What Is Coma?

Mihai D. Dimancescu, M.D.
Chairman of the Board, Coma Recovery Association, Inc.

Coma is a state of brain function. The human brain performs at different levels of consciousness. Each level does not have distinct boundaries, but rather, at one end blends into the level above it and at the other, blends into the level below it. At the highest level of performance the mind is perceived as alert, sharp, quick to respond to varying forms of input. Through a gentle phasing down, the brain may become progressively less responsive until, at the lowest level of function, the brain is in a state of coma. This represents the last state before death. This state most frequently occurs abruptly rather than in phases, usually followed by a progressive recovery.

The different shades of a color progress from extremely dark to so light that the color appears white. In this spectrum of shades, coma might be compared to the darkest shade where the color can still be distinguished before coming black. All the other shades represent lighter and lighter levels of consciousness to almost white, at which point the brain is in a state of full alertness.

Is this lowest end of the spectrum of consciousness not equivalent to the state of sleep that we all go through every night? In outward appearance indeed it is, but if brain function is measured during sleep, and indeed electroencephalography does measure such functions, the brain is then found to be in a state of readiness to respond to certain external or internal forms of stimulation and can jump from a "coma-like" state to full alertness in an instant.

The close outward similarity between sleep and coma triggered the most widely used definition of coma which states that "coma is a sleep-like state from which an individual cannot be aroused". In all its simplicity and apparent clarity, this definition is fraught with inaccuracy and danger. The very simple wording of the definition has made it easy to remember and to use and has allowed it to endure over many decades. Most professionals have accepted the definition and interpreted it in its most concrete sense, but herein lies the inaccuracy and the danger.

Upon closer scrutiny, looking at the first part of the definition - "coma is a sleep-like state", a redundancy appears. The word coma is derived from the Greek word Koma, meaning "state of sleep". The term was first used by our Greek father of medicine, Hippocrates, to describe this very state of the brain at the lowest end of the spectrum of function. If "Koma" is translated into English, the definition then reads "the state of sleep is a sleep-like state". To that redundancy we must add the danger implied in describing coma as a "sleep-like state". To most individuals, a "sleep-like state" sounds quite benign, a situation which should be short-lived and followed quite rapidly by an "awake-like state". When this does not happen, families are perplexed, frustrated and distraught.

The second half of the definition "from which an individual cannot be aroused" is clearly inaccurate, for thousands of individuals have eventually been aroused from coma. The danger in that portion of the definition is in its interpretation, not by the families, but by the professionals who erroneously assume that since the individual cannot be aroused, then no effort should be made to arouse the individual, and such a statement becomes a self-fulfilling prophecy. Such attitudes lead to further family frustration, now compounded by despair and by anger.

The late Dr. Edward B. LeWinn, former chief of medicine at the Albert Einstein College of Medicine in Philadelphia and later Medical Director of Clinical Research at the Institute for the Achievement of Human Potential in the same city, attempted to correct the definition, stating more accurately that "coma is a sleep-like state from which an individual has not yet been aroused".

The simple change from cannot to has not yet lifts all sense of hopelessness and creates a mindset in which efforts will be made to achieve the awaited arousal. The frustration, the depression and the anger of the families are significantly reduced. The motivation of the professional staff is increased. Potential for the future is enhanced as attitudes shift from negative to positive. A whole new mood is created in which relatives and professionals can work hand-in-hand and not in conflict with each other.

The LeWinn definition, while clearly creating a beneficial attitudinal problem, does not resolve the "sleep-like-state" issue. Sleep, and indeed coma, convey to the minds of most families and professionals a state of unawareness of one's surroundings. For many years this author taught families that when signs of awareness were present, the individual was no longer in a coma. But while an individual in a coma is unresponsive, we have no way of determining what the individual can hear or may be aware of. The term unresponsive applies to movement and language. When both are absent, an individual is incapable of letting anyone know whether he/she can see, hear, or understand. While a person described as being in a coma may be totally unaware of his or her state or environment, others may have some or even full awareness, contrary to our own perception of their condition. Many a recovered patient has related events that occurred when everybody believed they were still in a coma. I was impressed by twenty three year old Judy, who remained unresponsive in an intensive care unit bed for three months. When the professor, under whom I was working at the time, made his daily rounds of the patients, his whole staff in tow, several minutes would be spent at each bedside, talking to the patient and discussing the illness or injuries; but Judy's bed was always bypassed with a brief professorial comment such as "Judy is in a coma. She'll never wake up"! One day Judy did wake up and gradually regained her speech. As I sat on the end of her bed questioning her about her condition one afternoon, she told me that she "always remembered that darn professor refusing to stop by her bed, saying that she would not wake up"! Behind her apparent unawareness, Judy was totally conscious. Many similar stories abound. In fact, coma is a state of unresponsiveness and apparent unawareness.

Ambiguity of terminology was resolved by Dr. LeWinn for the second part of the traditional and still widespread definition. The author believes that all ambiguity can be eliminated if coma is redefined as "a state of unresponsiveness from which an individual has not yet been aroused".

