View source for Coma

{{Short description|State of unconsciousness}}
{{Distinguish|Comma}}
{{Other uses|Coma (disambiguation)|Comas (disambiguation)}}
{{Redirect|Comatose|other uses}}
{{Infobox medical condition (new)
| name          = Coma
| field         = [[Neurology]], [[critical care medicine]], [[psychiatry]]
| symptoms      = Unconsciousness
| complications = [[Persistent vegetative state]], [[death]]
| duration      = Can vary from a few days to several years
| image         = Comaventilator.jpg
| caption       = Image of a comatose man unresponsive to stimuli
}}
A '''coma''' is a deep state of prolonged [[unconsciousness]] in which a person cannot be awakened, fails to [[Nociception|respond normally]] to [[Pain|painful stimuli]], light, or sound, lacks a normal [[Circadian rhythm|sleep-wake cycle]] and does not initiate [[voluntary action]]s.<ref name="RR">{{cite book |last1=Weyhenmeyer |first1=James A. |last2=Gallman |first2=Eve A. |title=Neuroscience |date=2007 |publisher=Mosby |isbn=978-0-323-02261-3 |pages=177–179 }}</ref> The person may experience respiratory and circulatory problems due to the body's inability to maintain normal bodily functions. People in a coma often require extensive medical care to maintain their health and prevent complications such as [[pneumonia]] or [[blood clots]].<ref name="Huff Tadi Coma">{{cite book |last1=Huff |first1=J. Stephen |last2=Tadi |first2=Prasanna |title=StatPearls |date=2024 |publisher=StatPearls Publishing |chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK430722/ |chapter=Coma |pmid=28613473 }}</ref> Coma patients exhibit a complete absence of wakefulness and are unable to consciously feel, speak or move.<ref name=":0">{{cite journal |last1=Bordini |first1=Ana Luisa |last2=Luiz |first2=Thiago F. |last3=Fernandes |first3=Maurício |last4=Arruda |first4=Walter O. |last5=Teive |first5=Hélio A.G. |title=Coma scales: a historical review |journal=Arquivos de Neuro-Psiquiatria |date=December 2010 |volume=68 |issue=6 |pages=930–937 |doi=10.1590/S0004-282X2010000600019 |pmid=21243255 |doi-access=free }}</ref><ref>{{cite journal |last1=Cooksley |first1=Tim |last2=Holland |first2=Mark |title=The management of coma |journal=Medicine |date=February 2017 |volume=45 |issue=2 |pages=115–119 |doi=10.1016/j.mpmed.2016.12.001 }}</ref> Comas can be the result of natural causes, or can be [[Induced coma|medically induced]], for example, during [[General anaesthesia|general anesthesia]].<ref>{{Cite web |author1=Marc Lallanilla |date=2013-09-06 |title=What Is a Medically Induced Coma? |url=https://www.livescience.com/39483-what-is-a-medically-induced-coma.html |access-date=2022-04-23 |website=livescience.com |language=en}}</ref>

Clinically, a coma can be defined as the consistent inability to follow a one-step command.<ref>{{Cite web|url=https://www.glasgowcomascale.org/|title=The Glasgow structured approach to assessment of the Glasgow Coma Scale|website=www.glasgowcomascale.org|access-date=2019-03-06}}</ref><ref>{{cite book |doi=10.1016/B978-1-4160-3206-9.10059-X |chapter=Coma |title=Critical Care Secrets |date=2007 |last1=Bonovich |first1=David C. |pages=381–384 |isbn=978-1-4160-3206-9 }}</ref> For a patient to maintain consciousness, the components of ''wakefulness'' and ''awareness'' must be maintained. [[Wakefulness]] is a quantitative assessment of the degree of [[consciousness]], whereas [[awareness]] is a qualitative assessment of the functions mediated by the [[cerebral cortex]], including cognitive abilities such as attention, sensory perception, explicit memory, language, the [[Executive functions|execution of tasks]], temporal and spatial orientation and reality judgment.<ref name=":0" /><ref>{{cite book |doi=10.1016/B978-008045046-9.01770-8 |chapter=Coma |title=Encyclopedia of Neuroscience |date=2009 |last1=Laureys |first1=S. |last2=Boly |first2=M. |last3=Moonen |first3=G. |last4=Maquet |first4=P. |pages=1133–1142 |isbn=978-0-08-045046-9 }}</ref> [[Neuroscience|Neurologically]], consciousness is maintained by the activation of the cerebral cortex—the [[gray matter]] that forms the brain's outermost layer—and by the [[reticular activating system]] (RAS), a structure in the [[brainstem]].<ref name=med>{{cite book |author=Hannaman, Robert A.|title=MedStudy Internal Medicine Review Core Curriculum: Neurology 11th Ed|publisher=MedStudy| year=2005 |pages=(11–1) to (11–2) |isbn=1-932703-01-2}}</ref><ref>{{cite news |title=Persistent vegetative state: A medical minefield |url=https://www.newscientist.com/article/mg19526111-800-persistent-vegetative-state-a-medical-minefield/ |work=New Scientist |date=4 July 2007 }}</ref>

==Etymology==
The term 'coma', from the Greek {{lang|grc|κῶμα}} ''koma'', meaning deep sleep, had already been used in the [[Hippocratic Corpus|Hippocratic corpus]] (''Epidemica'') and later by [[Galen]] (second century AD). Subsequently, it was hardly used in the known literature up to the middle of the 17th century. The term is found again in [[Thomas Willis]]' (1621–1675) influential ''De anima brutorum'' (1672), where [[lethargy]] (pathological sleep), 'coma' (heavy sleeping), ''carus'' (deprivation of the senses) and [[apoplexy]] (into which ''carus'' could turn and which he localized in the [[white matter]]) are mentioned. The term ''carus'' is also derived from Greek, where it can be found in the roots of several words meaning soporific or sleepy. It can still be found in the root of the term 'carotid'. [[Thomas Sydenham]] (1624–89) mentioned the term 'coma' in several cases of fever (Sydenham, 1685).<ref>{{cite encyclopedia|url=http://www.etymonline.com/index.php?term=coma&allowed_in_frame=0|title=''Coma'' Origin|dictionary=[[Online Etymology Dictionary]]|access-date=14 August 2015}}</ref><ref>{{cite journal |last1=Koehler |first1=P. J. |last2=Wijdicks |first2=E. F. M. |title=Historical study of coma: looking back through medical and neurological texts |journal=Brain |date=7 February 2008 |volume=131 |issue=3 |pages=877–889 |doi=10.1093/brain/awm332 |pmid=18208847 |doi-access=free }}</ref>

