Vegetative state
Vegetative state | |
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Specialty | Neurology |
A vegetative state (VS) or post-coma unresponsiveness (PCU),
Definition
There are several definitions that vary by technical versus layman's usage. There are different legal implications in different countries.
Medical definition
Per the definition of the British Royal College of Physicians of London, "a wakeful unconscious state that lasts longer than a few weeks is referred to as a persistent (or 'continuing') vegetative state".[4]
"Vegetative state"
The vegetative state is a chronic or long-term condition. This condition differs from a coma: a coma is a state that lacks both awareness and wakefulness. Patients in a vegetative state may have awoken from a coma, but still have not regained awareness. In the vegetative state patients can open their eyelids occasionally and demonstrate sleep-wake cycles, but completely lack cognitive function. The vegetative state is also called a "coma vigil". The chances of regaining awareness diminish considerably as the time spent in the vegetative state increases.[5]
"Persistent vegetative state"
Persistent vegetative state is the standard usage (except in the UK) for a medical diagnosis, made after numerous neurological and other tests, that due to extensive and irreversible brain damage a patient is highly unlikely ever to achieve higher functions above a vegetative state. This diagnosis does not mean that a doctor has diagnosed improvement as impossible, but does open the possibility, in the US, for a judicial request to end life support.
In the UK, the term is discouraged in favor of two more precisely defined terms that have been strongly recommended by the Royal College of Physicians (RCP). These guidelines recommend using a continuous vegetative state for patients in a vegetative state for more than four weeks. A medical determination of a permanent vegetative state can be made if, after exhaustive testing and a customary 12 months of observation,[7] a medical diagnosis is made that it is impossible by any informed medical expectations that the mental condition will ever improve.[8] Hence, a "continuous vegetative state" in the UK may remain the diagnosis in cases that would be called "persistent" in the US or elsewhere.
While the actual testing criteria for a diagnosis of "permanent" in the UK are quite similar to the criteria for a diagnosis of "persistent" in the US, the semantic difference imparts in the UK a legal presumption that is commonly used in court applications for ending life support.[7] The UK diagnosis is generally only made after 12 months of observing a static vegetative state. A diagnosis of a persistent vegetative state in the US usually still requires a petitioner to prove in court that recovery is impossible by informed medical opinion, while in the UK the "permanent" diagnosis already gives the petitioner this presumption and may make the legal process less time-consuming.[6]
In common usage, the "permanent" and "persistent" definitions are sometimes conflated and used interchangeably. However, the acronym "PVS" is intended to define a "persistent vegetative state", without necessarily the connotations of permanence,[citation needed] and is used as such throughout this article. Bryan Jennett, who originally coined the term "persistent vegetative state", has now recommended using the UK division between continuous and permanent in his book The Vegetative State, arguing that "the 'persistent' component of this term ... may seem to suggest irreversibility".[9]
The Australian National Health and Medical Research Council has suggested "post coma unresponsiveness" as an alternative term for "vegetative state" in general.[10]
Lack of legal clarity
Unlike
This legal grey area has led to vocal advocates that those in PVS should be allowed to die. Others are equally determined that, if recovery is at all possible, care should continue. The existence of a small number of diagnosed PVS cases that have eventually resulted in improvement makes defining recovery as "impossible" particularly difficult in a legal sense.[6] This legal and ethical issue raises questions about autonomy, quality of life, appropriate use of resources, the wishes of family members, and professional responsibilities.
Signs and symptoms
Most PVS 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, PVS 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.[13]
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.
PVS 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 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.
Individuals in PVS are seldom on any life-sustaining equipment other than a
Recovery
Many people emerge spontaneously from a vegetative state within a few weeks.[9] 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 vegetative state 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 vegetative state. For non-traumatic injuries such as strokes, only 14% had recovered consciousness at one year, 47% had died, and 39% were still vegetative. Patients who were vegetative 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 vegetative at one month.[14] A New Scientist article from 2000 gives a pair of graphs[15] showing changes of patient status during the first 12 months after head injury and after incidents depriving the brain of oxygen.[16] After a year, the chances that a PVS patient will regain consciousness are very low[17] and most patients who do recover consciousness experience significant disability. The longer a patient is in a PVS, 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.[18] 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 state. The researchers describe a small number of cases in which removal of the chilled oxygen was followed by recovery from the PVS and recommend either warming of oxygen with a heated nebulizer or removal of the assisted oxygen if it is no longer needed.[18] 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 persistent vegetative state: 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.[19]
Causes
There are three main causes of PVS (persistent vegetative state):
- Acute traumatic brain injury
- Non-traumatic: neurodegenerative disorder or metabolic disorderof the brain
- Severe congenital abnormality of the central nervous system
Potential causes of PVS are:[20]
- Meningitis
- Encephalitis
- Increased intracranial pressure
- Brain tumor
- Brain abscess
- Ischemic stroke
- Intracerebral hemorrhage
- Subarachnoid hemorrhage
- Brain herniation
- Hypoxic-anoxic brain injury
- Toxins such as uremia, colloidal silver[21]
- Physical trauma: Concussion, contusion, etc.
