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 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. Diagnosis 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. Treatment 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 anintensive
care unitfollowed by aneurosurgicalward.[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]Internationalclinical
guidelineshave been proposed
with the aim of guiding decisions in TBI treatment, as defined by an
authoritative examination of currentevidence.[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 raisedintracranial pressure(ICP),[3]since high ICP deprives the brain of badly
needed blood flow[86]and can cause deadlybrain herniation.
Other methods to prevent damage include management of other injuries and
prevention ofseizures.[15][68]Some data supports the use ofhyperbaric oxygen therapyto improve outcomes.[87] Neuroimaging is helpful but not flawless in detecting raised
ICP.[88]A more accurate way to measure ICP is to place
acatheterinto aventricle
of the brain,[32]which has the added benefit of allowingcerebrospinal
fluidto 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,analgesicsandparalytic
agentsare often used.[44]Hypertonicsaline 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, anosmoticdiuretic,[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 causehypovolemia(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 causesischemia[3][32][93]and is, therefore, used only in the short
term.[3]Administration ofcorticosteroidsis associated with an increased risk of death,
and so it is recommended that they not be given routinely.[94] Endotracheal intubationandmechanical ventilationmay 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 givingintravenous
fluidsto 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 ofnorepinephrineor similar drugs; this helps maintain cerebralperfusion.[95]Body temperature is carefully regulated
because increased temperature raises the brain'smetabolicneeds, potentially depriving it of nutrients.[96]Seizures are common. While they can be treated
withbenzodiazepines,
these drugs are used carefully because they can depress breathing and lower
blood pressure.[44]TBI patients are more susceptible toside effectsand may react adversely or be inordinately sensitive to somepharmacologicalagents.[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 cardiacarrhythmias[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 onmass
lesionsor 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 usingsuctionorforcepsor 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
surgicallydebrided, andcraniotomymay 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 asubacuterehabilitation unit of the medical center or
to an independentrehabilitation 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, amultidisciplinaryapproach is key to optimising outcome.Physiatristsorneurologistsare 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 asphysiotherapy,speech and language therapy,cognitive rehabilitation therapy, andoccupational
therapywill be essential to
assess function and design the rehabilitation activities for each person.
Treatment ofneuropsychiatricsymptoms such as emotional distress and
clinical depression may involvemental healthprofessionals such astherapists,psychologists, andpsychiatrists, whileneuropsychologistscan help to evaluate and managecognitive deficits.[84] After discharge from the inpatient rehabilitation treatment
unit, care may be given on anoutpatientbasis. 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 controlpost-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,caregivingand 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]