== Signs and symptoms ==
General symptoms of a person in a comatose state are:
* Inability to voluntarily open the eyes
* A nonexistent sleep–wake cycle
* Lack of response to physical ([[Pain|painful]]) or verbal [[Stimulation|stimuli]]
* Depressed [[Brainstem#Clinical significance|brainstem reflexes]], such as [[Pupillary light reflex|pupils not responding to light]]
* Abnormal, difficulty, or irregular breathing or no breathing at all when coma was caused by [[cardiac arrest]] 
* Scores between 3 and 8<ref>{{cite web|title=Glasgow Coma Scale|author=Russ Rowlett|publisher=University of North Carolina at Chapel Hill|url=http://www.unc.edu/~rowlett/units/scales/glasgow.htm|access-date=2010-12-07|archive-date=2018-06-04|archive-url=https://web.archive.org/web/20180604074017/http://www.unc.edu/~rowlett/units/scales/glasgow.htm|url-status=dead}}</ref> on the [[Glasgow Coma Scale]]<ref name="RR" />

==Causes==
Many types of problems can cause a coma. Forty percent of comatose states result from [[drug poisoning]].<ref name="Liversedge 2010 337–339">{{cite journal|last1=Liversedge|first1=Timothy|last2=Hirsch|first2=Nicholas|year=2010|title=Coma|journal=Anaesthesia & Intensive Care Medicine|volume=11|issue=9|pages=337–339|doi=10.1016/j.mpaic.2010.05.008}}</ref> Certain drug use under certain conditions can damage or weaken the [[Synaptic vesicle|synaptic]] functioning in the [[Reticular formation|ascending reticular activating system]] (ARAS) and keep the system from properly functioning to arouse the brain.<ref name="Young 2009 32–47">{{cite journal |last1=Young |first1=G. Bryan |title=Coma |journal=Annals of the New York Academy of Sciences |date=March 2009 |volume=1157 |issue=1 |pages=32–47 |doi=10.1111/j.1749-6632.2009.04471.x |pmid=19351354 |bibcode=2009NYASA1157...32Y }}</ref> Secondary effects of drugs, which include [[Arrhythmia|abnormal heart rate]] and [[blood pressure]], as well as abnormal breathing and sweating, may also indirectly harm the functioning of the ARAS and lead to a coma. Given that drug poisoning is the cause for a large portion of patients in a coma, hospitals first test all comatose patients by observing [[pupil]] size and eye movement, through the [[Vestibulo-ocular reflex|vestibular–ocular reflex]]. (See ''Diagnosis'' below.)<ref name="Young 2009 32–47" />

The second most common cause of coma, which makes up about 25% of cases, is lack of oxygen, generally resulting from [[cardiac arrest]].<ref name="Liversedge 2010 337–339" /> The [[Central nervous system|central nervous system (CNS)]] requires a great deal of oxygen for its [[neurons]]. Oxygen deprivation in the [[Human brain|brain]], or ''[[cerebral hypoxia]]'', causes sodium and calcium from outside of the [[neuron]]s to decrease and [[Glossary of biology#I|intracellular]] calcium to increase, which harms neuron communication.<ref>{{cite journal |last1=Busl |first1=Katharina M. |last2=Greer |first2=David M. |title=Hypoxic-ischemic brain injury: Pathophysiology, neuropathology and mechanisms |journal=NeuroRehabilitation |date=28 January 2010 |volume=26 |issue=1 |pages=5–13 |doi=10.3233/NRE-2010-0531 |pmid=20130351 |doi-access=free }}</ref> Lack of oxygen in the brain also causes [[Adenosine triphosphate|ATP]] exhaustion and cellular breakdown from [[cytoskeleton]] damage and [[nitric oxide]] production.<ref>{{cite journal |last1=Siwicka-Gieroba |first1=Dorota |last2=Robba |first2=Chiara |last3=Gołacki |first3=Jakub |last4=Badenes |first4=Rafael |last5=Dabrowski |first5=Wojciech |title=Cerebral Oxygen Delivery and Consumption in Brain-Injured Patients |journal=Journal of Personalized Medicine |date=25 October 2022 |volume=12 |issue=11 |pages=1763 |doi=10.3390/jpm12111763 |pmc=9698645 |pmid=36573716 |doi-access=free }}</ref>

Twenty percent of comatose states result from an ischemic stroke, brain hemorrhage, or brain tumor.<ref name="Liversedge 2010 337–339" /> During a stroke, blood flow to part of the brain is restricted or blocked. An [[ischemic stroke]], [[Intracerebral hemorrhage|brain hemorrhage]], or brain tumor may cause restriction of blood flow. Lack of blood to cells in the brain prevents oxygen from getting to the neurons, and consequently causes cells to become disrupted and die. As brain cells die, brain tissue continues to deteriorate, which may affect the functioning of the ARAS, causing unconsciousness and coma.<ref>{{Cite web |last1=Durning |first1=Marijke Vroomen |last2=RN |title=Coma: Types, Causes, Treatments, Prognosis |url=https://www.webmd.com/brain/coma-types-causes-treatments-prognosis |access-date=2024-08-14 |website=WebMD |language=en}}</ref>

Comatose cases can also result from [[traumatic brain injury]], excessive [[blood loss]], [[malnutrition]], [[hypothermia]], [[hyperthermia]], [[hyperammonemia]],<ref>{{cite book |last1=Ali |first1=Rimsha |last2=Nagalli |first2=Shivaraj |title=StatPearls |date=2024 |publisher=StatPearls Publishing |chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK557504/ |chapter=Hyperammonemia |pmid=32491436 }}</ref> abnormal glucose levels, and many other biological disorders. Furthermore, studies show that 1 out of 8 patients with traumatic brain injury experience a comatose state.<ref>{{cite journal |last1=Lombardi |first1=Francesco FL |last2=Taricco |first2=Mariangela |last3=De Tanti |first3=Antonio |last4=Telaro |first4=Elena |last5=Liberati |first5=Alessandro |title=Sensory stimulation for brain injured individuals in coma or vegetative state |journal=Cochrane Database of Systematic Reviews |date=22 April 2002 |issue=2 |pages=CD001427 |doi=10.1002/14651858.cd001427 |pmid=12076410 |pmc=7045727 }}</ref>

Heart-related causes of coma include [[cardiac arrest]], [[ventricular fibrillation]], [[ventricular tachycardia]], [[atrial fibrillation]], [[myocardial infarction]], [[heart failure]], [[arrhythmia]] when severe, [[cardiogenic shock]], [[myocarditis]], and [[pericarditis]]. [[Respiratory arrest]] is the only lung condition to cause coma, but many different lung conditions can cause [[decreased level of consciousness]], but do not reach coma.

