Vegetative State (Persistent)

Synonyms

Coma vigile

Short Description or Definition

A vegetative state (VS) is a type of unconsciousness in which the patient is capable of wakefulness but not awareness. It is characterized by intermittent and sometimes prolonged wakeful eye opening in the absence of cognitive function, evidenced by lack of meaningful response or purposeful activity.

Categorization

Jennett (1997) noted that patients who were unconscious but demonstrated wakefulness have been described in the literature using terms, such as apallic syndrome and coma vigile; the term vegetative was applied to these patients beginning in 1963. Persistent vegetative state (PVS) was a term coined by Jennett and Plum (1972) in an attempt to bring some order to the inconsistent clinical description of patients who were unconscious but who had emerged from coma, demonstrated by eye opening and the presence of a discernable wakeful state. Jennett and Plum stated that the term was not meant to imply irreversibility, but the condition was later interpreted to be irreversible in certain circumstances by The 3Multi-Society Task Force on PVS (1994). Reports of late recovery from PVS prompted The Aspen Neurobehavioral Conference Work Group to recommend that the term PVS be abandoned. Currently, the VS that continues for longer than 1 month is commonly labeled as persistent despite the recommendation by the Aspen Work Group that the term be disregarded (Giacino et al. 2002).

Physically, the patient in VS is often not only in a decorticate position (arms flexed and legs fully extended) but also sometimes in a decerebrate position (both arms and legs fully extended). A positive clinical feature of VS includes periods of wakeful eye opening without sustained visual tracking. Reflexive responses, including orienting or a startle response to a visual or auditory stimulus, may occur without sustained pursuit of or fixation on the stimulus. For example, a patient may respond to a change in room lighting or the introduction of a light or object into the visual field, but the response will quickly cease. Such a response is reflexive and not indicative of awareness. Reflexive response may also be evidenced in motor movements, which are nonpurposeful and sometimes grasping. For example, a patient may demonstrate nonpurposeful movement of the arm, causing the hand to rub against an object in the patient’s personal space and grasp reflexively. Patients in VS may respond to pain, but like response to other stimuli, the response to pain is inconsistent and not commonly thought to be realized by the patients at a conscious level (but see Howsepian (1996) and Borthwick (1996) for opposing views). The patient in VS may have verbal output, including occasional laughter or other emotional behavior, although the sounds are generally unarticulated vowel-like groans. Moreover, patients in VS may demonstrate a swallow reflex and adequately manage saliva but not the coordinated management of food or drink necessary for safe oral intake.

The VS is a state of unconsciousness, which differs from coma in that it includes distinguishable periods of wakefulness and sleep, reflexive response to auditory or visual stimuli, and occasional nonpurposeful movement. Jennett and Plum (1972) supported a clear distinction between the unconscious states of coma and VS and the states of partial consciousness, such as delirium, stupor, obtundation, and the minimally conscious state. Unlike patients in VS, those in acute and chronic partially conscious states often demonstrate impaired cognition and perception but have variable awareness of themselves and the environment.

Jennett (2004) cautioned that family members and caregivers may misperceive the reflexive motor responses or other reflexive behavior as evidence of returning consciousness. Medical personnel need to be cognizant of changes that indicate consciousness. Although some patients do regain consciousness, careful observation commonly reveals that responses misinterpreted by caregivers to be consistent actually demonstrate no relationship with a stimulus. The perceptions of family members have medicolegal significance, discussed by Wijdicks (2006) in a discussion of the well-publicized cases of Terry Wallis and Terri Schiavo.

Epidemiology

Limited information is available regarding the epidemiological aspects of VS because it is not recognized by the International Classification of Diseases (ICD). Furthermore, while diagnostic accuracy and distinction from other disorders of consciousness is improving, there may be some patients who are still misdiagnosed. The range of prevalence of VS is between 5 and 140 cases per million population (PMP). The Multi-Society Task Force on PVS (1994) endorsed an estimate of 56–140 PMP for the United States. Incidence of VS continuing at least 6 months is approximately 5–25 PMP (Beaumont and Kenealy 2005).

