Disease Topics:Traumatic Brain Injury

Traumatic brain injury, also known as TBI or intracranial injury, is generally the result of a sudden, violent blow or jolt to the head. The brainis launched into a collision course with the inside of the skull, resulting in possible bruising of the brain, tearing of nerve fibers and bleeding.

Traumatic Brain Injury
Traumatic brain injury results from an impact to the head that disrupts normal brain function. Traumatic brain injury may affect a person’s cognitive abilities, including learning and thinking skills.
About Traumatic Brain Injury
Falls are the leading cause of traumatic brain injury for all ages. Those aged 75 and older have the highest rates of traumatic brain injury-related hospitalization and death due to falls.
Doctors classify traumatic brain injury as mild, moderate or severe, depending on whether the injury causes unconsciousness, how long unconsciousness lasts and the severity of symptoms. Although most traumatic brain injuries are classified as mild because they're not life-threatening, even a mild traumatic brain injury can have serious and long-lasting effects.
Traumatic brain injury is a threat to cognitive health in two ways:
1.    A traumatic brain injury's direct effects, which may be long-lasting or even permanent, can include unconsciousness, inability to recall the traumatic event, confusion, difficulty learning and remembering new information, trouble speaking coherently, unsteadiness, lack of coordination and problems with vision or hearing.
2.    Certain types of traumatic brain injury may increase the risk of developing Alzheimer's or another form of dementia years after the injury takes place
Symptoms of a brain injury include:
·         Unconsciousness
·         Inability to remember the cause of the injury or events that occurred Immediately before or up to 24 hours after
·         Confusion and disorientation
·         Difficulty remembering new information
·         Headache
·         Dizziness
·         Blurry vision
·         Nausea and vomiting
·         Ringing in the ears
·         Trouble speaking coherently
·         Changes in emotions or sleep patterns
The severity of symptoms depends on whether the injury is mild, moderate or severe.
·         Mild traumatic brain injury, also known as a concussion, either doesn't knock you out or knocks you out for 30 minutes or less. Symptoms often appear at the time of the injury or soon after, but sometimes may not develop for days or weeks. Mild traumatic brain injury symptoms are usually temporary and clear up within hours, days or weeks, but they can last months or longer.
·         Moderate traumatic brain injury causes unconsciousness lasting more than 30 minutes. Symptoms of moderate traumatic brain injury are similar to those of mild traumatic brain injury but more serious and longer-lasting.
·         Severe traumatic brain injury knocks you out for more than 24 hours. Symptoms of severe traumatic brain injury are also similar to those of mild traumatic brain injury but more serious and longer-lasting.
Evaluations by health care professionals typically include:
·         Questions about the circumstances of the injury
·         Assessment of the person's level of consciousness and confusion
·         Neurological examination to assess memory and thinking, vision, hearing, touch, balance, reflexes and other indicators of brain function
Depending on the nature of the traumatic brain injury and the severity of symptoms, brain imaging with computed tomography (CT) may be needed to determine if there's bleeding or swelling in the brain.
Causes and risksFalls  
are the most common cause of traumatic brain injury, and falling poses an especially serious risk for older adults. When a senior sustains a traumatic brain injury in a fall, direct effects of the injury may result in long-term cognitive changes, reduced ability to function and changes in emotional health.
Vehicle crashes are another common cause of traumatic brain injury. You can reduce your risk by keeping your vehicle in good repair, following the rules of the road, and buckling your seat belt.
Sports injuries are also a cause of traumatic brain injury. You can protect your head by wearing a helmet and other protective equipment when biking, inline skating or playing contact sports.
Other causes include
  • Indirect forces that jolt the brain violently within the skull, such as shock waves from battlefield explosion
  • Bullet wounds or other injuries that penetrate the skull and brain
Dementia and traumatic brain injury
Over the past 30 years, research has linked moderate and severe traumatic brain injury to a greater risk of developing Alzheimer's disease or another type of dementia years after the original head injury.
  • One of the key studies showing an increased risk found that older adults with a history of moderate traumatic brain injury had a 2.3 times greater risk of developing Alzheimer's than seniors with no history of head injury, and those with a history of severe traumatic brain injury had a 4.5 times greater risk.
  • Other studies — but not all — have found a link between moderate and severe traumatic brain injury and elevated risk.
  • Emerging evidence suggests that individuals who have experienced repeated traumatic brain injuries (concussions) or multiple blows to the head without loss of consciousness, such as professional athletes and combat veterans, are at higher risk of developing a brain condition calledchronic traumatic encephalopathy (CTE)than individuals who have not experienced repeated brain injuries.