Other causes of coma include [[Epilepsy|severe or persistent seizures]], [[kidney failure]], [[liver failure]], [[hyperglycemia]], [[hypoglycemia]], and infections involving the brain, like [[meningitis]] and [[encephalitis]].

==Pathophysiology==
Injury to either or both of the [[cerebral cortex]] or the [[reticular activating system]] (RAS) is sufficient to cause a person to enter coma.<ref>{{cite book |doi=10.1016/B978-0-12-374168-4.00011-3 |chapter=Coma |title=The Neurology of Consciousness |date=2009 |last1=Young |first1=G. Bryan |pages=137–150 |isbn=978-0-12-374168-4 }}</ref>

The [[cerebral cortex]] is the outer layer of [[neural tissue]] of the [[cerebrum]] of the [[brain]].<ref>{{cite book |last1=Saladin |first1=Kenneth S. |title=Human Anatomy |date=2011 |publisher=McGraw-Hill |isbn=978-0-07-352560-0 |oclc=318191613 }}{{pn|date=December 2024}}</ref> The cerebral cortex is composed of [[Grey matter|gray matter]] which consists of the [[Nucleus (neuroanatomy)|nuclei]] of [[neuron]]s, whereas the inner portion of the [[cerebrum]] is composed of [[white matter]] and is composed of the [[axon]]s of [[neuron]].<ref>{{cite book |last1=Mercadante |first1=Anthony A. |last2=Tadi |first2=Prasanna |title=StatPearls |date=2024 |publisher=StatPearls Publishing |chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK553239/ |chapter=Neuroanatomy, Gray Matter |pmid=31990494 }}</ref> White matter is responsible for [[perception]], relay of the sensory input via the [[thalamic pathway]], and many other neurological functions, including complex thinking.

The RAS, on the other hand, is a more primitive structure in the [[brainstem]] which includes the [[reticular formation]] (RF).<ref name="Arguinchona Neuroanatomy">{{cite book |last1=Arguinchona |first1=Joseph H. |last2=Tadi |first2=Prasanna |title=StatPearls |date=2024 |publisher=StatPearls Publishing |chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK549835/ |chapter=Neuroanatomy, Reticular Activating System |pmid=31751025 }}</ref> The RAS has two tracts, the ascending and descending tract. The ascending tract, or ascending reticular activating system (ARAS), is made up of a system of acetylcholine-producing neurons, and works to arouse and wake up the brain.<ref>{{cite book |doi=10.1016/B978-0-08-045396-5.00229-3 |chapter=Neuropsychology of Sleep |title=Encyclopedia of Behavioral Neuroscience |date=2010 |last1=Pace-Schott |first1=E.F. |pages=448–455 |isbn=978-0-08-045396-5 }}</ref> Arousal of the brain begins from the RF, through the [[thalamus]], and then finally to the cerebral cortex.<ref name="Young 2009 32–47" /> Any impairment in ARAS functioning, a neuronal dysfunction, along the arousal pathway stated directly above, prevents the body from being aware of its surroundings.<ref name="Arguinchona Neuroanatomy"/> Without the arousal and consciousness centers, the body cannot awaken, remaining in a comatose state.<ref name="Traub 2016 777–793">{{cite journal |last1=Traub |first1=Stephen J. |last2=Wijdicks |first2=Eelco F. |title=Initial Diagnosis and Management of Coma |journal=Emergency Medicine Clinics of North America |date=November 2016 |volume=34 |issue=4 |pages=777–793 |doi=10.1016/j.emc.2016.06.017 |pmid=27741988 }}</ref>

The severity and mode of onset of coma depends on the underlying cause. There are two main subdivisions of a coma: structural and diffuse neuronal.<ref name="Huff Tadi Coma"/> A structural cause, for example, is brought upon by a mechanical force that brings about cellular damage, such as physical pressure or a blockage in neural transmission.<ref>{{cite book |doi=10.1016/B978-0-323-35775-3.00001-1 |chapter=Mechanisms and Morphology of Cellular Injury, Adaptation, and Death |title=Pathologic Basis of Veterinary Disease |date=2017 |last1=Miller |first1=Margaret A. |last2=Zachary |first2=James F. |pages=2–43.e19 |pmc=7171462 |isbn=978-0-323-35775-3 }}</ref> By contrast, a diffuse cause is limited to aberrations of cellular function which fall under a metabolic or toxic subgroup. Toxin-induced comas are caused by extrinsic substances, whereas metabolic-induced comas are caused by intrinsic processes, such as body [[thermoregulation]] or ionic imbalances (e.g. sodium).<ref name="Traub 2016 777–793"/> For instance, severe [[hypoglycemia]] (low blood sugar) or [[hypercapnia]] (increased [[carbon dioxide]] levels in the blood) are examples of a metabolic diffuse neuronal dysfunction. Hypoglycemia or hypercapnia initially cause mild agitation and confusion, but progress to [[obtundation]], stupor, and finally, complete [[unconsciousness]].<ref>{{cite book |doi=10.1201/b15214-12 |chapter=Obtundation, stupor and coma Peter Dickinson |title=Small Animal Neurological Emergencies |date=2012 |pages=140–155 |isbn=978-0-429-15897-1 }}</ref> In contrast, coma resulting from a severe [[traumatic brain injury]] or [[subarachnoid hemorrhage]] can be instantaneous. The mode of onset may therefore be indicative of the underlying cause.<ref name="RR" />

Structural and diffuse causes of coma are not isolated from one another, as one can lead to the other in some situations. For instance, coma induced by a diffuse metabolic process, such as hypoglycemia, can result in a structural coma if it is not resolved. Another example is if cerebral edema, a diffuse dysfunction, leads to [[ischemia]] of the brainstem, a structural issue, due to the blockage of the circulation in the brain.<ref name="Traub 2016 777–793"/>

==Diagnosis==
Although diagnosis of coma is simple, investigating the underlying cause of onset can be rather challenging. As such, after gaining stabilization of the patient's airways, breathing and circulation (the basic [[ABC (medicine)|ABCs]]) various diagnostic tests, such as physical examinations and imaging tools ([[CT scan]], [[MRI]], etc.) are used to diagnose the underlying cause of the coma.<ref>{{cite journal |last1=Thim |first1=Troels |title=Initial assessment and treatment with the Airway, Breathing, Circulation, Disability, Exposure (ABCDE) approach |journal=International Journal of General Medicine |date=January 2012 |volume=5 |pages=117–121 |doi=10.2147/IJGM.S28478 |pmc=3273374 |pmid=22319249 |doi-access=free }}</ref>

