Concussion Classification and external resources
Deceleration can exert rotational forces in the brain, especially the midbrain and diencephalon.
ICD-10	S06.0
ICD-9	850
MedlinePlus	000799
eMedicine	aaem/123  sports/27
MeSH	D001924

Concussion, from the Latin concutere ("to shake violently"),^[1] is the most common and least serious type of traumatic brain injury. The terms mild brain injury, mild traumatic brain injury (MTBI), mild head injury (MHI), and minor head trauma and concussion may be used interchangeably,^[2][3] although the latter is often treated as a narrower category.^[4] The term 'concussion', has been used for centuries and is still commonly used in sports medicine, while 'MTBI' is a technical term used more commonly nowadays in general medical contexts. Frequently defined as a head injury with a transient loss of brain function, concussion can cause a variety of physical, cognitive, and emotional symptoms. Cover of Devilyns album XI Devilyn is death metal band from Poland. ... Acceleration is the time rate of change of velocity, and at any point on a v-t graph, it is given by the gradient of the tangent to that point In physics, acceleration (symbol: a) is defined as the rate of change (or time derivative) of velocity. ... In biological anatomy, the mesencephalon (or midbrain) is the middle of three vesicles that arise from the neural tube that forms the brain of developing animals. ... The diencephalon is the region of the brain that includes the epithalamus, thalamus, and hypothalamus. ... The International Statistical Classification of Diseases and Related Health Problems (most commonly known by the abbreviation ICD) provides codes to classify diseases and a wide variety of signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or disease. ... The International Statistical Classification of Diseases and Related Health Problems 10th Revision (ICD-10) is a coding of diseases and signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or diseases, as classified by the World Health Organization (WHO). ... // S00-T14 - Injury (S00-S09) head (S00) Superficial injury of head (S01) Open wound of head (S02) Fracture of skull and facial bones (S03) Dislocation, sprain and strain of joints and ligaments of head (S04) Injury of cranial nerves (S05) Injury of eye and orbit (S06) Intracranial injury (S07) Crushing... The International Statistical Classification of Diseases and Related Health Problems (most commonly known by the abbreviation ICD) provides codes to classify diseases and a wide variety of signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or disease. ... The following is a list of codes for International Statistical Classification of Diseases and Related Health Problems. ... MedlinePlus (medlineplus. ... eMedicine is an online clinical medical knowledge base that was founded in 1996. ... Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. ... For other uses, see Latins and Latin (disambiguation). ... Traumatic brain injury (TBI), traumatic injuries to the brain, also called intracranial injury, or simply head injury, occurs when a sudden trauma causes brain damage. ... This article or section is in need of attention from an expert on the subject. ... Head injury is a trauma to the head, that may or may not include injury to the brain (see also brain injury). ... Visual system Auditory system Olfactory system Gustatory system Somatosensory system Visual perception Motor cortex Brocas area (aka Language Area) Lateralization of brain function Phrenology Cybernetics Connectionism Modularity of mind Artificial intelligence Society of Mind Neuropsychology Electroencephalography Electrophysiology Magnetoencephalography Functional MRI Positron emission tomography Categories: | ... Look up Cognition in Wiktionary, the free dictionary. ...

Concussion can be diagnosed and assigned a level of severity based largely on symptoms. Treatment involves monitoring and rest. Symptoms usually go away entirely within three weeks, though they may persist, or complications may occur.^[5] Repeated concussions can cause cumulative brain damage such as dementia pugilistica or severe complications such as second-impact syndrome. Brain damage or brain injury is the destruction or degeneration of brain cells. ... Dementia pugilistica, also called chronic traumatic encephalopathy, pugilistic Parkinsons syndrome, boxers dementia, and punch-drunk syndrome, is a neurological disorder which affects some career boxers and others who receive multiple dazing blows to the head. ...

Due to factors such as widely varying definitions and possible underreporting of concussion, the rate at which it occurs annually is not known; however it may be more than 6 per 1000 people.^[6] Common causes include sports injuries, bicycle accidents, auto accidents, and falls; the latter two are the most frequent causes among adults.^[7] Concussion may be caused by a blow to the head, or by acceleration or deceleration forces without a direct impact. The forces involved disrupt cellular processes in the brain for days or weeks. Acceleration is the time rate of change of velocity and/or direction, and at any point on a velocity-time graph, it is given by the slope of the tangent to the curve at that point. ... For other uses, see Brain (disambiguation). ...

It is not known whether the concussed brain is structurally damaged the way it is in other types of brain injury (albeit to a lesser extent) or whether concussion mainly entails a loss of function with physiological but not structural changes.^[8] Cellular damage has reportedly been found in concussed brains, but it may have been due to artifacts from the studies.^[9] A debate about whether structural damage exists in concussion has raged for centuries and is ongoing. This article or section does not cite any references or sources. ...

Definitions

No single definition of concussion, mild head injury,^[10] or mild traumatic brain injury is universally accepted, though a variety of definitions have been offered.^[11] In 2001, the first International Symposium on Concussion in Sport was organized by the International Olympic Committee Medical Commission and other sports federations.^[12] A group of experts called the Concussion in Sport Group met there and defined concussion as "a complex pathophysiological process affecting the brain, induced by traumatic biomechanical forces."^[13] They agreed that concussion typically involves temporary impairment of neurological function which quickly resolves by itself, and that neuroimaging normally shows no gross structural changes to the brain as the result of the condition.^[5] It has been suggested that this article or section be merged with functional neuroimaging. ...

