In medicine Medicine is the art and science of healing. It encompasses a range of health care practices evolved to maintain and restore health by the prevention and treatment of illness, a coma (from the Greek Greek , an Indo-European language native to the southern Balkan peninsula, is the language of the Greeks. It forms an independent branch within Indo-European. It has the longest documented history of any Indo-European language, spanning 34 centuries of written records. In its ancient form, it is the language of classical Ancient Greek literature κῶμα koma, meaning deep sleep) is a profound state of unconsciousness Unconsciousness, more appropriately referred to as loss of consciousness or lack of consciousness, is a dramatic alteration of mental state that involves complete or near-complete lack of responsiveness to people and other environmental stimuli. Being in a comatose state or coma is an illustration of unconsciousness. Fainting due to a drop in. A comatose person cannot be awakened, fails to respond normally to pain or light, does not have sleep-wake cycles A circadian rhythm is a roughly-24-hour cycle in the biochemical, physiological or behavioral processes of living entities, including plants, animals, fungi and cyanobacteria . The term "circadian", coined by Franz Halberg, comes from the Latin circa, "around," and diem or dies, "day", meaning literally ", and does not take voluntary actions.

Coma may result from a variety of conditions, including intoxication Intoxication is the state of being affected by one or more psychoactive drugs. It can also refer to the effects caused by the ingestion of poison or by the overconsumption of normally harmless substances, metabolic Metabolism is the set of chemical reactions that occur in living organisms in order to maintain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories. Catabolism breaks down organic matter, for example to harvest energy in abnormalities, central nervous system diseases, acute neurologic injuries such as stroke A stroke is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia (lack of blood supply) caused by thrombosis or embolism or due to a hemorrhage. As a result, the affected area of the brain is unable to function, leading to inability to move one or more limbs on one side of, and hypoxia Hypoxia is a pathological condition in which the body as a whole or a region of the body (tissue hypoxia) is deprived of adequate oxygen supply. Variations in arterial oxygen concentrations can be part of the normal physiology, for example, during strenuous physical exercise. A mismatch between oxygen supply and its demand at the cellular level. A coma may also result from head trauma Head injury refers to trauma to the head. This may or may not include injury to the brain. However, the terms traumatic brain injury and head injury are often used interchangeably in the medical literature caused by mechanisms such as falls or car accidents A traffic collision is when a road vehicle collides with another vehicle, pedestrian, animal, or geographical or architectural obstacle. Traffic collisions can result in injury, property damage, and death. It may also be deliberately induced A barbiturate-induced coma, or barb coma, is a temporary coma brought on by a controlled dose of a barbiturate drug, usually pentobarbital or thiopental. Barbiturate comas are used to protect the brain during major neurosurgery, and as a last line of treatment in certain cases of status epilepticus that have not responded to other treatments by pharmaceutical agents in order to preserve higher brain function following another form of brain trauma, or to save the patient from extreme pain during healing of injuries or diseases. The underlying cause of coma is bilateral damage to the Reticular formation The reticular formation is a part of the brain that is involved in actions such as awaking/sleeping cycle, and filtering incoming stimuli to discriminate irrelevant background stimuli. It is essential for governing some of the basic functions of higher organisms, and is one of the phylogenetically oldest portions of the brain of the midbrain In biological anatomy, the mesencephalon comprises the tectum (or corpora quadrigemini), tegmentum, the ventricular mesocoelia (or "iter"), and the cerebral peduncles, as well as several nuclei and fasciculi. Caudally the mesencephalon adjoins the pons (metencephalon) and rostrally it adjoins the diencephalon (Thalamus, hypothalamus, et, which is important in regulating sleep.^[1]

If the cause of coma is not clear, various investigations (blood tests A blood test is a laboratory analysis performed on a blood sample that is usually extracted from a vein in the arm using a needle, or via fingerprick, medical imaging Medical imaging refers to the techniques and processes used to create images of the human body for clinical purposes (medical procedures seeking to reveal, diagnose or examine disease) or medical science (including the study of normal anatomy and physiology)) may be performed to establish the cause and identify reversible causes. Coma usually necessitates admission to hospital A hospital is an institution for health care providing patient treatment by specialized staff and equipment, and often but not always providing for longer-term patient stays and often the intensive care unit An intensive care unit , critical care unit (CCU), intensive therapy unit or intensive treatment unit (ITU) is a specialized department used in many countries' hospitals that provides intensive care medicine. Many hospitals also have designated intensive care areas for certain specialities of medicine, as dictated by the needs and available.