When an unconscious person enters a hospital, the hospital uses a series of diagnostic steps to identify the cause of [[unconsciousness]].<ref>{{cite news |last1=Johnson |first1=Jon |last2=Sharon |first2=Alina |last3=Stephens |first3=Carissa |title=First aid for unconsciousness: What to do and when to seek help |url=https://www.medicalnewstoday.com/articles/322872 |work=Medical News Today |date=24 August 2018 }}</ref> According to Young,<ref name="Young 2009 32–47"/> the following steps should be taken when dealing with a patient possibly in a coma:
# Perform a general examination and medical history check
# Make sure the patient is in an actual comatose state and is not in a [[Locked-in syndrome|locked-in state]] or experiencing psychogenic unresponsiveness. Patients with locked-in syndrome present with voluntary movement of their eyes, whereas patients with [[psychogenic coma]]s demonstrate active resistance to passive opening of the eyelids, with the eyelids closing abruptly and completely when the lifted upper eyelid is released (rather than slowly, asymmetrically and incompletely as seen in comas due to organic causes).<ref>{{cite journal |last1=Baxter |first1=Cynthia L. |last2=White |first2=William D. |title=Psychogenic Coma: Case Report |journal=The International Journal of Psychiatry in Medicine |date=September 2003 |volume=33 |issue=3 |pages=317–322 |doi=10.2190/YVP4-3GTC-0EWK-42E8 |pmid=15089013 }}</ref>
# Find the site of the brain that may be causing coma (e.g., [[brainstem]], back of brain...) and assess the severity of the coma with the [[Glasgow Coma Scale]]
# Take blood work to see if drugs were involved or if it was a result of [[hypoventilation]]/[[hyperventilation]]
# Check for levels of serum glucose, calcium, sodium, potassium, magnesium, phosphate, urea, and creatinine
# Perform brain scans to observe any abnormal brain functioning using either [[CT scan|CT]] or [[Magnetic resonance imaging|MRI]] scans
# Continue to monitor brain waves and identify [[Epileptic seizure|seizures]] of patient using [[Electroencephalography|EEGs]]

===Initial evaluation===
{{More citations needed section|date=August 2020}}
In the initial assessment of coma, it is common to gauge the [[level of consciousness]] on the [[AVPU]] (alert, vocal stimuli, painful stimuli, unresponsive) scale by spontaneously exhibiting actions and, assessing the patient's response to vocal and painful stimuli.<ref>{{cite book |last1=Romanelli |first1=David |last2=Farrell |first2=Mitchell W. |title=StatPearls |chapter=AVPU Scale |date=2024 |publisher=StatPearls Publishing |chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK538431/ |pmid=30860702 }}</ref> More elaborate scales, such as the [[Glasgow Coma Scale]], quantify an individual's reactions such as eye opening, movement and verbal response in order to indicate their extent of brain injury.<ref>{{cite book |last1=Jain |first1=Shobhit |last2=Iverson |first2=Lindsay M. |title=StatPearls |chapter=Glasgow Coma Scale |date=2024 |publisher=StatPearls Publishing |chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK513298/ |pmid=30020670 }}</ref> The patient's score can vary from a score of 3 (indicating severe brain injury and death) to 15 (indicating mild or no brain injury).<ref>{{EMedicine|article|326643|Classification and Complications of Traumatic Brain Injury}}</ref>

In those with deep unconsciousness, there is a risk of [[asphyxiation]] as the control over the muscles in the face and throat is diminished. As a result, those presenting to a hospital with coma are typically assessed for this risk ("[[airway management]]"). If the risk of asphyxiation is deemed high, doctors may use various devices (such as an [[oropharyngeal airway]], [[nasopharyngeal airway]] or [[endotracheal tube]]) to safeguard the airway.

===Imaging and testing===
Imaging encompasses [[CT scan|computed tomography]] (CAT or CT) scan of the brain, or [[MRI]] for example, and is performed to identify specific causes of the coma, such as [[hemorrhage]] in the brain or [[herniation]] of the brain structures.<ref name="Haupt Coma and cerebral imaging">{{cite journal |last1=Haupt |first1=Walter F |last2=Hansen |first2=Hans Christian |last3=Janzen |first3=Rudolf W C |last4=Firsching |first4=Raimund |last5=Galldiks |first5=Norbert |title=Coma and cerebral imaging |journal=SpringerPlus |date=December 2015 |volume=4 |issue=1 |page=180 |doi=10.1186/s40064-015-0869-y |pmc=4424227 |pmid=25984436 |doi-access=free }}</ref> Special tests such as an [[EEG]] can also show a lot about the activity level of the cortex such as semantic processing,<ref name="Daltrozzo01">{{cite journal |last1=Daltrozzo |first1=Jerôme |last2=Wioland |first2=Norma |last3=Mutschler |first3=Veronique |last4=Lutun |first4=Philippe |last5=Calon |first5=Bartholomeus |last6=Meyer |first6=Alain |last7=Pottecher |first7=Thierry |last8=Lang |first8=Simone |last9=Jaeger |first9=Albert |last10=Kotchoubey |first10=Boris |title=Cortical Information Processing in Coma |journal=Cognitive and Behavioral Neurology |date=March 2009 |volume=22 |issue=1 |pages=53–62 |doi=10.1097/WNN.0b013e318192ccc8 |pmid=19372771 }}</ref> presence of [[seizures]], and are important available tools not only for the assessment of the cortical activity but also for predicting the likelihood of the patient's awakening.<ref name="Daltrozzo02">{{cite journal |last1=Daltrozzo |first1=J. |last2=Wioland |first2=N. |last3=Mutschler |first3=V. |last4=Kotchoubey |first4=B. |title=Predicting coma and other low responsive patients outcome using event-related brain potentials: A meta-analysis |journal=Clinical Neurophysiology |date=March 2007 |volume=118 |issue=3 |pages=606–614 |doi=10.1016/j.clinph.2006.11.019 |pmid=17208048 }}</ref> In advanced cases, a technique called the [[Perturbational Complexity Index]] (PCI), which combines [[transcranial magnetic stimulation]] (TMS) with EEG, has been developed to assess the capacity for consciousness by measuring the complexity of brain responses. PCI has shown promise in distinguishing between [[Vegetative state|vegetative]] and [[Minimally conscious state|minimally conscious states]], even when behavioral signs are absent.<ref>{{cite journal |last1=Casali |first1=Adenauer G. |last2=Gosseries |first2=Olivia |last3=Rosanova |first3=Mario |last4=Boly |first4=Mélanie |last5=Sarasso |first5=Simone |last6=Casali |first6=Krysztof R. |last7=Casarotto |first7=Silvia |last8=Bruno |first8=Marie‑Aurélie |last9=Laureys |first9=Steven |last10=Tononi |first10=Giulio |last11=Massimini |first11=Marcello |title=A theoretically based index of consciousness independent of sensory processing and behavior |journal=Science Translational Medicine |volume=5 |issue=198 |pages=198ra105 |date=14 August 2013 |doi=10.1126/scitranslmed.3006294 |pmid=23946194 |url=https://www.science.org/doi/10.1126/scitranslmed.3006294}}</ref> The autonomous responses such as the [[skin conductance response]] may also provide further insight on the patient's emotional processing.<ref name="Daltrozzo03">{{cite journal |last1=Daltrozzo |first1=Jérôme |last2=Wioland |first2=Norma |last3=Mutschler |first3=Véronique |last4=Lutun |first4=Philippe |last5=Calon |first5=Bartholomeus |last6=Meyer |first6=Alain |last7=Jaeger |first7=Albert |last8=Pottecher |first8=Thierry |last9=Kotchoubey |first9=Boris |title=Emotional electrodermal response in coma and other low-responsive patients |journal=Neuroscience Letters |date=May 2010 |volume=475 |issue=1 |pages=44–47 |doi=10.1016/j.neulet.2010.03.043 |pmid=20346390 }}</ref>

