Traumatic brain injury

Traumatic brain injury is defined as damage to the brain resulting from external mechanical force, such as rapid acceleration or deceleration, impact, blast waves, or penetration by a projectile. TBI is one of two subsets of acquired brain injury (brain damage that occurs after birth); the other subset is non-traumatic brain injury, which does not involve external mechanical force (examples include stroke and infection). All traumatic brain injuries are head injuries, but the latter term may also refer to injury to other parts of the head; however, the terms head injury and brain injury are often used interchangeably. Similarly, brain injuries fall under the classification of central nervous system injuries and neurotrauma. In neuropsychology research literature, in general the term "traumatic brain injury" is used to refer to non-penetrating traumatic brain injuries. TBI is usually classified based on severity, anatomical features of the injury, and the mechanism (the causative forces). In general, it is agreed that a TBI with a GCS of 13 or above is mild, 9–12 is moderate, and 8 or below is severe. Damage from TBI can be focal or diffuse, confined to specific areas or distributed in a more general manner, respectively; Diffuse injury manifests with little apparent damage in neuroimaging studies, but lesions can be seen with microscopy techniques post-mortem, and in the early 2000s, researchers discovered that diffusion tensor imaging (DTI), a way of processing MRI images that shows white matter tracts, was an effective tool for displaying the extent of diffuse axonal injury. Types of injuries considered diffuse include edema (swelling), concussion and diffuse axonal injury, which is widespread damage to axons including white matter tracts and projections to the cortex. Focal injuries often produce symptoms related to the functions of the damaged area. Symptoms such as hemiparesis or aphasia can also occur when less commonly affected areas such as motor or language areas are, respectively, damaged. One type of focal injury, cerebral laceration, occurs when the tissue is cut or torn. Epidural hematoma involves bleeding into the area between the skull and the dura mater, the outermost of the three membranes surrounding the brain. In subdural hematoma, bleeding occurs between the dura and the arachnoid mater. Subarachnoid hemorrhage involves bleeding into the space between the arachnoid membrane and the pia mater. Intraventricular hemorrhage occurs when there is bleeding in the ventricles. ==Signs and symptoms==

is potentially a sign of a serious brain injury. Unconsciousness tends to last longer for people with injuries on the left side of the brain than for those with injuries on the right. Other symptoms of mild TBI include headache, vomiting, nausea, lack of motor coordination, dizziness, difficulty balancing, lightheadedness, blurred vision or tired eyes, ringing in the ears, bad taste in the mouth, fatigue or lethargy, and changes in sleep patterns. Alexithymia, a deficiency in identifying, understanding, processing, and describing emotions occurs in 60.9% of individuals with TBI. Cognitive and social deficits have long-term consequences for the daily lives of people with moderate to severe TBI, but can be improved with appropriate rehabilitation. When the pressure within the skull (intracranial pressure, abbreviated ICP) rises too high, it can be deadly. Other signs seen in young children include persistent crying, inability to be consoled, listlessness, refusal to nurse or eat, and irritability. ==Causes==

The most common causes of TBI in the U.S. include violence, transportation accidents, construction site mishaps, and sports. Motor bikes are major causes, increasing in significance in developing countries as other causes reduce. The estimates that between 1.6 and 3.8 million traumatic brain injuries each year are a result of sports and recreation activities in the US. In children aged two to four, falls are the most common cause of TBI, while in older children traffic accidents compete with falls for this position. TBI is the third most common injury to result from child abuse. Abuse causes 19% of cases of pediatric brain trauma, and the death rate is higher among these cases. as are work-related and industrial accidents. Firearms and blast injuries from explosions are other causes of TBI, which is the leading cause of death and disability in war zones. ==Mechanism==

