A coma-like state characterized by open eyes and the appearance of wakefulness is defined as vegetative.
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.
Causes and symptoms
The vegetative state can be caused by:
- cardiac arrest
- prolonged and profound hypoglycemia (an abnormal and severe decrease in blood sugar)
- carbon monoxide poisoning
- head injury
- brain hemorrhage
- compression of the brainstem
- bilateral hemispheric demyelination (a loss of nerve cells)
- injury of the brain following infections (meningitis or encephalitis)
- neurodegenerative diseases
- anencephaly (an abnormality of the brain and skull)
- diffuse nerve cell injury
Patients in a vegetative state apparently have functioning of a special area in the brain called the reticular activating system (RAS) responsible for sleep-wake cycles. The connections that integrate more complex abilities such as awareness are interrupted. Patients in the vegetative state can open and close eyes spontaneously. They may appear to track or follow objects with their eyes. Patients may chew and swallow food placed in the mouth. The vegetative patient does not respond to sound, hunger, or pain. Patients cannot obey verbal commands and lack local motor responses. Additionally these patients cannot talk in comprehendible terms and they may become noisy, restless, and hypermobility. These patients are in a state or arousal but completely lack awareness.
Diagnosis of vegetative state depends on the primary cause of brain dysfunction. A comprehensive history and neurological examination, neuroimaging studies, and chemical analysis of the blood are essential. Additionally, special tests such as cerebrospinal fluid (CSF, is the fluid that bathes and nourishes the brain and spinal cord) analysis and electroencephalographic (EEG analyzes the electrical activity within the brain) may be indicated to establish a diagnosis.
Treatment is directed to presenting symptoms and patient needs. Patients require constant monitoring and assistance with feeding, hydration hygiene, assisted movement (to help prevent ulcers and blood clots in the legs), and elimination of waste products.
There is no known alternative treatment for vegetative patients.
The prognosis is generally poor and the condition can persist chronically.
There is no known prevention since this state can occur as a result of unavoidable situations such as an accident, tumor, and bleeding or genetic abnormality.
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Laith Farid Gulli, M.D.
Cognitive—The ability (or lack of) to think, learn, and memorize.
Hypermobility—Increased movement of joints.