TRAUMATIC BRAIN INJURY (TBI)
Traumatic Brain Injury (TBI) is an injury to the brain caused by a trauma to the head (head injury). There are many possible causes, including road traffic accidents, assaults, falls and accidents at home or at work.
Effects and recovery
The effects of a traumatic brain injury can be wide ranging, and depend on a number of factors such as the type, location and severity of injury.
What happens in a TBI?
The Medical Disability Society Working Party Report on the Management of Traumatic Brain Injury (February 1988) defines traumatic brain injury (TBI) as:
'Brain injury caused by trauma to the head (including the effects upon the brain of other possible complications of injury, notably hypoxemia and hypotension, and intracerebral haematoma)'.
In other words, a brain injury is caused at least initially by outside force, but includes the complications which can follow, such as damage caused by lack of oxygen, and rising pressure and swelling in the brain.
A traumatic brain injury can be seen as a chain of events:
- The first injury occurs in the seconds after the accident
- The second injury happens in the minutes and hours after this, depending on when skilled medical intervention occurs
- A third injury can occur at any time after the first and second injuries, and can cause further complications.
The First Injury
There are three sorts of first injury - Closed, Open and Crush.
Closed Head Injuries
Closed head injuries are the most common type, and are so called because no break of the skin or open wound is visible. These often happen as a result of rapid acceleration or deceleration, for example when a car hits a brick wall, or a car is hit from behind at traffic lights. The head is rocked back and forth or rotated, and the brain must follow the movement of the skull. It can twist, and the billions of nerve fibres which make up the brain can be twisted, stretched and even torn in the process.
Even mild injuries of this sort can produce damage which is quite widespread throughout the brain. This is defined as diffuse brain injury. The front of the skull has sharp bony ridges with which the brain can also collide, causing more damage. Arteries and veins running through the brain can be damaged, allowing blood to leak.
Open or Penetrating Wounds
These are not so common. In this type of injury the skull is opened and the brain exposed and damaged. This could be due to a bullet wound, or collision with a sharp object such as a motorcycle brake lever, or being hit by a pickaxe. If the damage is limited to one specific area, outcomes can be quite good, even though the accident may have seemed horrific. In many cases, however, this type of injury may be combined with an acceleration type injury as well.
Crushing Injuries
In this type of injury, the head might be caught between two hard objects, such as the wheel of a car and the road. This is the least common type of injury, and often damages the base of the skull and nerves of the brain stem rather than the brain itself. There may be no loss of consciousness.
The Second Injury
This happens when the brain is starved of oxygen, which makes damage from the first injury worse. It can happen for several reasons. Examples are choking on vomit after an accident, blood blocking a person's airway, or by the position which someone is lying in obstructing their airway. If other injuries are present, as they often are, serious blood loss can affect blood flow to the brain. As a result, the amount of oxygen reaching the brain can be reduced.
Understanding the relationship between the first injury and the effects of lack of oxygen has led to improvements in the kind of emergency treatment administered at the site of an accident by paramedics. They will make sure breathing is maintained and blood pressure is brought back to normal levels by emergency transfusions.
The Third Injury
This can take place at any time after the first and second injury, in the days and sometimes weeks which follow, and could be as a result of bleeding, bruising or swelling in the brain or because blood clots have developed.
Blood leaking from torn blood vessels and other body fluids leaking into the area cause the brain to swell. This is a serious problem because the skull is a fixed space, and there is no room for expansion. It causes complications in two ways. Firstly, the walls of the skull are hard and unyielding, and damage the soft brain when it squeezes against them. Secondly, when the brain swells it can squeeze the blood vessels, limiting the brain's blood circulation. This can be fatal, so intracranial pressure is monitored very carefully once the patient is in hospital.
Measures to reduce the risk of raised pressure include putting the patient on a ventilator to ensure a good supply of oxygen, and controlling the amount of water and salts in the body to cut down on the flow of fluid into the brain.
