Coma

comatoseunresponsivecomatose statesemi-comatosea comachronic comacoma, post-head injurydeep unconsciousnessloss of consciousnessunconscious
Coma is a state of unconsciousness in which a person cannot be awakened; fails to respond normally to painful stimuli, light, or sound; lacks a normal wake-sleep cycle; and does not initiate voluntary actions.wikipedia
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Subarachnoid hemorrhage

subarachnoid haemorrhagesubarachnoidsubarachnoid hemorrhage, traumatic
In contrast, coma resulting from a severe traumatic brain injury or subarachnoid hemorrhage can be instantaneous.
Confusion, decreased level of consciousness or coma may be present, as may neck stiffness and other signs of meningism.

Reticular formation

reticular activating systemreticulospinal tractascending reticular activating system
The other is a structure located in the brainstem, called reticular activating system (RAS).
4) Sleep and consciousness – The reticular formation has projections to the thalamus and cerebral cortex that allow it to exert some control over which sensory signals reach the cerebrum and come to our conscious attention. It plays a central role in states of consciousness like alertness and sleep. Injury to the reticular formation can result in irreversible coma.

Induced coma

medically induced comaartificial comamedically-induced coma
It may also be deliberately induced by pharmaceutical agents during major neurosurgery, to preserve higher brain functions following brain trauma, or to save the patient from extreme pain during healing of injuries or diseases.
An induced coma, also known as a medically induced coma, a barbiturate-induced coma, or a barb coma, is a temporary coma (a deep state of unconsciousness) brought on by a controlled dose of a barbiturate drug, usually pentobarbital or thiopental.

Eclampsia

eclamptic psychosispregnancy-induced
Coma may result from a variety of conditions, including intoxication (such as drug abuse, overdose or misuse of over the counter medications, prescribed medication, or controlled substances), metabolic abnormalities, central nervous system diseases, acute neurologic injuries such as strokes or herniations, hypoxia, hypothermia, hypoglycemia, eclampsia or traumatic injuries such as head trauma caused by falls, drowning accidents, or vehicle collisions.
Following the seizure there is typically either a period of confusion or coma.

Cerebral hypoxia

cerebral anoxiahypoxic ischemic encephalopathyhypoxic-ischemic encephalopathy
Oxygen deprivation in the brain, also known as hypoxia, causes neuronal extracellular sodium and calcium to decrease and intracellular calcium to increase, which harms neuron communication.
Continued oxygen deprivation results in fainting, long-term loss of consciousness, coma, seizures, cessation of brain stem reflexes, and brain death.

Drug overdose

overdoseoverdosingoverdosed
Forty percent of comatose states result from drug poisoning.
If this overdose is not treated with chelation therapy, it can lead to death or a permanent coma.

Electroencephalography

EEGelectroencephalogramelectroencephalograph
Investigative methods are divided into physical examination findings and imaging (such as CAT scan, MRI, etc.) and special studies (EEG, etc.)
It is also used to diagnose sleep disorders, depth of anesthesia, coma, encephalopathies, and brain death.

Glasgow Coma Scale

GCSGlasgow Coma Scale (GCS)altered mental state
Generally, a person who is unable to voluntarily open the eyes, does not have a sleep-wake cycle, is unresponsive in spite of strong tactile (painful) or verbal stimuli, and who generally scores between 3 and 8 on the Glasgow Coma Scale is considered in a coma.
The lowest possible GCS (the sum) is 3 (deep coma or death), while the highest is 15 (fully awake person).

Altered level of consciousness

level of consciousnessaltered mental statusdecreased level of consciousness
In the initial assessment of coma, it is common to gauge the level of consciousness by spontaneously exhibited actions, response to vocal stimuli ("Can you hear me?"), and painful stimuli; this is known as the AVPU (alert, vocal stimuli, painful stimuli, unresponsive) scale.
Coma is the inability to make any purposeful response.

Thalamus

thalamicthalamimetathalamus
Made up of a system of acetylcholine-producing neurons, the ascending track, or ascending reticular activating system (ARAS), works to arouse and wake up the brain, from the RF, through the thalamus, and then finally to the cerebral cortex.
Damage to the thalamus can lead to permanent coma.

Unconsciousness

unconsciousloss of consciousnessnarcosis
Coma is a state of unconsciousness in which a person cannot be awakened; fails to respond normally to painful stimuli, light, or sound; lacks a normal wake-sleep cycle; and does not initiate voluntary actions.
Coma

Hypoglycemia

low blood sugarhypoglycemichypoglycaemia
Coma may result from a variety of conditions, including intoxication (such as drug abuse, overdose or misuse of over the counter medications, prescribed medication, or controlled substances), metabolic abnormalities, central nervous system diseases, acute neurologic injuries such as strokes or herniations, hypoxia, hypothermia, hypoglycemia, eclampsia or traumatic injuries such as head trauma caused by falls, drowning accidents, or vehicle collisions. For instance, severe hypoglycemia (low blood sugar) or hypercapnia (increased carbon dioxide levels in the blood) initially cause mild agitation and confusion, but progress to obtundation, stupor, and finally, complete unconsciousness.
As blood glucose levels fall below 10 mg/dL (0.55 mM), most neurons become electrically silent and nonfunctional, resulting in coma.

