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Jai Ganesh

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Registered: 2005-06-28

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Re: Miscellany

2500) Brain injury/Traumatic Brain Injury

Gist

A Traumatic Brain Injury (TBI) results from an external force—such as a blow, jolt, or penetrating object—causing temporary or permanent damage to brain function, ranging from concussions to severe cognitive, physical, and emotional impairments. Common symptoms include headache, confusion, dizziness, fatigue, and memory loss.

TBIs are sometimes called brain injuries or even head injuries. Some types of TBI can cause temporary or short-term problems with brain function, including problems with how a person thinks, understands, moves, communicates, and acts. More serious TBIs can lead to severe and permanent disability—and even death.

Summary

A traumatic brain injury (TBI) happens when a hit to the head or an object injures your brain. They range from mild to severe and may affect your thinking, movement or emotions. It can cause headaches, confusion or memory loss. Treatment options are available to help you recover.

What Is a Traumatic Brain Injury?

A traumatic brain injury (TBI) happens when an outside force damages your brain and affects how it works. This can occur after a fall, a hard hit to your head, a vehicle accident or when something goes through your skull.

Symptoms can affect your body, thinking and emotions. You may have headaches, confusion, short-term memory loss, and mood or behavior changes. TBIs may be life-threatening. They can cause short-term or long-term health problems that affect many parts of your daily life.

Treatment is available and depends on how serious the injury is.

Types of traumatic brain injuries

There are two types:

* Penetrating TBI: This is when something pierces your skull, enters your brain tissue and damages a part of your brain. Healthcare providers may call these open TBIs.
* Blunt TBI (closed head TBI): This is when something hits your head hard enough that your brain bounces or twists around inside your skull.

What are the severity levels of TBIs?

Healthcare providers classify traumatic brain injuries as being mild, moderate or severe. They may use the term “concussion” when talking about mild TBI. Providers typically group moderate and severe TBIs together.

* Mild TBI: More than 75% of all TBIs are mild. But even mild TBIs may cause significant and long-term issues. For example, you may have trouble returning to your daily routine, including being able to work.
* Moderate and severe TBI: These are medical emergencies. Many develop into significant and long-term health issues.

Details

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.

In addition, brain injuries can be classified by timing: primary injuries occur at the moment of trauma, while secondary injuries develop afterward due to physiological responses. They can also be categorized by location: focal injuries affect specific areas, whereas diffuse injuries involve widespread brain regions.

The symptoms and complications of brain injuries vary greatly depending on the area(s) of the brain injured, the individual case, the cause of the injury and whether the person receives treatment. People may suffer from headaches, vomit or lose consciousness (potentially falling into a coma or a similar disorder of consciousness) after a brain injury. Long-term cognitive impairment, disturbances in language and motor skills, emotional dysfunction and changes in personality are common.

Treatments for brain injuries include preventing further injuries, medication, physical therapy, psychotherapy, occupational therapy and surgery. Because of neuroplasticity, the brain can partially recover function by forming new neural connections to compensate for damaged areas. Patients may regain adaptive skills such as movement and speech, especially if they undergo therapy and practice.

Classification:

Focal and diffuse

Focal brain injuries affect only a single area of the brain; they result from direct force to the head[4] and manifest as haemorrhages, contusions, and subdural and epidural haematomas. Diffuse brain injuries cause widespread damage to all or many areas, and are caused by diffuse axonal injuries, hypoxia, ischaemia and vascular injuries. If both are severe, focal brain injuries are deadlier than diffuse ones; severe focal and diffuse injuries have mortality rates of 40% and 25% respectively. Although, diffuse brain injuries more often result in long-term neurological and cognitive deficits.

Primary and secondary

Primary brain injuries, most of which are traumatic brain injuries, occur directly because of mechanical forces that deform the brain. Secondary brain injuries result from conditions, such as hypoxia, ischaemia, oedema, hydrocephalus and intracranial hypertension, that may or may not be the aftereffects of primary brain injuries.

Signs and symptoms

Symptoms of brain injuries vary based on the severity of the injury, the area of the brain injured, and how much of the brain was affected. The three categories used for classifying the severity of brain injuries are mild, moderate and severe.

