Brain Injury

March is Brain Injury Awareness Month. Did you know that there are more than 5.3 million people in the US who are living with a disability cause by a permanent brain injury? At least 2.8 million Americans sustain a traumatic brain injury in the US every year. Some of them will recover fully, with no long-term effects but some will live with the residual effects for the rest of their lives. There were also over 64,000 deaths related to traumatic brain injury (TBI) in the US in 2020. That is about 176 TBI-related deaths every day. With so many people affected, I thought it was a good subject for us to explore.

Let's start by talking about some of the functions of the brain.

The human brain is a complex organ. It is made up of many parts, which each have a specific important function. There are four different lobes of the brain (they make up the cerebrum), plus the cerebellum, and the brain stem. The brain controls our ability to walk, talk, eat, balance. It regulates/coordinates our breathing, blood circulation, and heart rate. It allows us to speak, to process and remember information, make decisions, and feel emotions. The brain is always changing. Every person's brain is unique, even though they may look very similar. The brain is very sensitive to its environment and to injury. It also has the ability to adapt and can be "trained" in new ways to perform tasks when a part of it is damaged. Overall, I would say the brain is a magnificent structure!

Now let's learn some terms that apply to brain injuries.

An acquired brain injury (ABI) is an injury to the brain that is not hereditary, congenital, degenerative, or induced by birth trauma. Essentially, ABI refers to any brain injury that occurs after birth. There are two different types of ABI. They are 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 or trauma. There are two types of TBI. They are:

• Closed head injury, also called non-penetrating, is an injury that does not cause anything to penetrate the outer coating of the brain. This would include things like concussion. Even a skull fracture would be considered a closed injury if nothing penetrates to the brain.
• Open head injury, or penetrating injury, is a head injury in which the outer layer of the brain is breached. Penetrating injury can be caused by high-velocity projectiles, such as gun shot wounds, or lower velocity objects such as knives, or bone fragments from a skull fracture that are pushed into the brain from the force of impact.

A non-traumatic type of acquired brain injury is one in which damage to the brain is caused by internal factors. This could include lack of oxygen, pressure from a tumor, bleeding inside the skull, increased fluid inside the skull, etc.

Secondary brain injury is caused by swelling and release of chemicals that increase inflammation and lead to injury or death of brain cells. The primary injury is the trauma. The secondary injury leads to swelling in the brain, which may increase the pressure within the skull. This may prevent the cerebrospinal fluid from draining out of the skull, which further increases the pressure leading to more brain cell damage. If the secondary injury is not prevented or recognized, and controlled, the lower portion of the brain can be pushed through the base of the skull. This causes all basic functions of the body, such as breathing, to stop, leading to death.

The only way to prevent the primary injury is to prevent the trauma. Prevention of secondary brain injury is the focus of the acute medical care after the injury. It is the reason why quick and competent medical care is essential after a head injury.

What are some common causes of acquired brain injuries?

Traumatic brain injury causes include:

• Falls
• Assaults
• Motor vehicle crashes
• Sports or recreation injuries
• Abusive head trauma (such as shaken baby syndrome, other child abuse, or domestic violence)
• Gunshot wounds
• Workplace injuries
• Power tool injuries at home (woodworking, chainsaws, etc.)
• Military injuries (such as blast injury)

Non-traumatic brain injury causes include:

• Stroke
• Infections (including meningitis or encephalitis)
• Seizure
• Electric shock
• Tumors
• Exposure to certain toxins (such as lead, carbon monoxide, drug overdose, etc)
• Lack of oxygen (such as drowning, choking, etc.)
• Aneurysm rupture

Next week, we will explore this topic more.

If you have any questions about brain injuries, please log into your account and send us your question. We are here to help.

Dr. Anita Bennett MD - Health Tip Content Editor