Head injury

head traumahead injurieshead
Coma may result from a variety of conditions, including intoxication (such as drug abuse, overdose or misuse of over the counter medications, prescribed medication, or controlled substances), metabolic abnormalities, central nervous system diseases, acute neurologic injuries such as strokes or herniations, hypoxia, hypothermia, hypoglycemia, eclampsia or traumatic injuries such as head trauma caused by falls, drowning accidents, or vehicle collisions.
The most severe cases result in coma or even persistent vegetative state.

Oropharyngeal airway

oropharyngealOPA
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.
Oropharyngeal airways are indicated only in unconscious people, because of the likelihood that the device would stimulate a gag reflex in conscious or semi-conscious persons.

Apneustic respirations

apneustic breathing
Another pattern of breathing is apneustic breathing, which is characterized by sudden pauses of Inhalation and is due to a lesion of the pons.
Accompanying signs and symptoms may include decerebrate posturing; fixed, dilated pupils; coma or profound stupor; quadriparesis; absent corneal reflex; negative oculocephalic reflex; and obliteration of the gag reflex.

Abnormal posturing

decerebrate responsedecerebrate posturingdecerebrate rigidity
Decorticate posturing is a stereotypical posturing in which the patient has arms flexed at the elbow, and arms adducted toward the body, with both legs extended.
Since posturing is an important indicator of the amount of damage that has occurred to the brain, it is used by medical professionals to measure the severity of a coma with the Glasgow Coma Scale (for adults) and the Pediatric Glasgow Coma Scale (for infants).

Stroke

strokesischemic strokecerebrovascular accident
Coma may result from a variety of conditions, including intoxication (such as drug abuse, overdose or misuse of over the counter medications, prescribed medication, or controlled substances), metabolic abnormalities, central nervous system diseases, acute neurologic injuries such as strokes or herniations, hypoxia, hypothermia, hypoglycemia, eclampsia or traumatic injuries such as head trauma caused by falls, drowning accidents, or vehicle collisions.
If the stroke is severe enough, or in a certain location such as parts of the brainstem, coma or death can result.

Corneal reflex

blink reflexcorneal
It should include vital signs, a general portion dedicated to making observations about the patient's respiration (breathing pattern), body movements (if any), and of the patient's body habitus (physique); it should also include assessment of the brainstem and cortical function through special reflex tests such as the oculocephalic reflex test (doll's eyes test), oculovestibular reflex test (cold caloric test), nasal tickle, corneal reflex, and the gag reflex.
The examination of the corneal reflex is a part of some neurological exams, particularly when evaluating coma.

Human brain

brainbrain tissuebrains
Oxygen deprivation in the brain, also known as hypoxia, causes neuronal extracellular sodium and calcium to decrease and intracellular calcium to increase, which harms neuron communication.
This is characterised by coma, loss of reflexes, and apnoea, however, the declaration of brain death varies geographically and is not always accepted.

Rancho Los Amigos Scale

decreased cognitive functioning
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.
The Rancho Los Amigos Scale (RLAS), a.k.a. the Rancho Los Amigos Levels of Cognitive Functioning Scale (LOCF) or Rancho Scale, is a medical scale used to assess individuals after a closed head injury, including traumatic brain injury, based on cognitive and behavioural presentations as they emerge from coma.

Persistent vegetative state

vegetative statevegetativepermanent vegetative state
After this time, some patients gradually come out of the coma, some progress to a vegetative state, and others die.
This condition differs from a coma: a coma is a state that lacks both awareness and wakefulness.

Reversal of Fortune

1990Reversal Fortunethe 1990 film
Dr. 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 victim and the agony of waiting for a patient to awaken: Reversal of Fortune (1990) and The Dreamlife of Angels (1998).
It recounts the true story of the unexplained coma of socialite Sunny von Bülow, the subsequent attempted murder trial, and the eventual acquittal of her husband, Claus von Bülow, who had Dershowitz acting as his defense.

Brain death

brain deadbrain-deadbraindead
Brain death, lack of activity in both cortex, and lack of brainstem function
It is also distinct from an ordinary coma, whether induced medically or caused by injury and/or illness, even if it is very deep, as long as some brain and bodily activity and function remains; and it is also not the same as the condition known as locked-in syndrome.

Brain damage

brain injurybrain injuriesbrain
Time is the best general predictor of a chance of recovery: 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.
The most severe cases result in coma or even persistent vegetative state.

Coma scale

glasgow coma scale
Coma scale, a system to assess the severity of coma
A coma scale is a system to assess the severity of coma.