Coup and Contrecoup:
A major head injury may not always present with physical damage, however, on the inside, the brain may have suffered traumatic injuries due to being bounced around the skull. Bleeding, swelling, contusions, and damage of brain cells may occur from the site of the head injury impact where the brain hits the skull internally. This is known as a Coup injury. Damage may occur on an opposite side of the brain where the brain has bounced back and impacted the skull. This is known as a Contrecoup injury. A Coup-Contrecoup injury is where the brain impacts the skull internally at the site of injury, and on an opposite side when it bounces back. This would mean there is injury on both sides of the brain. With no visible injury it may be difficult to identify a Coup or Contrecoup injury, and the clinician will have to analyse the history of events, MOI, signs and symptoms, and surrounding factors to determine the significance of the patients’ injury.
A skull fracture can occur through a major head injury where there may have been blunt or penetrating trauma to the skull. TBI can occur from a skull fracture due to the forces required to fracture the skull. Damage to the brain can include Coup/Contrecoup, haemorrhage, swelling, contusion, leakage of Cerebrospinal Fluid (CSF), and potential increased Intracranial Pressure (ICP).
A skull fracture may include a simple fracture where there is only one break. In this case, it is possible for the brain to escape initial serious injury as the skull would have done its’ job in protecting the organ. However, there is also the likely possibility that TBI had occurred. Where the simple fracture is located, there would likely be visible damage to the area such as bruising, swelling, bleeding, and possibly some penetration/laceration.
A skull fracture can also include multiple fractures around the site of impact, allowing a section of the skull to depress. This section will show signs of physical damage, such as contusion, swelling, bleeding, and potentially some penetration/laceration. On palpation the site will also feel ‘boggy’ and/or ‘loose’. It is likely that TBI will occur from a multiple and depressed skull fracture due to the force required to cause the injury, and due to the compression that may have been exerted on the brain, and fragments of skull being pushed into brain tissue.
Base of skull fracture:
The base of the skull is made up of a network of bones which surround, protect, and support the brain. Base of skull fractures generally occur with blunt force trauma to the face or to the side of the skull, and are associated with high impact forces. TBI is likely due to the force required, and can result in Coup/Contrecoup, haemorrhage, swelling, contusion, leakage of CSF, and potentially lead to increased ICP.
A history of trauma to the head and face can be an indicator for a base of skull fracture, along with visible injury such as contusion, swelling, bleeding, potentially some penetration/laceration, potentially some bogginess on palpation. Further signs more specific to base of skull fracture include bleeding and CSF from the ear/ears and/or nose, significant bruising behind the ears (which can be a late sign), and bruising around both eyes (which can be a late sign).
The brain is immediately surrounded by three layers of tissue, called meninges. These sit between the skull and the brain, with 2 spaces also included between them. Named from outside inwards there is the dura matter, the subdural space, the arachnoid matter, the subarachnoid space, and the pia matter. The dura matter consists of 2 layers. Where there is a subdural haemorrhage as a result of major head injury, a collection of blood occurs below the inner layer of dura mater, in the subdural space. A subdural haemorrhage can sometimes be slow in progression, and a patient may not have any TBI symptoms initially. As pressure increases on the brain, this can then lead to neurological symptoms developing, such as confusion, agitation, and slurred speech. Further haemorrhage can lead to greater ICP which can cause further issues.
A subarachnoid haemorrhage occurs between the arachnoid and pia matters, in the subarachnoid space. This is generally a more fast-flowing blood collection, causing significantly more pressure on the brain tissues, and quickly increasing ICP. Greater pressure on the brain and increasing ICP can cause herniation of tissue and significant cellular damage. Neurological symptoms can be more severe such as a decreased level of consciousness, nausea/vomiting, seizures, confusion, and severe pain. Further increase in ICP can lead to further negative outcomes.