Physical forces s through the skull and brain, resulting in tissue damage. When a moving object impacts the stationary head, coup injuries are typical, while contrecoup injuries are usually produced when the moving head strikes a stationary object. Primary and secondary injury showing damage due to brain herniation after TBI A large percentage of the people killed by brain trauma do not die right away but rather days to weeks after the event; rather than improving after being hospitalized, some 40% of TBI patients deteriorate. Primary brain injury (the damage that occurs at the moment of trauma when tissues and blood vessels are stretched, compressed, and torn) is not adequate to explain this deterioration; rather, it is caused by secondary injury, a complex set of cellular processes and biochemical cascades that occur in the minutes to days following the trauma. These secondary processes can dramatically worsen the damage caused by primary injury Secondary injury events include damage to the blood–brain barrier, release of factors that cause inflammation, free radical overload, excessive release of the neurotransmitter glutamate (excitotoxicity), influx of calcium and sodium ions into neurons, and dysfunction of mitochondria. Intracranial pressure may rise due to swelling or a mass effect from a lesion, such as a hemorrhage. As a result, cerebral perfusion pressure (the pressure of blood flow in the brain) is reduced; ischemia results. When the pressure within the skull rises too high, it can cause brain death or brain herniation, in which parts of the brain are squeezed by structures in the skull. ==Diagnosis==

Diagnosis is suspected based on lesion circumstances and clinical evidence, most prominently a neurological examination, for example checking whether the pupils constrict normally in response to light and assigning a Glasgow Coma Score. A mTBI, or concussion, cannot be seen on a CT or MRI. The preferred radiologic test in the emergency setting to determine the severity of a TBI is computed tomography (CT): it is quick, accurate, and widely available. Other techniques may be used to confirm a particular diagnosis. X-rays are still used for head trauma, but evidence suggests they are not useful; head injuries are either so mild that they do not need imaging or severe enough to merit the more accurate CT. Angiography may be used to detect blood vessel pathology when risk factors such as penetrating head trauma are involved. Neuropsychological assessment can be performed to evaluate the long-term cognitive sequelae and to aid in the planning of the rehabilitation. ==Prevention==

Since a major cause of TBI are vehicle accidents, their prevention or the amelioration of their consequences can both reduce the incidence and gravity of TBI. In accidents, damage can be reduced by use of seat belts, child safety seats and presence of roll bars and airbags. Due to the possibility that repeatedly "heading" a ball practicing soccer could cause cumulative brain injury, the idea of introducing protective headgear for players has been proposed. Improved equipment design can enhance safety; softer baseballs reduce head injury risk. Rules against dangerous types of contact, such as "spear tackling" in American football, when one player tackles another head first, may also reduce head injury rates. Gun safety, including keeping guns unloaded and locked, is another preventative measure. Studies on the effect of laws that aim to control access to guns in the United States have been insufficient to determine their effectiveness preventing number of deaths or injuries. ==Treatment==