According to the classic definition, no structural brain damage occurs in concussion;^[14] it is a functional state, meaning that symptoms are caused primarily by temporary biochemical changes in neurons, taking place for example at their cell membranes and synapses.^[5] However, in recent years researchers have included injuries in which structural damage does occur under the rubric of concussion. According to the National Institute for Health and Clinical Excellence definition, concussion may involve a physiological or physical disruption in the brain's synapses.^[15] Wöhler observes the synthesis of urea. ... This article is about cells in the nervous system. ... Look up cell membrane in Wiktionary, the free dictionary. ... Illustration of the major elements in a prototypical synapse. ... Injury is damage or harm caused to the structure or function of the body caused by an outside agent or force, which may be physical or chemical. ... The National Institute for Health and Clinical Excellence or NICE is an agency of the National Health Service in the United Kingdom. ... Illustration of the major elements in a prototypical synapse. ...

Definitions of mild traumatic brain injury (M.T.B.I) have been inconsistent since the 1970s, but the World Health Organization's International Statistical Classification of Diseases and Related Health Problems (ICD-10) described MTBI-related conditions in 1992, providing a consistent, authoritative definition across specialties.^[3] In 1993, the American Congress of Rehabilitation Medicine defined MTBI as 30 minutes or fewer of loss of consciousness (LOC), 24 hours or fewer of post-traumatic amnesia (PTA), and a Glasgow Coma Scale (GCS) score of at least 13.^[16] In 1994, the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders defined MTBI using PTA and LOC.^[3] Other definitions of MTBI incorporate focal neurological deficit and altered mental status, in addition to PTA and GCS.^[11] WHO redirects here. ... The International Statistical Classification of Diseases and Related Health Problems (commonly known by the abbreviation ICD) is a detailed description of known diseases and injuries. ... 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. ... The Glasgow Coma Scale 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 continuing assessment. ... Due to the epidemic of medical errors, readers are cautioned to be aware that the American Psychiatric Association isnt immune to this. ... The Diagnostic and Statistical Manual published by the American Psychiatric Association The Diagnostic and Statistical Manual of Mental Disorders (DSM) is a handbook for mental health professionals that lists different categories of mental disorder and the criteria for diagnosing them, according to the publishing organization the American Psychiatric Association. ...

Concussion falls under the classification of mild TBI.^[17] It is not clear whether concussion is implied in mild brain injury or mild head injury.^[18] "MTBI" and "concussion" are often treated as synonyms in medical literature.^[16] However, other injuries such as intracranial hemorrhages (e.g. intra-axial hematoma, epidural hematoma, and subdural hematoma) are not necessarily precluded in MTBI^[5] or mild head injury,^[19][20] but they are in concussion.^[21] MTBI associated with abnormal neuroimaging may be considered "complicated MTBI".^[22] "Concussion" can be considered to imply a state in which brain function is temporarily impaired and "MTBI" to imply a pathophysiological state, but in practice few researchers and clinicians distinguish between the terms.^[5] Descriptions of the condition, including the severity and the area of the brain affected, are now used more often than "concussion" in clinical neurology.^[23] This article needs cleanup. ... Intra-axial hemorrhages, or intra-axial hematomas, are a subtype of intracranial hemorrhage that occur within the brain tissue itself. ... Nontraumatic epidural hematoma in a young woman. ... A subdural hematoma (SDH) is a form of traumatic brain injury in which blood collects between the dura (the outer protective covering of the brain) and the arachnoid (the middle layer of the meninges). ... Pathophysiology is the study of the disturbance of normal mechanical, physical, and biochemical functions, either caused by a disease, or resulting from a disease or abnormal syndrome or condition that may not qualify to be called a disease. ...

Although the term "concussion" is still used in sports literature as interchangeable with "MHI" or "MTBI", the general clinical medical literature now uses "MTBI" instead.^[24]

Controversy exists about whether the definition of concussion should include only those injuries in which loss of consciousness occurs.^[1] Historically, concussion by definition involved a loss of consciousness, but the definition has changed over time to include a change in consciousness, such as amnesia.^[25] The best-known concussion grading scales count head injuries in which loss of consciousness does not occur to be mild concussions and those in which it does to be more severe.^[26] Unconsciousness is the absence of consciousness. ...

Causes

The leading causes of MTBI in adults are falls and vehicle accidents, and other causes include sports injuries, assaults, industrial and work-related injuries, and injuries that occur in the home.^[11] Among children aged 5 to 14, sports and bicycle accidents cause the greatest number of concussions.^[7] Soldiers are at elevated risk for concussion from causes such as bomb blasts, with as many as 15% of U.S. infantry soldiers who return from the Iraq War meeting the criteria for MTBI.^[27] For other uses, see Iraq war (disambiguation). ...

The relative contribution of causes of mild head injury differs by region, gender, and age.^[5] For example, in Scotland and Sweden, falls account for the greatest percentage of MHIs, while in the U.S. and Australia, transportation is the largest cause.^[5]

Mechanism

Rotational force is key in concussion. Punches in boxing deliver more rotational force to the head than impacts in sports such as football, and boxing carries a higher risk of concussion than football.^[28]

The brain is surrounded by cerebrospinal fluid, one of the functions of which is to protect it from light trauma, but more severe impacts or the forces associated with rapid acceleration and deceleration may not be absorbed by this cushion.^[8] Concussion may be caused by impact forces, in which the head strikes or is struck by something, or impulsive forces, in which the head moves without itself being subject to blunt trauma (for example, when the chest hits something and the head snaps forward).^[4] A human brain. ... Cerebrospinal fluid (CSF), Liquor cerebrospinalis, is a clear bodily fluid that occupies the subarachnoid space in the brain (the space between the skull and the cerebral cortex—more specifically, between the arachnoid and pia layers of the meninges). ... For other uses, see Force (disambiguation). ... In medical terminology, blunt trauma, blunt injury, non-penetrating trauma or blunt force trauma refers to a type of physical trauma caused to a bodypart, either by impact, injury or physical attack; the latter usually being referred to as blunt force trauma. ...

