A head injury is a comprehensive term that describes various injuries of the scalp, brain, skull and tissues, membranes, and blood vessels in the head. The head injury can be mild, like a bump, bruise, or a minor cut on the head. Moderate to severe traumatic brain injury may lead to concussion, open wound, deep cut, fractured skull bones, internal bleeding, or damage to the brain.
Classification of head injury
Depending on the mechanism, head injuries are classified as closed and penetrating injuries. They are classified as fractures, focal intracranial injury, and diffuse intracranial injury as per the morphology. Based on severity, head injuries are divided into mild, moderate, and severe traumatic brain injury.
Different head injuries
Some common types of head injuries include the following.
Edema: Various types of head injuries can cause edema or swelling of brain tissues. As the skull cannot stretch to accommodate the swelling, it leads to pressure build-up in the brain, causing damage.
Concussion: A concussion can cause instant loss of alertness or awareness for a few seconds up to a few hours after a head injury. It occurs when the external impact on the head is serious enough to cause the brain to impact the interior of the skull. However, repeated concussions may lead to permanent brain damage.
Skull fracture: Skull does not have bone marrow. Hence, it is strong and sturdy, making it difficult to break. However, a broken skull due to head injury cannot absorb the impact, making it susceptible to damage to the brain. Various types of skull fractures occur in different head injuries that include the following.
- Linear skull fractures: It is the most common type of skull fracture. It is a break in the cranial bone resembling a thin linear line, without splintering, depression, or distortion. This type of fracture does not need treatment. The patient can resume normal activities in days.
- Depressed skull fractures: In depressed skull fractures, there is a broken or crushed cranial bone portion. With this type of fracture, part of the skull has bone depression towards the brain from the trauma. Severely depressed skull fractures need surgery to correct the deformity.
- Diastatic skull fractures: The sutures fuse during childhood and lie between the bones in the head. This type of head fracture occurs in newborns and older infants as their sutures are not yet fused. However, in rare cases, it can also occur in adults. The fracture transverses through one or more skull sutures. It causes a widening of the suture.
- Basilar skull fracture: In these head injuries, there is a breakage in the bone present at the skull base. It involves bruises around the eyes and behind the ear. Clear fluid may drain from the nose or ears because of a tear in the brain’s covering.
Hematoma: Brain hematoma is serious. It is a collection or clotting of blood outside the blood vessels. The blood clotting leads to pressure build-up in the skull. This can cause permanent brain damage or loss of consciousness. Intracranial hematoma (ICH) is the clotting of blood in or around the brain. Various head injuries can lead to hematomas and can cause mild to severe and potentially life-threatening head injuries. Hematomas are of different types and are classified as per their brain location that includes the following.
Epidural hematoma: When a blood clot forms beneath the skull, it is known as ‘epidural hematoma.’ It occurs because of a tear in an artery that runs underneath the skull. Usually, these types of hematomas are linked with a skull fracture.
Subdural hematoma: They appear when the blood gathers between the dura mater’s inner layer and the arachnoid mater of the brain. These can form because of a tear in the bridging veins that go from the brain to the dura.
Contusion or intracerebral hematoma: A contusion in simple medical terms is a bruise to the brain. It leads to bleeding and swelling inside and around the brain area where any head injuries occur. An intracerebral hemorrhage (ICH) occurs when a blood vessel bleeds and leaks blood into the brain tissue.
Hemorrhage: Subarachnoid hemorrhage occurs when there is uncontrolled bleeding into the cerebrospinal fluid (CSF). It is associated with a subdural hemorrhage or contusion. If the bleeding occurs within your brain tissue, then it is called ‘intracerebral hemorrhage.’
Diffuse axonal injury (DAI): It is a sheer injury to the brain. This type of injury doesn’t cause bleeding but seriously damages the brain cells. DAI occurs because of accidents, shaken baby syndrome, etc. It can cause swelling and is not easily visible when compared to other types of head injuries. Thus, it is the most dangerous type of head injury that can lead to permanent brain damage or even death.
Penetrating injuries: They result when a foreign object pierces through the head, which damages the underlying bones and tissues. Penetrating injuries cause open wounds from bullets, stabbing, etc.