What are the types of brain injury and damage that occurs?
Traumatic brain injuries can be defined as open (penetrating) or closed (or non-penetrating). In a closed head injury, the brain and the skull remains intact after the physical impact of an outside force, whereas in an open head Injury, a sharp item may penetrate or break open the skull and enter the brain. Other types of head injuries include:
Diffuse axonal injury
A diffuse axonal injury (sheer injury) is an injury to the brain that is caused by intense shaking or strong rotation of the head (such as shaken baby syndrome) or by rotational forces during a car accident. It doesn’t lead to bleeding but causes damage to the brain cells which results in gradual loss of axons (neural cells) and their functions. It can also cause swelling in the brain, which leads to further damage. Although it isn’t as visible from outside as with other forms of brain injury, diffuse axonal injury is known to be one of the most dangerous types of head injuries that can lead to permanent brain damage and even death.
A hematoma is a blood clot that occurs within the brain or on its surface. It may be referred to a collection or clotting of blood outside the blood vessels. They can occur anywhere in the brain. Hematoma can be very serious as clotting can increase the pressure the skull. This may cause loss of consciousness or result in permanent brain damage.
- An epidural hematoma occurs when blood collects between the dura mater (the protective covering of the brain) and inside of the skull.
- A subdural hematoma occurs when blood collects between the dura mater and the arachnoid layer (located directly on the surface of the brain).
A brain hemorrhage is uncontrolled bleeding in the brain. It can be –
- Intracerebral hemorrhage (ICH): The bleeding occurs within the brain tissue and may be associated with other brain injuries, such as contusions. Depending on the size and location of the hemorrhage the doctor can determine if it needs to be removed surgically.
- Subarachnoid hemorrhage: This occurs when there is bleeding in the space around the brain or bleeding into the subarachnoid space. It is commonly after a TBI and appears as diffuse blood spreading thinly over the surface of the brain. Most cases of subarachnoid hemorrhages related to head trauma are usually mild. However, it can lead to a condition called hydrocephalus, accumulation of excessive fluid in the brain.
Subarachnoid hemorrhages may cause headaches and vomiting while the severity of intracerebral hemorrhage depends on the amount of bleeding there is and over time it results in pressure buildup.
A concussion occurs due to an impact or blow to the head and is severe enough to cause brain injury. It can result when a person’s brain hits against the hard walls of the skull due to the forces of sudden acceleration and deceleration. Generally, the loss of function related to a concussion is temporary, but repeated concussions may eventually lead to a permanent damage.
A cerebral contusion is referred to bruising – bleeding of the brain tissue. Under a microscope, cerebral contusions seem comparable to bruises that occur in other parts of the body. It includes the areas of injured or swollen brain tissue mixed with blood which leaked out of the blood vessels due to the blow. Contusions most commonly occur on the base of the front parts of the brain, but it can occur in other places too.
A brain injury may lead to edema or swelling. Most injuries can cause swelling of the surrounding tissues in the affected area, but it becomes more serious when this occurs in the brain. As the skull can’t stretch or mold to accommodate the swelling, pressure starts to build up within the brain, resulting in pressing of the brain against the skull.
Unlike many other bones in the body, the skull doesn’t have soft inner part called bone marrow. This makes the skull very hard or strong and difficult to break. When the skull breaks, it is unable to absorb the impact of a blow and chances are that there will also be damage to the brain.
Depressed skull fractures occur when the bone presses on or into the brain. They may require surgical intervention and the damage caused by a depressed skull fracture depends on the part of the brain affected and also whether it is accompanied by an associated diffuse brain injury.