Traumatic brain injury.
How common is traumatic brain injury?
Traumatic brain injury is one of the most common causes of death in Germany, especially among men under 30 years of age. However, it is difficult to gather precise data on the incidence of this type of trauma as a substantial number of patients with minor traumatic brain injury do not seek medical care. However, even in these cases, inpatient monitoring and further diagnostics would be necessary, especially for at-risk patients (e.g. those aged over 65 years), particularly as the onset of symptoms such as impaired consciousness may only occur some time after the trauma occurs.
10,000 deaths per year caused by traumatic brain injury
The number of patients with traumatic brain injury in Germany is about 280,000 per year. Eighty percent of the patients hospitalised in these cases exhibit minor traumatic brain injury, while approximately 10 percent are suffering from moderate and another 10 percent from severe traumatic brain injury. About 10,000 patients die each year from the direct and indirect consequences of traumatic brain injury, with almost 5,000 patients requiring nursing care. Happily, this number is falling year on year, primarily thanks to a drop in the incidence of such injuries in younger people.
Traumatic Brain Injury. Information from A-Z
Information. What happens at traumatic brain injury?
What is understood by traumatic brain injury?
Traumatic brain injury includes injury to the bone of the skull and/or brain caused either by direct external impacts to the head or by sudden acceleration and deceleration of the head and cervical spine, e.g. during vehicle accidents. A basic distinction must be made between open-head and closed-head traumatic brain injury. In contrast to closed-head traumatic brain injury, an open-head traumatic brain injury includes not only injury to the bone in the skull, but also a tear in the outer layer of the meninges, the layer of connective tissue surrounding the brain. This results in contact between the inside of the skull and the external environment. This in turn means a high risk of infection, which is a potential and feared complication.
Symptoms. Signs of traumatic brain injury
Classification of traumatic brain injury according to severity.
Traumatic brain injury is classified according to severity based on evaluation of the patient's state of consciousness. The Glasgow Coma Scale (GCS) is a proven method used to evaluate the state of consciousness. The duration of any loss of consciousness can also be used to provide a preliminary assessment. The Glasgow Coma Scale is a scale used to grade problems with consciousness. Points are used to score motor response, verbal response and eye opening. The points for each of the three functions checked are totalled to give a score. The maximum score that a patient who is awake can achieve is 15 points, while the lowest score is three points and indicates a coma. The Glasgow Coma Scale can be used on the scene of an accident to classify traumatic brain injury as mild, moderate or severe. Apart from having an impact on treatment - such as safeguarding a patient's airway by inserting a breathing tube if the GCS is 8 or lower - the GCS also provides information regarding what further inpatient care is required (intensive care unit, observation ward, regular ward), as well as having a certain amount of value for the prediction of a prognosis.
Different patterns of damage in traumatic brain injury.
Depending on the type and intensity of the impacting forces, there are different patterns of damage possible with traumatic brain injury. These damage patterns may affect the bone in the skull, the brain, the meninges and the blood vessels in the brain.
A basic distinction is drawn between:
- confined, limited injuries (such as fractures, cerebral compression or haemorrhages)
- non-confined, diffuse injuries (such as diffuse axonal injury). This consists of shearing and tearing injuries to the nerve fibres inside the brain
A distinction is also made between:
- primary injuries, which occur immediately at the time of the accident and
- secondary injuries (such as a lack of oxygen supply to the brain, constriction of areas deep within the brain, strokes and cerebral oedema); these secondary injuries are complications that occur subsequently and that can be mitigated or avoided altogether given rapid and optimal acute care.
Damage to the bone in the skull in cases of traumatic brain injury.
Injuries to the bones of the skull are classified according to their location and the type of fracture. They may affect the scalp area (cap of the skull), the facial area or the base of the skull. With regard to fracture types, a distinction is drawn between linear fractures, which are associated with forces impacting a wider area, and compression fractures, which result from a narrower force of impact.
