Traumatic brain injury in the context of "Vision therapy"

A vocabulary (also known as a lexicon) is a set of words, typically the set in a language or the set known to an individual. The word vocabulary originated from the Latin vocabulum, meaning "a word, name". It forms an essential component of language and communication, helping convey thoughts, ideas, emotions, and information. Vocabulary can be oral, written, or signed and can be categorized into two main types: active vocabulary (words one uses regularly) and passive vocabulary (words one recognizes but does not use often). An individual's vocabulary continually evolves through various methods, including direct instruction, independent reading, and natural language exposure, but it can also shrink due to forgetting, trauma, or disease. Furthermore, vocabulary is a significant focus of study across various disciplines, like linguistics, education, psychology, and artificial intelligence. Vocabulary is not limited to single words; it also encompasses multi-word units known as collocations, idioms, and other types of phraseology. Acquiring an adequate vocabulary is one of the largest challenges in learning a second language.

Hearing loss is a partial or total inability to hear. Hearing loss may be present at birth or acquired at any time afterwards. Hearing loss may occur in one or both ears. In children, hearing problems can affect the ability to acquire spoken language. In adults, it can create difficulties with social interaction and at work. Hearing loss can be temporary or permanent. Hearing loss related to age usually affects both ears and is due to cochlear hair cell loss. In some people, particularly older people, hearing loss can result in loneliness.

Hearing loss may be caused by a number of factors, including: genetics, ageing, exposure to noise, some infections, birth complications, trauma to the ear or brain, and certain medications or toxins. A common condition that results in hearing loss is chronic ear infections. Certain infections during pregnancy, such as cytomegalovirus, syphilis and rubella, may also cause hearing loss in the child. Hearing loss is diagnosed when hearing testing finds that a person is unable to hear 25 decibels in at least one ear. Testing for poor hearing is recommended for all newborns. Hearing loss can be categorized as minimal/slight (15 to 25 dB), mild (25 to 40 dB), moderate (41 to 55 dB), moderate-severe (56 to 70 dB), severe (71 to 90 dB), or profound (greater than 90 dB). There are three main types of hearing loss: conductive hearing loss, sensorineural hearing loss, and mixed hearing loss.

Hyperthermia, also known as overheating, is a condition in which an individual's body temperature is elevated beyond normal due to failed thermoregulation. The person's body produces or absorbs more heat than it dissipates. According to the International Emergency Medicine Education Project, severe hyperthermia (body temperature elevation of beyond 40 °C (104 °F)) "becomes a medical emergency requiring immediate treatment to prevent disability or death". Almost half a million deaths are recorded every year from hyperthermia.

The most common causes include heat stroke and adverse reactions to drugs. Heat stroke is an acute temperature elevation caused by exposure to excessive heat, or combination of heat and humidity, that overwhelms the heat-regulating mechanisms of the body. The latter is a relatively rare side effect of many drugs, particularly those that affect the central nervous system. Malignant hyperthermia is a rare complication of some types of general anesthesia. Hyperthermia can also be caused by a traumatic brain injury.

Unconsciousness is a state in which a living individual exhibits a complete, or near-complete, inability to maintain an awareness of self and environment or to respond to any human or environmental stimulus. Unconsciousness may occur as the result of traumatic brain injury, brain hypoxia (inadequate oxygen, possibly due to a brain infarction or cardiac arrest), severe intoxication with drugs that depress the activity of the central nervous system (e.g., alcohol and other hypnotic or sedative drugs), severe fatigue, pain, anaesthesia, and other causes.

Loss of consciousness should not be confused with the notion of the psychoanalytic unconscious, cognitive processes that take place outside awareness (e.g., implicit cognition), and with altered states of consciousness such as sleep, delirium, hypnosis, and other altered states in which the person responds to stimuli, including trance and psychedelic experiences.