- Seizure, both nonconvulsive status epilepticus and postconvulsive state (postictal state)
- Electrolyte imbalance, which involves hypercalcemia, and hypocalcemia
- Postinfectious: Acute disseminated encephalomyelitis (ADEM)
- Endocrine disorders such as adrenal insufficiency and thyroid disorders
- Degenerative and metabolic diseases including urea cycle disorders, Reye syndrome, and mitochondrial disease
- Systemic infection and sepsis
- Hepatic encephalopathy
In addition, these authors claim that doctors sometimes use the mnemonic device AEIOU-TIPS to recall portions of the differential diagnosis: Alcohol ingestion and acidosis, epilepsy and encephalopathy, infection, opiates, uremia, trauma, insulin overdose or inflammatory disorders, poisoning and psychogenic causes, and shock.
Diagnosis
Despite converging agreement about the definition of persistent vegetative state, recent reports have raised concerns about the accuracy of diagnosis in some patients, and the extent to which, in a selection of cases, residual
Diagnostic experiments
Researchers have begun to use functional neuroimaging studies to study implicit cognitive processing in patients with a clinical diagnosis of persistent vegetative state. Activations in response to sensory stimuli with
For example, PET studies have shown the identification of residual cognitive function in persistent vegetative state. That is, an external stimulation, such as a painful stimulus, still activates "primary" sensory cortices in these patients but these areas are functionally disconnected from "higher order" associative areas needed for awareness. These results show that parts of the cortex are indeed still functioning in "vegetative" patients.[23]
In addition, other PET studies have revealed preserved and consistent responses in predicted regions of auditory cortex in response to intelligible speech stimuli. Moreover, a preliminary fMRI examination revealed partially intact responses to semantically ambiguous stimuli, which are known to tap higher aspects of speech comprehension.[24]
Furthermore, several studies have used PET to assess the central processing of
Also, there is evidence of partially functional cerebral regions in catastrophically injured brains. To study five patients in PVS with different behavioral features, researchers employed PET, MRI and
Misdiagnoses
Statistical PVS misdiagnosis is common. An example study with 40 patients in the United Kingdom diagnosed with PVS reported 43% of the patients were considered to have been misdiagnosed, and another 33% had recovered whilst the study was underway.[27] Some PVS cases may actually be a misdiagnosis of patients being in an undiagnosed minimally conscious state.[28] Since the exact diagnostic criteria of the minimally conscious state were only formulated in 2002, there may be chronic patients diagnosed as PVS before the secondary notion of the minimally conscious state became known.
Whether or not there is any conscious awareness with a patient's vegetative state is a prominent issue. Three completely different aspects of this should be distinguished. First, some patients can be conscious simply because they are misdiagnosed (see above). In fact, they are not in vegetative states. Second, sometimes a patient was correctly diagnosed but is then examined during the early stages of recovery. Third, perhaps some day the notion itself of vegetative states will change so to include elements of conscious awareness. Inability to disentangle these three example cases causes confusion. An example of such confusion is the response to an experiment using functional magnetic resonance imaging which revealed that a woman diagnosed with PVS was able to activate predictable portions of her brain in response to the tester's requests that she imagine herself playing tennis or moving from room to room in her house. The brain activity in response to these instructions was indistinguishable from those of healthy patients.[29][30][31]
In 2010, Martin Monti and fellow researchers, working at the MRC Cognition and Brain Sciences Unit at the
In November 2011, a publication in The Lancet presented bedside EEG apparatus and indicated that its signal could be used to detect awareness in three of 16 patients diagnosed in the vegetative state.[34]
Treatment
Currently no treatment for vegetative state exists that would satisfy the efficacy criteria of
Zolpidem
There is limited evidence that the hypnotic drug zolpidem has an effect.[36] The results of the few scientific studies that have been published so far on the effectiveness of zolpidem have been contradictory.[37][38]
Epidemiology
In the United States, it is estimated that there may be between 15,000 and 40,000 patients who are in a persistent vegetative state, but due to poor nursing home records exact figures are hard to determine.[39]
History
The syndrome was first described in 1940 by
Society and culture
Ethics and policy
An ongoing debate exists as to how much care, if any, patients in a persistent vegetative state should receive in health systems plagued by limited resources. In a case before the New Jersey Superior Court, Betancourt v. Trinitas Hospital, a community hospital sought a ruling that dialysis and CPR for such a patient constitutes futile care. An American bioethicist, Jacob M. Appel, argued that any money spent treating PVS patients would be better spent on other patients with a higher likelihood of recovery.[42] The patient died naturally prior to a decision in the case, resulting in the court finding the issue moot.