Forces may cause linear, rotational, or angular movement of the brain, or a combination of these types of motion.^[4] In rotational movement, the head turns around its center of gravity, and in angular movement it turns on an axis other than its center of gravity.^[4] The amount of rotational force is thought to be the major type of force to cause concussion^[29] and the largest component in its severity.^[5] Studies with athletes have shown that the amount of force and the location of the impact are not necessarily correlated to the severity of the concussion or its symptoms, and have called into question the threshold for concussion previously thought to exist at around 70-75g.^[30][31] The term g force or gee force refers to the symbol g, the force of acceleration due to gravity at the earths surface. ...

The parts of the brain most affected by rotational forces are the midbrain and diencephalon.^[1][7] It is thought that the forces from the injury disrupt the normal cellular activities in the reticular activating system located in these areas, and that this disruption produces the loss of consciousness often seen in concussion.^[7] Other areas of the brain that may be affected include the upper part of the brain stem, the fornix, the corpus callosum, the temporal lobe, and the frontal lobe.^[32] In biological anatomy, the mesencephalon (or midbrain) is the middle of three vesicles that arise from the neural tube that forms the brain of developing animals. ... The diencephalon is the region of the brain that includes the epithalamus, thalamus, and hypothalamus. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell being used to describe the smallest unit of a living organism Cells in culture, stained for keratin (red) and DNA (green) The cell is the... The reticular activating system is the name given to part of the brain (the Reticular Formation and its connections) believed to be the centre of arousal and motivation in animals (including humans). ... The brain stem is the lower part of the brain, adjoining and structurally continuous with the spinal cord. ... The fornix is also the name of part of the cervix. ... The corpus callosum is a structure of the mammalian brain in the longitudal fissure that connects the left and right cerebral hemispheres. ... The temporal lobes are part of the cerebrum. ... {{Infobox Brain| Name = Frontal lobe | Latin = lobus frontalis | GraySubject = 189 | GrayPage = 821 | Map = Cerebrum map| MapPos = | MapCaption = Principal fissures and lobes of the cerebrum viewed laterally. ...

Pathophysiology

In both animals and humans, MTBI can alter the brain's physiology for hours to weeks, setting into motion a variety of pathological events.^[33] Though these events are thought to interfere with neuronal and brain function, the metabolic processes that follow concussion are reversed in a large majority of affected brain cells; however a few cells may die after the injury.^[22] A renal cell carcinoma (chromophobe type) viewed on a hematoxylin & eosin stained slide Pathologist redirects here. ... Structure of the coenzyme adenosine triphosphate, a central intermediate in energy metabolism. ... Brain cells incude mostly neurons and glial cells. ...

Included in the cascade of events unleashed in the brain by concussion is impaired neurotransmission, loss of regulation of ions, deregulation of energy use and cellular metabolism, and a reduction in cerebral blood flow.^[22] Excitatory neurotransmitters, chemicals such as glutamate that serve to stimulate nerve cells, are released in excessive amounts as the result of the injury.^[34] The resulting cellular excitation causes neurons to fire excessively.^[35] This creates an imbalance of ions such as potassium and calcium across the cell membranes of neurons (a process like excitotoxicity).^[22] Since the neuron firing involves a net influx of positively charged ions into the cell, the ionic imbalance causes cells to have a more positive membrane potential (i.e. it leads to neuronal depolarization). This depolarization in turn causes ion pumps that serve to restore resting potential within cells to work more than they normally do.^[22] This increased need for energy leads cells to require greater-than-usual amounts of glucose, which is made into ATP, an important source of energy for cells.^[22] The brain may stay in this state of hypermetabolism for days or weeks.^[36] At the same time, cerebral blood flow is relatively reduced for unknown reasons,^[37] though the reduction in blood flow is not as severe as it is in ischemia.^[22] Thus cells get less glucose than they normally do, which causes an "energy crisis".^[37] Neurotransmitters are chemicals that are used to relay, amplify and modulate electrical signals between a neuron and another cell. ... This article is about the electrically charged particle. ... Cerebral blood flow, or CBF, is the amount of blood that enters the brain. ... Chemical structure of D-aspartic acid, a common amino acid neurotransmitter. ... Glutamate is the anion of glutamic acid. ... A. A schematic view of an idealized action potential illustrates its various phases as the action potential passes a point on a cell membrane. ... Potassium is the main intracellular ion for all types of cells. ... Calcium (Ca2+) plays a vital role in the anatomy, physiology and biochemistry of organisms and of the cell, particularly in signal transduction pathways. ... Excitotoxicity is the pathological process by which nerve cells are damaged and killed by glutamate and similar substances. ... Electric charge is a fundamental property of some subatomic particles, which determines their electromagnetic interactions. ... Membrane potential (or transmembrane potential or transmembrane potential difference or transmembrane potential gradient), is the electrical potential difference (voltage) across a cells plasma membrane. ... In biology, depolarization is the event a cell undergoes when its membrane potential grows more positive with respect to the extracellular solution. ... Sputter ion pumps are a class of vacuum pump designed to operate in very low pressure (i. ... The resting potential of a cell is the membrane potential that would be maintained if there were no action potentials, synaptic potentials, or other active changes in the membrane potential. ... Glucose (Glc), a monosaccharide (or simple sugar), is an important carbohydrate in biology. ... Adenosine 5-triphosphate (ATP) is a multifunctional nucleotide that is most important as a molecular currency of intracellular energy transfer. ... In medicine, ischemia (Greek ισχαιμία, isch- is restriction, hema or haema is blood) is a restriction in blood supply, generally due to factors in the blood vessels, with resultant damage or dysfunction of tissue. ...

