By Paul Ranalli, M.D.

What goes on in the mind of a patient who, tragically, has suffered severe brain damage? The answer has eluded doctors and scientists for years, but a new research study may have taken us a small step closer. Its findings may have ramifications both for patients and their families and for the controversy surrounding the Terri Schindler-Schiavo case, as well as others who have experienced brain injuries.

Dr. Paul Ranalli

In a small, unique experiment carried out by research physicians from Cornell and Columbia universities in New York and Georgetown University in Washington, two brain-injured patients showed remarkable evidence of a potential ability to hear and understand the voices of close family members, with a brain response indistinguishable from that of a normal, alert person. The results of the study were published in the latest issue of Neurology, the journal of the American Neurology Association.

The background to this study arises from the observation that after a catastrophic brain injury, patients left in a coma, or semi-comatose state, may retain different forms of hidden, preserved brain function. A patient who does not die from such an injury may eventually move out of intensive care onto a regular hospital ward, once he or she is able to breathe on his or her own.

But further neurological recovery may then stall. Those patients who, to the observer, show no obvious awareness of themselves or their environment will have their condition labeled with the term "persistent vegetative state" (PVS). They behave as if they are in a permanent state of sleep.

Some patients, however, eventually appear to be able to react and respond to those around them, even though they may do so only intermittently. This episodic lifting of unconsciousness is puzzling to doctors and therapists, and a source of both hope and frustration for loving family members. They ask very good, emotionally laden questions: "Can my husband hear me? Does my daughter recognize my voice, and understand anything I tell her?" The problem is, there are often no answers.

Our hands-on clinical neurological exam can only tell us so much. The exam can be extended by recording the pattern of electrical brain waves with an electroencephalogram (EEG). But what "thoughts," if any, do they represent?

Brain-imaging tests such as CT and MRI brain scans show the damaged areas in detail. But, the paper's authors point out, in patients with this higher level of function (termed the "minimally conscious") "wide differences in structural injury patterns are present in patients with behavioral evidence of consciousness." In other words, you just can't tell.

To explore this problem, researchers obtained consent from the families of two severely brain-injured young men (ages 21 and 33) to conduct a simple but ingenious experiment.

A close family member recorded an audiotape telling a story with content familiar to the patient. This was then played through headphones placed on the patient's ears while he lay in an MRI machine tuned to display the changes in blood flow that occur when various parts of the brain are active (so-called "functional" MRI, or fMRI). The object was to see which areas of the brain might "light up" in response to the family story.

However, any stimulus, including the sound of a person's voice, will stimulate various parts of the brain, especially areas of the temporal lobes (on each side of the brain, just inside the ears). Thus an fMRI pattern of activity would not necessarily imply that the minimally conscious patient recognizes his relative's voice, much less derives meaning from the story.

Researchers controlled for this effect in two ways. First, they played audiotapes of recorded paragraphs to seven healthy volunteers while they had their brain function imaged by fMRI.

The content had no personal meaning to the volunteers, so the evoked response in their brains would be restricted to the reception of spoken language. Somewhat surprisingly to the researchers, the patterns of brain activity seen in the two young men with brain damage were similar to those of the healthy volunteers.

The other method of control was necessary to answer the question of whether the personal content of the stories was truly meaningful to the patients. To do this, the researchers played the taped stories backwards to the patients and volunteers, again while recording regional brain activity in the fMRI.

This would deliver the same tone of voice but would be devoid of personal meaning. The result was remarkable: responses from the minimally conscious patients were markedly reduced compared to the healthy volunteers.

In other words, hearing the voice of a close family member telling a personally memorable story appeared to be registering with the visibly unconscious patient. It was not a mere response to sounds.

Equally as intriguing, the voice-reception areas of the temporal lobes were not the only part of the brain to show activity. In what the paper's authors describe as a "haunting" observation, some areas of the occipital lobes (at the back of the brain) also showed increased activity as the stories were being told.

The significance of this? The occipital lobes contain the brain's prime vision-reception and interpretation function. This suggests the verbal stories were triggering internal visual images in the minimally conscious patients.

This study presents a method of testing brain-damaged patients who may look similar on the surface but, on further examination, possess different levels of internal brain ability. The results may offer some families the hope of an improved prognosis for eventual recovery, and may be crucial to directing new methods of therapy to help these patients recover to the best of their abilities.

On the negative side, this type of testing may reveal patients with a lower level of function who do not respond to meaningful voiced stories. One day that might lead to their relegation to a lower level of respect, perhaps to a decision by some to terminate their crucial life support.

There is a glimmer of hope even here, however.

It has taken over 60 years - - the modern era of neurological research - - for medical scientists to discover that there is much more internal brain activity in so-called "minimally conscious" patients than they ever imagined. As the technology grows increasingly sophisticated, it may be possible to detect certain levels of brain activity in patients in a so-called PVS.

This study reveals a level of awareness and subtle interpretative abilities within severely brain-injured patients that surprised the doctors conducting the study, and the profession as a whole. It also cautions hardened scientists and physicians, once again, not to underestimate the strength of the inner human spirit at any level of challenging illness.

Dr. Paul Ranalli is a neurologist at the University of Toronto, and an advisory board member of the deVeber Institute of Bioethics and Social Research (www.deveber.org).

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