The brain is a vital part of the central nervous system and serves as the control center for all of the body's functions including conscious activities such as walking and talking, and unconscious ones such as breathing, heart rate, etc. The brain controls thought, comprehension, speech and emotion. Injury to the brain--whether the result of severe head trauma such as a gunshot wound or a skull fracture, or a closed head injury in which there is no fracture or penetration of the skull - can disrupt some or all of these functions.

Enclosed within the skull, the brain is a gelatinous material that floats within a protective sea of cerebrospinal fluid. This fluid supports the brain and acts as a shock absorber in rapid head movements. Both the brain and the cerebrospinal fluid are protected to some degree within the bony framework of the skull. The outer surface of the skull is smooth, but the inner surface is rough and jagged and can cause significant damage in closed head injuries. In such injuries, the head and body in motion are abruptly stopped, causing the brain to rebound within the skull and move over these rough bony structures.

There are three main areas of the brain:

1. Cortex - The cortex is the largest of the three and is the center where most thinking functions occur. It is divided into four lobes, each of which controls particular functions and skills. Additionally, the cortex is divided into two hemispheres: the right and the left. The left hemisphere is usually the dominant of the two and controls verbal functions such as speaking, writing, reading, and calculating. The right hemisphere usually controls more visual-spatial functions such as visual memory, copying, drawing, and rhythm.

2. Cerebellum - the cerebellum controls coordination, balance and posture.

3. Brain stem (diencephalon) - The brain stem acts as a relay station between incoming sensations and the cortex, which processes and interprets those sensations. The brain stem connects the two hemispheres of the brain to the spinal cord and is also the point of origin for 12 cranial nerves. When incoming stimuli travel through the brain stem and are received by the cortex, a response is generated and then relayed back through the brain stem to the body. Because of its vital role as a relay station and its function in controlling consciousness, alertness and basic bodily functions, the brain stem is perhaps the most critical area in terms of damage to the brain.

The term "traumatic brain injury" refers to any injury of the brain caused by a trauma to the head. The injury can be caused by fracture or penetration of the skull (such as in the case of a vehicle accident, fall or gunshot wound), or a closed head injury such as in the case of rapid acceleration or deceleration of the head, including Shaken Baby Syndrome (1). These injuries can have devastating lifelong effects on physical and mental functioning (2).

Depending on the location and severity of the injury, the body can be affected in a myriad of ways. When the injury results from head trauma, damage to the brain may occur at the time of impact or may develop later due to swelling (cerebral edema) and bleeding into the brain (intracerebral hemorrhage) or bleeding around the brain (epidural or subdural hemorrhage). When the head is hit with sufficient force, the brain turns and twists on its axis (the brain stem), interrupting normal nerve pathways and causing a loss of consciousness. If this unconsciousness persists over a long period of time, the injured person is considered to be in a coma, a condition caused by the disruption of the nerve fibers going from the brain stem to the cortex.

If the injury is severe, as in the case of an acceleration-deceleration injury in which the moving head impacts against a hard, fixed surface, multiple areas of the brain are damaged. For example, a compression fracture occurs in the area where the head impacted the fixed surface. Upon impact, the brain rebounds forward and backward against the skull (this is called coup-contracoup), which tears the subdural veins, causes damage to the temporal lobes as they move across the rough bony structures within the skull, and results in bleeding, swelling of the brain stem, and shearing of the blood vessels and nerve fibers.

The term "closed head injury" is used when the brain has been damaged without penetration of the skull by another object. One example of this is Shaken Baby Syndrome, in which the brain is damaged by severe and violent shaking or twisting. Such injury often occurs without leaving obvious external signs. The difference between closed and penetrating injuries can be profound. In a bullet wound to the head, for example, a large area of the brain may be destroyed but the resulting neurologic deficit may be minor if that area was not a critical one. In contrast, closed head injuries result in more widespread damage and can result in more extensive neurologic deficits. These deficits can include partial to complete paralysis, cognitive, behavioral, and memory dysfunction, persistent vegetative state, and death. These last two are the most feared outcomes in cases of brain injury, however advances in trauma care have led to decreased rates for both in recent years.