In excitotoxicity, nerve cells suffer damage or death when the levels of otherwise necessary and safe neurotransmitters such as glutamate become pathologically high, resulting in excessive stimulation of receptors. For example, when glutamate receptors such as NMDA receptors or AMPA receptors encounter excessive levels of the excitatory neurotransmitter, glutamate, significant neuronal damage might ensue. Different mechanisms might lead to increased extracellular glutamate concentrations, e.g. reduced uptake by glutamate transporters (EAATs), synaptic hyperactivity, or abnormal release from different neural cell types. Excess glutamate allows high levels of calcium ions (Ca) to enter the cell. Ca influx into cells activates a number of enzymes, including phospholipases, endonucleases, and proteases such as calpain. These enzymes go on to damage cell structures such as components of the cytoskeleton, membrane, and DNA. In evolved, complex adaptive systems such as biological life it must be understood that mechanisms are rarely, if ever, simplistically direct. For example, NMDA, in subtoxic amounts, can block glutamate toxicity and induce neuronal survival. In addition to abnormally high neurotransmitter concentrations, also elevation of the extracellular potassium concentration, acidification and other mechanisms may contribute to excitotoxicity.

Excitotoxicity may be involved in cancers, spinal cord injury, stroke, traumatic brain injury, hearing loss (through noise overexposure or ototoxicity), and in neurodegenerative diseases of the central nervous system such as multiple sclerosis, Alzheimer's disease, amyotrophic lateral sclerosis (ALS), Parkinson's disease, alcoholism, alcohol withdrawal or hyperammonemia and especially over-rapid benzodiazepine withdrawal, and also Huntington's disease. Other common conditions that cause excessive glutamate concentrations around neurons are hypoglycemia. Blood sugars are the primary energy source for glutamate removal from inter-synaptic spaces at the NMDA and AMPA receptor site. Persons in excitotoxic shock must never fall into hypoglycemia. Patients should be given 5% glucose (dextrose) IV drip during excitotoxic shock to avoid a dangerous build up of glutamate. When 5% glucose (dextrose) IV drip is not available high levels of fructose are given orally. Treatment is administered during the acute stages of excitotoxic shock along with glutamate receptor antagonists. Dehydration should be avoided as this also contributes to the concentrations of glutamate in the inter-synaptic cleft and "status epilepticus can also be triggered by a build up of glutamate around inter-synaptic neurons."

Disorders of diminished motivation (DDM) are a group of disorders involving diminished motivation and associated emotions. Many different terms have been used to refer to diminished motivation. Often however, a spectrum is defined encompassing apathy, abulia, and akinetic mutism, with apathy the least severe and akinetic mutism the most extreme.

DDM can be caused by psychiatric disorders like depression and schizophrenia, brain injuries, strokes, and neurodegenerative diseases. Damage to the anterior cingulate cortex and to the striatum, which includes the nucleus accumbens and caudate nucleus and is part of the mesolimbic dopamine reward pathway, have been especially associated with DDM. Diminished motivation can also be induced by certain drugs, including antidopaminergic agents like antipsychotics, selective serotonin reuptake inhibitors (SSRIs), and cannabis, among others.

Brain injury, also known as brain damage or neurotrauma, is the destruction or degeneration of brain cells. It may result from external trauma, such as accidents or falls, or from internal factors, such as strokes, infections, or metabolic disorders.

Traumatic brain injury (TBI), the most common type of brain injury, is typically caused by external physical trauma to the head. Acquired brain injuries occur after birth, in contrast to congenital brain injuries that patients are born with.

An induced coma – also known as a medically induced coma (MIC), barbiturate-induced coma, or drug-induced coma – is a temporary coma (a deep state of unconsciousness) brought on by a controlled dose of an anesthetic drug, often a barbiturate such as pentobarbital or thiopental. Other intravenous anesthetic drugs such as midazolam or propofol may be used.

Drug-induced comas are used to protect the brain during major neurosurgery, as a last line of treatment in certain cases of status epilepticus that have not responded to other treatments, and in refractory intracranial hypertension following traumatic brain injury.