Traumatic Brain Injury

“A brain disorder due to an external force that causes a reduction or malfunction in an individual’s state of consciousness and causes alterations in that individual’s cognitive, physical, and/or emotional abilities”

TBI IN FIGURES

In Spain, there are around 200 cases of TBI per 100,000 population. Approximately 10% are serious, 10% are moderate, and 80% are mild.

TBI is three times more common in men than in women, and the most commonly affected age group is 15–35 year olds.

In Spain, road traffic accidents are the most common causes of TBI, causing around 75% of instances of TBI. The second most common cause of TBI is falls (20%), and sporting injuries cause the remaining 5% of cases. There are age and gender differences in the number of cases of TBI. Accidents and falls are more common in children and in adults aged 65 or over, whereas motorcycle accidents mostly affect people aged 25 or under, and car accidents mostly affect adults.

Around one in five survivors of TBI develops a moderate or severe disability.

Overall, mortality from TBI occurs in 11% of cases, and the annual mortality rate per 100,000 population is 15. TBI is the principal cause of death or disability in individuals younger than 45 years old.

Severe TBI is particularly relevant because of the high rate of mortality and sequelae. Nevertheless, mild and moderate cases of TBI represent a challenge for emergency services. This pathology has a high incidence, and establishing the severity of the TBI is paramount because of the potential risk of complications or an unfavourable clinical course in the hours directly following the TBI.

ELEMENTS OF TBI

The definition of TBI has three key elements:

An external force acting on the brain

The effect on the brain due to this force

The brain malfunction caused by this effect

Fisioterapia para la rehabilitación de traumatismo craneoencefálico

1- The external force that leads to TBI acts on the cranium, either through direct contact (assaults, falls, blows, sporting accidents, etc.) or through inertia (road traffic accidents).

Forces due to direct contact (static) usually lead to focal injuries. The most common focal injuries include:

Subdural haematoma:  bleeding below the dura mater, which is one of the layers covering the brain. In many cases, the bleeding is venous, which gradually creates a build-up of blood. These haematomas should be carefully monitored because they tend to cause an increasing number of symptoms as they grow.

Epidural haematoma: bleeding above the dura mater. In many cases, bleeding is arterial, which quickly creates a build-up of blood. The patient may not present symptoms until some time after the head injury. After some hours, the patient may then present red flag symptoms (nausea and vomiting, severe headache, disorientation), sometimes accompanied by localized symptoms such as weakness on one side of the body and pupil dilation. This type of haematoma is a neurosurgical emergency.

Subarachnoid haemorrhage: Bleeding into the subarachnoid space.

Brain contusion: Injuries in specific regions of the brain parenchyma due to damage to the tissue or blood vessels or due to ischemia or oedema.

Dynamic forces cause injuries through acceleration/deceleration mechanisms. This can cause focal injury (contusions due to blows or counter-blows) or diffuse injury (diffuse axonal injury).

Often, the forces exerted when the head injury occurs are mixed, so it is common to find focal and diffuse brain injuries in the same case. This poses a challenge for doctors when trying to determine the medical relevance of these injuries.

Tipos de lesiones de traumatismo craneoencefálico

Head injuries can be classified depending on whether the force exerted when the head injury occurs is large enough to break the skull and expose the brain tissue:

Closed: When this type of head injury occurs, the bone and the layer protecting the brain tissue remain intact, and the brain is NOT exposed. A classic example of this type of TBI is an acceleration/deceleration injury in a road traffic accident.

Open or penetrating: When this type of head injury occurs, the layer protecting the brain is broken, and the brain is exposed. The classic example of this type of TBI is an attack involving a firearm.

2- The effects on the brain due to the forces pexerted when a head injury occurs vary greatly, which explains the broad range of cases presented by TBI patients. Essentially, there is a distinction between primary, secondary, and tertiary brain injury.

2) exerted when a head injury occurs vary greatly, which explains the broad range of cases presented by TBI patients. Essentially, there is a distinction between primary, secondary, and tertiary brain injury.

Primary injury is directly related to the mechanism and energy involved when the head injury occurs. The anatomopathological substrate of this type of injury is cell injury (focal injury), tearing and retraction of axons (diffuse injuries), and vascular complications caused by the head injury.

Secondary and tertiary brain injury may occur as a result of: 

  • The effect of external injuries to the brain parenchyma, including subdural and epidural haemorrhages that cause an increase in intracranial pressure;
  • Intracerebral irregularities such as the presence of early epileptic seizures or intracerebral oedemas; or
  • Systemic complications that may occur in the TBI, including a drop in blood pressure (arterial hypotension), a drop in oxygenation (hypoxemia), and an increase in temperature (hyperthermia).
Traumatismo craneoencefálico

Brain malfunction caused by focal injury depends on the extent and location of the injury. In general:

Focal injuries are usually clustered around the frontal lobes (prefrontal region) and the temporal lobe of the brain because of the impact of the brain tissue on the bone structures. Hence, the most common problems are behavioural problems and trouble storing new information. As with other CNS diseases, symptoms that suggest focal injuries include aphasia, apraxia, agnosia, acalculia, etc.

Diffuse injuries mainly affect the connectivity between brain areas. These injuries cause symptoms such as trouble paying attention and concentrating and a reduction in the time required to process information.

Different kinds of TBI can be classified depending on the severity of the malfunction:

Mild TBI or concussion: Mild TBI is the most common type of TBI. Indeed, concussions account for the highest number of brain injuries in Spain. Patients suffering concussions rarely lose consciousness, and if they do, the period of unconsciousness usually lasts for just a few minutes. Although most people suffering mild TBI make a full recovery, a relatively high percentage of these patients may present with persisting, limiting problems that constitute ‘post-concussion syndrome’. This unpleasant and incapacitating syndrome leads to physical symptoms such as a tendency to tire easily, headaches, sleeping problems, and vertigo or dizziness; cognitive problems such as trouble paying attention, concentrating, and remembering information; emotional problems such as anxiety and mood swings; and behavioural problems such as irritability, apathy, and other changes in the normal behaviour of the TBI sufferer.

Moderate TBI: In cases where this type of head injury occurs, the period of loss of consciousness lasts longer than 30 minutes but never lasts more than one day. The period that the patient has trouble learning new information (period of post-traumatic amnesia) lasts less than one week.

Severe TBI: In cases where this type of head injury occurs, the period of loss of consciousness lasts longer than one day, and/or the period during which the patient has trouble to learn new information (period of post-traumatic amnesia) lasts longer than one week.

Escala de Glasgow. Daño Cerebral

THE COST OF TBI

The annual health cost of TBI in Europe is 2.9 billion Euros. In Spain, the estimated direct cost of patients who have been hospitalized because of TBI is 2,833 Euros per hospitalization, with a cost of 987 Euros per patient with concussion, and 6,362 Euros per patient with severe ABI. These values lie somewhere in the middle of the range of costs in other European countries. The average cost in Germany is 2,529 Euros, and the average cost in Sweden is 3,024 Euros. In fact, in Sweden, the average cost during the first year of hospital care for a patient with TBI has been calculated at 4,562 Euros. In Spain, the only reliable data on indirect costs derived from the loss of productivity, use of resources for care, and other aspects come from a recent epidemiological study conducted in the Basque Country and Navarra (Spain) in May 2011. According to this study, the annual cost of formal care for TBI is 61.4 million Euros, and annual informal costs are 55.57 million Euros. In this study, the cost of informal care is calculated at 11.591 Euros per year.