Understanding common types of brain injury
Each brain injury is different. A primary injury refers to the moment of impact, and a secondary injury refers to complications from the primary injury. Issues such as cerebral edema, hypoxia, ischemia, or herniation are all considered secondary injuries. After the primary injury, preventing secondary injuries becomes the focus in emergency and intensive care units.
Types of problems, as well as length and amount of recovery, vary considerably from person to person, depending on the location, type, and extent of injury. Some problems affect many people while others seldom occur.
Types of traumatic brain injury
A traumatic brain injury (TBI) is defined as an alteration in brain function or other evidence of brain pathology that’s caused by an external force.
- A closed head injury is a trauma caused by a blow to the head leading to the brain knocking against the skull. Nothing penetrates the brain.
- An open head injury, also called a penetrating brain injury, results when an object penetrates the skull and enters the brain, causing focal damage to that tissue.
Specific types of TBIs include:
- Diffuse axonal injury: A diffuse axonal injury (DAI) is the result of widespread shearing trauma of the axons, the parts of the nerve cells that allow neurons to send messages, are disrupted. This force is caused when the head rapidly accelerates or decelerates causing the brain to shift forward, backward, or rotationally within the skull.
- Concussion: A concussion is the immediate, temporary loss of consciousness from an external strike or force to the brain.
- Contusion: A contusion is bruising to the brain tissue.
- Hemorrhagic injury: A hemorrhagic injury is a type of stroke caused by an artery in the brain bursting and causing localized bleeding. Head trauma is the most common cause of hemorrhage.
- Intra-cerebral hemorrhage occurs when a blood vessel in the brain bursts, allowing the blood to leak and causes pressure on the brain which can cause damage.
- Subarachnoid hemorrhage refers to blood leaking within the subarachnoid space between the brain and the tissue that covers the brain.
- Coup/contrecoup injury: A coup or countrecoup injury involves a blow to one side of the head. It may cause an injury at that location, called a coup, and on the opposite side, called the contrecoup, due to rapid brain movement.
- Each person and each brain injury is different. Some problems affect many people while others seldom occur.
- Types of problems, as well as length and amount of recovery, vary considerably from person to person depending on the location, type, and extent of injury. Localized injuries may cause local swelling of certain parts of the brain. Other injuries may result in bleeding or bruising.
Hematomas
- A hematoma is an abnormal collection of blood outside a blood vessel.
- A subdural hematoma occurs because of trauma, usually to the veins in the brain, and causes a slow leak of blood which enters the subdural space below the dura. The blood accumulates over time and may stop in time, or if large enough can cause brain swelling.
- An epidural hematoma occurs because of trauma, often to the temple. Bleeding accumulates in the epidural space between the dura, or lining of the brain, and the skull. Hemtomas cause significant pressure and further brain injury.
Types of non-traumatic brain injury (NTBI)
Non-traumatic brain injury (NTBI) refers to damage to the brain at the cellular level in the brain which is not hereditary, congenital, degenerative, or induced by birth trauma. Specific types of NTBIs include:
- Vascular injury: A cerebral vascular accident (CVA) occurs when a blood vessel that carries oxygen and nutrients to the brain is either blocked by a clot or bursts. The brain cannot get the blood and oxygen it needs, and therefore the cells die. CVA can be either a lack of blood flow or bleeding in the brain.
- Hypoxic anoxic injury: With a hypoxic anoxic injury (HAI), the brain is not getting enough oxygen due to choking, drowning, suffocating, or cardiac arrest. Hypoxic means a partial lack of oxygen and the term anoxic means complete lack of oxygen.
- Brain tumor: A tumor is an abnormal mass of tissue, and it may be solid or filled with fluid. Damage can be caused by the pressure of swelling or by the abnormal tissue destroying brain cells.
- Infections: Infections can be caused by bacteria or viruses that infect that cause inflammation to a particular location. Types of infections include:
- Meningitis is an inflammation of the meninges and the fluid around the brain and spinal cord.
- Encephalitis is an inflammation of the brain itself.
- Myelitis is an inflammation of the spinal cord itself.
- An abscess is an accumulation of infectious material and offending microorganisms with the central nervous system.
- Diffuse axonal injury: With a diffuse axonal injury, larger areas are injured when the axons, or the tails of nerves that carry messages in the brain, are stretched or torn. When injuries are diffuse, many different types of symptoms can exist.
Recovery from a brain injury
The recovery process varies from person to person. It may take 12 to 18 months and be steady in nature or stair-stepped. The length and amount of recovery depends on many factors. Doctors may talk about the person’s level of consciousness and discuss certain assessments, such as the Glasgow Coma Scale, Coma Recovery Scale, and/or the Rancho Los Amigos Scale, when addressing the recovery process.
Recovery begins to happen when the swelling, bleeding, and/or infection in the brain start to heal. Certain parts of the brain heal while other parts may remain injured. Sometimes, the brain creates new connections to take over for areas that are not working. It is like learning a new way to do something.
The amount of recovery and the length of time it takes will be different depending on the person and the exact nature of the injury.