It is important to begin emergency treatment within the so-called "golden hour" following the injury. People with moderate to severe injuries are likely to receive treatment in an intensive care unit followed by a neurosurgical ward. Certain facilities are equipped to handle TBI better than others; initial measures include transporting patients to an appropriate treatment center. Further research is required to determine the effectiveness and clinical importance of positioning the head at different angles (degrees of head-of-bed elevation) while the person is being treated in intensive care. Neuroimaging is helpful but not flawless in detecting raised ICP. A more accurate way to measure ICP is to place a catheter into a ventricle of the brain, Mannitol, an osmotic diuretic, however, some concerns have been raised regarding some of the studies performed. Hyertonic saline is also suitable in children with severe traumatic brain injury. Hyperventilation (larger and/or faster breaths) reduces carbon dioxide levels and causes blood vessels to constrict; this decreases blood flow to the brain and reduces ICP, but it potentially causes ischemia and is, therefore, used only in the short term. There is no strong evidence that the following pharmaceutical interventions should be recommended to routinely treat TBI: magnesium, monoaminergic and dopamine agonists, progesterone, aminosteroids, excitatory amino acid reuptake inhibitors, beta-2 antagonists (bronchodilators), haemostatic and antifibrinolytic drugs. Endotracheal intubation and mechanical ventilation may be used to ensure proper oxygen supply and provide a secure airway. Body temperature is carefully regulated because increased temperature raises the brain's metabolic needs, potentially depriving it of nutrients. Seizures are common. While they can be treated with benzodiazepines, these drugs are used carefully because they can depress breathing and lower blood pressure. and neurogenic pulmonary edema. These conditions must be adequately treated and stabilised as part of the core care. Surgery can be performed on mass lesions or to eliminate objects that have penetrated the brain. Mass lesions such as contusions or hematomas causing a significant mass effect (shift of intracranial structures) are considered emergencies and are removed surgically. Decompressive craniectomy (DC) is performed routinely in the very short period following TBI during operations to treat hematomas; part of the skull is removed temporarily (primary DC). Chronic stage Once medically stable, people may be transferred to a subacute rehabilitation unit of the medical center or to an independent rehabilitation hospital. As for any person with neurologic deficits, a multidisciplinary approach is key to optimizing outcome. Physiatrists or neurologists are likely to be the key medical staff involved, but depending on the person, doctors of other medical specialties may also be helpful. Allied health professions such as physiotherapy, speech and language therapy, cognitive rehabilitation therapy, and occupational therapy will be essential to assess function and design the rehabilitation activities for each person. Treatment of neuropsychiatric symptoms such as emotional distress and clinical depression may involve mental health professionals such as therapists, psychologists, and psychiatrists, while neuropsychologists can help to evaluate and manage cognitive deficits. Social workers, rehabilitation support personnel, nutritionists, therapeutic recreationists, and pharmacists are also important members of the TBI rehabilitation team. Pharmacological treatment can help to manage psychiatric or behavioral problems. Medication is also used to control post-traumatic epilepsy; however the preventive use of anti-epileptics is not recommended. In those cases where the person is bedridden due to a reduction of consciousness, has to remain in a wheelchair because of mobility problems, or has any other problem heavily impacting self-caring capacities, caregiving and nursing are critical. The most effective research documented intervention approach is the activation database guided EEG biofeedback approach, which has shown significant improvements in memory abilities of the TBI subject that are far superior than traditional approaches (strategies, computers, medication intervention). Gains of 2.61 standard deviations have been documented. The TBI's auditory memory ability was superior to the control group after the treatment. Effect on the gait pattern In patients who have developed paralysis of the legs in the form of spastic hemiplegia or diplegia as a result of the traumatic brain injury, various gait patterns can be observed, the exact extent of which can only be described with the help of complex gait analysis systems. In order to facilitate interdisciplinary communication in the interdisciplinary team between those affected, doctors, physiotherapists and orthotists, a simple description of the gait pattern is useful. J. Rodda and H. K. Graham already described in 2001 how gait patterns of CP patients can be more easily recognized and defined gait types which they compared in a classification. They also described that gait patterns can vary with age. Building on this, the Amsterdam Gait Classification was developed at the free university in Amsterdam, the VU medisch centrum. A special feature of this classification is that it makes different gait patterns very recognizable and can be used in patients in whom only one leg and both legs are affected. The Amsterdam Gait Classification was developed for viewing patients with cerebral palsy; however, it can be used just as well in patients with traumatic brain injuries. According to the Amsterdam Gait Classification, five gait types are described. To assess the gait pattern, the patient is viewed visually or via a video recording from the side of the leg to be assessed. At the point in time at which the leg to be viewed is in mid stance and the leg not to be viewed is in mid swing, the knee angle and the contact of the foot with the ground are assessed on the one hand. Classification of the gait pattern according to the Amsterdam Gait Classification: In gait type 1, the knee angle is normal and the foot contact is complete. In gait type 2, the knee angle is hyperextended and the foot contact is complete. In gait type 3, the knee angle is hyperextended and foot contact is incomplete (only on the forefoot). In gait type 4, the knee angle is bent and foot contact is incomplete (only on the forefoot). With gait type 5, which is also known as crouch gait, the knee angle is bent and the foot contact is complete. An orthosis can support physiotherapeutic treatment in setting the right motor impulses in order to create new cerebral connections. The orthosis must meet the requirements of the medical prescription. In addition, the orthosis must be designed by the orthotist in such a way that it achieves the effectiveness of the necessary levers, matching the gait pattern, in order to support the proprioceptive approaches of physiotherapy. The orthotic concepts of the treatment are based on the concepts for the patients with cerebral palsy. The characteristics of the stiffness of the orthosis shells and the adjustable dynamics in the ankle joint are important elements of the orthosis to be considered. The orthotic concepts of the treatment are based on the concepts for the patients with cerebral palsy. Due to these requirements, the development of orthoses has changed significantly in recent years, especially since around 2010. At about the same time, care concepts were developed that deal intensively with the orthotic treatment of the lower extremities in cerebral palsy. Modern materials and new functional elements enable the rigidity to be specifically adapted to the requirements that fits to the gait pattern of the patient. The adjustment of the stiffness has a decisive influence on the gait pattern and on the energy cost of walking. It is of great advantage if the stiffness of the orthosis can be adjusted separately from one another via resistances of the two functional elements in the two directions of movement, dorsiflexion and plantar flexion. ==Prognosis==

