TBI Inform - Persistent Loss of Consciousness Following Brain Injury
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Persistent Loss of Consciousness Following Brain Injury
By: Thomas Novack, PhD; Jay Meythaler, JD,MD; Heather Nissley; Katie Frabrivzio
What is meant by consciousness?
Normal conscious behavior requires arousal and awareness. Arousal refers to a person’s level of wakefulness and determines the capacity to detect events in the surrounding environment. Awareness, on the other hand, which by definition requires arousal, reflects a person’s ability to attend to the environment. Thus, consciousness can best be thought of as awareness of surrounding events and response to those events.
Consciousness is dependent on brain functioning, particularly an area called the ascending reticular activating system (ARAS). The reticular activating system is the attention center in the brain and is essential to “turning on” the brain.
Disruption of the ARAS results in loss of consciousness and is believed to be the cause of the loss of consciousness associated with traumatic brain injury. Other brain areas can be associated with impaired consciousness, but the ARAS is always involved.
The reticular activating system is connected at its base to the spinal cord where it receives information projected directly from the ascending sensory tracts. The brain stem reticular formation runs all the way up to the mid brain. As a result, the reticular activating system is a very complex collection of neurons, which serve as a point of convergence for signals from the external world and from interior environment. In other words, it is the part of your brain where the world outside of you, and your thoughts and feelings from "inside" of you, meet. When the reticular activating system fails to activate the cortex, arousal and attention can be disrupted and a disorder of consciousness can result.
Disorders of Consciousness
Perhaps one of the best-recognized and most well defined disorders of consciousness is coma. Coma has been described as a state of “unarousable unresponsiveness.” It is a condition in which there is no evidence of awareness for either the self or the environment. People in coma have an absence of sleep/wake cycles, lack purposeful motor activity, and are unable to be awakened by sensory stimulation, including pain.
The vegetative state (VS) is the least understood and most controversial disorder of consciousness. The term “vegetative” is medical in nature and refers to neurological functions. It is not meant to refer to vegetables that we grow. In general, people in VS have lost their thinking abilities and awareness of their surroundings even though they may appear to be alert, based on eye opening. They are unable to interact with others, sustain purposeful or voluntary responses, or comprehend and use language. What movements do occur are largely confined to reflex withdrawals or posturing. Thus, some VS people may reflexively turn their head or dart their eyes toward a moving object, but will not fixate on or consistently track objects. People in VS can, however, exhibit normal sleep patterns and demonstrate episodes of increased arousal, as reflected by eye opening or moaning. When a vegetative state has lasted for a month or more it is often referred to as a persistent vegetative state.
Some people with alteration in consciousness do not meet the criteria for coma or VS. These people demonstrate signs of consciousness periodically, but not consistently. This condition has recently been defined as minimally conscious state (MCS). MCS is often a transition from coma or VS to a more wakeful state. MCS is distinguished from VS by the partial preservation of conscious awareness. Thus, people in MCS are able to demonstrate, even though inconsistently and often incompletely, some level of awareness of their surroundings. People in MCS, at times, may be able follow simple commands, gesture or verbalize yes/no responses, or produce intelligible verbalizations. They may also exhibit appropriate episodes of crying, smiling, and laughter, and reach, touch, or hold objects. The episodes of responsiveness may be very short and unpredictable.
Once an individual is stabilized medically, the medical care team focuses on preventing medical complications for those who are still unconscious. This will often include preventing pneumonia and bedsores and providing balanced nutrition. Therapy focuses on enhancing natural brain recovery through stimulation of all of the senses. Physical therapy may be used to prevent permanent muscular contractions and deformities of the bones, joints, and muscles that would limit recovery for those who regain consciousness. Therapists may expose the person to varying levels of pressure and temperature. Efforts are also often made to establish functional communication and environmental interaction when possible.
Although not extensively supported in research, strategies designed to engage individuals with their environment may be a beneficial adjunct to traditional medical treatment. Suggested activities include playing audiotapes of familiar voices, reading literature, exposing the individual to familiar smells, and including the individual as a passive participant in conversations and activities while in his/her presence.
Prognosis, Outcome, and Long-Term Care
Recovery from a disorder of consciousness is often gradual. Unfortunately, some individuals may remain in an unresponsive state until death or achieve only very basic responses. It is impossible to predict which people will regain consciousness. Some guidelines have been established based on research. The longer the person remains in an unresponsive state, the less likely it is that they will achieve consciousness or functional recovery. A coma rarely lasts more than 2 or 4 weeks. When coma persists beyond 4 weeks, there is an increased likelihood that the person will be severely disabled or unresponsive at one year. Similar findings have also been reported in the VS literature.
Approximately 30 percent of people who are VS at three months following a traumatic brain injury will recover consciousness by one year. Thirty percent will still be exhibiting VS at one year after injury and the remaining third will have died, usually due to an infection. After six months in VS, the chance of recovery to consciousness declines to 15 percent. For those people in VS, the mortality rate 5 years post-injury is approximately 65%. In people that do emerge, it is likely that they will continue to experience long-term physical, cognitive, and/or psychological difficulties. For people in MCS, the chances of recovery tend to be better. At least one study has found that people in MCS improved more rapidly, showed a longer course of recovery, and had significantly better scores on a test of functional outcome than those in a persistent VS. Keep in mind that these statistics apply to groups of people. Applying these numbers to individual cases is difficult.
People in the midst of coma, VS, or MCS require a high level of care and supervision. It is difficult, but not impossible in some settings, for family members to provide the around-the-clock care that is necessary. In many cases, placement in a long-term treatment program is necessary. Depending on the situation, this could be a subacute care program or a skilled nursing facility. These facilities are able to monitor medications and physical condition, provide therapy services, and assist in feeding, grooming, and bathing.
People with impaired consciousness may be placed on a ventilator and/or feeding tube to assist with breathing and the delivery of proper nutrition. As the name “life support” suggests, these devices are critical in maintaining and prolonging the person’s life. Some families may face the difficult decision to withdraw life support from their loved one. This decision is reached after careful consideration of many factors, including the person’s current physical and cognitive status, prognosis, the person’s expected wishes, religious considerations, and the family’s emotional and financial burdens. In arriving at the decision to withdraw life support, the physician must first determine, with overwhelming probability, that the person’s higher-level brain functioning is no longer present. Second, the person’s opinions regarding life support are taken into account. If the person has indicated in the past that they would or would not desire life-support treatment, courts will typically uphold the person’s desires, if these wishes were “clearly and convincingly” expressed. In practice, most individuals do not have formal documentation of their opinions regarding life support. In those cases, decisions to terminate treatment are then made by family members or guardians acting on behalf of the person. One concern that families often express is that they fear the person will experience pain once the ventilator or feeding tube is removed. For one to feel pain, some level of consciousness must be present, suggesting that those in a coma will not be able to experience the sensation of pain as we know it. In some cases there may be legal challenges to removing life support, such as if there is disagreement among family members. The decision to remove life support obviously deserves careful and prolonged thought on the part of family members, with advice provided by medical professionals as well as religious authorities as appropriate.