Traumatic brain injury can have serious and lifelong effects on the physical and mental functioning of the survivor. Numerous studies have documented the physical, cognitive, social, emotional and behavioral impairments caused by TBI (2-5). Loss of consciousness, permanently altered memory and/or personality, partial or complete paralysis, and persistent vegetative state are just some of the devastating possibilities brain injury survivors and their families face. The Centers for Disease Control and Prevention (CDC) estimates that each year, 80,000 to 90,000 people will experience long-term disability as a result of a TBI (6). Beyond the obvious physical effects of brain injury, survivors frequently cope with depression, anxiety, loss of self esteem, altered personality, and in some cases, a lack of self-awareness by the injury survivor of any existing deficits.

Mild TBI (MTBI) is one of the most common forms of brain injury. Mild TBI occurs when an impact or forceful motion of the head results in a brief alteration of mental status. This is in contrast to more severe TBI, which is associated with extended periods of unconsciousness, prolonged amnesia or penetrating skull injury. The CDC has recommended a definition for MTBI as an injury to the head as a result of blunt trauma or acceleration or deceleration forces that result in one or more of the following conditions: any period of observed or self-reported transient confusion, disorientation, or impaired consciousness; dysfunction of memory around the time of injury; loss of consciousness lasting less than 30 minutes; and observed signs of neurological or neuropsychological dysfunction such as seizure acutely following injury to the head. Among infants and very young children: irritability, lethargy or vomiting following head injury also met the CDC definition for MTBI (7).

There is no standard classification system for concussions. Four of the leading researchers in head injuries maintain their own classification system. The symptoms of each degree of concussion are often very similar, and one can be confused when accessing a head injury.

Concussions can be divided into five grades, 0 thru 4.

Grade 0: results when the head is struck or moved rapidly. It is characterized by a post injury headache and difficulty with concentration. The athlete may not notice any other symptoms.

Grade 1: concussions occur in the same manner but the athlete may appear stunned or dazed. There is no loss of consciousness (LOC), and sensory difficulties clear in less than one minute. Grade 1 concussions are the typical I got my bell rung description from the athlete.

Grade 2: concussions are characterized by headache, cloudy senses lasting longer than one minute, and no LOC. The athlete may have other symptoms including, tinnitus, amnesia, irritability, confusion, or dizziness. One, all or none of these symptoms could be present.

Grade 3: concussions are characterized by LOC of less than one minute, the athlete will not be comatose, and exhibit the same symptoms as a grade 2 concussion.

Grade 4: concussions are characterized by LOC of greater than one minute. The athlete will not be comatose, and will also exhibit the symptoms of the grade 2 and 3 concussions.

The Rancho Los Amigos Cognitive Scale is one of the ways to document a patient's recovery from a coma. This scale is used by professionals to communicate consistently with other health care providers about a patient. The goals of this system are:

1. To document systematically the patient's behavioral responses to people and things in th environment.

2. To allow some limited ability to predict what types of behaviors can be expected from the patient in the future.

3. to allow for suggestions as to how to help the patient interact and communicate with the family, friends and medical staff more effectively and consistently.

Level I: No resonse to pain, touch, sound or sight.

Level II: Generalized reflex response to pain.

Level III: Localized response. Blinks to strong light, turns toward/away from sound, respondes to physical discomfort, inconsistent response to commands.

Level IV: Confused-Agitated. Alert, very active, agressive or bizarre behaviors, performs motor activities, but behavior is non-purposeful, extremely short attention span.

Level V: Confused - Non-agitated. Gross attention to evnironment, highly distractable, requires continual redirection, difficulty relearning new tasks, agitated by too much stimulation. May engage in social conversation but with inappropriate verbalizations.

Level VI: Confused - Appropriate. Inconsistent orientation to time and place, retention span/recent memory impaired, begins to recall past, consistently follows simple directions, goal-directed behavior with assistance.

Level VII: Automatic - Appropriate. Performs daily routine in highly familiar environment in a non-confused but automatic robot-like manner. Skills noticeably deteriorate in unfamiliar environment. Lacks realistic planning for own future.

Level VIII: Purposeful - Appropriate.

From 1995 to 2001, the CDC estimated that at least 1.4 million TBIs occurred in the United States (9).

Of these 1.4 million TBIs, 50,000 resulted in death, 235,000 resulted in hospitalization and 1.1 million were treated and released from the emergency department (9).

It is unknown how many people will experience a TBI and not be seen in a hospital or ED or who will receive no care at all (9).

The risk of TBI is higher for males than females, with adolescents, young adults and the elderly at the highest risk of TBI injuries (6,9-11).

