Owen presented a patient with all the stigmata of PVS from traumatic brain injury with diffuse axonal injury. This vegetative patient, however, when asked to think about a place or to think about riding a bike showed fMRI activation absolutely the same as that produced when an ordinary awake patient responded to the same command. In fact this patient was fully able to interact with the investigators in this manner. “If you can hear me think about riding a bike” leading to the bike riding pattern. I took a picture of this slide showing this and reproduce it here:
The fMRI of the PVS patient is at the top and the control volunteers at the bottom. The left images are those of tennis playing imagery and on the right of spatial recollection imagery. I believe this is going to have implications for decisions about extent of life support in such patients. Certainly many(probably most) PVS patients really are in PVS. Unlike this case, I don’t expect patients with neocortical death will be responsive like this. Nonetheless it does suggest that before we make such PVS declarations that we should make sure on tests like those presented by Dr Owen that the PVS patient really is in PVS.
For starts, in those patients in whom we find that PVS is really “pseudoPVS,” I expect this will be an objective measure to use for rehab. Just keep thinking about that bike riding and after awhile the physiatrists, wonder workers that they are, may be able to have the patient really bike riding or doing other cognitive things. It will tell them to not give up.
So it seems that what we thought we knew for sure we’re not so sure of anymore. Déjà vu.