Editing Coma (section)

==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 employed to access 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 utilizes 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=http://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=http://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> 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 4 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.