The End of Life: Medical Considerations - Disorders Of Consciousness

A coma is a deep state of unconsciousness caused by damage to the brain, often from illness or trauma. Most people in a coma recover within a few days, but some do not. Figure 4.2 shows the possible outcomes for those who do not recover from a coma quickly. For some, their brain dies. That is, they irreversibly lose all cerebral and brainstem function. Table 2.1 in Chapter 2 lists the clinical criteria for brain death.

More typically, patients who do not recover quickly from a coma progress to a vegetative state. Those in a vegetative state for one month are then referred to as being in a persistent vegetative state (PVS), and after a longer period (see Figure 4.2) are referred to as being in a permanent vegetative state. "Permanent" implies no chance of recovery.

Table 2.2 in Chapter 2 lists the criteria for the diagnosis of a persistent vegetative state. As Table 2.2 shows, patients in a PVS are unaware of themselves or their environment. They do not respond to stimuli, understand language, or have control of bowel and bladder functions. They are intermittently awake but are not conscious—a condition often referred to as "eyes open unconsciousness."

FIGURE 4.2 Flow chart of cerebral insult and coma Steven Laureys, et al., "Figure 1. Flow Chart of Cerebral Insult and Coma," in "Brain Function in Coma, Vegetative State, and Related Disorders," The Lancet Neurology, vol. 3, no. 9, September 2004, pp. 537-46, © 2004 with permission from Elsevier

Some patients in a PVS may recover further to regain partial consciousness. This condition is called a minimally conscious state (MCS). Table 4.4 lists the criteria for a minimally conscious state. Partial consciousness (MCS) means that perception is severely altered, but the patient shows an awareness of self or the environment and exhibits behaviors such as following simple commands and smiling or crying at appropriate times. Some patients emerge from a MCS and some remain in a minimally conscious state permanently.

Another disorder of consciousness that rarely occurs after a coma is locked-in syndrome. The patient with locked-in syndrome has full consciousness, but all the voluntary muscles of the body are paralyzed except (usually) for those that control vertical eye movement and blinking. Persons with locked-in syndrome communicate primarily with eye or eyelid movements.

Treatment of PVS Patients

In "The Vegetative and Minimally Conscious States: Consensus-Based Criteria for Establishing Diagnosis and Prognosis" (Neurorehabilitation, vol. 19, no. 4, 2004), Joseph T. Giacino discusses implications for treatment of patients in both a vegetative and a minimally conscious state. He notes that early interventions should focus on maintaining the patient's physical health and preventing complications. Standard interventions include stretching exercises, skin care, nutritional supplementation, and pain management. In minimally conscious patients, functional communication systems and interaction should be established. If the patient does not improve and the criteria for permanence of the condition are met, decisions must be made concerning changes in the level of care and whether life-sustaining treatment should be withdrawn. At this time professionals having expertise in the evaluation and management of patients with disorders of consciousness should be consulted to determine an appropriate course of action.

TABLE 4.4

Criteria for a minimally conscious state (MCS)

To diagnose a minimally conscious state, limited but clearly discernible evidence of self- or environmental awareness must be demonstrated on a reproducible or sustained basis by one or more of the following behaviors

1. Follows simple commands
2. Gestural or verbal yes/no responses (regardless of accuracy)
3. Intelligible verbalization
4. Purposeful behavior, including movements or affective behaviors that occur in contingent relationship to relevant environmental stimuli and are not due to reflexive activity. Some examples of qualifying purposeful behavior are

   Appropriate smiling or crying in response to the linguistic or visual content of emotional but not to neutral topics or stimuli

   Vocalizations or gestures that occur in direct response to the linguistic content of questions

   Reaching for objects that demonstrates a clear relationship between object location and direction of reach

   Touching or holding objects in a manner that accommodates the size and shape of the object

   Pursuit eye movement of sustained fixation that occurs in direct response to moving or salient stimuli

SOURCE: Eelco F.M. Wijdicks and Ronald E. Cranford, "Table 2. Criteria for a Minimally Conscious State," in "Clinical Diagnosis of Prolonged States of Impaired Consciousness in Adults," Mayo Clinic Proceedings, vol. 80, no. 8, August 2005

Chances of Recovery

Giacino summarizes the consensus opinion of the major professional organizations in neurorehabilitation and neurology concerning, among other things, the prognosis of patients in a vegetative state (VS). The article notes that the probability of recovery of consciousness from a vegetative state depends on the length of time a patient has been in this condition and whether it was brought on by traumatic injuries or by non-traumatic causes.

After three months in a vegetative state, the probability of recovering from a trauma-induced VS is approximately 35% and from a non-trauma-induced VS is 10%. Of the 35% who will recover from a trauma-induced VS, about 20% will still have severe disabilities at one year post-injury while the remaining 15% will have moderate to good outcomes.

Of those persons with trauma-induced VS who do not begin recovery by three months, 35% will die and the other 30% will remain in a VS at one year post-injury. Of those alive at six months, approximately 30% will die, 50% will remain in a VS, and 15% will recover consciousness by twelve months.

Of those people with non-trauma-induced VS who do not begin recovery by three months, approximately half will die during the next nine months and the other half will remain in a VS. No cases of recovery after six months in a non-trauma-induced VS have been documented.