The most common causes of TBI deaths are attributed to motor vehicle crashes, falls and violence (23).

In the US, African Americans have higher rates brain injury than other groups (9,11).

Lower socioeconomic status is also associated with increased risk of brain injury (12).

Males are significantly more likely to sustain a TBI that results in death or medical treatment compared to females (8). Overall, approximately 1.5 times as many TBIs occur among males as females. In almost every age group, TBI rates are higher for males that for females(9).

The elderly (i.e. those aged 75 and older) and young adults (i.e. 15-24) sustain the highest rates of TBI-related deaths and hospitalizations whereas infants and young children (i.e., 0 - 14 years of age) are the most likely to visit the emergency department or a physician's office for a minor TBI (6,9,11). For children aged 0 to 14 years, TBI results in an estimated 2,685 deaths, 37,000 hospitalizations and 435,000 ED visits annually (9).

Ethnic and socio-economic origin are significant risk factors in the occurrence of TBI. The African-American population has a higher death rate from TBI than other ethnic groups in the United States (9,11). Most of these incidents are related to homicide. TBI hospitalization rates are highest among African Americans and American Indians/Alaska Natives (9). Lower socioeconomic status is also associated with increased risk of TBI (12).

Another significant risk factor in the incidence of brain injury is the occurrence of a previous brain injury. These repeated insults to the brain are most office related to multiple concussions. In the sports literature, there is strong evidence that suggests a prior history of a TBI is associated with an increased risk of another TBI among athletes (13-15) After a TBI incident, the potential risk for subsequent multiple injuries is extremely common. Among people with an initial TBI incident, the risk of a second injury is three times that of the general population, and after a second brain injury, the potential risk for a third one increases to eight times that of the normal average (16). While there have been studies of persons with a repeat TBI which document the proportion of a TBI group with a prior history of TBI, no studies have systematically evaluated the risk of recurrent TBI among persons who sustain a TBI severe enough to require a hospitalization or ED visit (17,18).

The economic consequences of TBI are enormous. It is estimated that the cost of acute care and rehabilitation for new cases of TBI was $9 to $10 billion in the US. The estimates for the average cost of care over a lifetime for a person with severe TBI raged from $600,000 to $1,875,000 (2). The direct medical costs and indirect costs such as lost productivity of TBI totaled an estimated $60 billion in the United States in 2000 (19). These figures are underestimates, since it is difficult to estimate the family and societal costs of TBI as well as lost earnings, cost to services systems and the lost time and wages of family members caring for their loved ones with a TBI (2).

Worldwide Brain injury is the leading cause of death and disability (20). Worldwide TBI mortality rates range from about 15 to 30 per 100,000 population annually. Based on current census reports, it is estimated that TBI claims approximately 1,165,000 lives per year. Of the five to ten percent of deaths related to general injuries, approximately 40% is associated with traumatic brain injury (21). The human toll of brain injury -- loss of life, identity, relationships, and employment -- is incalculable.

TBI is a leading cause of death and lifelong disability among children and adults in the United States. The CDC has estimated that each year at least 1.4 million people will sustain a TBI. Of these people, 50,000 will die, 235,000 will be hospitalized and 1.1. million will be treated and released from the emergency department (ED) (9). It remains unknown how many people will experience a TBI and see a family physician or who will receive no care at all (9). Approximately, 75% of all TBI is classified as mild TBI (MTBI) (18). MTBI is most often treated in the emergency department or in non-hospital medical settings or is not treated at all (18).

Although mild TBI-related hospitalizations have decreased significantly, there appears to be an increase in TBI-related ED visits. Using data from the National Health Interview Survey in 1991, it was estimated that the incidence of TBI-related ED visits was 216 per 100,000 persons (8). Using 1995-1996 data from the National Hospital Ambulatory Care Survey (NHAMCS), it was estimated the TBI-related ED visit rate was 392 per 100,000 persons (4). This increase in TBI-related ED visit rates could have resulted from using different data sources to estimate TBI-related ED visits, or it may reflect actual changes in the hospital practices to shift care of persons with less severe forms of TBI from hospital inpatient care to ED and outpatient treatment (22).

The leading causes of TBI are falls, motor vehicle injuries, and being struck by or against an object or person. The most common causes of TBI death are firearms, motor vehicle injuries and falls (23). Although firearms are a major cause of TBI-related death, they account for less than 10% of all TBI-related hospitalization. The majority of the TBIs which required hospitalization were caused by motor vehicle injuries and falls (6).