In the treatment of traumatic brain injury (TBI), there are four examination methods that have proved useful: skull x-ray, angiography, computed tomography (CT), and magnetic resonance imaging (MRI).<ref>{{Cite journal |last1=Lee |first1=Bruce |last2=Newberg |first2=Andrew |date=April 2005 |title=Neuroimaging in Traumatic Brain Imaging |journal=NeuroRx |volume=2 |issue=2 |pages=372–383 |doi=10.1602/neurorx.2.2.372 |pmc=1064998 |pmid=15897957}}</ref> The skull x-ray can detect linear fractures, impression fractures (expression fractures) and burst fractures.<ref>{{cite journal |last1=Nakahara |first1=Kuniaki |last2=Shimizu |first2=Satoru |last3=Utsuki |first3=Satoshi |last4=Oka |first4=Hidehiro |last5=Kitahara |first5=Takao |last6=Kan |first6=Shinichi |last7=Fujii |first7=Kiyotaka |title=Linear Fractures Occult on Skull Radiographs: A Pitfall at Radiological Screening for Mild Head Injury |journal=Journal of Trauma: Injury, Infection & Critical Care |date=January 2011 |volume=70 |issue=1 |pages=180–182 |doi=10.1097/TA.0b013e3181d76737 |pmid=20495486 }}</ref> Angiography is used on rare occasions for TBIs i.e. when there is suspicion of an aneurysm, carotid sinus fistula, traumatic vascular occlusion, and vascular dissection.<ref>{{cite journal |last1=Korkmazer |first1=Bora |last2=Kocak |first2=Burak |last3=Tureci |first3=Ercan |last4=Islak |first4=Civan |last5=Kocer |first5=Naci |last6=Kizilkilic |first6=Osman |title=Endovascular treatment of carotid cavernous sinus fistula: A systematic review |journal=World Journal of Radiology |date=2013 |volume=5 |issue=4 |pages=143–155 |doi=10.4329/wjr.v5.i4.143 |pmc=3647206 |pmid=23671750 |doi-access=free }}</ref> A CT can detect changes in density between the brain tissue and hemorrhages like subdural and intracerebral hemorrhages. MRIs are not the first choice in emergencies because of the long scanning times and because fractures cannot be detected as well as CT. MRIs are used for the imaging of soft tissues and lesions in the posterior fossa which cannot be found with the use of CT.<ref name="Haupt Coma and cerebral imaging"/>

===Body movements===
Assessment of the brainstem and cortical function through special reflex tests such as the [[oculocephalic reflex]] test (doll's eyes test), [[Vestibulo-ocular reflex|oculovestibular reflex]] test (cold caloric test), [[corneal reflex]], and the [[gag reflex]].<ref>{{Cite web|url=https://www.lhsc.on.ca/media/2014/download|title=Neurological Assessment Tips|date=2014|website=London Health Sciences Centre}}</ref> Reflexes are a good indicator of what [[cranial nerves]] are still intact and functioning and is an important part of the physical exam. Due to the unconscious status of the patient, only a limited number of the nerves can be assessed. These include the cranial nerves number 2 (CN II), number 3 (CN III), number 5 (CN V), number 7 (CN VII), and cranial nerves 9 and 10 (CN IX, CN X).

{| class="wikitable"
!Type of reflex
!Description
|-
|[[Oculocephalic reflex]]
|Oculocephalic reflex, also known as the doll's eye, is performed to assess the integrity of the brainstem.
* Patient's eyelids are gently elevated and the cornea is visualized.
* The patient's head is then moved to the patient's left, to observe whether the eyes stay or deviate toward the patient's right; same maneuver is attempted on the opposite side.
* If the patient's eyes move in a direction opposite to the direction of the rotation of the head, then the patient is said to have an intact brainstem.
* However, failure of both eyes to move to one side can indicate damage or destruction of the affected side. In special cases, where only one eye deviates and the other does not, this often indicates a lesion (or damage) of the [[medial longitudinal fasciculus]] (MLF), which is a brainstem nerve tract.
|-
|[[Pupillary light reflex]]
|Pupil reaction to light is important because it shows an intact retina, and cranial nerve number 2 (CN II)
* If pupils are reactive to light, then that also indicates that the cranial nerve number 3 (CN III) (or at least its [[parasympathetic]] fibers) are intact.
|-
|[[Caloric reflex test|Oculovestibular reflex<br>(Cold Caloric Test)]]
|Caloric reflex test also evaluates both cortical and brainstem function
* Cold water is injected into one ear and the patient is observed for eye movement
* If the patient's eyes slowly deviate toward the ear where the water was injected, then the brainstem is intact, however failure to deviate toward the injected ear indicates damage of the brainstem on that side.
* The cortex is responsible for a rapid [[nystagmus]] away from this deviated position and is often seen in patients who are conscious or merely lethargic.
|-
|[[Corneal reflex]]
|The corneal reflex assesses the proper function of the [[trigeminal nerve]] (CN 5) and [[facial nerve]] (CN 7), and is present at infancy.
* Lightly touching the [[cornea]] with a tissue or cotton swab induces a rapid blink reflex of both eyes.
* Touching the sclera or eyelashes, presenting a light flash, or stimulating the [[supraorbital nerve]] will induce a less rapid but still reliable response.
* Those in a comatose state will have altered corneal reflex depending on the severity of their unconscious and the location of their lesion.<ref>{{cite book |doi=10.1016/B978-1-4160-3618-0.X1000-4 |title=Textbook of Clinical Neurology |date=2007 |isbn=978-1-4160-3618-0 }}{{pn|date=December 2024}}</ref>
|-
|[[Gag reflex]]
|The gag, or pharyngeal, reflex is centered in the medulla and consists of the reflexive motor response of pharyngeal elevation and constriction with tongue retraction in response to sensory stimulation of the pharyngeal wall, posterior tongue, [[tonsil]]s, or faucial pillars.
* This reflex is examined by touching the posterior [[pharynx]] with the soft tip of a cotton applicator and visually inspecting for elevation of the pharynx.
* Those in comatose states will often demonstrate poor gag reflexes if there has been damage to their glossopharyngeal (CN 9) or vagus nerve (CN 10).<ref>{{cite book |doi=10.1016/b978-141603618-0.10013-x |chapter=Cranial Nerves IX (Glossopharyngeal) and X (Vagus) |title=Textbook of Clinical Neurology |date=2007 |last1=Hermanowicz |first1=Neal |pages=217–229 |isbn=978-1-4160-3618-0 }}</ref>
|}

