What is traumatic brain injury? - Chapter 15

What does a traumatic brain injury look like in clinical practice?

Traumatic brain injury (TBI) is the most common type of acquired brain injury (ABI) among people under 50 years of age. In this context, traumatic refers to violent: with mechanical force. If there is no (temporary) loss of consciousness after the impact, then we cannot speak of TBI: the severity and duration of this disorder provide an indication of the severity of the brain injury. Loss of memory is a major symptom of TBI. The retrograde amnesia (RA) immediately after the onset of consciousness diminishes over time. The patient is unable to remember the accident itself as well as a period of time preceding it. Patients also experience anterograde amnesia. Furthermore, a distinction can be made between the period of 'post-traumatic amnesia' (PTA), which is characterized by disturbed encoding and disorientation, and the loss of memory that occurs in the chronic phase. In addition to loss of memory, disorders in various domains may occur. 

How often does TBI occur?

About four percent of European patients who experience TBI die. The largest group of patients consists of young people aged 15-24 years. Most of the patients are victims of traffic accidents. Twice as many men as women suffer traumatic brain injury. 90% may return home after hospitalization; while ten percent are referred to a nursing home, a rehabilitation center, or a psychiatric hospital.

What is the neuropathology of TBI?

Primary damage

A distinction is made between ‘open’ craniocerebral injury (where objects or bone fragments penetrate the meninges, these injuries are commonly focally located) and the more frequent ‘closed’ cerebral brain injury. In the latter category, the damage is diffuse, often in the form of white matter injury (‘diffuse axonal injury’ or DAI): axons are damaged or torn off completely by the rotating forces. White matter injuries are usually combined with microhaemorrhages and ultimately axonal degeneration. These effects are most distinctive in the transitional areas between grey matter and the white matter connecting pathways, often in the deeper brain structures. If the violence impacts more linear than rotational, the moving skull suddenly makes contact with a hard surface, or the stationary skull is moved by a forceful blow, causing the brain to come into violent contact with the internal structures of the skull. This primarily results in damage to the grey matter (contusions). This is frequently found in the orbitofrontal and temporal brain regions. If the force is strong enough, a coup-contrecoup injury may result, where the location of cortical damage is diagonally opposite the location of the injury.

What does the secondary damage consist of?

The secondary damage is not caused by the forces that act on the skull, but by complications. These complications are intracranial or extracranial. With intracranial damage, complications such as swelling (oedema) or bleeding (haematoma) occur. Extracranial damage can disrupt the autoregulation. This may lead to shock, hypotension or hypoglycaemia, as a result of which the brain receives insufficient oxygen (hypoxia). Traumatic subarachnoid haemorrhage (TSAH) occurs regularly in moderate and severe brain injury combined with local bruises (contusions). TBI coupled with TSAH is usually associated with poorer and slower cognitive recovery. A general consequence of the secondary processes is increased intracranial pressure, causing secondary diffuse brain damage.

How are TBI patients diagnosed?

Some patients only experience a drop in consciousness; some go into a coma. For some patients, the coma will change to a temporary PTA, which means that the patient is unable to store new information for a certain period (ranging from hours to months). The duration of the PTA is the strongest indicator of the severity of the injury and a useful predictor of recovery (Brooks and colleagues, 1980). The PTA gradually disappears through 'islands of memory'. A minor injury: the patient has only been unconscious for a maximum of 15 minutes. This is the case in 80-85% of the cases. Severe injury: the patient has been unconscious for about an hour.

What are the neuropsychological consequences of a moderate to severe TBI?

Patients with moderate to severe brain injury almost always have permanent neuropsychological sequelae. Most disorders manifest themselves in the speed of information processing, attention and concentration, executive functions, and memory.

Is speed of information processing affected?

The most commonly reported complaint after brain injury is mental slowness (resulting in mental fatigue). This forms the core of most other disorders.

Is attention affected?