Signs and symptoms

The severity and mode of onset of coma depends on the underlying cause. For instance, deepening hypoglycemia Hypoglycemia or hypoglycaemia is the medical term for a pathologic state produced by a lower than normal level of blood glucose. The term hypoglycemia literally means "under-sweet blood" (low blood sugar) or hypercapnia Hypercapnia or hypercapnea , also known as hypercarbia, is a condition where there is too much carbon dioxide (CO2) in the blood. Carbon dioxide is a gaseous product of the body's metabolism and is normally expelled through the lungs (increased carbon dioxide Carbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state levels in the blood) initially causes mild agitation and confusion, then progressing to obtundation Obtunded refers to a patient who has less than full mental capacity, typically as a result of a medical condition or trauma. The root word, obtund, means dulled or less sharp, stupor and finally complete unconsciousness. In contrast, coma resulting from a severe traumatic brain injury Traumatic brain injury occurs when an outside force traumatically injures the brain. TBI can be classified based on severity, mechanism (closed or penetrating head injury), or other features (e.g. occurring in a specific location or over a widespread area). Head injury usually refers to TBI, but is a broader category because it can involve damage or subarachnoid hemorrhage A subarachnoid hemorrhage (SAH, pronounced /ˌsʌbəˈræknɔɪd ˈhɛmrɪdʒ/, or subarachnoid haemorrhage in British English) is bleeding into the subarachnoid space—the area between the arachnoid membrane and the pia mater surrounding the brain. This may occur spontaneously, usually from a ruptured cerebral aneurysm, or may result from head can be instantaneous. The mode of onset may therefore be indicative of the underlying cause.

In the initial assessment of coma, it is common to gauge the level of consciousness Level of consciousness is a measurement of a person's arousability and responsiveness to stimuli from the environment. A mildly depressed level of consciousness may be classed as lethargy; someone in this state can be aroused with little difficulty. People who are obtunded have a more depressed level of consciousness and cannot be fully aroused 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, unconscious) scale. More elaborate scales, such as the Glasgow coma scale Glasgow Coma Scale or GCS, is a neurological scale which aims to give a reliable, objective way of recording the conscious state of a person, for initial as well as subsequent assessment. A patient is assessed against the criteria of the scale, and the resulting points give a patient score between 3 and either 14 (original scale) or 15 (the more (see below), quantify individual reactions such as eye opening, movement and verbal response on a scale.

In those with deep unconsciousness, there is a risk of asphyxiation Asphyxia (from Greek a-, "without" and σφυγμός , "pulse, heartbeat") is a condition of severely deficient supply of oxygen to the body that arises from being unable to breathe normally. An example of asphyxia is choking. Asphyxia causes generalized hypoxia, which primarily affects the tissues and organs as the control over the muscles in the face and throat is diminished. As a result, those presenting to hospital with coma are typically assessed for this risk ("airway management In nearly all circumstances airway management is the highest priority for clinical care. This is because if there is no airway, there can be no breathing, hence no oxygenation of blood and therefore circulation will soon cease. Getting oxygen to the lungs is the first step in almost all clinical treatments. The ‘A’ is for ‘airway’ in the â€"). If the risk of asphyxiation is deemed to be high, doctors may use various devices (such as an oropharyngeal airway Oropharyngeal airways come in a variety of sizes, from infant to adult, and are used mostly in pre-hospital emergency care. This piece of equipment is utilized by certified first responders, emergency medical technicians, and paramedics when intubation is either not available or not advisable, nasopharyngeal airway In medicine, a nasopharyngeal airway, also known as an NPA or a nasal trumpet because of its flared end, a type of airway adjunct, is a tube that is designed to be inserted into the nasal passageway to secure an open airway. When a patient becomes unconscious, the muscles in the jaw commonly relax and can allow the tongue to slide back and or endotracheal tube An endotracheal tube is used in general anaesthesia, intensive care and emergency medicine for airway management and mechanical ventilation. The tube is inserted into a patient's trachea in order to ensure that the airway is not closed off and that air is able to reach the lungs. The endotracheal tube is regarded as the most reliable available) to safeguard the airway.

