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Repairing Lost Consciousness in PVS Patients

What did the Schiavo affair teach us?  Pundits were quick to answer this after the medical examiner released Schiavo’s autopsy report in June 2005.

They told us her vegetative state was “irreversible [1]”; “no amount of treatment or rehabilitation [2]” would have helped her.  The eager pro-lifers were wrong, Slate’s Will Saletan told [3] us: “This is what happens when you deny reality.  First you lose your senses, then your mind, then your soul.”

What was the reality we denied?  According to Saletan, we denied that Schiavo’s vegetative state was intractably persistent, that she was totally and irreversibly unconscious.  (Actually, pro-lifers denied that she would have wanted to be terminally starved and dehydrated under the circumstances.)  New evidence demonstrates that the denial of which we were accused may have been well grounded.

Persistent Vegetative State (PVS)

The “vegetative state” is not itself a pathology but rather a series of expressed symptoms.  Patients who experience cycles of sleep and wakefulness but with no evidence of awareness of self or environment are said to lie in a vegetative state.  The condition can be caused by a variety of factors such as traumatic brain injury, stroke, or advanced Alzheimer’s disease (although in Terri’s case, the cause, even after the autopsy, was still uncertain).  When the unresponsive condition endures for at least one month, the state is tagged “persistent.”  Hence the diagnostic term Persistent Vegetative State.  Unfortunately, in the minds of many people, persistent means irreversible.

We are told [4] the chances of recovering consciousness after 12 months of unresponsive behavior are quite low.  Nevertheless, reports [5] of PVS patients recovering consciousness are well documented; and studies [6] demonstrating the ability of PVS patients mentally to communicate are numerous [7].

From PVS To Minimally Conscious State

A study [8] published at the end of September demonstrates once again that we should retire the malignant term “persistent vegetative state.”

A 35-year-old man who suffered traumatic brain injury in a car accident at the age of twenty had lain in a PVS for fifteen years.  After a team of scientists and clinicians treated him with something called vagus nerve stimulation (VNS), the man began to show manifest signs of consciousness.  The treatment, the research team writes, “helps to restore consciousness even after many years of being in a vegetative state, thus challenging the belief that disorders of consciousness persisting after 12 months are irreversible.”

The vagus nerve (vagus in Latin means “wandering”) is the longest and most complex cranial nerve in the body.  It “wanders” from the face down the neck to thorax and into the abdomen, connecting, with its thousands of fibers, the brain to the upper digestive tract and the organs of the chest cavity and abdomen.  It is involved in the regulation of digestion, respiration, heart rate and the immune and endocrine systems.  Its activity is also important in waking, alertness, concentration and memory.

The researchers chose a patient whose state had persisted for more than a decade to ensure that any improvement would not easily be explained away by chance factors.

The man’s vagus nerve was stimulated for one month.  The patient expressed improvements in responsiveness, attention, wakefulness and brain activity.  He became able to follow simple orders that were impossible for him before, such as to track an object with his eyes or to turn his head; he expressed new “threat” responses to sudden movements towards his face, showing a startled look and opening wide his eyes; he became able to stay awake for longer periods of time when his therapist read him books; and his brain activity as recorded on several devices significantly increased.

The team concluded [8] that their treatment enabled this man astonishingly to “transition from a vegetative to minimally conscious state.”

The minimally conscious state [9], unlike the vegetative state, is characterized by expressions of manifest, albeit impaired, consciousness.  Patients make eye contact, reach for objects, respond to questions, follow lights with their eyes and react to commands.  Most are able to improve slowly with therapy, and some even regain the ability to understand and communicate in more sophisticated ways.

PVS And Irreversibility

Is the vegetative state then truly irreversible, as the pundit writing of Terri Schiavo’s case assures us?  The better question is, Can we ever know with diagnostic certainty that this or that patient’s state of unresponsiveness is irreversible?

I am neither a scientist nor a clinician, but those who conducted the study above concluded that their results challenged “the belief that disorders of consciousness persisting after 12 months are irreversible.”

We now know that the once-sacred maxim—brain tissue does not regenerate—is wrong.  The brain’s plasticity (i.e., its ability to reorganizes itself by forming new neural connections) is well documented [10].

Since neurogenesis can and does occur in humans, and treatments and therapies such as VNS are being developed to stimulate it in patients with disorders of consciousness, clinicians should be extremely modest in making diagnostic determinations of irreversibility.

As the Schiavo case tragedy illustrated, the consequences otherwise may be fatal.