Brain Injury Attorney
Traumatic brain injury (TBI, also called intracranial injury) occurs when an outside force traumatically injures the brain. TBI can be classified based on severity, mechanism (closed or penetrating head injury), or other features (e.g. occurring in a specific location or over a widespread area). Head injury usually refers to TBI, but is a broader category because it can involve damage to structures other than the brain, such as the scalp and skull.
TBI is a major cause of death and disability, especially in children and young adults. Causes include falls, motor vehicle collisions, and violence. Prevention measures include use of safety equipment, such as seat belts and sports or motorcycle helmets, as well as efforts to reduce the number of accidents, such as safety education programs, enforcement of traffic laws, and tort litigation.
Brain trauma can be caused by a direct impact or by acceleration/deceleration of the head resulting in coup-contrecoup type brain injury. In addition to the damage caused at the moment of injury, brain trauma causes secondary injury, a variety of events that take place in the minutes and days following the injury. These processes, which include alterations in cerebral blood flow and the pressure within the skull, contribute substantially to the damage from the initial injury.
TBI can cause a host of physical, cognitive, emotional, and behavioral effects, and outcome can range from complete recovery to permanent disability or death.
Severity
Head injuries can be classified into mild, moderate, and severe categories. The Glasgow Coma Scale (GCS), a universal system for classifying TBI severity, grades a person's level of consciousness on a scale of 3–15 based on verbal, motor, and eye-opening reactions to stimuli. It is generally agreed that a TBI with a GCS of 13 or above is mild, 9–12 is moderate, and 8 or below is severe. Similar systems exist for determining the level of brain injury in young children. Other classification systems such as the one shown in the table determine severity based on the GCS at the time of initial evaluation, after resuscitation, the duration of post-traumatic amnesia (PTA), loss of consciousness (LOC), or combinations thereof. It is also possible to classify TBI based on prognosis or indicators of damage visible with neuroimaging, such as mass lesions and signs of diffuse injury. Grading scales also exist to classify the severity of mild TBI, commonly called concussion; these use duration of loss of consciousness, PTA, and other concussion symptoms.
Glasgow Coma Scale
Systems for Determining Severity
| Glasgow Coma Scale |
Post-Traumatic Amnesia | Loss of Consciousness | |
| Mild | 13-15 | < 1 hour | < 30 minutes |
| Moderate | 9-12 | 30 min–24 hours | 1-24 hours |
| Severe | 3-8 | > 1 day | > 24 hours |
Signs and symptoms
Symptoms are dependent on the type of TBI (diffuse or focal) and the part of the brain that is affected. Unconsciousness tends to last longer for people with injuries on the left side of the brain than for those with injuries on the right. Symptoms are also dependent on the injury's severity. With mild TBI, the patient may remain conscious or may lose consciousness for a few seconds or minutes. Other symptoms of mild TBI include disorientation to date, time and place, headache, vomiting, nausea, lack of motor coordination, dizziness, difficulty balancing, light-headedness, blurred vision or tired eyes, ringing in the ears, bad taste in the mouth, fatigue or lethargy, and changes in sleep patterns. Cognitive and emotional symptoms include behavioral or mood changes, confusion, and trouble with memory, concentration, attention, or thinking. Mild TBI symptoms may also be present in moderate and severe injuries.
Unequal pupil size is a sign of a serious brain injury. A person with a moderate or severe TBI may have a headache that does not go away, repeated vomiting or nausea, convulsions, an inability to awaken, dilation of one or both pupils, slurred speech, weakness or numbness in the limbs, loss of coordination, and increased confusion, restlessness, or agitation.
When the pressure within the skull (intracranial pressure, abbreviated ICP) rises too high, it can be deadly. Signs of increased ICP include decreasing level of consciousness, paralysis or weakness on one side of the body, and a blown pupil, one that fails to constrict in response to light or is slow to do so. Cushing's triad, a slow heart rate with high blood pressure and respiratory depression is a classic manifestation of significantly raised ICP. Anisocoria, unequal pupil size, is another sign of serious TBI. Abnormal posturing, a characteristic positioning of the limbs caused by severe diffuse injury or high ICP results from brain herniation, and is an ominous sign.
Small children with moderate to severe TBI may have some of these symptoms but have difficulty communicating them. Other signs seen in young children include persistent crying, inability to be consoled, listlessness, refusal to nurse or eat, and irritability.
Causes
The most common causes of TBI include falls, motor vehicle collisions, on the job injuries and recreational activity injuries. In the U.S., falls account for 28% of TBI, motor vehicle (MV) collisions for 20%, being struck by an object for 19%, violence for 11%, and non-MV bicycle accidents for 3%. Bicycles and motor bikes are major causes. The estimates are that between 1.6 and 3.8 million traumatic brain injuries each year are a result of sports and recreation activities in the U.S. In children aged two to four, falls are the most common cause of TBI, while in older children bicycle and auto accidents compete with falls for this position.
Mechanism and pathophysiology
Physical forces
It is important to remember that the brain is composed of billions of individual functional units known as neurons with countless interconnections throughout the brain. This is especially important in the understanding of diffuse or traumatic brain injury, which literally involves damage to countless numbers of neurons and their interconnections.
Ricochet of the brain within the skull may account for the coup-contrecoup phenomenon. The type, direction, intensity, and duration of forces all contribute to the characteristics and severity of TBI. Forces that may contribute to TBI include angular, rotational, shear, and translational forces.
Even in the absence of an impact, significant acceleration or deceleration of the head can cause TBI; however in most cases a combination of impact and acceleration/deceleration is probably to blame. Forces involving the head striking or being struck by something, termed contact or impact loading, are the cause of most focal injuries, and movement of the brain within the skull, termed non contact or inertial loading, usually causes diffuse injuries. In impact loading, the force sends shock waves through the skull and brain, resulting in tissue damage.
Damage may occur directly under the site of impact, or it may occur on the side opposite the impact (coup and contrecoup injury, respectively). When a moving object impacts the stationary head, coup injuries are typical while contrecoup injuries are usually produced when the moving head strikes a stationary object.