Severity of injuries:

Mild brain injuries

When caused by a blow to the head, a mild brain injury is known as a concussion. Symptoms of a mild brain injury include headaches, confusion, tinnitus, fatigue and changes in sleep patterns, mood or behavior. Other symptoms include trouble with memory, concentration, attention or thinking. Because mental fatigue can be attributed to many disorders, patients may not realise the connection between fatigue and a minor brain injury.

Moderate/severe brain injuries

Cognitive symptoms include confusion, aggression, abnormal behavior and slurred speech. Physical symptoms include a loss of consciousness, headaches that worsen or do not go away, vomiting or nausea, convulsions, brain pulsation, abnormal dilation of the eyes, inability to wake from sleep, weakness in extremities and a loss of coordination.

Symptoms in children

Young children could be unable to communicate their physical states, emotions and thought processes, so parents, physicians and caregivers may need to observe their behaviours to discern symptoms. Signs include changes in eating habits, persistent anger, sadness, attention loss, losing interest in activities they used to enjoy, or sleep problems.

Complications:

Physiological effects

Physiological complications of a brain injury, caused by damage to the neurons, nerve tracts or sections of the brain, can occur immediately or at varying times after the injury. The immediate response can take many forms. Initially, there may be symptoms such as swelling, pain, bruising, or loss of consciousness. Headaches, dizziness and fatigue, which can develop as time progresses, may become permanent or persist for a long time.

Brain damage predisposes patients to seizures, Parkinson's disease, dementia and hormone-secreting gland disorders; monitoring is essential for detecting the development of these diseases and treating them promptly.

Diffuse brain injuries, brain injuries that result in intracranial hypertension and brain injuries affecting parts of the brain responsible for consciousness may induce a coma, a prolonged period of deep unconsciousness. Severe brain injuries may cause a persistent vegetative state in which a patient displays wakefulness without any awareness of his or her surroundings.

Brain death occurs when all activity of the brain is deemed to have irreversibly ceased. The prerequisite for considering brain death is the presence of an injury, bodily status (e.g. hyperpyrexia) or disease that has severely damaged the entire brain. After this has been confirmed, the criteria for ascertaining brain death are an absence of brain activity 24 hours after a patient has been resuscitated, an absence of brainstem reflexes (including the pupillary response and gag reflex) and an absence of spontaneous breathing when the lungs are filled with carbon dioxide.

Cognitive effects

Post-traumatic amnesia, and issues with both long- and short-term memory, are common with brain damage, as is temporary aphasia, or impairment of language. Tissue damage and loss of blood flow caused by the injury may cause both of these issues to become permanent. Apraxia, the impairment of motor coordination and movement, has also been documented.

Cognitive effects can depend on the location of the brain that was damaged, and certain types of impairments can be attributed to damage to certain areas of the brain. Larger lesions tend to cause worse symptoms and more complicated recoveries.

Brain lesions in Wernicke's and Broca's areas are correlated with language, speech and category-specific disorders. Wernicke's aphasia is associated with word retrieval deficits, unknowingly making up words (neologisms), and problems with language comprehension. The symptoms of Wernicke's aphasia are caused by damage to the posterior section of the superior temporal gyrus.

Damage to Broca's area typically produces symptoms like omitting functional words (agrammatism), sound production changes, alexia, agraphia, and problems with comprehension and production. Broca's aphasia is indicative of damage to the posterior inferior frontal gyrus of the brain.

The impairment of a cognitive process following a brain injury does not necessarily indicate that the damaged area is wholly responsible for the process that is impaired. For example, in pure alexia, the ability to read is destroyed by a lesion damaging both the left visual field and the connection between the right visual field and the language areas (Broca's area and Wernicke's area). However, this does not mean one with pure alexia is incapable of comprehending speech—merely that there is no connection between their working visual cortex and language areas—as is demonstrated by the fact that people with pure alexia can still write, speak, and even transcribe letters without understanding their meaning.

Lesions to the fusiform gyrus often result in prosopagnosia, the inability to distinguish faces and other complex objects from each other. Lesions in the amygdala would eliminate the enhanced activation seen in occipital and fusiform visual areas in response to fear with the area intact. Amygdala lesions change the functional pattern of activation to emotional stimuli in regions that are distant from the amygdala.

