Is it possible for someone to appear to be in a deep coma, paralyzed, yet have a brain that is silently aware of all that’s going on around them?
Yes. This condition is called “locked-in syndrome,” which is an extreme example of the dichotomy of having a totally paralyzed body (except for the eyes), but an awake, perfectly conscious brain and mind.
But there are other, perhaps less well-known, medical conditions that result in a state of “semi-consciousness;” states that result from a variety of brain injuries, like stroke or head trauma, that persist sometimes for many weeks, even years.
These are called the Vegetative State (or, more correctly now, the Unresponsive Wakefulness Syndrome-UWS) and The Minimally Conscious State-MCS.
Before discussing these fascinating neurological states, to address the question, “What is consciousness?”: I believe it depends on who is offering its meaning. Neurologists, like me, will describe it as a state of being aware of one’s environment, including one’s inner environment of the “self.” Philosophers will have a different definition: consciousness is what it feels like from the inside, what constitutes “intentionality,” how we engage with the world.
In my Neurological ICU, we assess “consciousness,” or “awareness,” by asking our patients to follow commands: Give me a thumbs up. Open your eyes. Our nurses ask this every hour on the hour, as part of their around-the-clock neurological examination. The ability to follow commands will often be our first indication that someone is coming out of a coma, our first glimpse of recovery.
But if our patient cannot follow commands at the bedside, this doesn’t necessarily mean they are unaware, or unconscious. “Cognitive Motor Dissociation” is a state of disordered consciousness in which a person will not demonstrate brain activity by following commands at the bedside but is able to do so covertly. For example, a person who cannot visibly respond to commands will be able to perform a requested mental task, such as imagining lifting a finger, or playing tennis, when they are receiving specialized neurotechnology such as task-based electroencephalograms (EEGs) or functional MRI scans.
Patients who have been treated as unarousable or comatose are shown to actually “be there” by these specialized tests. Unfortunately, most of this technology is still primarily reserved for research studies at academic medical centers and is not readily available at the bedside.
So, it’s frightening to think that a patient in an apparent unconscious state has been aware all along: when their arm is caught under them while being turned, while people are speaking about their prognosis at their bedside, and they can’t object or ask questions—when they are unable to cry out or grimace or express what’s going on in their head.
After severe brain injury or illness, people don’t usually stay in a coma (from the Greek “koma,” deep sleep) very long; generally two to four weeks. If they survive, they progress to one of the “in-between” states of Unresponsive Wakefulness State or Minimally Conscious State, and then, hopefully, wake up. Some never wake up. People in the UWS retain the vegetative functions of the body, like digestion, cardiac and respiratory function, so they don’t necessarily need to be on a ventilator, and they have normal sleep-wake cycles. People in the MCS are moving closer to consciousness, although their awareness and interactions with us and their environment are inconsistent… reflecting isolated areas of cortical connectivity. Full consciousness, on the other hand, requires sustained integration of cortical nerve cell activity throughout the brain.
These in-between states can be difficult to distinguish from the “locked-in syndrome,” in which patients are paralyzed, but preserve the ability to move the eyes and to blink. Patients can look up and down and can blink to command. So, they consistently and correctly answer questions by these movements. Locked-in syndrome can occur from tumors, strokes or demyelinating diseases that knock out the ventral pons in the brainstem. The cortex above remains intact. Patients are quadriplegic, their face is paralyzed, they often cannot breathe on their own, and they can lose the all-important brainstem reflexes that permit us to cough and swallow.
Yet these patients are fully conscious. The French journalist Jean-Dominique Bauby, who at 43, suffered a pontine stroke that left him alert, but locked-in, wrote his memoir The Diving Bell and the Butterfly by painstakingly dictating one letter at a time using only his left eyelid and a code written down by his partner at his bedside. The book took about 200,000 blinks to write. Remarkable. Bauby died of pneumonia in 1997, just two days after the book was published in France.
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Today, we can offer locked-in patients a way to communicate their invisible thoughts with brain-computer interface systems that allow them to select a letter through a detectable brain signal via scalp EEG or implanted cortical electrodes.
What these remarkable patients have taught me is to never assume unconsciousness. Instead, assume the best: that the person in front of me in the ICU is invisibly conscious and aware of all we are saying. They can hear what their families and their visiting friends are saying to them. And I tell each patient on rounds every day what the day will hold, how they’re doing, what we plan next.
If I am wrong, and they are completely unconscious, no harm done. If I am right, whether proven by a task-based EEG or functional MRI scan, or better yet, by their waking up one day, those days and weeks have not been spent in stillness and stupor.
They have not been alone.