In 2010, British and Belgian researchers reported in an article in the
Notable cases
- Tony Bland – first patient in English legal history to be allowed to die
- Paul Brophy – first American to die after court-authorization
- Sunny von Bülow – lived almost 28 years in a persistent vegetative state until her death
- Gustavo Cerati – Argentine singer-songwriter, composer and producer who died after four years in a coma
- Prichard Colón – Puerto Rican former professional boxer and gold medal winner who spent years in a vegetative state after a bout
- Nancy Cruzan – American woman involved in a landmark United States Supreme Court case
- Gary Dockery – American police officer who entered, emerged and later reentered a persistent vegetative state
- Eluana Englaro – Italian woman from Lecco whose life was ended after a legal case after spending 17 years in a vegetative state
- Elaine Esposito – American woman who was a previous record holder for having spent 37 years in a coma
- Lia Lee – Hmong girl who spent 26 years in a vegetative state after a seizure, and was the subject of a 1997 book by Anne Fadiman
- Martin Pistorius South African man who is a rare example of a survivor as his state progressed to minimally conscious after 3 years, locked in syndrome after another 4 more years, and fully came out of a coma after another 5 years. He is now a web designer, developer, and author. In 2011, he wrote a book called Ghost Boy, in which he describes his many years of being comatose.
- Annie ShapiroCanadian woman who is another rare example of a survivor, as it is known that she could not think for the first 2 years of her 29 total years of being comatose. In 1992 she awakened fully recovered and lived her last 10 years peacefully. It is the longest a person has been in a coma and woken up.
- Haleigh Poutre
- Karen Ann Quinlan
- Terri Schiavo
- Rita Greene
- Aruna Shanbaug – Indian woman in persistent vegetative state for 42 years until her death. Owing to her case, the Supreme Court of India allowed passive euthanasiain the country.
- Ariel Sharon
- Chayito Valdez
- Vice Vukov
- Helga Wanglie
- Otto Warmbier
See also
- Anencephaly
- Brain death
- Botulism
- Catatonia
- Karolina Olsson
- Locked-in syndrome
- Process-oriented coma work, an approach to working with residual consciousness in patients in comatose and persistent vegetative states
References
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- ^ a b "Prolonged Disorders of Consciousness: National Clinical Guidelines". Royal College of Physicians. 2013.
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- ^ Guidance on diagnosis and management: Report of a working party of the Royal College of Physicians. Royal College of Physicians: London. 1996.
- ^ a b c Jennett B. The Vegetative State: Medical facts, ethical and legal dilemmas (PDF). Scotland: University of Glasgow. Retrieved 2007-11-09.
- ^ Post-coma unresponsiveness (Vegetative State): a clinical framework for diagnosis. National Health and Medical Research Council (NHMRC): Canberra. 2003. Archived from the original on 2006-08-20.
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- ^ Royal College of Physicians 2013 Prolonged Disorders of Consciousness: National Clinical Guidelines
- ^ a b Emmett PA (1989). A Biblico-Ethical Response to the Question of Withdrawing Fluid and Nutrition from Individuals in the Persistent Vegetative State (Master's thesis). Vol. 4–5. Bethel Theological Seminary. pp. 248–49.
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- ^ "Vegetative patient 'communicates': A patient in a vegetative state can communicate just through using her thoughts, according to research". BBC News. September 7, 2006. Retrieved 2008-08-14.
- ^ Stein R (September 8, 2006). "Vegetative patient's brain active in test: Unprecedented experiment shows response to instructions to imagine playing tennis". San Francisco Chronicle. Retrieved 2007-09-26.
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- ^ a b c d e f Alleyne R, Beckford M (4 February 2010). "Patients in 'vegetative' state can think and communicate". Telegraph. United Kingdom. Archived from the original on 6 February 2010.
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This article contains text from the NINDS public domain pages on TBI. [1] Archived 2005-10-19 at the Wayback Machine and [2].
Further reading
- Sarà M, Sacco S, Cipolla F, Onorati P, Scoppetta C, Albertini G, Carolei A (January 2007). "An unexpected recovery from permanent vegetative state". Brain Injury. 21 (1): 101–03. S2CID 22730610.
- Canavero S, Massa-Micon B, Cauda F, Montanaro E (May 2009). "Bifocal extradural cortical stimulation-induced recovery of consciousness in the permanent post-traumatic vegetative state". Journal of Neurology. 256 (5): 834–36. S2CID 17087007.
- Canavero S, ed. (2009). Textbook of therapeutic cortical stimulation. New York: Nova Science. ISBN 978-1-60692-537-9.
- Canavero S, Massa-Micon B, Cauda F, Montanaro E (May 2009). "Bifocal extradural cortical stimulation-induced recovery of consciousness in the permanent post-traumatic vegetative state". Journal of Neurology. 256 (5): 834–36. S2CID 17087007.
- Connolly K (23 November 2009). "Car crash victim trapped in a coma for 23 years was conscious". The Guardian.
- Machado C, Estévez M, Rodríguez R, Pérez-Nellar J, Gutiérrez J, Carballo M, Olivares A, Fleitas M, Pando A, Beltrán C (January 2012). "A Cuban perspective on management of persistent vegetative state". MEDICC Review. 14 (1): 44–48. PMID 22334112.