Other lesions to the visual cortex have different effects depending on the location of the damage. Lesions to V1, for example, can cause blindsight in different areas of the brain depending on the size of the lesion and location relative to the calcarine fissure. Lesions to V4 can cause color-blindness, and bilateral lesions to MT/V5 can cause the loss of the ability to perceive motion. Lesions to the parietal lobes may result in agnosia, an inability to recognize complex objects, smells, or shapes, or amorphosynthesis, a loss of perception on the opposite side of the body.

Psychological effects

There are documented cases of lasting psychological effects as well, such as emotional changes often caused by damage to the various parts of the brain that control emotions and behaviour. Individuals may experience sudden, severe mood swings that subside quickly. Emotional changes, which may not be triggered by a specific event, can cause distress to the injured party and their family and friends. Brain injuries increase the risk of developing depression, bipolar disorder and schizophrenia. The more severe a brain injury is the likelier it is to cause bipolar disorder or schizophrenia; the correlation between brain injuries and mental illness is stronger in female and older patients. Often, counseling in either a one-on-one or group setting is suggested for those who experience emotional dysfunction after their injury.

Any type of acquired brain injury can result in changes in personality, including, with regards to the Big Five personality traits, increased neuroticism, decreased extraversion and decreased conscientiousness. If the patient is aware of the change in his or her cognitive capacity, personality and mental state after an injury, he or she might feel disconnected from his or her pre-injury identity, leading to irritability, emotional distress and a disrupted concept of self.

Additional Information

Traumatic brain injury (TBI) happens when a sudden, external, physical assault damages the brain. It is one of the most common causes of disability and death in adults. TBI is a broad term that describes a vast array of injuries that happen to the brain. The damage can be focal (confined to one area of the brain) or diffuse (happens in more than one area of the brain). The severity of a brain injury can range from a mild concussion to a severe injury that results in coma or even death.

What are the different types of TBI?

Brain injury may happen in one of two ways:

* Closed brain injury. Closed brain injuries happen when there is a nonpenetrating injury to the brain with no break in the skull. A closed brain injury is caused by a rapid forward or backward movement and shaking of the brain inside the bony skull that results in bruising and tearing of brain tissue and blood vessels. Closed brain injuries are usually caused by car accidents, falls, and increasingly, in sports. Shaking a baby can also result in this type of injury (called shaken baby syndrome).

* Penetrating brain injury. Penetrating, or open head injuries happen when there is a break in the skull, such as when a bullet pierces the brain.

What is diffuse axonal injury (DAI)?

Diffuse axonal injury is the shearing (tearing) of the brain's long connecting nerve fibers (axons) that happens when the brain is injured as it shifts and rotates inside the bony skull. DAI usually causes coma and injury to many different parts of the brain. The changes in the brain are often microscopic and may not be evident on computed tomography (CT scan) or magnetic resonance imaging (MRI) scans.

What is primary and secondary brain injury?

Primary brain injury refers to the sudden and profound injury to the brain that is considered to be more or less complete at the time of impact. This happens at the time of the car accident, gunshot wound, or fall.

Secondary brain injury refers to the changes that evolve over a period of hours to days after the primary brain injury. It includes an entire series of steps or stages of cellular, chemical, tissue, or blood vessel changes in the brain that contribute to further destruction of brain tissue.

What causes a head injury?

There are many causes of head injury in children and adults. The most common injuries are from motor vehicle accidents (where the person is either riding in the car or is struck as a pedestrian), violence, falls, or as a result of shaking a child (as seen in cases of child abuse).

What causes bruising and internal damage to the brain?

When there is a direct blow to the head, the bruising of the brain and the damage to the internal tissue and blood vessels is due to a mechanism called coup-contrecoup. A bruise directly related to trauma at the site of impact is called a coup lesion (pronounced COO). As the brain jolts backward, it can hit the skull on the opposite side and cause a bruise called a contrecoup lesion. The jarring of the brain against the sides of the skull can cause shearing (tearing) of the internal lining, tissues, and blood vessels leading to internal bleeding, bruising, or swelling of the brain.

What are the possible results of brain injury?

