The effects of traumatic brain injury on brain function 

Damage to the nerve fibres deep in the central part of the brain, which is 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 head (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.

Coma

Coma can be defined as a state of depressed consciousness where the patient is unresponsive to the outside world. Unconsciousness follows traumatic brain injury, whether for a few seconds or for a few weeks, and is the most typical symptom of a head injury. There are different levels of coma, and the Glasgow Coma Scale is used to rate the unconscious patient's ability to open his eyes, move and speak. A patient is assigned a number in each of three categories, namely eye opening, motor response and verbal response. The minimum number is 3 and the maximum possible number is 15. The more severe the injury, the lower the performance, and the lower the number. Awakening from a coma is gradual, starting with eyes opening, then responses to pain, and then responding to speech. The longer a person stays in coma, the more likely it is that the long term effects will be severe.

This is a very distressing time for family and friends, and it is easy to feel helpless and to long to do something constructive. It is generally accepted that someone in a coma may be able to hear speech, but not be able to respond. Talk to the person as if they can hear. Coma arousal programmes in which carefully planned periods of stimulation (in the form of sound, touch, smell and taste) are combined with periods of complete rest in order not to overload the person's senses, are still controversial. However, they give relatives and friends something useful to do, and may well have some beneficial effect. Headway has a publication on this subject titled Coma After Brain Injury: How you can Help, with practical suggestions for what to use and how to go about coma stimulation. It is important to gain the consent of the medical team before beginning this approach.

Severity of the Injury

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 is important as it gives an indication of the severity of the injury. Used in combination with length of time in coma, these two give the best measure of eventual outcome.

Minor Head Injury

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% of all head injuries fall into this category. 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. 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 can be misunderstood by GP's, sometimes being considered as almost hypochondria on the part of the patient. Although it is true that in some cases where the symptoms persist for months a psychological element such as depression can come into play. Whist 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 neuro-psychologist.

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. 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.

Moderate Head Injury

A moderate head injury is defined as loss of consciousness for between 15 minutes and 6 hours, and 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. Like those with a minor head injury, 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 Head Injury

A severe head injury is usually defined as being a condition where the patient has been in a coma 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.

Persistent Vegetative State

Various terms are used to describe this condition, with a current move away from Persistent Vegetative State to Vegetative State, Minimum Conscious State or Minimally Responsive State.

A small number of people sustain a head injury so severe that they remain in a state of coma for months and years without recovering sufficient consciousness to make any form of communication, but can breathe without mechanical assistance. They may have sleeping and waking cycles allowing them to be fed, but they do not speak, follow commands or have any understanding of what has been said. The Glasgow Coma Scale score for such people is usually below 9. When this is the case, despite all reasonable application of rehabilitation measures for at least 3 years, a person may be described as being in a Persistent Vegetative State or PVS. There are normally just less than 100 people in the UK in PVS at any one time.