Diagnosis

Once a person in a coma is stable, investigations are performed to assess the underlying cause. These may be simple; a computed tomography Computed tomography is a medical imaging method employing tomography. Digital geometry processing is used to generate a three-dimensional image of the inside of an object from a large series of two-dimensional X-ray images taken around a single axis of rotation. The word "tomography" is derived from the Greek tomos (slice) and graphein ( scan of the brain, for example, is performed to identify specific causes of the coma, such as hemorrhage Bleeding, technically known as hemorrhaging or haemorrhaging is the loss of blood from the circulatory system. Bleeding can occur internally, where blood leaks from blood vessels inside the body or externally, either through a natural opening such as the vagina, mouth, nose, or anus, or through a break in the skin. The complete loss of blood is.

Classification

The severity of coma impairment 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.

Two scales of measurement often used in Traumatic Brain Injury Traumatic brain injury occurs when an outside force traumatically injures the brain. TBI can be classified based on severity, mechanism (closed or penetrating head injury), or other features (e.g. occurring in a specific location or over a widespread area). Head injury usually refers to TBI, but is a broader category because it can involve damage (TBI) diagnosis to determine the level of coma are the Glasgow Coma Scale Glasgow Coma Scale or GCS, is a neurological scale which aims to give a reliable, objective way of recording the conscious state of a person, for initial as well as subsequent assessment. A patient is assessed against the criteria of the scale, and the resulting points give a patient score between 3 and either 14 (original scale) or 15 (the more (GCS) and the Ranchos Los Amigos Scale The Rancho Los Amigos Scale is a medical scale intended to assess the level of recovery of brain injury patients and those recovering from coma. It is named after the Rancho Los Amigos National Rehabilitation Center (RLAS). The GCS is a simple 3 to 15-point scale (3 being the worst and 15 being that of a normal person) used by medical professionals to assess severity of neurologic trauma, and establish a prognosis. The RLAS is a more 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.

Prognosis

Outcomes range from recovery to death Death is the state of terminated life. The term "death" refers to both to the event of life's termination and to the state of lack of life. The true nature of the latter has for millennia been a central concern of the world's religious traditions and of philosophical enquiry. Many religions maintain faith in either some kind of afterlife. Comas generally last a few days to a few weeks. They rarely last more than 2 to 5 weeks but some have lasted as long as several years. After this time, some patients gradually come out of the coma, some progress to a vegetative state A persistent vegetative state is a condition of patients with severe brain damage who were in a coma, but then progressed to a state of wakefulness without detectable awareness. It is a diagnosis of some uncertainty in that it deals with a syndrome. It is classified as a Permanent Vegetative State after approximately 1 year of being in a, and others die. Some patients who have entered a vegetative state go on to regain a degree of awareness. Others remain in a vegetative state for years or even decades (the longest recorded period being 37 years).^[2]

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, because some people in deep coma recover well while others in a so-called milder coma sometimes fail to improve.

People may emerge from a coma with a combination of physical, intellectual and psychological difficulties that need special attention. Recovery usually occurs gradually — patients acquire more and more ability to respond. Some patients never progress beyond very basic responses, but many recover full awareness. Regaining consciousness is not instant: in the first days, patients are only awake for a few minutes, and duration of time awake gradually increases.

Predicted chances of recovery are variable owing to different techniques used to measure the extent of neurological damage. All the predictions are based on statistical Statistics is a mathematical science pertaining to the collection, analysis, interpretation or explanation, and presentation of data. Statisticians improve the quality of data with the design of experiments and survey sampling. Statistics also provides tools for prediction and forecasting using data and statistical models. Statistics is applicable rates with some level of chance for recovery present: a person with a low chance of recovery may still awaken. Time is the best general predictor of a chance of recovery: after 4 months of coma caused by brain damage Brain damage may occur due to a wide range of conditions, illnesses, injuries, and as a result of iatrogenesis. Possible causes of widespread brain damage include prolonged hypoxia (shortage of oxygen), poisoning by teratogens (including alcohol), infection, and neurological illness. Chemotherapy can cause brain damage to the neural stem cells and, the chance of partial recovery is less than 15%, and the chance of full recovery is very low.^[3][4]

The most common cause of death for a person in a vegetative state is secondary infection An infection is the detrimental colonization of a host organism by a foreign species. In an infection, the infecting organism seeks to utilize the host's resources to multiply, usually at the expense of the host. The infecting organism, or pathogen, interferes with the normal functioning of the host and can lead to chronic wounds, gangrene, loss such as pneumonia The alveoli are microscopic air-filled sacs in the lungs responsible for absorbing oxygen. Pneumonia can result from a variety of causes, including infection with bacteria, viruses, fungi, or parasites, and chemical or physical injury to the lungs. Its cause may also be officially described as idiopathic—that is, unknown—when infectious causes which can occur in patients who lie still for extended periods.