Prognosis worsens with the severity of injury. Most TBIs are mild and do not cause permanent or long-term disability; however, all severity levels of TBI have the potential to cause significant, long-lasting disability. Permanent disability is thought to occur in 10% of mild injuries, 66% of moderate injuries, and 100% of severe injuries. Most mild TBI is completely resolved within three weeks. Almost all people with mild TBI are able to live independently and return to the jobs they had before the injury, although a small portion have mild cognitive and social impairments. Subdural hematoma is associated with worse outcome and increased mortality, while people with epidural hematoma are expected to have a good outcome if they receive surgery quickly. Medical complications are associated with a bad prognosis. Examples of such complications include: hypotension (low blood pressure), hypoxia (low blood oxygen saturation), lower cerebral perfusion pressures, and longer times spent with high intracranial pressures. Life satisfaction has been known to decrease for individuals with TBI immediately following the trauma, but evidence has shown that life roles, age, and depressive symptoms influence the trajectory of life satisfaction as time passes. Many people with traumatic brain injuries have poor physical fitness following their acute injury and this may result with difficulties in day-to-day activities and increased levels of fatigue. ==Complications==

(in which patients show minimal signs of being aware of self or environment). Lying still for long periods can cause complications including pressure sores, pneumonia or other infections, progressive multiple organ failure, and deep venous thrombosis, which can cause pulmonary embolism. The risk of post-traumatic seizures increases with severity of trauma and is particularly elevated with certain types of brain trauma such as cerebral contusions or hematomas. People may lose or experience altered vision, hearing, or smell. Cognitive deficits that can follow TBI include impaired attention; disrupted insight, judgement, and thought; reduced processing speed; distractibility; and deficits in executive functions such as abstract reasoning, planning, problem-solving, and multitasking. Memory loss, the most common cognitive impairment among head-injured people, occurs in 20–79% of people with closed head trauma, depending on severity. People who have had TBI may also have difficulty with understanding or producing spoken or written language, or with more subtle aspects of communication such as body language. which causes cognitive, behavioral, and physical impairments that can present as dementia, and the tremors and lack of coordination of parkinsonism. CTE primarily affects boxers years after their career has ended. TBI may cause emotional, social, or behavioral problems and changes in personality. These may include emotional instability, depression, anxiety, hypomania, mania, apathy, irritability, problems with social judgment, and impaired conversational skills. TBI appears to predispose survivors to psychiatric disorders including obsessive compulsive disorder, substance abuse, dysthymia, clinical depression, bipolar disorder, and anxiety disorders. In patients who have depression after TBI, suicidal ideation is not uncommon; the suicide rate among these persons is increased 2- to 3-fold. Social and behavioral symptoms that can follow TBI include disinhibition, inability to control anger, impulsiveness, lack of initiative, inappropriate sexual activity, asociality and social withdrawal, and changes in personality. TBI also has a substantial impact on the functioning of family systems Caregiving family members and TBI survivors often significantly alter their familial roles and responsibilities following injury, creating significant change and strain on a family system. Typical challenges identified by families recovering from TBI include: frustration and impatience with one another, loss of former lives and relationships, difficulty setting reasonable goals, inability to effectively solve problems as a family, increased level of stress and household tension, changes in emotional dynamics, and overwhelming desire to return to pre-injury status. In addition, families may exhibit less effective functioning in areas including coping, problem solving and communication. Psychoeducation and counseling models have been demonstrated to be effective in minimizing family disruption. ==Epidemiology==

also appears to affect TBI rates; people with lower levels of education and employment and lower socioeconomic status are at greater risk. ==History==