[[File:Decorticate.PNG|thumb|alt=Illustration of characteristic pose laying face-up, arms bent with knuckles held together at sternum, legs together and straight|[[Decorticate posturing]], indicating a [[lesion]] at the [[red nucleus]] or above. This positioning is stereotypical for upper [[brain stem]], or [[Cortex (anatomy)|cortical]] damage. The other variant is [[decerebrate posturing]], not seen in this picture.]]

Assessment of posture and physique is the next step. It involves general observation about the patient's positioning. There are often two stereotypical postures seen in comatose patients. [[Decorticate posturing]] is a stereotypical posturing in which the patient has arms [[Flexion|flexed]] at the elbow, and arms adducted toward the body, with both legs [[Extension (kinesiology)|extended]]. [[Decerebrate posturing]] is a stereotypical posturing in which the legs are similarly extended (stretched), but the arms are also stretched (extended at the elbow). The posturing is critical since it indicates where the damage is in the central nervous system. A decorticate posturing indicates a lesion (a point of damage) at or above the [[red nucleus]], whereas a decerebrate posturing indicates a lesion at or below the red nucleus. In other words, a decorticate lesion is closer to the [[Cortex (anatomy)|cortex]], as opposed to a decerebrate posturing which indicates that the lesion is closer to the [[brainstem]].

=== Pupil size ===
Pupil assessment is often a critical portion of a comatose examination, as it can give information as to the cause of the coma; the following table is a technical, medical guideline for common pupil findings and their possible interpretations:<ref name=med />

{| class="wikitable"
! Pupil sizes (left eye vs. right eye) !! Possible interpretation
|-
| [[File:Darkblue.jpg|alt=Eyes open and pupils equal-dilation, normal size|250px]] || Normal eye with two pupils equal in size and reactive to light. This means that the patient is probably not in a coma and is probably lethargic, under influence of a drug, or sleeping.
|-
| [[File:Myosis due to opiate use.jpg|alt=Eyes open, pupils smaller than expected and equal|250px]] || "Pinpoint" pupils indicate [[heroin]] or opiate overdose, which can be responsible for a patient's coma. The pinpoint pupils are still reactive to light [[wikt:bilateral|bilaterally]] (in both eyes, not just one). Another possibility is damage to the [[pons]].<ref name=med />
|-
| [[File:Anizokoria.JPG|alt=Eyes open, right pupil much larger than left|250px]] || One pupil is dilated and unreactive, while the other is normal (in this case, the right eye is dilated, while the left eye is normal in size). This could mean damage to the [[oculomotor nerve]] (cranial nerve number 3, CN III) on the right side, or indicate the possibility of vascular involvement.
|-
| [[File:Cyclopentolate 1 percent Pupils.jpg|alt=Eyes open, both pupils widely dilated|250px]] || Both pupils are dilated and unreactive to light. This could be due to overdose of certain medications, [[hypothermia]] or severe [[Hypoxia (medical)|anoxia]] (lack of oxygen).
|}

===Severity===
{{Main|Coma scale}}

A coma can be classified as (1) [[Tentorium cerebelli|supratentorial]] (above [[Tentorium cerebelli]]), (2) [[Tentorium cerebelli|infratentorial]] (below Tentorium cerebelli), (3) metabolic or (4) diffused.<ref name=med /> This classification is merely dependent on the position of the original damage that caused the coma, and does not correlate with severity or the prognosis. The severity of coma impairment however is categorized into several levels. Patients may or may not progress through these levels. In the first level, the brain responsiveness lessens, normal reflexes are lost, the patient no longer responds to pain and cannot hear.

The [[Rancho Los Amigos Scale]] is a complex scale that has eight separate levels, and is often used in the first few weeks or months of coma while the patient is under closer observation, and when shifts between levels are more frequent.

==Treatment==

Treatment for people in a coma will depend on the severity and cause of the comatose state. Upon admittance to an emergency department, coma patients will usually be placed in an [[Intensive care unit|Intensive Care Unit]] (ICU) immediately,<ref name="Young 2009 32–47" /> where maintenance of the patient's respiration and circulation become a first priority. Stability of their respiration and circulation is sustained through the use of [[Tracheal intubation|intubation]], [[Bag valve mask|ventilation]], administration of [[Intravenous therapy|intravenous]] fluids or blood and other supportive care as needed.