Child maltreatment involving physical abuse is the leading cause of serious head injury in children of which the majority occurs in children younger than 2 years (24,25). A population-based study of inflicted traumatic brain injury in young children found that the majority of children who were hospitalized with TBI were injured intentionally, and that infant boys were more likely than infant girls to suffer TBI due to physical abuse (26).

Each year in the United States, 567,000 people go to an ED with bicycle-related injuries, of which approximately 350,000 are children under 15. Of those children, approximately 130,000 sustain brain injuries (27). Children ages 10 to 14 are at greater risk for traumatic brain injury from a bicycle-related injury compared with younger children, most likely because helmet use declines as children age (28).

Overall, about 1 in 8 of the cyclists with reported injuries had a brain injury. Two-thirds of the deaths from bicycles injuries are from traumatic brain injury. A very high percentage of cyclists' brain injuries can be prevented by a helmet, estimated at anywhere from 45% to 88% (29). Most bicycle-related brain injury deaths occur during the summer months (i.e., July, August and September) (30).

The problems caused by traumatic brain injury are extensive and complex. The areas of impact include cognitive, physical/perceptual, behavioral, psychosocial, along with an inability to generalize on the part of the injured individual, and a frank denial of deficits.

Within the cognitive arena, there is the inability to self-regulate, impaired memory, impaired judgment, decreased processing skills, and impaired organizational skills.

Within the physical/perceptual arena, the individual has a very real decreased functional capacity and moves on through life with decreased safety awareness.

Within the behavioral arena, the individual and family members must deal with their impulsivity, their lack of initiation, their irritability, and lowered frustration tolerance.

Within the psychosocial arena, there is a very real impact on all existing relationships and any new relationships over a lifetime. There is a very real inability to sustain relationships.

The consequences of these changes include, with some variability, all of the following:

Breakdown of family support systems

Withdrawal of friends

Physical deterioration

Isolation

Substance Abuse

Unemployment

Increased health risk

Increased risk of repeat hospitalization

Helmets, seat belts, airbags, and car seats have been proven to reduce TBI incidents and death (31). Brain injury is the leading cause of death in bicycle incidents. Between 70% and 80% of all fatal bicycle crashes involve brain injuries (29). If everyone wore a helmet when riding a bicycle, then one death every day could be prevented as well as one brain injury every four minutes (29). Wearing bicycle helmet regularity is the single most effective protection against brain injury (27). Every dollar spent on a bike helmet saves society $30 in direct medical costs and other costs to society (28). In addition to riding a bicycle, the proper use of a helmet when riding a scooter could reduce brain injuries by 85% (32)

Proper Helmet Usage for every time you ride a bicycle, scooter or in-line skates(28):

• Wear a bicycle helmet that meets or exceeds the safety standards developed by the U.S. Consumer Product Safety Commission.

• A helmet should sit on top of your head in a level position, and it should not rock forward and backward or side to side.

• The helmet straps must always be buckled but not too tightly.

• Ensure proper bike fit by bringing the child along when shopping for a bike.

• Buy a bicycle that is the right size for the child, not one he will grow into.

• When sitting on the seat, the child's feet should touch the ground.

An astounding 80 percent of police-reported motorcycle crashes result in injury or death to involved riders. Motorcycle rider fatalities have increased each year since reaching a historic low of 2,116 fatalities in 1997 to 4,008 in 2004, an increase of 89 percent (33).

Data for 2004 shows that motorcycle rider fatalities increased for every age group, with the largest number of fatalities in the 20-29 and the 40 and over age groups. About two-thirds of the fatally injured motorcycle riders were not wearing helmets in States without universal helmet laws compared to 15 percent in States with universal helmet laws. Alcohol-related crashes killed over 1,500 motorcyclists in 2004, which is a 1 percent increase from 2003 (33).

Brain injury is the leading cause of death in motorcycle crashes. A recent NHTSA study estimates that helmets saved the lives of 1,546 motorcyclists in 2005. If all motorcyclists had worn helmets, an additional 728 lives could have been saved. Helmets are estimated to be 37% effective in preventing fatal injuries to motorcyclists. This translates to: for every 100 motorcyclists killed in crashes while not wearing a helmet, 37 of them could have been saved had all 100 worn helmets (34).

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