  • Current research on how traumatic brain injury changes brain chemistry indicates a relationship between traumatic brain injury and hallmark protein abnormalities (beta-amyloid and tau) linked to Alzheimer's.
  • Some research suggests that traumatic brain injury may be more likely to cause dementia in individuals who have a variation of the gene for apolipoprotein E (APOE) called APOE-e4. More research is needed to understand the link between APOE-e4 and dementia risk in those who've had a brain injury.

Mechanisms of Injury
These mechanisms are the highest causes of brain injury: Open head Injury, Closed Head Injury, Deceleration Injuries, Chemical/Toxic, Hypoxia, Tumors, Infections and Stroke.
1. Open Head Injury
§  Results from bullet wounds, etc.
§  Largely focal damage
§  Penetration of the skull
§  Effects can be just as serious as closed brain injury
2. Closed Head Injury
§  Resulting from a slip and fall, motor vehicle crashes, etc.
§  Focal damage and diffuse damage to axons
§  Effects tend to be broad (diffuse)
§  No penetration to the skull
3. Deceleration Injuries (Diffuse Axonal Injury)
The skull is hard and inflexible while the brain is soft with the consistency of gelatin.  The brain is encased inside the skull.  During the movement of the skull through space (acceleration) and the rapid discontinuation of this action when the skull meets a stationary object (deceleration) causes the brain to move inside the skull.  The brain moves at a different rate than the skull because it is soft.  Different parts of the brain move at different speeds because of their relative lightness or heaviness.  The differential movement of the skull and the brain when the head is struck results in direct brain injury, due to diffuse axonal shearing, contusion and brain swelling.
Diffuse axonal shearing: when the brain is slammed back and forth inside the skull it is alternately compressed and stretched because of the gelatinous consistency.  The long, fragile axons of the  neurons (single nerve cells in the brain and spinal cord) are also compressed and stretched.  If the impact is strong enough, axons can be stretched until they are torn.  This is called axonal shearing.  When this happens, the neuron dies.  After a severe brain injury, there is massive axonal shearing and neuron death.
4. Chemical / Toxic
§  Also known as metabolic disorders
§  This occurs when harmful chemicals damage the neurons
§  Chemicals and toxins can include insecticides, solvents, carbon monoxide poisoning, lead poisoning, etc.
5. Hypoxia (Lack of Oxygen)
§  If the blood flow is depleted of oxygen, then irreversible brain injury can occur from anoxia (no oxygen) or hypoxia (reduced oxygen)
§  It may take only a few minutes for this to occur
§  This condition may be caused by heart attacks, respiratory failure, drops in blood pressure and a low oxygen environment
§  This type of brain injury can result in severe cognitive and memory deficits
6. Tumors
§  Tumors caused by cancer can grow on or over the brain
§  Tumors can cause brain injury by invading the spaces of the brain and causing direct damage
§  Damage can also result from pressure effects around an enlarged tumor
§  Surgical procedures to remove the tumor may also contribute to brain injury
7. Infections
§  The brain and surrounding membranes are very prone to infections if the special blood-brain protective system is breached
§  Viruses and bacteria can cause serious and life-threatening diseases of the brain (encephalitis) and meninges (meningitis)
8. Stroke
§  If blood flow is blocked through a cerebral vascular accident (stroke), cell death in the area deprived of blood will result
§  If there is bleeding in or over the brain (hemorrhage or hematoma) because of a tear in an artery or vein, loss of blood flow and injury to the brain tissue by the blood will also result in brain damage.

The most serious traumatic brain injuries require specialized hospital care and can require months of inpatient rehabilitation. Most traumatic brain injuries are mild and can be managed with either a short hospital stay for observation or at-home monitoring followed by outpatient rehab, if needed.
Treatment of dementia in a person with a history of traumatic brain injuries varies depending on the type of dementia diagnosed. Strategies for treating Alzheimer's or another specific type of dementia are the same for individuals with and without a history of traumatic brain injury.
Alzheimer's disease and other dementias that may occur as a long-term result of traumatic brain injury are progressive disorders that worsen over time. As with all dementias, they affect quality of life, shorten lifespan and complicate the effort to manage other health conditions effectively.