This new definition remains as simple as the original, easy to remember, uncomplicated and far more accurate. In fact the same statement could apply to normal sleep and one might be able to say that "sleep is a coma like state", the exact corollary of the Hippocratic definition.

Commonly, when coma lasts for a month or more, the individual's eyes may be open and may blink even though the person's stare is vacant, no purposeful responses occur, and no signs of awareness appear. At this state, most physicians will say that the individual is in a "persistent vegetative state" or PVS. This term was developed by Drs. Brian Jennett and Fred Plum, an outstanding neurosurgeon and a well recognized neurologist respectively. The intent was to describe a condition in which the vegetative or anatomic functions, such as breathing, maintaining a normal blood pressure, digesting and eliminating foods were maintained and would persist indefinitely in the absence of awareness. Unfortunately, the term has become horribly misused and has been a sentence to death for many, aside from another devastating misinterpretation by most nonprofessionals. The word vegetative is read by families as meaning "vegetable-like", giving them the impression that their loved one is now being treated like a cabbage or a turnip. All human dignity is destroyed. The permanence of the condition reflected in the the word "persistent" removes all sense of hope and since there is no hope, then no significant treatment should be applied. The end result is a slow death by infection or even by slow starvation, often in individuals who may have full awareness despite appearances to the contrary. Compounding the devastating sentence, many physicians do not even wait a full month to assign their verdict, despite the recommendation of Drs. Jennett and Plum, originators of the term PVS, to wait three months before making a determination. Many physicians will solemnly announce to a family two or three days after onset of coma that their loved one is in a persistent vegetative state and declare unambiguously that nothing can be done, adding insult to injury and preventing treatment at the most treatable stage. Only brain death is untreatable in the spectrum of brain functions.

With the new definition of coma as "a state of unresponsiveness from which an individual has not yet been aroused" there are no time boundaries to which the definition need be confined. No requirements for a new term, or a new description become necessary when an individual remains unresponsive for a long time. Indeed weeks or months after onset of a coma unresponsiveness represents only a prolongation of the initial state. The new definition does not preclude continuation of treatment or onset of new treatments even weeks and months after the original insult to the brain.

Additional qualifications of a coma have led to further confusion. Physicians and nurses frequently classify coma as light, moderate or deep. The implication is that a deep coma has a worse prognosis than a light coma. While the implication in itself is totally false, the qualifications are highly subjective.

What appears as a "light coma" to one observer, may be a "moderate coma" to a different observer. Fluctuation in the levels of an individual's reflex responses frequently vary from moment to moment several times a day. As a result, a single observer may at different time of the same day classify a coma as deep, light or moderate. There are no qualitative, quantitative or prognostic values to such a classification, but there are frequent frustrations and moments of despair for families who never obtain a clear determination of the state of their loved one. Jennett and Teasdale, recognizing the pitfalls of subjective qualifications, developed what is known as the Glasgow Coma Scale or GCS. Assessing three simple parameters consisting of eye opening, use of the voice, and best movement, the GCS assigns a score to each function with the highest number going to the best function and lowest number (one) going to the absence of function. The three scores are then added giving a range from a high of fifteen (15) to a low of three (3). A score of eight (8) or less defines coma. The lower scores indicate less brain function and suggest a higher degree of injury. While the score may be used to try to determine outcome, some very low scoring individuals have achieved excellent recoveries, as some higher scoring patients have failed to show any meaningful improvement.

The GCS has gained widespread use, particularly in the assessment of traumatic brain injury (brain injury resulting from an accidental blow to the head). The scale is highly reproducible from one observer to another, is quickly performed at the bedside and provides useful information on the progress of an individual. A family may be somewhat reassured if a score progresses from a four to a five over twenty four hours. A measurable function has greater value than a subjective assessment.

One limitation to the use of the GCS is the uncertainty as to how long after the onset of coma or injury to the brain it remains a useful assessment tool, and whether it is applicable to brain injuries resulting from causes other than a blow to the head. The author has used the scale in all forms of brain injury with equal satisfaction.

Other scales have tried to improve on the Glasgow Coma Scale, measuring different functions, sometimes in great detail. Neurorehabilitationists (therapists specialized in rehabilitation of brain injured individuals) are fond of the Rancho Los Amigos scale, developed at the rehabilitation institute of the same name in California. The scale assigns a value of I to VIII to the different levels of brain function from low to high. The main deficit in this system resides on the number of progressively improving function within one category that go unrecognized. Some therapies are designed as a function of the level assigned to an individual, some therapies may be delayed or denied because progress has not been recognized. Some scales are on the contrary so detailed that they become cumbersome, take too long on the assessment and assign points up to 135 or 160 and are thus difficult to qualify even though they give quantitative information. They remain of academic interest, but have no practical value in terms of treatment.

Coma represents the last and lowest level of function of the brain prior to death. As a general rule, if a patient in a coma survives the first seven to ten days following the injury to the brain, then long-term survival can be expected. The quality of that survival remains a subject of the debate.