Blood clots occur when blood has leaked from damaged veins and arteries and then pools into a clot. They can press on the surrounding brain tissue which can damage it, and they also raise pressure in the brain. Clots can occur in the brain itself (an intercerebral clot) or in the space between the brain and the skull (a subdural or an extradural clot). Blood clots, also called haematomas, can occur after quite minor injuries, and this is why patients are often kept under observation in hospital until the risk of a clot forming is likely to be over.
The Effects of Traumatic Brain Injury on Brain Function
Damage to the nerve fibres deep in the central part of the brain, which normally keeps a person awake and alert, results in the most obvious of symptoms - coma.
This link between damage to particular parts of the brain and a corresponding lack of brain function means, for example, that damage to the side of the brain (parietal lobes) results in weakness in the limbs on the opposite side of the body. Injury to the left side of the brain or the brain stem itself tends to cause speech and language impairment.
Coma, loss of power in the arms and legs, and speech impairment are the most visible signs of brain injury. However, traumatic brain injury causes numerous 'hidden disabilities' in that it results in changes to personality, thinking and memory. For example, damage to the brain behind the forehead (frontal lobes) results in behavioural problems, such as loss of insight and self-restraint.
INJURY SEVERITY
After a traumatic brain injury, whether or not the person was actually unconscious, a state occurs where the person seems to be aware of things around them but is confused and disorientated. They are not able to remember everyday things or conversations, and often do or say bizarre things. This is called Post-Traumatic Amnesia (PTA), and is a stage through which the person will pass.
The length of PTA and/or loss of consciousness are important as they give an indication of the severity of the injury.
The term 'Coma' is often used to describe longer periods of unconsciousness.
The table below gives a rough guide to how these measures affect the severity of the injury, although it is worth noting that everyone is different and categorising injuries in this way doesn't always give an accurate measure of the long-term effects.
Loss of consciousness - Post traumatic amnesia
- Minor brain injury 15 mins< 1 hour
- Moderate brain injury15 mins - 6 hours1 hour - 24 hours
- Severe brain injury6 hours - 48 hours24 hours - 7 days
- Very severe brain injury> 48 hours> 7 days
MINOR HEAD INJURY AND CONCUSSION
A brief period of unconsciousness, or just feeling sick and dizzy, may result from a person banging their head getting into the car, walking into the top of a low door way, or slipping over in the street. It is estimated that 75-80% of all head injuries fall into this category.
Here we explain the effects of a minor brain injury, which is also known as a minor head injury, concussion or post-concussion syndrome.
Returning home
On returning home it is important that, if possible, you are accompanied by a responsible adult. While unlikely, there is a small risk of developing complications, so if you experience any of the following symptoms in the next few days you should return to A&E as soon as possible:
- Loss of consciousnessIncreasing
- disorientation
- New deafness in one or both ears
- Problems understanding or speaking
- Loss of balance or problems walking
- Blurred or double vision
- Any weakness in one or both arms or legs
- Inability to be woken
- Any vomiting
- Bleeding from one or both ears
- Clear fluid coming out of your ears or nose
- Any fits (collapsing or passing out suddenly)
- Drowsiness when you would normally be wide awake
- Severe headache not relieved by painkillers such as paracetamol
Dos and Don'ts
- DO make sure you stay within reach of a telephone and medical help in the next few days
- DO have plenty of rest and avoid stressful situations
- DO show this factsheet to a friend or family member who can keep an eye on your condition
- DO take painkillers such as paracetamol for headaches
- DON'T stay at home alone for 48 hours after leaving hospital
- DON'T drink alcohol until you feel better
- DON'T take aspirin or sleeping tablets without consulting a doctor
- DON'T return to work until you feel ready
- DON'T play any contact sport for at least three weeks without consulting your doctor
- DON'T return to driving until you feel you have recovered. If in doubt consult your doctor.
Post-concussion syndrome
The effects of a minor head injury can be anything but minor to the person concerned. They can include nausea, headaches, dizziness, impaired concentration, memory problems, extreme tiredness, intolerance to light and noise, and can lead to anxiety and depression. When problems like this persist, they are often called post-concussion syndrome.
