What is a traumatic brain injury?

Without the protection of the skull, our brains are very vulnerable to injury.  Medical pathologists describe the consistency of living brain tissue to be like ‘jello’ or ‘soft dessert tofu’.  Sometimes even doctors who trained with fixed tissue cadavers don’t understand how vulnerable brain tissue can be. Brain tissue can be damaged by trauma but also infections, tumours or strokes. Traumatic brain injuries refer specifically to brain injury caused by a blow or other trauma to the head or body. This can include trauma from a car accident or from a lack of oxygen or swelling.  ABI, or Acquired Brain Injury, refers to brain injuries from all other causes.

Most TBIs happen when the brain tissue is bruised, bleeding, twisted or torn. Damage may occur right away or develop later as a result of swelling or bleeding within the head. Brain damage may also develop from medical complications caused by the injury. A TBI can result in a loss of consciousness and hospitalization. The brain damage may be temporary or permanent.

If you’ve suffered a blow to the head or body, seek medical care immediately. Even seemingly mild brain and head injuries (such as whiplash) can be dangerous.

Depending on the severity of the accident, TBIs may be classified as mild traumatic brain injuries or moderate and severe traumatic brain injuries.

How Common Are TBIs?

Traumatic brain injury (TBI) is the leading cause of disability for people 45 years and under. According to the Canadian Institutes of Health Research (CIHR), the annual incidence of TBI is estimated at 600 per 100,000 people in North America and Europe. The World Health Organization (WHO) predicts that deaths from road traffic incidents (primarily due to TBI) will double between 2000 and 2020 and TBI will become the third leading cause of global mortality and disability by 2020 (WHO 2009).

Two-thirds of TBIs occur in males and are most common in the young and the elderly. Acute and long-term risk factors associated with youth and sports concussions are a major concern, and there is evidence that multiple mild TBIs may predispose to early onset dementia, later substance-use disorders and mental illness (CIHR 2012).

Causes of Traumatic Brain Injury (TBI)

The leading causes of traumatic brain injury (TBI) are:

• Falls that occur down stairs, from ladders or slipping in the bathtub are the leading cause of TBI and happen most often to young children and older adults.
• Vehicle-related collisions. Accidents with cars, motorcycles or bicycles (including pedestrians involved in these accidents) are the second leading cause of TBI.
• Violent assault. Around 10% of traumatic brain injuries are caused by violence, such as gunshot wounds, domestic violence or child abuse. Shaken baby syndrome is a TBI caused by violent shaking of an infant that damages brain cells.
• Sports injuries. Many sports injuries result in TBIs, including soccer, boxing, football, baseball, lacrosse, skateboarding, hockey, and other high-impact or extreme sports.

Learn more about causes of brain injury at brainstreams.ca.

Brain Anatomy

The brain is a three-pound, jellylike mass made up of millions of microscopic cells that are suspended in cerebrospinal fluid. The brain is composed of individual cells called neurons. Traumatic brain injury (TBI) can cause these cells to malfunction or even die.

Three main areas in the brain are the: cortex, cerebellum and brain stem.

1) Cortex

The cortex is the largest part of the brain and is where most thinking functions occur. It has four lobes that control specific functions and skills, and two hemispheres: the right and the left. The left hemisphere is usually dominant and controls verbal functions such as speaking, writing, reading and calculating. The right controls visual-spatial functions such as visual memory, copying, drawing and rhythm. The frontal lobe of the cortex is involved in many cognitive functions and is considered to be our emotional and personality control center. This area is often damaged because of its size and location near the front of the cranium. Damage to temporal lobes has been associated with behavioral disorders.

2) Cerebellum

The cerebellum is located at the bottom-rear of the brain, behind the brain stem. It is responsible for coordination, balance and posture as well as some cognitive functions such as language, attention and mental imagery. It may also be involved in some emotional functions, such as regulating fear and pleasure responses. People with damage to the cerebellum can become slow and uncoordinated and experience staggering while walking and the tendency to fall. They may also experience difficulty judging distance, slurred speech, and abnormal eye movements.

3) Brain Stem

Perhaps the most critical part of the brain is the brain stem. It connects the brain to the spinal cord and controls survival functions, such as breathing, heart rate, consciousness and alertness. The brain is protected by the cranium or skull. The outside of the skull is smooth, but the inner surface contains ribbing and pronounced bony structures. When the brain moves inside the skull, it can be thrust into these bony protrusions, which tear or bruise the tissue, causing injury. The swelling and compression that follow this injury can cause long-term damage.

Learn more about brain anatomy at brainline.org

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