A persistent vegetative state (PVS) is a condition of patients with severe brain damage in whom coma has progressed to a state of wakefulness without detectable awareness.
As opposed to brain death, PVS is not recognized as death in any legal system. This legal grey area has led to several court cases involving people in a PVS, those who believe that they should be allowed to die, and those who are equally determined that, if recovery is possible, care should continue.
History
The syndrome was first described in 1940 by Ernst Kretschmer who called it ''apallic Syndrome''.
The term ''persistent vegetative state'' was coined in 1972 by Scottish spinal surgeon Bryan Jennett and American neurologist Fred Plum to describe a syndrome that seemed to have been made possible by medicine's increased capacities to keep patients' bodies alive.
Description
The vegetative state is a chronic or long-term condition. This condition differs from a persistent vegetative state (PVS, a state of coma that lacks both awareness and wakefulness) since patients have awakened from coma, but still have not regained awareness.
In the vegetative state patients can open their eyelids occasionally and demonstrate sleep-wake cycles. They also completely lack cognitive function. The vegetative state is also called coma vigil.
The continuing vegetative state describes a patient's diagnosis prior to confirmation of the permanence of the condition. The permanent vegetative state occurs when the vegetative state is deemed permanent; a prediction is being made that the patient will never recover awareness. This prediction cannot be made with absolute certainty. However, the chances of regaining awareness diminish considerably as the time spent in the vegetative state increases.
Signs and Symptoms
- Most PVS patients are unresponsive to external stimuli and their conditions are associated with different levels of consciousness.
- PVS patients often open their eyes, whereas patients in a coma subsist with their eyes closed.
- PVS patients' eyes might be in a relatively fixed position, or track moving objects, or move in a ''disconjugate'' (i.e. completely unsynchronised) manner.
- They may experience sleep-wake cycles, or be in a state 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.
Causes
There are three different causes of PVS:
- Brain injuries which may be either acute and traumatic, or non-traumatic;
- Degenerative and metabolic brain disorders, and severe congenital abnormalities of the central nervous system.
- Toxins such as uremia, ethanol, atropine, opiates, lead, substance abuse, colloidal silver.
One study of 40 patients in the United Kingdom reported that 43% of those patients classified as in a PVS were misdiagnosed and another 33% able to recover whilst the study was underway. Some cases of PVS may actually be cases of patients being in an undiagnosed minimally conscious state.
Recovery Possibility
Many patients emerge spontaneously from a vegetative state within a few weeks.
Possible Treatment and Cures
As of April 2007, no treatment for vegetative state exists that would satisfy the efficiency criteria of evidence-based medicine. Several methods have been proposed which can roughly be subdivided into four categories: pharmacological methods, surgery, physical therapy, and various stimulation techniques.
Pharmacological therapy mainly uses activating substances such as tricyclic antidepressants or methylphenidate. Promising results have been reported on dopaminergic drugs, particularly amantadine.
Surgical methods such as deep brain stimulation are rarely used.
Stimulation techniques include sensory stimulation, sensory regulation, music and musicokinetic therapy, social-tactile interaction, etc.
References
http://en.wikipedia.org/wiki/Persistent_vegetative_state
Medical Encylopedia for MobileReference
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