=== Continued care ===
Once a patient is stable and no longer in immediate danger, there may be a shift of priority from stabilizing the patient to maintaining the state of their physical wellbeing. Moving patients every 2–3 hours by turning them side to side is crucial to avoiding [[Pressure ulcer|bed sores]] as a result of being confined to a bed. Moving patients through the use of [[physical therapy]] also aids in preventing [[atelectasis]], [[contracture]]s or other orthopedic deformities which would interfere with a coma patient's recovery.<ref name="sr" />

Pneumonia is also common in coma patients due to their inability to swallow which can then lead to [[Pulmonary aspiration|aspiration]]. A coma patient's lack of a gag reflex and use of a feeding tube can result in food, drink or other solid organic matter being lodged within their [[Respiratory tract|lower respiratory tract]] (from the trachea to the lungs). This trapping of matter in their lower respiratory tract can ultimately lead to infection, resulting in [[aspiration pneumonia]].<ref name="sr" />

Coma patients may also deal with restlessness or seizures. Soft cloth restraints may be used to prevent them from pulling on tubes or dressings and side rails on the bed should be kept up to prevent patients from falling.<ref name="sr">{{cite web|title=Coma|url=http://medicalcenter.osu.edu/PatientEd/Materials/PDFDocs/dis-cond/general/coma.pdf|access-date=2010-12-08|url-status=dead|archive-url=https://web.archive.org/web/20100627165642/http://medicalcenter.osu.edu/PatientEd/Materials/PDFDocs/dis-cond/general/coma.pdf|archive-date=2010-06-27}}</ref>

=== Caregivers ===
Coma has a wide variety of emotional reactions from the family members of the affected patients, as well as the primary care givers taking care of the patients. Research has shown that the severity of injury causing coma was found to have no significant impact compared to how much time has passed since the injury occurred.<ref>{{cite journal |last1=Qadeer |first1=Anam |last2=Khalid |first2=Usama |last3=Amin |first3=Mahwish |last4=Murtaza |first4=Sajeela |last5=Khaliq |first5=Muhammad F |last6=Shoaib |first6=Maria |title=Caregiver's Burden of the Patients With Traumatic Brain Injury |journal=Cureus |date=21 August 2017 |volume=9 |issue=8 |pages=e1590 |doi=10.7759/cureus.1590 |doi-access=free |pmc=5650257 |pmid=29062622 }}</ref> Common reactions, such as desperation, anger, frustration, and denial are possible. The focus of the patient care should be on creating an amicable relationship with the family members or dependents of a comatose patient as well as creating a rapport with the medical staff.<ref>{{cite web|title=Caring for Care Giver and Family|author=Coma Care|date=2010-03-30|access-date=2010-12-08|url=http://www.comacare.com/cgi-bin/giga.cgi}}{{dead link|date=March 2018 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> Although there is heavy importance of a primary care taker, secondary care takers can play a supporting role to temporarily relieve the primary care taker's burden of tasks.

== Prognosis ==
Comas can last from several days to, in particularly extreme cases, years. Some patients eventually gradually come out of the coma, some progress to a [[Persistent vegetative state|vegetative state]] or a [[minimally conscious state]], and others die. Some patients who have entered a vegetative state go on to regain a degree of awareness; and in some cases may remain in vegetative state for years or even decades such as the [[Aruna Shanbaug case]]<ref>{{cite news |title=Aruna Shanbaug: Brain-damaged India nurse dies 42 years after rape |url=https://www.bbc.com/news/world-asia-india-32776897 |work=BBC News |date=18 May 2015 }}</ref> or [[Edwarda O'Bara]].<ref>{{cite news |url=https://www.miamiherald.com/2012/11/22/3109800/edwarda-obara-who-spent-4-decades.html |archive-url=https://web.archive.org/web/20131212223430/https://www.miamiherald.com/2012/11/22/3109800/edwarda-obara-who-spent-4-decades.html |archive-date=12 December 2013 |title=Edwarda O'Bara, who spent 4 decades in a coma, dies at 59 |first1=Diana |last1=Moskovitz |date=22 November 2012 |newspaper=Miami Herald }}</ref>

Predicted chances of recovery will differ depending on which techniques were used to measure the patient's severity of neurological damage. Predictions of recovery are based on [[statistical]] rates, expressed as the level of chance the person has of recovering. Time is the best general predictor of a chance of recovery. For example, after four months of coma caused by [[brain damage]], the chance of partial recovery is less than 15%, and the chance of full recovery is very low.<ref>{{cite journal |last1=Formisano |first1=R. |last2=Carlesimo |first2=G. A. |last3=Sabbadini |first3=M. |last4=Loasses |first4=A. |last5=Penta |first5=F. |last6=Vinicola |first6=V. |last7=Caltagirone |first7=C. |title=Clinical predictors and neuropsychological outcome in severe traumatic brain injury patients |journal=Acta Neurochirurgica |date=May 2004 |volume=146 |issue=5 |pages=457–462 |doi=10.1007/s00701-004-0225-4 |pmid=15118882 }}</ref>

The outcome for coma and vegetative state depends on the cause, location, severity and extent of neurological damage. A deeper coma alone does not necessarily mean a slimmer chance of recovery; similarly, a milder coma does not indicate a higher chance of recovery. The most common cause of death for a person in a vegetative state is secondary [[infection]] such as [[pneumonia]], which can occur in patients who lie still for extended periods.

=== Recovery ===
People may emerge from a coma with a combination of physical, intellectual, and psychological difficulties that need special attention. It is common for coma patients to awaken in a profound state of confusion and experience [[dysarthria]], the inability to articulate any speech. Recovery is usually gradual. In the first days, the patient may only awaken for a few minutes, with increased duration of wakefulness as their recovery progresses, and they may eventually recover full awareness. That said, some patients may never progress beyond very basic responses.<ref>{{cite web|url=http://www.ninds.nih.gov/disorders/coma/coma.htm#What_is_the_prognosis|title=Coma Information Page: National Institute of Neurological Disorders and Stroke (NINDS)|author=NINDS|date=October 29, 2010|archive-url=https://web.archive.org/web/20101204112240/http://www.ninds.nih.gov/disorders/coma/coma.htm#What_is_the_prognosis|archive-date=December 4, 2010|url-status=dead|access-date=2010-12-08|df=mdy-all}}</ref>

There are reports of people coming out of a coma after long periods of time. After 19 years in a [[minimally conscious state]], [[Terry Wallis]] spontaneously began speaking and regained awareness of his surroundings.<ref>{{cite news |title=Mother stunned by coma victim's unexpected words |url=https://www.smh.com.au/national/mother-stunned-by-coma-victims-unexpected-words-20030712-gdh315.html |work=The Sydney Morning Herald |date=12 July 2003 }}</ref>

A man with brain damage and trapped in a coma-like state for six years was brought back to consciousness in 2003 by doctors who planted electrodes deep inside his brain. The method, called [[deep brain stimulation]] (DBS), successfully roused communication, complex movement and eating ability in the man with a traumatic brain injury. His injuries left him in a minimally conscious state, a condition akin to a coma but characterized by occasional, but brief, evidence of environmental and self-awareness that coma patients lack.<ref>{{cite news |title=Electrodes stir man from six-year coma-like state |url=http://www.cosmosmagazine.com/news/electrodes-stir-man-six-year-coma-state/ |work=Cosmos Magazine |date=2 August 2007 |url-status=bot: unknown |archive-url=https://web.archive.org/web/20140306083843/http://www.cosmosmagazine.com/news/electrodes-stir-man-six-year-coma-state/ |archive-date=6 March 2014}}</ref>

