Although it is most common for a brain injury to occur from an accident or fall, lasting injury to the brain can be caused by lack of oxygen (anoxia), concussion - loss of consciousness (extended = coma), cardiac arrest or stroke, exposure to toxic substances (street drugs, lead paint chips, carbon monoxide), diabetic coma, near-electrocution, taking the wrong medication or incorrect dosage, untreated spinal cord or brain infection, criminal assaults and domestic violence.

The trauma referred to by Traumatic Brain Injury (TBI) may be from impact to the head or from the effect of the motion of the head on the brain. Impact injury can result from a moving object striking a stationary head (a sign falling on someone’s head) or from a moving head striking a stationary object (tripping and striking one’s head on the sidewalk). Motion injury involves the sudden acceleration/deceleration of the brain within the skull (whiplash from car accident).

The acceleration forces acting on the brain may be linear (transitional) or angular (rotational). A linear force would be a baseball striking the head and propelling the brain straight against the opposite side of the skull. A rotational force would be any force which rapidly twists the brain such as a rear-end car crash which occurs when the driver’s head is turned left or right. Rotational force tends to be more injurious to the brain because the brain is built up of layers of tissue that may fissure from rapid rotation. Impact injuries tend to cause focal contusions (bruises) with bleeding to the brain tissue. Motion injuries tend to cause diffuse damage to nerve fiber and junctions throughout the brain. A given event may cause both an impact injury and a motion injury to the brain (a crate falling off a high shelf, striking one’s head and twisting the head in the fall).

A traumatic brain injury may be closed head or open head. A closed head injury refers to an injury that does not penetrate or fracture the skull. An open head injury refers to the entry of a "missile" into the brain through the skull (bullet or knife) or an inward cracking of the skull with depression of the fractured fragments into the brain.

The trauma causing brain injury can be a one-time event (auto accident) or cumulative events (boxing, heading soccer balls) or domestic physical abuse. The risk of sustaining a second TBI injury geometrically increases the scope of damage. Prevention of a second injury is very important for all head injury survivors. This is why student athletes must be aggressively monitored for concussion.

• Motivation
• Controls attention
• Judgment
• Problem solving
• Decision making
• Guide/control social behavior
• Emotional responses/control
• Expressive language
• Motor integration
• Voluntary movements

• Loss of simple movement of body parts (Paralysis)
• Inability to plan a sequence of movements needed to complete multi-step tasks such as making coffee (Sequencing)
• Inability to focus on a task (Attending)
• Difficulty with problem solving
• Loss of spontaneity in interactions with others
• Loss of flexibility in thinking
• Persistence of a single thought (Perservation)
• Inability to express language
• Mood changes
• Changes in social behavior
• Changes in personality

• Visual attention
• Touch perception
• Manipulation of objects
• Awareness of spatial relationships
• Academic skills (reading)

• Inability to attend to more than one object at a time
• Inability to name an object (Anomia)
• Inability to locate the words for writing (Agraphia)
• Problems with reading
• Difficulty drawing objects
• Difficulty distinguishing left from right
• Problems with mathematics
• Lack of awareness of certain body parts and/or surrounding space that leads to difficulties in self-care
• Inability to focus visual attention
• Difficulties with hand to eye coordination

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• Defects in vision
• Difficulty locating objects in current environment
• Difficulty identifying colors
• Hallucinations
• Visual illusions - inaccurately seeing objects
• Inability to recognize words
• Difficulty recognizing drawn objects
• Inability to recognize the movement of an object
• Difficulty reading and writing

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• Hearing (musical awareness)
• Learning
• Memory acquisition
• Emotions

• Difficulty recognizing faces
• Difficulty understanding spoken words
• Disturbance of selective attention - visual and hearing
• Difficulty identifying and verbalizing about objects
• Short-term memory loss
• Interference with long-term memory
• Changes in sexual behavior
• Inability to categorize objects
• Right lobe damage can cause persistent talking
• Increased aggressive behavior

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• Breathing
• Heart rate
• Swallowing
• Reflexes for seeing and hearing
• Controls sweating, blood pressure, digestion, temperature (Autonomic Nervous System)
• Affects level of alertness
• Affects ability to sleep
• Sense of balance

• Decreased vital capacity for breathing - important for speech
• Difficulty swallowing food and water
• Difficulty with organization and perception of environment
• Problems with balance and movement
• Dizziness and nausea (Vertigo)
• Sleeping difficulties

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• Coordination of voluntary movements
• Balance and equilibrium
• Memory for reflex motor acts

• Loss of ability to coordinate fine movements
• Loss of ability to walk
• Inability to reach out and grab objects
• Tremors
• Dizziness
• Slurred speech
• Inability to make rapid movements

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The brain functions by interrelating its component parts and uses a network of neuron cells to send "messages" to all parts of the body. An injury to one part of the brain disrupts the "message system" and activity associated with that part of the brain is no longer connected to the message network. This interruption of activity, at any particular step, reveals problems associated with the injury. Everyone has a unique set of neurons transmitting these messages; therefore every injury has a unique set of associated problems.

Physical and behavioral effects of TBI present significant challenges for rehabilitation but the cognitive deficits are often the most difficult for the caregivers and family. Cognitive deficits are not physically obvious and are therefore more difficult for others to understand.

Advances in medical treatment and emergency services are providing brain-injured patients with better diagnoses and specialized care. Identification of the effects of a head injury is an important step in helping the injured and their families. Rehabilitation programs include physical restoration, psychosocial and vocational programs designed to help the patient to live a functional life.