Natural History, Prognostic Factors, and Outcomes

The natural history of VS is highly variable for the first year in terms of rate and extent of recovery. Potential outcomes range from death to independence, with the majority of patients remaining severely disabled and dependent and with prognosis for children consistently better than prognosis for adults. Whyte et al. (2005) reported that neuroimaging findings and injury characteristics were not significant predictors of functional status in a study of 124 patients in minimally conscious or vegetative states. Moreover, Whyte and colleagues found that time post-injury, current level of functioning, and rate of functional change predicted the degree of functional improvement in patients in either minimally conscious or vegetative states. The most comprehensive data to date come from review conducted by The Multi-Society Task Force on PVS (1994), who reported outcome for 754 patients at 1-, 3-, 6-, and 12-month post-injury. Table 1 below shows the percentage of patients in VS at 1-, 3-, and 6-month post-insult that were conscious and independent at 1 year post-insult.

Vegetative State (Persistent), Table 1 Percentage of patients in VS at 1, 3, and 6-month post insult that were conscious, and independent at 1 year post insult.

The Task Force determined that VS could be declared permanent when caused by nontraumatic injuries if it persisted longer than 3 months and declared permanent when caused by traumatic injuries if it persisted longer than 12 months. This recommendation was superseded by a recommendation by the Aspen Work Group (Giacino et al. 2002), who suggested that factors such as the nature and extent of injury and the time post-insult are more constructive means of prognostication.

Evaluation

The diagnosis of patients in VS has been most influenced by criteria developed by The Multi-Society Task Force (1994). Those criteria are as follows:

• 1. No evidence of awareness of themselves or their environment; they are incapable of interacting with others.

• 2. No evidence of sustained, reproducible, purposeful, or voluntary behavioral responses to visual, auditory, tactile, or noxious stimuli.

• 3. No evidence of language comprehension or expression.

• 4. Intermittent wakefulness manifested by the presence of sleep-wake cycles.

• 5. Sufficient preserved hypothalamic and brainstem autonomic functions to survive if given medical and nursing care.

• 6. Bowel and bladder incontinence.

• 7. Variably preserved cranial nerve (pupillary, oculocephalic, corneal, vestibulo-ocular, and gag) and spinal reflexes.

Wijdicks and Cranford (2005) suggested that in addition to basic neurological examination of common reflexes, visual and auditory orienting and tracking can be assessed easily with the introduction of stimuli and careful observation for consistency of response. Jennett (2004) noted that vegetative patients do not habituate (i.e., produce less and less response) to a repetitious stimulus. The JFK Coma Recovery Scale-Revised (Giacino et al. 2004) is a tool designed to detect neurobehavioral subtleties that differentiate patients in states of dysconsciousness. Giacino and Whyte (2005) detail procedures for individual quantitative assessment of patients in states of impaired consciousness. The Aspen Work Group (Giacino et al. 2002) suggested utilizing conditions in repeated evaluations, which maximize arousal, minimize distractions, and which are sensitive to the physical limitations and anecdotal reports of caregivers and families.

Treatment

Wijdicks and Cranford (2005) cautioned that medical management of patients in states of impaired consciousness is complex. Specialized care for patients in vegetative and minimally conscious states depends on the availability of appropriate facilities and, in privatized systems of medical care, adequate payer support. Rehabilitation efforts during acute states of impaired consciousness are directed toward preventing contractures, ensuring proper nutrition, and maintaining integrity of the skin. If the VS persists, respiratory and urinary tract infections can be troublesome and require prompt attention. Lombardi et al. (2002) conducted a Cochrane review of programs designed to enhance the rate or extent of recovery through sensory stimulation. The results of the review indicated that none of the available studies offers valid results that support this type of intervention for patients in unconscious states (i.e., VS and coma).

Dopaminergic agents have been used in the majority of pharmacological studies with severe brain injury. A Cochrane review of the use of psychostimulants after brain injury concluded that there was insufficient evidence to recommend their use to improve acute recovery (Forsyth and Jayamoni 2003). Since that review, Giacino, Whyte, and colleagues conducted a placebo-controlled trial of amantadine hydrochloride, which enrolled 184 patients in vegetative state or minimally conscious state for a 4-week trial. The results suggested that “amantadine accelerated the functional recovery during active treatment in post-traumatic disorders of consciousness” (Giacino et al. 2012). In both vegetative and minimally conscious states, the likelihood of functional improvement diminishes as time passes (Giacino et al. 2002). Neuropsychological support for families and caregivers is important throughout the duration of the patient’s recovery from brain injury (Rotundi et al. 2007). Jennett (2004) discussed the issues families face at the time when rehabilitative efforts end, including decisions about cardiopulmonary resuscitation, antibiotics, dialysis, and artificial nutrition and hydration.

Cross-References

• Coma

• Decerebrate Posturing

• Decorticate Posturing

• Minimally Conscious State

• Stupor