Head injury is present in ancient myths that may date back before recorded history. Skulls found in battleground graves with holes drilled over fracture lines suggest that trepanation may have been used to treat TBI in ancient times. Ancient Mesopotamians knew of head injury and some of its effects, including seizures, paralysis, and loss of sight, hearing or speech. The Edwin Smith Papyrus, written around 1650–1550 BC, describes various head injuries and symptoms and classifies them based on their presentation and tractability. Ancient Greek physicians including Hippocrates understood the brain to be the center of thought, probably due to their experience observing the effects of head trauma. Medieval and Renaissance surgeons continued the practice of trepanation for head injury. Concussion symptoms were first described systematically in the 16th century by Berengario da Carpi. At that time a debate arose around whether post-concussion syndrome was due to a disturbance of the brain tissue or psychological factors. The 20th century saw the advancement of technologies that improved treatment and diagnosis such as the development of imaging tools including CT and MRI, and, in the 21st century, diffusion tensor imaging (DTI). The introduction of intracranial pressure monitoring in the 1950s has been credited with beginning the "modern era" of head injury. Until the 20th century, the mortality rate of TBI was high and rehabilitation was uncommon; improvements in care made during World War I reduced the death rate and made rehabilitation possible. Blast-related injuries are now common problems in returning veterans from Iraq & Afghanistan; research shows that the symptoms of such TBIs are largely the same as those of TBIs involving a physical blow to the head. In the 1970s, awareness of TBI as a public health problem grew, and a great deal of progress has been made since then in brain trauma research, ==Research directions==

Diagnosis Quantitative EEG and EEG, which has no specific patterns in TBI is used in research settings to differentiate between mild TBI and no TBI. Medications As of 2008, no medication is approved to halt the progression of the initial injury to secondary injury. The variety of pathological events presents opportunities to find treatments that interfere with the damage processes. Further research is necessary to determine if the vasoconstrictor indomethacin (indometacin) can be used to treat increased pressure in the skull following a TBI. In addition, drugs such as NMDA receptor antagonists to halt neurochemical cascades such as excitotoxicity showed promise in animal trials but failed in clinical trials. barbiturates, magnesium (no strong evidence), and calcium channel blockers. A 2024 review reported inconsistent findings regarding the potential of amphetamine and methylphenidate to improve cognitive and motor function following stroke and TBI, noting that further research was required to understand the treatment time window. Procedures Although neuroprotection methods to decrease secondary injury have been the subject of interest follows TBI, trials to test agents that could halt these cellular mechanisms have met largely with failure as of 2008. Maintaining a normal temperature in the immediate period after a TBI appeared useful. One review found a lower than normal temperature was useful in adults but not children. While two other reviews found it did not appear to be useful. Intraparenchymal brain tissue oxygen monitoring systems (either Licox or Neurovent-PTO) are used routinely in neurointensive care in the US. A non invasive model called CerOx is in development. Research is also planned to clarify factors correlated to outcome in TBI and to determine in which cases it is best to perform CT scans and surgical procedures. Hyperbaric oxygen therapy (HBO) has been evaluated as an add on treatment following TBI. The findings of a 2012 Cochrane systematic review does not justify the routine use of hyperbaric oxygen therapy to treat people recovering from a traumatic brain injury. This review also reported that only a small number of randomized controlled trials had been conducted at the time of the review, many of which had methodological problems and poor reporting. As of 2010, the use of predictive visual tracking measurement to identify mild traumatic brain injury was being studied. In visual tracking tests, a head-mounted display unit with eye-tracking capability shows an object moving in a regular pattern. People without brain injury are able to track the moving object with smooth pursuit eye movements and correct trajectory. The test requires both attention and working memory which are difficult functions for people with mild traumatic brain injury. The question being studied, is whether results for people with brain injury will show visual-tracking gaze errors relative to the moving target. Monitoring pressure Pressure reactivity index is used to correlate intracranial pressure with arterial blood pressure to give information about the state of cerebral perfusion, thus guiding treatment and prevent excessively high or low blood flow to the brain. However, such method of monitoring intracranial pressure of equal or less than 20 mmHg is no better than imaging and clinical examination that monitor the neurological status of the brain in prolonging the survival, preserving the mental or functional status of the subject. Sensory processing In animal models of TBI, sensory processing has been widely studied to show systematic defects arise and are slowly but likely only partially recovered. It is especially characterised by an initial period of decreased activity in upper cortical layers. This period of decreased activity has also been characterised as by specific timing effects in the patterns of cortical activity in these upper layers in response to regular sensory stimuli. == References ==

• • • • The original version of this article contained text from the NINDS public domain pages on TBI == External links ==