Most<unk>  patients are unresponsive to external stimuli and their conditions are associated with different levels of consciousness. Some level of consciousness means a person can still respond, in varying degrees, to stimulation. A person in a coma, however, cannot. In addition,<unk>  patients often open their eyes in response to feeding, which has to be done by others; they are capable of swallowing, whereas patients in a coma subsist with their eyes closed. Cerebral cortical function (e.g. communication, thinking, purposeful movement, etc) is lost while brainstem functions (e.g. breathing, maintaining circulation and hemodynamic stability, etc) are preserved. Non-cognitive upper brainstem functions such as eye-opening, occasional vocalizations (e.g. crying, laughing), maintaining normal sleep patterns, and spontaneous non-purposeful movements often remain intact.<unk>  patients' eyes might be in a relatively fixed position, or track moving objects, or move in a disconjugate (i.e., completely unsynchronized) manner. They may experience sleep-wake cycles, or be in a<unk>  of chronic wakefulness. They may exhibit some behaviors that can be construed as arising from partial consciousness, such as grinding their teeth, swallowing, smiling, shedding tears, grunting, moaning, or screaming without any apparent external stimulus. Individuals in<unk>  are seldom on any life-sustaining equipment other than a feeding tube because the brainstem, the center of<unk>  functions (such as heart rate and rhythm, respiration, and gastrointestinal activity) is relatively intact. Recovery Many people emerge spontaneously from a<unk><unk>  within a few weeks. The chances of recovery depend on the extent of injury to the brain and the patient's age – younger patients having a better chance of recovery than older patients. A 1994 report found that of those who were in a<unk><unk>  a month after a trauma, 54% had regained consciousness by a year after the trauma, whereas 28% had died and 18% were still in the<unk><unk> . For non-traumatic injuries such as strokes, only 14% had recovered consciousness at one year, 47% had died, and 39% were still<unk> . Patients who were<unk>  six months after the initial event were much less likely to have recovered consciousness a year after the event than in the case of those who were simply reported<unk>  at one month. A New Scientist article from 2000 gives a pair of graphs showing changes of patient<unk> s during the first 12 months after head injury and after incidents depriving the brain of oxygen. After a year, the chances that a<unk>  patient will regain consciousness are very low and most patients who do recover consciousness experience significant disability. The longer a patient is in a<unk> , the more severe the resulting disabilities are likely to be. Rehabilitation can contribute to recovery, but many patients never progress to the point of being able to take care of themselves. The medical literature also includes case reports of the recovery of a small number of patients following the removal of assisted respiration with cold oxygen. The researchers found that in many nursing homes and hospitals unheated oxygen is given to non-responsive patients via tracheal intubation. This bypasses the warming of the upper respiratory tract and causes a chilling of aortic blood and chilling of the brain which the authors believe may contribute to the person's nonresponsive<unk> . The researchers describe a small number of cases in which removal of the chilled oxygen was followed by recovery from the<unk>  and recommend either warming of oxygen with a heated nebulizer or removal of the assisted oxygen if it is no longer needed. The authors further recommend additional research to determine if this chilling effect may either delay recovery or even may contribute to brain damage. There are two dimensions of recovery from a<unk> : recovery of consciousness and recovery of function. Recovery of consciousness can be verified by reliable evidence of awareness of self and the environment, consistent voluntary behavioral responses to visual and auditory stimuli, and interaction with others. Recovery of function is characterized by communication, the ability to learn and to perform adaptive tasks, mobility, self-care, and participation in recreational or vocational activities. Recovery of consciousness may occur without functional recovery, but functional recovery cannot occur without recovery of consciousness.
Persistent vegetative state
Emergence delirium
Excited delirium
Organic brain syndrome
Post-stroke depression
Diabetic coma
Vascular thalamic amnesia
Diencephalic syndrome