Brain Injury Basics
Brain injuries unpredictable in its consequences. Brain injury affects who we are and the way we think, act, and feel. It can change everything about us in a matter of seconds. The most important things to remember are:
- A person with a brain injury is a person first.
- No two brain injuries are exactly the same.
- The effects of a brain injury are complex and vary greatly from person to person.
- The effects of a brain injury depend on such factors as cause, location, and severity.
Functions of the Brain
The human brain is magnificent and complex. The brain is made up of many parts, each with a specific and important function. It controls our ability to balance, walk, talk, and eat. It coordinates and regulates our breathing, blood circulation, and heart rate. It is responsible for our ability to speak, to process and remember information, make decisions, and feel emotions. Every brain is unique, ever-changing, and extremely sensitive to its environment.
The brain is divided into functional sections, called lobes:
- Frontal Lobe (shown in orange)
- Temporal Lobe (pink)
- Parietal Lobe (blue)
- Occipital Lobe (green)
- Cerebellum (red)
- Brain Stem (yellow)
Each lobe has an important and specific function, detailed below.
FrontalLobes Functions (Orange)
· Expressive Language (Speaking)
· Motor Planning & Initiation
· Awareness of Abilities
· Awareness of Limitations
· Mental Flexibility
· Inhibition of Behavior
· Problem Solving
An injury to the frontal lobes may affect an individual's ability to control emotions, impulses, and behavior or may cause difficulty recalling events or speaking.
Brain StemFunctions (Yellow)
· Heart Rate
· Sleep & Wake Cycles
The brainstem controls the body's involuntary functions that are essential for survival, such as breathing and heart rate.
TemporalLobes Functions (Pink)
· Understanding Language (ReceptiveLanguage)
An injury to the temporal lobes may lead individuals to demonstrate difficulty with communication or memory.
ParietalLobes Functions (Blue)
· Sense of Touch
· Spatial Perception (Depth Perception)
· Identification of Sizes, Shapes, Colors
· Visual Perception
Individuals who have injured their parietal lobes may have trouble with their five primary senses.
· Balance & Coordination
· Skilled Motor Activity
· Visual Perception
An injury to the cerebellum may affect balance, movement, and coordination.
OccipitalLobes Functions (Green)
An injury to one's occipital lobes may lead to trouble seeing or perceiving the size and shape of objects.
The functional sections (lobes) of the brain are also categorized by side - the right side and the left side. If you split the brain down the middle into two equally-sized parts, they are not the same and do not carry the same functions. The right side of the brain controls the left side of the body, while the left side of the brain controls the right side of the body. Each side is responsible for different functions, and general patterns of dysfunction may occur depending on the side of the brain sustaining an injury.
The traits of each side are detailed below:
LEFT SIDE TRAITS
Injuries of the left side of the brain can cause:
· Difficulties understanding language (receptive language)
· Difficulties in speaking or verbal output (expressive language)
· Catastrophic reactions (depression, anxiety)
· Difficulty speaking
· Impaired logic
· Sequencing difficulties
· Decreased control over right-sided body movements
RIGHT SIDE TRAITS
Injuries of the right side of the brain can cause:
· Visual-spatial impairment
· Visual memory deficits
· Left neglect (inattention to the left side of the body)
· Decreased awareness of deficits
· Altered creativity and music perception
· Loss of “the big picture” type of thinking
· Decreased control over left-sided body movements
An acquired brain injury (ABI) is an injury to the brain that is not hereditary, congenital, degenerative, or induced by birth trauma. Essentially, this type of brain injury is one that has occurred after birth. The injury results in a change to the brain's neuronal activity, which affects the physical integrity, metabolic activity, or functional ability of nerve cells in the brain.
There are two types of acquired brain injury: traumatic and non-traumatic.
A traumatic brain injury (TBI) is defined as an alteration in brain function, or other evidence of brain pathology, caused by an external force. Traumatic impact injuries can be defined as closed (or non-penetrating) or open (penetrating).
Anon-traumatic brain injury is an alteration in brain function or pathology caused by an internal force.
TRAUNATICBRAIN INJURY CAUSES
· Motor Vehicle Accidents
· Sports/Recreation Injuries
· Abusive Head Trauma (Shaken BabySyndrome)
· Gunshot Wounds
· Workplace Injuries
· Child Abuse
· Domestic Violence
· Military Actions (Blast Injury)
NON-TRAUMATICBRAIN INJURY CAUSES
· Stroke (Hemorrhage, Blood Clot)
· Infectious Disease (Meningitis,Encephalitis)
· Electric Shock
· Toxic Exposure
· Metabolic Disorders
· Neurotoxic Poisoning (Carbon Monoxide,Lead Exposure)
· Lack of Oxygen (Drowning, Choking,Hypoxic/Anoxic Injury)
· Drug Overdose
Understanding the Injury
Brainin juries may be classified as traumatic or non-traumatic to describe the cause of the injury. They may also be classified as mild, moderate, or severe to indicate the initial severity of the injury. Other terms, such as diffuse or penetrating, may be used to describe the type injury. The most commonly used terms are shown below:
Diffuse Axonal Injury
A diffuse axonal injury can be caused by shaking or strong rotation of the head, as with shaken baby syndrome, or by rotational forces, such as with a ca accident.