Concurrently with these processes, the activity of mitochondria may be reduced, which causes cells to rely on anaerobic metabolism to produce energy, which increases levels of the byproduct lactate.^[22] Electron micrograph of a mitochondrion showing its mitochondrial matrix and membranes In cell biology, a mitochondrion (plural mitochondria) is a membrane-enclosed organelle that is found in most eukaryotic cells. ... Glycolysis is the initial metabolic pathway of carbohydrate catabolism. ... Lactic acid is a chemical compound that plays a role in several biochemical processes. ...

For a period of minutes to days after a concussion, the brain is especially vulnerable to changes in intracranial pressure, blood flow, and anoxia.^[37] According to studies performed on animals, large numbers of neurons can die during this period in response to slight, normally innocuous changes in blood flow.^[37] Intracranial pressure, (ICP), is the pressure exerted by the cranium on the brain tissue, cerebrospinal fluid (CSF), and the brains circulating blood volume. ... Hypoxia is a pathological condition in which the body as a whole (generalised hypoxia) or region of the body (tissue hypoxia) is deprived of adequate oxygen supply. ...

Concussion involves diffuse brain injury (as opposed to focal brain injury), meaning that the dysfunction occurs over a widespread area of the brain rather than in a particular spot.^[38] Concussion is thought to be a milder type of diffuse axonal injury because axons may be injured to a minor extent due to stretching.^[4] Animal studies in which primates were concussed have revealed damage to brain tissues such as small petechial hemorrhages and axonal injury.^[39] Axonal damage has been found in the brains of concussion sufferers who died from other causes, but inadequate blood flow to the brain due to other injuries may have contributed to the damage.^[9] Diffuse axonal injury (DAI) is one of the most common and devastating types of brain injury (Iwata , 2004), occurring in almost half of all cases of severe head trauma (Park and Hyun, 2004). ... An axon or nerve fiber, is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neurons cell body or soma. ... This article is in need of attention from an expert on the subject. ...

Signs and symptoms

Common symptoms in MTBI include headache and difficulty concentrating.^[16]

Concussion can be associated with a variety of symptoms, which typically occur rapidly after the injury.^[12] Early symptoms usually subside within days or weeks.^[9] The number and type of symptoms a person suffers varies widely.^[11]

Physical

Headache is the most common MTBI symptom.^[16] Other symptoms include dizziness, vomiting, nausea, lack of motor coordination, difficulty balancing,^[16] or other problems with movement or sensation. Visual symptoms include light sensitivity,^[37] seeing bright lights,^[40] blurred vision,^[9] and double vision.^[41] Tinnitus, or a ringing in the ears, is also commonly reported.^[9] In one in about seventy concussions, concussive convulsions occur, but these are not actual post-traumatic epilepsy, which is a symptom of more serious injury.^[42] Concussive convulsions are thought to result from temporary loss of brain function rather than from structural damage and are usually associated with a good outcome.^[43] A headache (cephalgia in medical terminology) is a condition of pain in the head; sometimes neck or upper back pain may also be interpreted as a headache. ... For other uses, see Nausea (disambiguation). ... Explain the dystonias connected with motor coordination. ... It has been suggested that this article or section be merged with Sensation and perception psychology. ... Photophobia (also light sensitivity) or fear of light, is a symptom of excessive sensitivity to light and the aversion to sunlight or well-lit places. ... Diplopia, commonly known as double vision, is the perception of two images from a single object. ... Tinnitus (pronounced or ,[1] from the Latin word for ringing[2]) is the perception of sound in the human ear in the absence of corresponding external sound(s). ... This article is about the medical condition. ...

Cognitive and emotional

Cognitive symptoms include confusion, disorientation, and difficulty focusing attention. Loss of consciousness may occur but is not necessarily correlated with the severity of the concussion if it is brief.^[13] Post-traumatic amnesia, in which the person cannot remember events leading up to the injury or after it, or both, is a hallmark of concussion.^[16] Confusion, another concussion hallmark, may be present immediately or may develop over several minutes.^[16] A patient may, for example, repeatedly ask the same questions,^[44] be slow to respond to questions or directions, have a vacant stare, or have slurred^[16] or incoherent speech.^[45] Other MTBI symptoms include changes in sleeping patterns^[9] and difficulty with reasoning,^[41] concentrating, and performing everyday activities.^[16] Orientation is a function of the mind involving awareness of three dimensions: (1) time, (2) place and (3) person. ... This article is about psychological concept of attention. ... Severe confusion of a degree considered pathological usually refers to loss of orientation (ability to place oneself correctly in the world by time, location, and personal identity), and often memory (ability to correctly recall previous events or learn new materal). ...