It is important to begin emergency treatment within the so-called "golden hour" following the injury.[83] People with moderate to severe injuries are likely to receive treatment in an intensive care unit followed by a neurosurgical ward.[84] Treatment depends on the recovery stage of the patient. In the acute stage the primary aim of the medical personnel is to stabilize the patient and focus on preventing further injury because little can be done to reverse the initial damage caused by trauma.[84] Rehabilitation is the main treatment for the subacute and chronic stages of recovery.[84] International clinical guidelines have been proposed with the aim of guiding decisions in TBI treatment, as defined by an authoritative examination of current evidence.[2]
Acute stage
Certain facilities are equipped to handle TBI better than others; initial measures include transporting patients to an appropriate treatment center.[44][85] Both during transport and in hospital the primary concerns are ensuring proper oxygen supply, maintaining adequate blood flow to the brain, and controlling raised intracranial pressure (ICP),[3] since high ICP deprives the brain of badly needed blood flow[86] and can cause deadly brain herniation. Other methods to prevent damage include management of other injuries and prevention of seizures.[15][68]Some data supports the use of hyperbaric oxygen therapy to improve outcomes.[87]
Neuroimaging is helpful but not flawless in detecting raised ICP.[88] A more accurate way to measure ICP is to place a catheter into aventricle of the brain,[32] which has the added benefit of allowing cerebrospinal fluid to drain, releasing pressure in the skull.[32] Treatment of raised ICP may be as simple as tilting the patient's bed and straightening the head to promote blood flow through the veins of the neck.Sedatives, analgesics and paralytic agents are often used.[44] Hypertonic saline can improve ICP by reducing the amount of cerebral water (swelling), though it is used with caution to avoid electrolyte imbalances or heart failure.[2] Mannitol, an osmotic diuretic,[2] appears to be equally effective at reducing ICP.[89][90][91] Some concerns; however, have been raised regarding some of the studies performed.[92]Diuretics, drugs that increase urine output to reduce excessive fluid in the system, may be used to treat high intracranial pressures, but may cause hypovolemia (insufficient blood volume).[32] 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[3][32][93] and is, therefore, used only in the short term.[3] Administration of corticosteroids is associated with an increased risk of death, and so it is recommended that they not be given routinely.[94]
Endotracheal intubation and mechanical ventilation may be used to ensure proper oxygen supply and provide a secure airway.[68]Hypotension (low blood pressure), which has a devastating outcome in TBI, can be prevented by giving intravenous fluids to maintain a normal blood pressure. Failing to maintain blood pressure can result in inadequate blood flow to the brain.[15] Blood pressure may be kept at an artificially high level under controlled conditions by infusion of norepinephrine or similar drugs; this helps maintain cerebralperfusion.[95] Body temperature is carefully regulated because increased temperature raises the brain's metabolic needs, potentially depriving it of nutrients.[96] Seizures are common. While they can be treated with benzodiazepines, these drugs are used carefully because they can depress breathing and lower blood pressure.[44] TBI patients are more susceptible to side effects and may react adversely or be inordinately sensitive to some pharmacological agents.[84] During treatment monitoring continues for signs of deterioration such as a decreasing level of consciousness.[2][3]
Traumatic brain injury may cause a range of serious coincidental complications that include cardiac arrhythmias[97] and neurogenicpulmonary edema.[98] These conditions must be adequately treated and stabilised as part of the core care for these patients.
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.[15]For intracranial hematomas, the collected blood may be removed using suction or forceps or it may be floated off with water.[15] Surgeons look for hemorrhaging blood vessels and seek to control bleeding.[15] In penetrating brain injury, damaged tissue is surgically debrided, andcraniotomy may be needed.[15] Craniotomy, in which part of the skull is removed, may be needed to remove pieces of fractured skull or objects embedded in the brain.[99] 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).[100] DC performed hours or days after TBI in order to control high intracranial pressures (secondary DC) has not been shown to improve outcome in some trials and may be associated with severe side-effects.[2][100]
Chronic stage
Once medically stable, people may be transferred to a subacute rehabilitation unit of the medical center or to an independent rehabilitation hospital.[84] Rehabilitation aims to improve independent function at home and in society and to help adapt to disabilities [84] and has demonstrated its general effectiveness, when conducted by a team of health professionals who specialise in head trauma.[101] As for any person with neurologic deficits, a multidisciplinary approach is key to optimising 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, andpsychiatrists, while neuropsychologists can help to evaluate and manage cognitive deficits.[84]
After discharge from the inpatient rehabilitation treatment unit, care may be given on an outpatient basis. Community-based rehabilitation will be required for a high proportion of people, including vocational rehabilitation; this supportive employment matches job demands to the worker's abilities.[102] People with TBI who cannot live independently or with family may require care in supported living facilities such as group homes.[102] Respite care, including day centers and leisure facilities for the disabled, offers time off for caregivers, and activities for people with TBI.[102]
Pharmacological treatment can help to manage psychiatric or behavioral problems.[103] Medication is also used to control post-traumatic epilepsy; however the preventive use of anti-epileptics is not recommended.[104] 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.[57]
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