Within the focus area, it is especially difficult for patients to (1) focus attention when distracted, (2) divide one's attention between several tasks while under time pressure, and (3) sustain attention over time. For patients with moderate brain injury, this is explained by the mental slowness; for patients with serious brain injury, it is related to a primary attention disorder.

Are executive functions affected?

The frontal cortex is almost always affected by this TBI (both contusions and DAI), as a result of which the executive functions such as organising, planning, initiation, executing, control and evaluation of tasks are impaired.

Is memory affected?

Disorders within memory are already present in the acute phase. Learning can be disturbed, and the ability to retrieve information from memory is also impaired. But in fact, all aspects of memory can be affected following TBI.

Are language and speech affected?

The most common language problems are subtle problems in the areas of naming and word finding, verbal word fluency, and understanding of complex language. The classic aphasia syndromes rarely occur following TBI, but may develop after severe focal injuries in the left hemisphere. Dysarthria is slightly more common (after serious damage in the right hemisphere).

Is social cognition affected?

Most closely involved with the patient often report changes in behavior and emotions. For example that the patient exhibits disinhibited behavior, is more self-centered, no longer takes other people into consideration, cannot adapt their behaviour to the social situation, and is emotionally flat. This can be explained by the fact that he / she is no longer properly aware of social information due to social disorder and has difficulty creating ToM. They are bad at making decisions and stopping inappropriate behavior (even after negative feedback). The patient is often not aware of this.

What other complaints can be reported?

Other common complaints are emotional instability and a lower workload: the patient is tired, dizzy and irritated faster. PTSD symptoms are more often found in milder cases of brain injury. Emotional responses such as fear, feelings of depression, and decreased self-confidence may develop at a later stage, when the patient does develop insight into the consequences of the injury.

What are the neuropsychological consequences of mild TBI?

After mild TBI, the neuropsychological consequences (as mentioned in the case of moderate to severe injury) usually disappear within 3 months (Frencham, Fox & Maybery, 2005). The main complaints in the acute phase are within the domain of (working) memory, attention, and the speed of information processing. However, sometimes the symptoms persist and one speaks of a post-concussion syndrome or a post-concussion disorder. This is explained on the basis of a biopsychosocial model: the duration of PTA cannot predict these chronic complaints, while psychological factors (such as stress) are predictive.

The premorbid personality traits, and mood problems are strongly associated with the experience of cognitive complaints following mild TBI. Patients are subdivided into two groups: in one group patients think they have recovered well and they only notice the residual symptoms when they return to work (the connection with the brain injury that has been experienced is not always made), the second group is preoccupied with the possible serious consequences. The latter group experiences complaints that are excessive and not in proportion to the injury. They ultimately become stuck because of the increasing avoidance of cognitive load. A cogniform disorder (Delis & Wetter, 2007) is the term given to patients who report unlikely severe cognitive consequences due to their injury. These patients are most likely to blame brain injury for their long-lasting symptoms: this is not necessarily consciously. If there is a suspicion of a conscious thrust of the complaints or the simulation thereof, this is classified as "malingering". Symptom validity tasks and questionnaires about personality, mood and coping style are indispensable if a neuropsychological assessment is executed.

What is a whiplash?

'Whiplash-associated disorders' (WAD) arise after the patient is hit from behind in a car accident. The head first swings backwards (extension) and then flies forward (flexion). This is not a brain injury (because there is no absence of consciousness nor post-traumatic amnesia), but an injury to the neck. A whiplash is sometimes difficult to distinguish from mild brain injury due to the similarities in symptoms. 80% of whiplash patients recover within six weeks; the other patients experience persisting symptoms. The latter group suffers from a post-whiplash syndrome. They usually also have other symptoms such as mood disorders, visual disorders, concentration problems and many others. The differential diagnosis between post-whiplash syndrome and post-commotional syndrome is based on the presence of pain in the case of a whiplash.