Affective results of concussion include crankiness, loss of interest in favorite activities or items,^[46] tearfulness,^[4] and displays of emotion that are inappropriate to the situation.^[45] Common symptoms in concussed children include restlessness, lethargy, and irritability.^[36] In psychology, affect is the scientific term used to describe a subjects externally displayed mood. ...

Diagnosis

Diagnosis of MTBI is based on physical and neurological exams, duration of unconsciousness (usually less than 30 minutes) and post-traumatic amnesia (PTA; usually less than 24 hours), and the Glasgow Coma Scale (MTBI sufferers have scores of 13 to 15).^[47] Neuropsychological tests exist to measure cognitive function.^[9] The tests may be administered hours, days, or weeks after the injury, or at different times to determine whether there is a trend in the patient's condition.^[48] Athletes may be tested before a sports season begins to provide a baseline comparison in the event of an injury.^[49] Neuropsychological tests are specifically designed tasks used to measure a psychological function known to be linked to a particular brain structure or pathway. ...

Unequal pupil size is a sign of a brain injury more serious than concussion.

Health care providers examine head trauma survivors to ensure that the injury is not a more severe medical emergency such as an intracranial hemorrhage. Indications that screening for more serious injury is needed include worsening of symptoms such as headache, persistent vomiting,^[50] increasing disorientation or a deteriorating level of consciousness,^[51] seizures, and unequal pupil size.^[52] Patients with such symptoms, or who are at higher risk for a more serious brain injury, are given MRIs or CT scans to detect brain lesions and are observed by medical staff. {{Otheruses4|the medical term|the Australian television series|Medical Emergenc an immediate threat to a persons life or long term health. ... Anisocoria is a condition characterized by an unequal size of the pupils. ... MRI redirects here. ... CAT apparatus in a hospital Computed axial tomography (CAT), computer-assisted tomography, computed tomography, CT, or body section roentgenography is the process of using digital processing to generate a three-dimensional image of the internals of an object from a large series of two-dimensional X-ray images taken around...

Health care providers make the decision about whether to give a CT scan using the Glasgow Coma Scale.^[7] In addition, they may be more likely to perform a CT scan on people who would be difficult to observe after discharge or those who are intoxicated, at risk for bleeding, older than 60,^[7] or younger than 16. Most concussions cannot be detected with MRI or CT scans.^[29] However, changes have been reported to show up on MRI and SPECT imaging in concussed people with normal CT scans, and post-concussion syndrome may be associated with abnormalities visible on SPECT and PET scans.^[22] Mild head injury may or may not produce abnormal EEG readings.^[53] ... Post-concussion syndrome, also known as postconcussive syndrome or PCS, is a set of symptoms that a person may experience for weeks, months, or even years after a concussion, a mild form of traumatic brain injury. ... Single photon emission computed tomography (SPECT) is a nuclear medicine tomographic imaging technique using gamma rays. ... Image of a typical positron emission tomography (PET) facility Positron emission tomography (PET) is a nuclear medicine medical imaging technique which produces a three-dimensional image or map of functional processes in the body. ... EEG redirects here. ...

Concussion may be under-diagnosed. The lack of the highly noticeable signs and symptoms that are frequently present in other forms of head injury could lead clinicians to miss the injury, and athletes may cover up their injuries in order to be allowed to remain in the competition.^[24] A retrospective survey in 2005 found that more than 88% of concussions go unrecognized.^[54] Clinician is a term used generically to describe a wide range of medical professionals See Doctor, Medicine Category: ...

Diagnosis of concussion can be complicated because it shares symptoms with other conditions. For example, post-concussion symptoms such as cognitive problems may be misattributed to brain injury when they are in fact due to post-traumatic stress disorder (PTSD).^[55] Post-traumatic stress disorder (PTSD) is a term for certain severe psychological consequences of exposure to, or confrontation with, stressful events that the person experiences as highly traumatic. ...

Grading systems

Main article: Concussion grading systems

At least 41 systems exist to measure the severity, or grade, of a mild head injury,^[5] and there is little agreement among professionals about which is the best.^[40] Several of the systems use loss of consciousness and amnesia as the primary determinants of the severity of the concussion.^[40]

The decision about when to allow athletes to return to contact sports is frequently based on the grade of concussion. Injured athletes are prohibited from returning to play before they are symptom-free during rest and exertion and their neuropsychological tests are normal again, in order to avoid a risk of cumulative effects.

Three grading systems are followed most widely: one was developed by Robert Cantu, one by the Colorado Medical Society, and a third by the American Academy of Neurology.^[26] Each divides concussion into three grades, as summarized in the following table:^[40] The Colorado Medical Society (CMS) is the largest group of organized physicians in Colorado. ... The American Academy of Neurology (AAN) is a professional society for neurologists and neuroscientists. ...

Prevention

Further information: Association football headgear, Bicycle helmet, Football helmet, Hockey helmet, Motorcycle helmet, and Ski helmet

Prevention of MTBI involves taking general measures to prevent traumatic brain injury, such as wearing seat belts and using airbags in cars.^[16] Older people are encouraged to try to prevent falls, for example by keeping floors free of clutter and wearing thin, flat, shoes with hard soles that do not interfere with balance.^[46] Bicycle helmet A bicycle helmet is a helmet intended to be worn while riding a bicycle. ... Group of men drilling in football helmets A football helmet is a protective device used primarily in American football and Canadian football which was created by Paul Brown. ... A hockey helmet is worn by ice hockey players and field hockey goalkeepers to protect the head from potential injury. ... Two white motorcycle helmets, full-face and open-face. ... The ski helmet is an essential protection measure in skiing that is built and designed for multiple impacts. ... This article is about the safety device. ... For the Mozilla crash reporting software previously called Airbag, see Breakpad. ...