· Injury occurs because the unmoving brain lags behind the movement of the skull, causing brain structures to tear.
· There is extensive tearing of nerve tissue throughout the brain. This can cause brain chemicals to be released, causing additional injury.
· The tearing of the nerve tissue disrupts the brain’s regular communication and chemical processes.
· This disturbance in the brain can produce temporary or permanent widespread brain damage, coma, or death.
· A person with a diffuse axonal injury could present a variety of functional impairments depending on where the shearing (tears) occurred in the brain.
Concussion/Mild Traumatic Brain Injury(mTBI)
A concussion can be caused by direct blows to the head, gunshot wounds, violent shaking of the head, or force from a whiplash-type injury. Both closed and open head injuries can produce a concussion. A concussion is the most common type of traumatic brain injury.
· A concussion is caused when the brain receives trauma from an impact or a sudden momentum or movement change. The blood vessels in the brain may stretch and cranial nerves may be damaged.
· A person may or may not experience a brief loss of consciousness (not exceeding20 minutes). A person may remain conscious, but feel “dazed” or “punch drunk”.
· A concussion may or may not show up on a diagnostic imaging test, such as a CAT scan.
· Skull fracture, brain bleeding, or swelling may or may not be present.
· A concussion can cause injury resulting in permanent or temporary damage.
· It may take a few months to a few years for a concussion to heal.
A contusion is a bruise (bleeding) on the brain caused by a force (blow or jolt)to the head.
· A contusion can be the result of a direct impact to the head.
· Large contusions may need to be surgically removed.
Coup-contrecoup injury describes contusions that are both at the site of the impact and on the complete opposite side of the brain. This occurs when the force impacting the head is not only great enough to cause a contusion at the site of impact, but is also able to move the brain and cause it to slam into the opposite side of the skull.
Second Impact Syndrome
Second impact syndrome, also termed "recurrent traumatic brain injury," can occur when a person sustains a second traumatic brain injury before the symptoms of the first traumatic brain injury have healed. The second injury may occur from days to weeks following the first. Loss of consciousness is not required. The second impact is more likely to cause brain swelling and widespread damage.
Because death can occur rapidly, emergency medical treatment is needed as soon as possible.
The long-term effects of recurrent brain injury can be muscle spasms, increased muscle tone, rapidly changing emotions, hallucinations, and difficulty thinking and learning.
Penetrating injury to the brain occurs from the impact of a bullet, knife, or other sharp object that forces hair, skin, bone, and fragments from the object into the brain.
Objects traveling at a low rate of speed through the skull and brain can ricochet within the skull, which widens the area of damage.
· A"through-and-through" injury occurs when an object enters the skull, goes through the brain, and exits the skull. Through-and-through traumatic brain injuries include the effects of penetration injuries, plus additional shearing, stretching, and rupture of brain tissue.
· Firearms are the single largest cause of death from traumatic brain injury.
Abusive Head Trauma (Shaken BabySyndrome)
Abusive head trauma, also known as shaken baby syndrome, is a violent criminal act that causes traumatic brain injury. Abusive head trauma occurs when the perpetrator aggressively shakes a baby or young child. The forceful whiplash-like motion causes the brain to be injured.
· Blood vessels between the brain and skull rupture and bleed.
· The accumulation of blood causes the brain tissue to compress while the injury causes the brain to swell. This damages the brain cells.
· Abusive head trauma can cause seizures, lifelong disability, coma, and death.
· Irritability, changes in eating patterns, tiredness, difficulty breathing, dilated pupils, seizures, and vomiting are signs of abusive head trauma. A baby experiencing such symptoms needs immediate emergency medical attention.
Locked-in syndrome is a rare neurological condition in which a person cannot physically move any part of their body aside from their eyes.
· The individual is conscious and able to think.
· Vertical eye movements and eye blinking can be used to communicate with others and operate environmental controls.
Open Head Injury
An open head injury, also known as a penetrating head injury, is a head injury in which the dura mater (the outer layer of the meninges) is breached. Penetrating injury can be caused by high-velocity projectiles or objects of lower velocity such as knives, or bone fragments from a skull fracture that are driven into the brain.