A traumatic brain injury without substantial damage to the brain is called concussion. This involves a completely reversible form of cerebral dysfunction. Computed tomography will not detect any defects in the brain matter (damage to the tissues). This diagnosis is made based on clinical findings if the patient exhibits impaired consciousness or gaps in memory (amnesia) of less than 60 minutes in duration. The clinical picture of concussion does not include any signs of neurological deficits. Meanwhile, common symptoms include headache, dizziness, nausea and vomiting. The memory loss persists for a short period after the onset of the injury (also known as anterograde amnesia).
In contrast to this condition, cerebral contusion is a condition in which imaging procedures indicate trauma-related damage to the brain. Foci of bruising in the cerebral cortex (also known as contusions - see below) are evident as a primary consequence of the injury. Neurological symptoms such as central paralysis, cranial nerve deficits or speech disorders may become evident as soon as immediately after the injury has occurred. Follow-up clinical assessment reveals impaired consciousness lasting over 60 minutes and a gap in the patient's memory in excess of 24 hours. By contrast to concussion, the amnesia is both anterograde and retrograde, also affecting the period before the accident.
So-called cerebral compression is a secondary form of brain injury. Localised contusional brain injury or bleeding results in disruption to the blood-brain barrier. This means that the connections between cells in the blood vessels are disrupted, resulting in fluid flowing into the cerebral tissue (cerebral oedema), which in turn is followed by further increased swelling in the brain. The consequence of this is reduced blood flow in the brain and thus a reduced supply of oxygen. This, in its turn, impairs cell metabolism and the result is yet further oedema, this time due to the accumulation of fluid in the brain cells. The two forms of cerebral oedema can continue to feed one another. If left untreated, a vicious cycle develops that will prove fatal. Because the brain only has vary limited room for expansion as it is surrounded by bone, an unchecked increase in swelling in the brain leads to increased pressure on the brain, with the danger that areas deep inside the brain may become constricted. Typical symptoms of such constriction include impaired consciousness up to coma, extension spasms, broad pupils with no light response and the failure of respiratory and cardiovascular functions.
Focal traumatic brain injuries.
For trauma-related damage to the brain matter in defined (focal areas), the following distinctions are drawn:
Cerebral cortical contusions.
Blunt-force trauma to the head or acceleration trauma causes the brain to impact against the inside of the roof of the skull. The brain's inertia causes a drop in pressure on the opposite side when the impact occurs. The overall result is damage to the tissues in the brain not only on the side of the head on which the impact occurs (also known as a 'coup' injury, but also on the side opposite the direct impact site (also known as a 'contrecoup' injury). These are primarily found in the frontal and temporal lobes of the brain. Injury to blood vessels may result in bleeding into the injuries in the cortex (contusional lesions).
Epidural Haemorrhage (EDH).
In most cases, this occurs as a result of damage to the middle meningeal artery, which in turn results in bleeding (a haematoma) between the bone of the skull and the outer layer of the meninges. What is particularly problematic about this form of haemorrhage is that initial unconsciousness is often followed by a period without any symptoms before the patient's condition starts to worsen again. Epidural haemorrhages in the posterior cranial fossa are associated with a particularly high rate of deaths. In these cases, the bleeding originates from the venous outflow system of the brain (the cerebral sinuses). Epidural haematomas are limited in terms of their area. However, they form a bulge in the shape of half a ball and thus compress the adjacent cerebral tissue. Clinical indicators include widening of the pupil on one side corresponding to the side on which the bleeding has occurred, as well as signs of neurological deficits such as paralysis in the opposite half of the body.
Subdural haemorrhage (SDH).
This is situated between the leathery outer meningeal layer (called the dura mater) and the outer layer of the next meningeal layer beneath this (the arachnoid). It results from traumatic injury to venous blood vessels, what are known as bridging veins, which pass from the surface of the brain to the venous sinuses in the dura mater. Because it originates from veins, this form of haemorrhage often develops more slowly than epidural haemorrhages, spreading by oozing out, occasionally over an entire hemisphere of the brain. Symptoms may also develop only weeks after the trauma (chronic subdural haematoma). Subdural haemorrhages are often associated with compression (contusions) in the underlying cerebral tissue. So-called subdural hygromas occur in about 10 percent of cases of severe cerebral trauma. They comprise an accumulation of fluid (known as cerebrospinal fluid) after damage to the outer part of the inner membranous layer around the brain (the arachnoid), which is adjacent to the outer CSF spaces. Hygromas may be affected by secondary haemorrhaging.