Use of protective equipment such as headgear has been found to reduce the number of concussions in athletes.^[28] Improvements in the design of protective athletic gear such as helmets may decrease the number and severity of such injuries.^[56] Changes to the rules or the practices of enforcing existing rules in sports, such as those against "head-down tackling", or "spearing", which is associated with a high injury rate, may also prevent concussions.^[28]

Treatment

Usually concussion symptoms go away without treatment,^[57] and no specific treatment exists.^[58] About one percent of people who receive treatment for MTBI need surgery for a brain lesion.^[47] Traditionally, concussion sufferers are prescribed rest,^[58] including plenty of sleep at night plus rest during the day.^[52] Health care providers recommend a gradual return to normal activities at a pace that does not cause symptoms to worsen.^[52] Education about symptoms, how to manage them, and their normal time course can lead to an improved outcome.^[11]

Medications may be prescribed to treat symptoms such as sleep problems and depression.^[11] Analgesics such as ibuprofen can be taken for the headaches that frequently occur after concussion.^[5] Concussed individuals are advised not to drink alcohol or take drugs that have not been approved by a doctor, as they could impede healing.^[52] An analgesic (colloquially known as a painkiller) is any member of the diverse group of drugs used to relieve pain (achieve analgesia). ... Ibuprofen (INN) (IPA: ) (from the earlier nomenclature iso-butyl-propanoic-phenolic acid) is a non-steroidal anti-inflammatory drug (NSAID) originally marketed as Nurofen and since under various trademarks, including Act-3, Advil, Brufen, Dorival, Herron Blue, Panafen, Motrin, Nuprin and Burana (Finland), Ipren or Ibumetin (Denmark and Sweden), Ibuprom... Alcoholic beverages An alcoholic beverage is a drink containing ethanol, commonly known as alcohol, although in chemistry the definition of alcohol includes many other compounds. ... For other uses, see Drug (disambiguation). ...

Observation to monitor for worsening condition is an important part of treatment.^[59] Health care providers recommend that those suffering from concussion return for further medical care and evaluation 24 to 72 hours after the concussive event if the symptoms worsen. Athletes, especially intercollegiate or professional athletes, are typically followed closely by team trainers during this period. But others may not have access to this level of health care and may be sent home with no medical person monitoring them unless the situation gets worse. Patients may be released from the hospital to the care of a trusted person with orders to return if they display worsening symptoms^[7] or those which might indicate an emergent condition, like unconsciousness or altered mental status; convulsions; severe, persistent headache; extremity weakness; vomiting; or new bleeding or deafness in either or both ears.^[60] Repeated observation for the first 24 hours after concussion is recommended; however it is not known whether it is necessary to wake the patient up every few hours.^[7] A physician visiting the sick in a hospital. ... Professional sports began at North Panola High School in the early 1600s. ... Mental status examination, or MSE, is a medical process where a clinician working in the field of mental health (usually a psychotherapist, social worker, psychiatrist, psychiatric nurse or psychologist) systematically examines a patients mind. ...

Prognosis and lasting effects

MTBI has a mortality rate of almost zero.^[47] The symptoms of most concussions resolve within weeks, but problems may persist.^[5] It is not common for problems to be permanent, and outcome is usually excellent.^[22] People over age 55 may take longer to heal from MTBI or may heal incompletely.^[61] Similarly, factors such as a previous head injury or a coexisting medical condition have been found to predict longer-lasting post-concussion symptoms.^[39] Other factors that may lengthen recovery time after MTBI include psychological problems such as substance abuse or clinical depression, poor health before the injury or additional injuries sustained during it, and life stress.^[22] Longer periods of amnesia or loss of consciousness immediately after the injury may indicate longer recovery times from residual symptoms.^[62] For unknown reasons, having had one concussion significantly increases a person's risk of having another.^[48] The prognosis may differ between concussed adults and children.^[48] Little research has been done on concussion in the pediatric population, but concern exists that severe concussions could interfere with brain development in children.^[48] Also see Alcoholism and Drug addiction. ... On the Threshold of Eternity. ... Pediatrics (also spelled paediatrics or pædiatrics) is the branch of medicine that deals with the medical care of infants and children. ... The study of neural development draws on both neuroscience and developmental biology to describe the cellular and molecular mechanisms by which complex nervous systems emerge during embryonic development and throughout life. ...

Post-concussion syndrome

Main article: Post-concussion syndrome

In post-concussion syndrome, symptoms do not resolve for weeks, months, or years after a concussion, and may occasionally be permanent.^[63] Symptoms may include headaches, dizziness, fatigue, anxiety, memory and attention problems, sleep problems, and irritability.^[64] There is no scientifically established treatment, and rest, a recommended recovery technique, has limited effectiveness.^[58] Symptoms usually go away on their own within months.^[21] The question of whether the syndrome is due to structural damage or other factors such as psychological ones, or a combination of these, has long been the subject of debate.^[55] Post-concussion syndrome, also known as postconcussive syndrome or PCS, is a set of symptoms that a person may experience for weeks, months, or even years after a concussion, a mild form of traumatic brain injury. ... This article is about state anxiety. ...

