4 Types of Primary Brain Injury

The brain is probably the most complicated organ in the body, so it makes sense that there are many different ways to classify injuries affecting it. There are traumatic brain injuries, in which the function of the brain is disrupted by a strong impact such as a blow or jolt, and there are acquired brain injuries in which damage is caused by a condition other than external force.

There are also different ways to categorize traumatic brain injuries. Primary injuries are those sustained directly from the traumatic event, while secondary injuries are physiologic or metabolic changes potentially lasting for hours or days after the initial trauma. There are also different types of primary brain injuries.


In a coup-contrecoup, injury to the brain occurs in two places: At the point of impact and on the other side of the brain. The most common explanation for this is that the brain moves within the skull and strikes the other side, causing the contrecoup injury. This may occur during a rear-end motor vehicle collision that causes the driver’s head to jerk violently back and forth. However, not all researchers agree that this is the cause of coup-contrecoup injuries.

Intracranial Hematoma

Part of the reason that the brain may be able to move around within the skull if sufficient force is applied is that the brain does not fill up the space within the skull with no room to spare. There are empty areas within the skull, and a broken or damaged blood vessel can cause blood to collect in them. The collection of blood is called a hematoma, and it can be dangerous because it can put pressure on the brain.

Diffuse Axonal Injury

A violent stop or rotational forces on the brain can cause tearing of the connections between neural cells. Diffuse axonal injury can be difficult to diagnose because the damage often occurs at the microscopic level.

Skull Fracture

The skull’s function is to protect the brain. A fracture of the skull can lead to brain damage or infection. Different types of skull fractures can pose specific risks. For example, the brain is surrounded by a liquid called cerebrospinal fluid. If a fracture occurs at the base of the skull, it can cause the CSF to leak out. A depressed skull fracture is one in which a portion of the skull gets crushed and collapses in on itself, potentially putting pressure on the brain in the process.