Symptoms of post-concussion syndrome include:
- Headaches
- Irritability
- Feelings of dizziness
- Restlessness
- Nausea
- Impulsivity and self-control problems
- Sensitivity to light
- Difficulties with concentration
- Sensitivity to noise
- Feeling depressed, tearful, anxious
- Sleep disturbance
- Fatigue
- Memory problems
- Difficulties thinking and problem-solving
In most cases the symptoms of post-concussion syndrome will resolve themselves within two weeks. However, in some cases they may persist much longer. Try not to rush back into normal activities as this may delay recovery. If you still have any symptoms of concussion after two weeks we suggest you see your GP and take our 'Minor head injury discharge advice' factsheet with you. It may be possible to seek referral to a head injury specialist such as a neurologist or neuropsychologist.
A common problem is that either no scans were done at the time of the accident, or subsequent scans show no damage. This frequently gives rise to the impression that there is nothing medically wrong. The persistent problems of post-concussion syndrome can be misunderstood by GPs, sometimes being considered as almost hypochondria on the part of the patient. In some cases where the symptoms of concussion persist for months a psychological element such as depression can come into play. While this may make existing conditions even more difficult to live with, it is not on the whole true or helpful to say that 'it is all in the mind'. A second opinion should be sought from a neurologist or neuropsychologist.
You can read more about the symptoms of post-concussion syndrome in the 'Effects of brain injury' section.
Practical issues
It is important that relatives and employers are warned about the possible effects of a minor head injury, and for plans to be made accordingly. These might include not rushing to return to work, keeping stress to a minimum in the short term, and abstaining from alcohol. One study showed that almost one third of people with a minor head injury were not working full-time three months after receiving the injury, although other studies have been much more optimistic. Difficulties are certainly made much worse if the person has a mentally demanding job where there is a low margin for error.
Recovery and further information
The general conclusion seems to be that the vast majority of people who experience a minor head injury make a full recovery, usually after 3-4 months. However there is a very small sub-group whose recovery is not so good.
Sport concussion
If you have had a minor head injury and play contact sports, make sure you seek medical advice before continuing to play.
Repeated minor head injuries can have cumulative effects and it is dangerous to expose yourself to the risk of a second injury while still recovering from the first one. Sports such as rugby have a compulsory rest period, followed by a gradual return to play following a concussion, but other sports such as football have less rigorous rules.
Consult your doctor and don't feel rushed to return to contact sport until you are ready.
MODERATE BRAIN INJURY
A moderate head injury is defined as loss of consciousness for between 15 minutes and 6 hours, or a period of post-traumatic amnesia of up to 24 hours. The patient can be kept in hospital overnight for observation, and then discharged if there are no further obvious medical injuries. Patients with moderate head injury are likely to suffer from a number of residual symptoms.
The most commonly reported symptoms include tiredness, headaches and dizziness (physical effects) difficulties with thinking, attention, memory planning, organising, concentration and word-finding problems (cognitive effects) and irritability (an emotional and behavioural problem). These symptoms are accompanied by understandable worry and anxiety. This can be particularly pronounced if the patient has not been warned that these problems are likely to arise. If the patient expects to be perfectly well within a few days and symptoms are still prominent after a few weeks, they may worry or feel guilty. This has the effect of creating a vicious circle leading to more symptoms and so on.
A large proportion of people find that when they return to work they have difficulties and feel that they are not functioning at their highest level. For the majority of people these residual symptoms gradually improve, although this can sometimes take 6 to 9 months.
SEVERE BRAIN INJURY
Severe head injury is usually defined as being a condition where the patient has been in an unconscious state for 6 hours or more, or a post-traumatic amnesia of 24 hours or more. These patients are likely to be hospitalised and receive rehabilitation once the acute phase has passed. Depending on the length of time in coma, these patients tend to have more serious physical deficits.
A further category of very severe injury is defined by a period of unconsciousness of 48 hours or more, or a period of PTA of 7 days or more. The longer the length of coma and PTA, the poorer will be the outcome. However, there are exceptions to this rule and, just as there is a small group of people who have a mild head injury who make a poor recovery, so there is a small group of individuals who have a severe or very severe injury who do exceptionally well.