Cumulative effects

Cumulative effects of concussions are poorly understood. The severity of concussions and their symptoms may worsen with successive injuries, even if a subsequent injury occurs months or years after an initial one.^[65] Symptoms may be more severe and changes in neurophysiology can occur with the third and subsequent concussions.^[48] Studies have had conflicting findings on whether athletes have longer recovery times after repeat concussions and whether cumulative effects such as impairment in cognition and memory occur.^[28] Neurophysiology is a part of physiology as a science, which is concerned with the study of the nervous system. ...

Cumulative effects may include psychiatric disorders and loss of long-term memory. For example, the risk of developing clinical depression has been found to be significantly greater for retired football players with a history of three or more concussions than for those with no concussion history.^[66] Three or more concussions is also associated with a five-fold greater chance of developing Alzheimer's disease earlier and a three-fold greater chance of developing memory deficits.^[66] Mental disorder or mental illness are terms used to refer psychological pattern that occurs in an individual and is usually associated with distress or disability that is not expected as part of normal development or culture. ... Long-term memory (LTM) is memory, stored as meaning, that can last as little as 30 seconds or as long as decades. ... For other uses, see Memory (disambiguation). ...

Dementia pugilistica

Main article: Dementia pugilistica

Chronic encephalopathy is an example of the cumulative damage that can occur as the result of multiple concussions or less severe blows to the head. The condition called dementia pugilistica, or "punch drunk" syndrome, which is associated with boxers, can result in cognitive and physical deficits such as parkinsonism, speech and memory problems, slowed mental processing, tremor, and inappropriate behavior.^[67] It shares features with Alzheimer's disease.^[68] Dementia pugilistica, also called chronic traumatic encephalopathy, pugilistic Parkinsons syndrome, boxers dementia, and punch-drunk syndrome, is a neurological disorder which affects some career boxers and others who receive multiple dazing blows to the head. ... Encephalopathy literally means disease of the brain. ... Dementia pugilistica, also called chronic traumatic encephalopathy, pugilistic Parkinsons syndrome, boxers dementia, and punch-drunk syndrome, is a neurological disorder which affects some career boxers and others who receive multiple dazing blows to the head. ... Parkinsonism (also known as Parkinsons syndrome, atypical Parkinsons, or secondary Parkinsons) is a neurological syndrome characterized by tremor, hypokinesia, rigidity, and postural instability. ...

Second-impact syndrome

Main article: Second-impact syndrome

Second-impact syndrome, in which the brain swells dangerously after a minor blow, may occur in very rare cases. The condition may develop in people who receive a second blow days or weeks after an initial concussion, before its symptoms have gone away.^[37] No one is certain of the cause of this often fatal complication, but it is commonly thought that the swelling occurs because the brain's arterioles lose the ability to regulate their diameter, causing a loss of control over cerebral blood flow.^[48] As the brain swells, intracranial pressure rapidly rises.^[50] The brain can herniate, and the brain stem can fail within five minutes.^[37] Except in boxing, all cases have occurred in athletes under age 20.^[34] Due to the very small number of documented cases, the diagnosis is controversial, and doubt exists about its validity.^[69] An arteriole is a small diameter blood vessel that extends and branches out from an artery and leads to capillaries. ... Edema (BE: oedema, formerly known as dropsy) is swelling of any organ or tissue due to accumulation of excess fluid. ... Herniation, a deadly side effect of very high intracranial pressure, occurs when the brain shifts across structures within the skull. ...

Epidemiology

Annual incidence of MTBI by age group in Canada^[70]

Most cases of traumatic brain injury are concussions. A World Health Organization (WHO) study estimated that between 70 and 90% of head injuries that receive treatment are mild.^[6] However, due to underreporting and to the widely varying definitions of concussion and MTBI, it is difficult to estimate how common the condition is.^[3] Estimates of the incidence of concussion may be artificially low, for example due to underreporting. At least 25% of MTBI sufferers fail to get assessed by a medical professional.^[22] The WHO group reviewed studies on the epidemiology of MTBI and found a hospital treatment rate of 1–3 per 1000 people, but since not all concussions are treated in hospitals, they estimated that the rate per year in the general population is over 6 per 1000 people.^[6]

Young children have the highest concussion rate among all age groups.^[7] A Canadian study found that the yearly incidence of MTBI is lower in older age groups (graph at right).^[70] Studies suggest males suffer MTBI at about twice the rate of their female counterparts.^[6] However, female athletes may be at a higher risk for suffering concussion than their male counterparts.^[71] Incidence is a measure of the risk of developing some new condition within a specified period of time. ...

Up to five percent of sports injuries are concussions.^[34] The U.S. Centers for Disease Control and Prevention estimates that 300,000 sports-related concussions occur yearly in the U.S., but that number includes only athletes who lost consciousness.^[72] Since loss of consciousness is thought to occur in less than 10% of concussions,^[73] the CDC estimate is likely lower than the real number.^[72] Sports in which concussion is particularly common include football and boxing (a boxer aims to "knock out", i.e. give a mild traumatic brain injury to, the opponent). The injury is so common in the latter that several medical groups have called for a ban on the sport, including the American Academy of Neurology, the World Medical Association, and the medical associations of the UK, the U.S., Australia, and Canada.^[74] Tackles like this one in Womens Australian rules football can cause injuries. ... The Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia, is recognized as the leading United States agency for protecting the public health and safety of people. ... A boxer is knocked down and receives the 10-count. ... The World Medical Association (WMA), an international organization of physicians, was formally established on September 17, 1947, pursuant to the resolutions of the First General Assembly of WMA held in Paris, France. ...