Some brain injuries are mild, with symptoms disappearing over time with proper attention. Others are more severe and may result in permanent disability. The long-term or permanent results of brain injury may need post-injury and possibly lifelong rehabilitation. Effects of brain injury may include:

* Cognitive deficits

** Coma
** Confusion
** Shortened attention span
** Memory problems and amnesia
** Problem-solving deficits
** Problems with judgment
** Inability to understand abstract concepts
** Loss of sense of time and space
** Decreased awareness of self and others
** Inability to accept more than one- or two-step commands at the same time

* Motor deficits

** Paralysis or weakness
** Spasticity (tightening and shortening of the muscles)
** Poor balance
** Decreased endurance
** Inability to plan motor movements
** Delays in getting started
** Tremors
** Swallowing problems
** Poor coordination

* Perceptual or sensory deficits

** Changes in hearing, vision, taste, smell, and touch
** Loss of sensation or heightened sensation of body parts
** Left- or right-sided neglect
** Difficulty understanding where limbs are in relation to the body
** Vision problems, including double vision, lack of visual acuity, or limited range of vision

* Communication and language deficits

** Difficulty speaking and understanding speech (aphasia)
** Difficulty choosing the right words to say (aphasia)
** Difficulty reading (alexia) or writing (agraphia)
** Difficulty knowing how to perform certain very common actions, like brushing one's teeth (apraxia)
** Slow, hesitant speech and decreased vocabulary
** Difficulty forming sentences that make sense
** Problems identifying objects and their function
** Problems with reading, writing, and ability to work with numbers

* Functional deficits

** Impaired ability with activities of daily living (ADLs), such as dressing, bathing, and eating
** Problems with organization, shopping, or paying bills
** Inability to drive a car or operate machinery

* Social difficulties

** Impaired social capacity resulting in difficult interpersonal relationships
** Difficulties in making and keeping friends
** Difficulties understanding and responding to the nuances of social interaction

* Regulatory disturbances

** Fatigue
** Changes in sleep patterns and eating habits
** Dizziness
** Headache
** Loss of bowel and bladder control

* Personality or psychiatric changes

** Apathy
** Decreased motivation
** Emotional lability
** Irritability
** Anxiety and depression
** Disinhibition, including temper flare-ups, aggression, cursing, lowered frustration tolerance, and inappropriate sexual behavior

Certain psychiatric disorders are more likely to develop if damage changes the chemical composition of the brain.

* Traumatic Epilepsy

** Epilepsy can happen with a brain injury, but more commonly with severe or penetrating injuries. While most seizures happen immediately after the injury, or within the first year, it is also possible for epilepsy to surface years later. Epilepsy includes both major or generalized seizures and minor or partial seizures.

Can the brain heal after being injured?

Most studies suggest that once brain cells are destroyed or damaged, for the most part, they do not regenerate. However, recovery after brain injury can take place, especially in younger people, as, in some cases, other areas of the brain make up for the injured tissue. In other cases, the brain learns to reroute information and function around the damaged areas. The exact amount of recovery is not predictable at the time of injury and may be unknown for months or even years. Each brain injury and rate of recovery is unique. Recovery from a severe brain injury often involves a prolonged or lifelong process of treatment and rehabilitation.

What is coma?

Coma is an altered state of consciousness that may be very deep (unconsciousness) so that no amount of stimulation will cause the patient to respond. It can also be a state of reduced consciousness, so that the patient may move about or respond to pain. Not all patients with brain injury are comatose. The depth of coma, and the time a patient spends in a coma varies greatly depending on the location and severity of the brain injury. Some patients emerge from a coma and have a good recovery. Other patients have significant disabilities.

How is coma measured?

Depth of the coma is usually measured in the emergency and intensive care settings using a Glasgow coma scale. The scale (from 3 to 15) evaluates eye opening, verbal response, and motor response. A high score shows a greater amount of consciousness and awareness.

In rehabilitation settings, here are several scales and measures used to rate and record the progress of the patient. Some of the most common of these scales are described below.

* Rancho Los Amigos 10 Level Scale of Cognitive Functioning. This is a revision of the original Rancho 8 Level Scale, which is based on how the patient reacts to external stimuli and the environment. The scales consist of 10 different levels and each patient will progress through the levels with starts and stops, progress and plateaus.

* Disability Rating Scale (DRS). This scale measures functional change during the course of recovery rating the person's disability level from  none to extreme. The DRS assesses cognitive and physical function, impairment, disability, and handicap and can track a person's progress from "coma to community."

* Functional Independent Measure (FIM). The FIM scale measures a person's level of independence in activities of daily living. Scores can range from 1 (complete dependence) to 7 (complete independence).

* Functional Assessment Measure (FAM). This measure is used along with FIM and was developed specifically for people with brain injury.

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