==Society and culture==
Research by Eelco Wijdicks on the depiction of comas in movies was published in Neurology in May 2006. Wijdicks studied 30 films (made between 1970 and 2004) that portrayed actors in prolonged comas, and he concluded that only two films accurately depicted the state of a coma patient and the agony of waiting for a patient to awaken: ''[[Reversal of Fortune]]'' (1990) and ''[[The Dreamlife of Angels]]'' (1998). The remaining 28 were criticized for portraying miraculous awakenings with no lasting side effects, unrealistic depictions of treatments and equipment required, and comatose patients remaining muscular and tanned.<ref>{{cite journal |last1=Wijdicks |first1=Eelco F.M. |last2=Wijdicks |first2=Coen A. |title=The portrayal of coma in contemporary motion pictures |journal=Neurology |date=9 May 2006 |volume=66 |issue=9 |pages=1300–1303 |doi=10.1212/01.wnl.0000210497.62202.e9 |pmid=16682658 }}</ref>

=== Bioethics ===
A person in a coma is said to be in an  [[Unconsciousness|unconscious]] state. Perspectives on [[personhood]], [[Identity (social science)|identity]] and [[consciousness]] come into play when discussing the [[Metaphysics|metaphysical]] and [[Bioethics|bioethical]] views on comas.

It has been argued that unawareness should be just as ethically relevant and important as a state of awareness and that there should be metaphysical support of unawareness as a state.<ref name=":3" />

In the ethical discussions about disorders of consciousness (DOCs), two abilities are usually considered as central: ''experiencing well-being'' and ''having interest''. Well-being can broadly be understood as the positive effect related to what makes life good (according to specific standards) for the individual in question.<ref name=":1">{{cite book |doi=10.1093/acprof:oso/9780190280307.003.0011 |chapter=What is Good for Them? Best Interests and Severe Disorders of Consciousness |title=Finding Consciousness |date=2016 |last1=Hawkins |first1=Jennifer |pages=180–206 |isbn=978-0-19-028030-7 }}</ref> The only condition for well-being broadly considered is the ability to experience its 'positiveness'. That said, because experiencing positiveness is a basic emotional process with [[Phylogenetics|phylogenetic]] roots, it is likely to occur at a completely unaware level and, therefore, introduces the idea of an unconscious well-being.<ref name=":3">{{Cite journal|last1=Farisco|first1=Michele|last2=Evers|first2=Kathinka|date=December 2017|title=The ethical relevance of the unconscious|journal=Philosophy, Ethics, and Humanities in Medicine|volume=12|issue=1|pages=11|doi=10.1186/s13010-017-0053-9|pmid=29284489 |pmc=5747178 |doi-access=free }} [[File:CC-BY icon.svg|50px]] Material was copied from this source, which is available under a [https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International License].</ref> As such, the ability of having interests is crucial for describing two abilities which those with comas are deficient in. Having an interest in a certain domain can be understood as having a stake in something that can affect what makes our life good in that domain. An interest is what directly and immediately improves life from a certain point of view or within a particular domain, or greatly increases the likelihood of life improvement enabling the subject to realize some good.<ref name=":1" /> That said, sensitivity to reward signals is a fundamental element in the learning process, both consciously and unconsciously.<ref>{{cite journal |title=Henry Adams: The Middle Years. By Ernest Samuels. (Cambridge, Mass.: Belknap Press of Harvard University Press. 1958. Pp. xiv, 514. $7.50.) and Henry Adams: The Major Phase. By Ernest Samuels. (Cambridge, Mass.: Belknap Press of Harvard University Press. 1964. Pp. xv, 687. $10.00.) |journal=The American Historical Review |date=January 1966 |doi=10.1086/ahr/71.2.709 |last1=Holt |first1=W. Stull |volume=71 |issue=2 |pages=709–710 }}</ref> Moreover, the unconscious brain is able to interact with its surroundings in a meaningful way and to produce meaningful information processing of stimuli coming from the external environment, including other people.<ref name=":2">{{cite book |doi=10.4324/9781315723983 |title=Neurotechnology and Direct Brain Communication |date=2016 |isbn=978-1-317-52959-0 |editor-last1=Farisco |editor-last2=Evers |editor-first1=Michele |editor-first2=Kathinka }}{{pn|date=December 2024}}</ref>

According to Hawkins, "1. A life is good if the subject is able to value, or more basically if the subject is able to care. Importantly, Hawkins stresses that caring has no need for cognitive commitment, i.e. for high-level cognitive activities: it requires being able to distinguish something, track it for a while, recognize it over time, and have certain emotional dispositions ''vis-à-vis'' something. 2. A life is good if the subject has the capacity for relationship with others, i.e. for meaningfully interacting with other people."<ref name=":1" /> This suggests that unawareness may (at least partly) fulfill both conditions identified by Hawkins for life to be good for a subject, thus making the unconscious ethically relevant.<ref name=":2" />

==See also==
{{Portal|Medicine}}
* [[Brain death]], lack of activity in both cortex, and lack of brainstem function
* [[Coma scale]], a system to assess the severity of coma
* [[Locked-in syndrome]], paralysis of most muscles, except ocular muscles of the eyes, while patient is conscious
* [[Near-death experience]], type of experience registered by people in a state of coma.
* [[Persistent vegetative state]] (vegetative coma), deep coma without detectable awareness. Damage to the cortex, with an intact brainstem.
* [[Process Oriented Coma Work]], for an approach to working with residual consciousness in comatose patients.
* [[Suspended animation]], the inducement of a temporary cessation or decay of main body functions.

==References==
{{Reflist}}

== External links ==
*{{Merriam-Webster|Coma}}
{{wiktionary|coma}}
{{Scholia}}
{{Medical resources
| DiseasesDB = 16940
| ICD11 = {{ICD11|MB20.1}}
| ICD10 = {{ICD10|R40.2}}
| ICD9 = {{ICD9|780.01}}
| MeshID = D003128
}}

{{Disorders of consciousness}}
{{Authority control}}

[[Category:Coma| ]]
[[Category:Intensive care medicine]]
[[Category:Emergency medicine]]
[[Category:Symptoms and signs of mental disorders]]
[[Category:Symptoms, signs or clinical findings involving consciousness]]