Due to the lack of a consistent definition, the economic costs of MTBI are not known, but they are estimated to be very high.^[75] These high costs are due in part to the large percentage of hospital admissions for head injury that are due to mild head trauma,^[18] but indirect costs such as lost work time and early retirement account for the bulk of the costs.^[75] These direct and indirect costs cause the expense of mild brain trauma to rival that of moderate and severe head injuries.^[76]

History and controversy

The Hippocratic Corpus mentioned concussion.^[62]

The Hippocratic Corpus, collection of medical works from ancient Greece, mentions concussion, later translated to commotio cerebri, and discusses loss of speech, hearing and sight that can result from "commotion of the brain".^[62] This idea of disruption of mental function by 'shaking of the brain' remained the widely accepted understanding of concussion until the 19th century.^[62] The Persian physician Muhammad ibn Zakarīya Rāzi was the first to write about concussion as distinct from other types of head injury in the 10th century AD.^[77] He may have been the first to use the term "cerebral concussion", and his definition of the condition, a transient loss of function with no physical damage, set the stage for the medical understanding of the condition for centuries.^[4] In the 13th century, the physician Lanfranc of Milan's Chiurgia Magna described concussion as brain "commotion", also recognizing a difference between concussion and other types of traumatic brain injury (though many of his contemporaries did not), and discussing the transience of post-concussion symptoms as a result of temporary loss of function from the injury.^[77] In the 14th century, the surgeon Guy de Chauliac pointed out the relatively good prognosis of concussion as compared to more severe types of head trauma such as skull fractures and penetrating head trauma.^[77] In the 16th century, the term "concussion" came into use, and symptoms such as confusion, lethargy, and memory problems were described.^[77] The 16th century physician Ambroise Paré used the term commotio cerebri,^[4] as well as "shaking of the brain", "commotion", and "concussion".^[62] Image File history File links Download high-resolution version (696x983, 586 KB) Twelfth-century Byzantine manuscript the oath was written out in the form of a cross, relating it visually to Christian ideas from the Folio Biblioteca Vaticana. ... Image File history File links Download high-resolution version (696x983, 586 KB) Twelfth-century Byzantine manuscript the oath was written out in the form of a cross, relating it visually to Christian ideas from the Folio Biblioteca Vaticana. ... Hippocrates: a conventionalized image in a Roman portrait bust (19th century engraving) Hippocrates of Cos (c. ... Hippocrates: a conventionalized image in a Roman portrait bust (19th century engraving) Hippocrates of Cos (c. ... For other uses, see Razi. ... A renowned French surgeon of the 14th century, Guy de Chauliac (1300-1368), was the physician for Pope Clement VI. In Avignon, France, he attended to the Pope and survived an infection of the Black Plague. ... A skull fracture is a break in one or more of the bones in the skull caused by a head injury. ... A penetrating head injury, or open head injury, is a head injury in which the dura mater, the outer layer of the meninges, is breached. ... Ambroise Paré. Ambroise Paré (1510 – December 20, 1590) was a French surgeon, the official royal surgeon for kings Henry II, Francis II, Charles IX and Henry III, is considered by some as one of the Fathers of Surgery. ...

Guillaume Dupuytren distinguished between concussion and unconsciousness associated with brain contusion.^[62]

Until the 17th century, concussion was usually described by its clinical features, but after the invention of the microscope, more physicians began exploring underlying physical and structural mechanisms.^[77] However, the prevailing view in the 17th century was that the injury did not result from physical damage, and this view continued to be widely held throughout the 18th century.^[77] The word "concussion" was used at the time to describe the state of unconsciousness and other functional problems that resulted from the impact, rather than a physiological condition.^[77] Image File history File links Baron Guillaume Dupuytren, French surgeon and anatomist. ... Image File history File links Baron Guillaume Dupuytren, French surgeon and anatomist. ... Guillaume Dupuytren, Baron (October 6, 1777 - February 8, 1835) was a French anatomist and military surgeon. ... Brain contusion, latin contusio cerebri, a form of traumatic brain injury, is a bruise of the brain tissue. ...

In 1839, Guillaume Dupuytren described brain contusions, which involve many small hemorrhages, as contusio cerebri and showed the difference between unconsciousness associated with damage to the brain parenchyma and that due to concussion, without such injury.^[62] In 1941, animal experiments showed that no macroscopic damage occurs in concussion.^[62][78] Guillaume Dupuytren, Baron (October 6, 1777 - February 8, 1835) was a French anatomist and military surgeon. ... Parenchyma is a term used to describe a bulk of a substance. ... Macroscopic is commonly used to describe physical objects that are measurable and observable by the naked eye. ...

The debate over whether concussion is a functional or structural phenomenon is ongoing.^[77] Structural damage has been found in the mildly traumatically injured brains of animals, but it is not clear whether these changes would be applicable to humans.^[1] Such changes in brain structure could be responsible for certain symptoms such as visual disturbances, but other sets of symptoms, especially those of a psychological nature, are more likely to be caused by reversible pathophysiological changes in cellular function that occur after concussion, such as alterations in neurons' biochemistry.^[5] These reversible changes could also explain why dysfunction is frequently temporary.^[77] A task force of head injury experts called the Concussion In Sport Group met in 2001 and decided that "concussion may result in neuropathological changes but the acute clinical symptoms largely reflect a functional disturbance rather than structural injury."^[12]

References