Subarachnoid haemorrhage (SAH).
Subarachnoid haemorrhages are bleeds into the outer spaces containing the brain's cerebrospinal fluid (also known as the subarachnoid space, which is located beneath the middle membranous layer around the brain, the arachnoid. These occur mostly as a result of severe contusions. In approximately one third of patients with a traumatic SAH, the irritation to blood vessels caused by the haemorrhaging results in what is known as vasospasm, i.e. active narrowing of the arteries supplying blood to the brain. The result of this process is a risk of a stroke caused by the associated lack of an oxygen supply to the brain. A later-stage complication is the formation of a build-up of cerebrospinal fluid inside the skull (hydrocephalus). The bleeding into the subarachnoid space results in adhesions between the meningeal layers and thus to impaired circulation of the cerebrospinal fluid, which is no longer adequately absorbed. The consequence of this is enlargement spaces containing CSF inside and around the brain. This has the affect of occupying space and increasing pressure in the brain. The condition is treated by insertion of a catheter to drain the cerebrospinal fluid outwards. In some cases, permanent drainage, e.g. via a shunt system into the abdominal cavity, may also be required.
Diffuse brain injury.
Diffuse damage to the brain may occur due to cerebral oedema (see above), as well as due to shearing and tearing injuries to nerve fibres within the brain (diffuse axonal injury, DAI). In such cases, rotational and accelerational forces such as those particularly commonly observed during vehicle accidents, result in the movement of parts of the brain in opposite or different directions. Because grey and white matter in particular exhibit different degrees of elasticity, shearing injuries to nerve fibres are particularly common in the area of the structure that connects the two hemispheres of the brain (corpus callosum) and the brainstem. Tiny areas of haemorrhaging only evident in computed tomography (CT) images taken early on are indicative of this type of damage. These can also be detected later on by magnetic resonance imaging using special sequences that are able to spot small deposits of iron. DAI is commonly a cause of long-term impairment of consciousness.
Secondary brain injury.
Avoiding secondary brain injury after brain trauma is a priority in any optimal acute care provided to the patient. Steps to achieve this begin at the actual accident scene. In such cases, it is particularly important to try to maintain an adequate blood pressure level and supply of oxygen. Secondary brain injuries include cerebral oedema and elevated intracranial pressure. The associated compression (pressing together) of blood vessels, which results in a limited supply of blood and oxygen to the brain, may lead to strokes. Apart from the vasospasm after subarachnoid haemorrhage described above, another mechanism behind strokes in cases of traumatic brain injury is damage to the carotid arteries in the neck that supply the brain and/or the vertebral artery resulting from tears in the blood vessel walls (dissection). This leads to bleeding into the injured segments of the vascular walls and secondary clotting (thrombosis), resulting in blockage of the vessels. Further secondary brain injuries may occur in cases of open-head traumatic brain injury due to abscesses or inflammation in the meningeal membranes and brain.
Causes. What causes traumatic brain injury?
While traffic accidents are the most common cause of traumatic brain injury among younger patients aged up to 30 years old, falls are the most frequent cause of injuries of this type in patients over 70. Other causes include accidents in the home, as well as workplace accidents and sports injuries, as well as perforating injuries (such as gunshot wounds) and blunt trauma (such as a blow). About 30 percent of cases of traumatic brain injury are complicated by what is known as multiple trauma. This means concurrent injury to several areas of the body (e.g. chest and abdomen), of which at least one or a combination of more than one are life threatening. Along with rehabilitation and mobilisation at the earliest possible point, acute care tailored to the severity of the traumatic brain injury is a decisive factor for patient recovery.