Occasionally people come out of coma after long periods of time. After 19 years in a minimally conscious state A minimally conscious state is a condition distinct from coma or the vegetative state, in which a patient exhibits deliberate, or cognitively mediated, behavior often enough, or consistently enough, for clinicians to be able to distinguish it from entirely unconscious, reflexive responses, Terry Wallis spontaneously began speaking and regained awareness of his surroundings.^[5] Similarly, Polish Poland /ˈpoʊlənd/ (Polish: Polska), officially the Republic of Poland (Rzeczpospolita Polska), is a country in Central Europe. Poland is bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north. The total railroad worker Jan Grzebski woke up from a 19-year coma in 2007.

A brain-damaged man, 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 In neurotechnology, deep brain stimulation is a surgical treatment involving the implantation of a medical device called a brain pacemaker, which sends electrical impulses to specific parts of the brain. DBS in select brain regions has provided remarkable therapeutic benefits for otherwise treatment-resistant movement and affective disorders such (DBS) successfully roused communication, complex movement and eating ability in the 38-year-old American man who suffered a traumatic brain injury. His injuries left him in a minimally conscious state A minimally conscious state is a condition distinct from coma or the vegetative state, in which a patient exhibits deliberate, or cognitively mediated, behavior often enough, or consistently enough, for clinicians to be able to distinguish it from entirely unconscious, reflexive responses (MCS), a condition akin to a coma but characterized by occasional, but brief, evidence of environmental and self-awareness that coma patients lack.^[6]

Comas in Movies

Research by Dr. Eelco Wijdicks on the depiction of comas in movies was published in Neurology in May 2006. 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). The remaining 28 were criticised for portraying miraculous awakenings with no lasting side effects; unrealistic depictions of treatments and equipment required; and comatose patients remaining tanned, muscular, and suspiciously well turned out.

See also

• Persistent vegetative state A persistent vegetative state is a condition of patients with severe brain damage who were in a coma, but then progressed to a state of wakefulness without detectable awareness. It is a diagnosis of some uncertainty in that it deals with a syndrome. It is classified as a Permanent Vegetative State after approximately 1 year of being in a (vegetative coma), deep coma without detectable awareness
• Brain death Brain death is a legal definition of death that refers to the irreversible end of all brain activity due to total necrosis of the cerebral neurons following loss of blood flow and oxygenation. It should not be confused with a persistent vegetative state. The concept of brain death emerged in the 1960s, as the ability to resuscitate individuals and (irreversible coma), irreversible end of all brain activity
• Process Oriented Coma Work, for an approach to working with residual consciousness in comatose patients
• Level of consciousness Level of consciousness is a measurement of a person's arousability and responsiveness to stimuli from the environment. A mildly depressed level of consciousness may be classed as lethargy; someone in this state can be aroused with little difficulty. People who are obtunded have a more depressed level of consciousness and cannot be fully aroused

References

1. ^ Sundsten, John W.; Nolte, John (2001). The human brain: an introduction to its functional anatomy. St. Louis: Mosby. ISBN 0-323-01320-1.
2. ^ According to the Guinness Book of Records Guinness World Records, known until 2000 as The Guinness Book of Records , is a reference book published annually, containing an internationally recognized [vague] collection of world records, both human achievements and the extremes of the natural world. The book itself holds a world record, as the best-selling copyrighted series of all-time, the longest period spent in coma was by Elaine Esposito. She did not wake up after being anaesthetized for an appendectomy on August 6, 1941, at age 6. She died on November 25, 1978 at age 43 years 357 days, having been in a coma for 37 years 111 days.
3. ^ Formisano R, Carlesimo GA, Sabbadini M, et al. (May 2004). "Clinical predictors and neuropsychological outcome in severe traumatic brain injury patients". Acta Neurochir (Wien) 146 (5): 457–62. doi:10.1007/s00701-004-0225-4. PMID 15118882.
4. ^ brain injury .com | Coma traumatic brain injury - Brain Injury Coma
5. ^ Mother stunned by coma victim's unexpected words - smh.com.au
6. ^ "Electrodes stir man from six-year coma-like state". Cosmos Magazine. 2 August 2007. http://www.cosmosmagazine.com/node/1513.

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