'Consciousness' - Harvard Gazette

"In the movies, a comatose patient can be unreachable one moment, just fine the next. "That suggests there's a clearly demarcated border between unconsciousness and consciousness," said Joseph Giacino, a professor of physical medicine and rehabilitation at the Harvard School of Medicine and the director of rehabilitation neuropsychology at Spalding Rehabilitation Hospital. "That couldn't be further from the truth.""

"There is no universally accepted definition of consciousness, Giacino said. But clinicians see it as a "dynamic, fluctuating" state, easy to miss when it's there or see when it's absent. "Everybody has this sense of what consciousness is, but when you try to operationalize it, you quickly realize how elusive a full understanding can be," he said."

"Clinicians have a well-defined list of behavioral criteria that are used to detect consciousness at the bedside. Some, like command-following, are obvious: If I ask you to do something and you do it, you're conscious. Further down the list, there are more subtle indicators, like the ability to visually track a person or object that appears in the visual field."

There is no universally accepted definition of consciousness. Clinicians treat consciousness as a dynamic, fluctuating state that can be easy to miss or to misidentify as absent. Bedside behavioral criteria include clear signs such as command-following and subtler indicators like visual tracking. Specialized behavioral assessments and neuroimaging can reveal covert responsiveness not evident on routine bedside exams. Consciousness recovery has often been viewed as linear, but evidence shows fluctuations over time. In intensive care settings, repeated and careful assessment is essential to detect intermittent signs of awareness and to guide prognosis and care planning.

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