Closed Head Injury
A closed head injury is an injury to the brain caused by an outside force without any penetration of the skull. With a closed head injury, when the brain swells, it has no place to expand. This can cause an increase in intracranial pressure, which is the pressure within the skull.
As the brain swells, it may expand through any available opening in the skull, including the eye sockets. When the brain expands through the eye sockets, it can compress and impair the functions of the eye nerves. For instance, if an eye nerve, Cranial Nerve III, is compressed, a person's pupil (the dark center part of the eye) will appear dilated (big). This is one reason why medical personal may monitor a person's pupil size and intracranial pressure.
After the Injury
Immediately following a brain injury, two things occur:
1. Brain tissue reacts to the trauma from the injury with a series of biochemical and other physiological responses. Substances that once were housed safely within these cells now flood the brain, further damaging and destroying brain cells in what is called secondary cell death.
2. Depending on the severity of brain injury, effects may include temporary loss of consciousness or coma, respiratory (breathing) problems, and/or damaged motor functions.
Unlike what is seen in the movies, waking up following loss of consciousness is not immediate and sometimes can be quite difficult for the individual and their loved ones. It is important to be aware of the various neurologically-based symptoms that may occur during this period, such as irritability, aggression, posturing, and other issues. Post-traumatic amnesia(PTA) is also typically experienced as an injured person regains consciousness.PTA refers to the period when the individual feels a sense of confusion and disorientation (i.e., wondering who or where they are and what has happened to them) and an inability to remember recent events.
As time passes, these responses typically subside, and the brain and other body systems approach stability. Unlike bones or muscle tissue, the neurons in the brain do not mend themselves. New nerves do not grow in ways that lead to full recovery.In fact, certain areas of the brain remain damaged, and the functions that were controlled by those areas may be disrupted and lead to challenges in the individual's life.
The severity of damage to the brain after an injury is the primary factor in predicting the injury's impact on the individual. Brain injury is typically categorized as mild, moderate, or severe.
MILD BRAIN INJURY
· Brief, if any, loss of consciousness
· Vomiting and Dizziness
· Memory Loss
MODERATE BRAIN INJURY
· Unconsciousness up to 24 hours
· Signs of brain trauma
· Contusions or bleeding
· Signs of injury on neuro imaging
SEVERE BRAIN INJURY
· Unconsciousness exceeding 24 hours (coma)
· No sleep/wake cycle during loss of consciousness (LOC)
· Signs of injury appear on neuro imaging tests
A severe brain injury may cause the individual to experience an unconscious state, where one appears to be in a deep sleep and cannot be aroused or respond purposefully. Assessments will typically reveal that the individual has no sleep and wake cycles. This loss of consciousness (LOC) is referred to as a coma. Depending on varying factors and the severity of injury, the individual may remain in a coma, emerge from a coma, or experience an increased level of consciousness.
A person who is truly in a coma will not be considered for any type of brain injury rehabilitation program. People can, however, experience different states of consciousness after brain injury. Understanding these disorders of consciousness can be important when discussing treatment and possible rehabilitation options.
An individual is unaware, but begins to have sleep and wake cycles; normal digestion, breathing, and heart rates; and may open his or her eyes. The individual may occasionally respond to stimuli.
Persistent Vegetative State
Doctors consider a person to be in a persistent vegetative state one year after traumatic brain injury or three to six months after a hypoxic or anoxic brain injury.
However, in certain rare cases, individuals with traumatic brain injury have emerged from a vegetative state after more than one year, and individuals with hypoxic anoxic brain injury have done the same after more than three months.Research continues to study the recovery process of people who are considered to be in this state.
Minimally Conscious State
An individual shows slight but definite self-awareness or awareness of their environment.
They may inconsistently speak short phrases or words, respond to simple commands, may make "yes or no" gestures or verbalizations (sometimes incorrectly), follow people with their eyes, grasp or hold objects, and show appropriate emotional responses, such as smiling or crying. One person may only demonstrate a few of these behaviors, while others exhibit all of them. A minimally responsive state may be a transition level to a higher level of consciousness. An individual is considered out of a minimally conscious state if he or she can communicate consistently (at least “yes” and “no”) or can use common objects, such as a glass or brush.
An individual can only move his or her eyes, not any other part of their body, and is conscious and able to think.
The person may use vertical eye movements and eye blinking codes to communicate and operate environmental controls. Locked-in syndrome is rare.
A person with brain death is not alive because all the brain functions, including the brain stem, no longer work.
Physicians refer to the Uniform Determination of Death Act (UDDA) to make the determination of brain death based on several specific medical criteria. Brain death is not reversible.