Engelska - What is acquired brain injury?
Suddenly, one day, it happens. You or someone in your family or someone you know is affected by brain injury. How could it happen? What is it that has happened? Who is affected by brain injury? Why? What will the future look like? Is there any cure? What can I do? There are many questions to be answered, and the uncertainty is often a heavy burden.
These fact sheets have been created to answer some of these questions and help you find out what you want to know. This particular sheet clarifies what acquired brain injury is.
How many are affected and why?
It is estimated that around 70,000 people survive acquired brain injury in Sweden every year. Acquired brain injury means injury that is not congenital and has not arisen during the first few years of childhood. The injury is usually caused on a single occasion, for example as a result of external force or a stroke. Tumours, infections and oxygen deficiency after nearly drowning or cardiac arrest or sugar deficiency in insulin coma are other causes. Haemorrhaging from vascular deformities, for example arterial aneurysms, can also be mentioned. Symptoms resembling those seen in acquired brain injury can also be observed in other diseases in the brain. In this presentation, however, we will limit ourselves to acquired brain injury where the most common causes are as follows.
Stroke
Stroke is the most common cause of brain injury with lasting harm and is the most common cause of long hospitalisation. Around 30,000 people suffer a stroke every year in Sweden. The average age at which a stroke is suffered is 73. However, many are younger, with 20-25% under the age of 65. The symptoms can range from very mild, sometimes temporary, to very severe, where the person affected needs constant help. Strokes are caused by clots or bleeding from one of the blood vessels in the brain. Clots are most common and occur in around 80% of cases. In the case of clots the person suffers a cerebral infarction because the blood supply to part of the brain is shut off. In haemorrhaging the person suffers injury because of the pressure of the blood on the brain tissue.
Traumatic brain injury
Around 22,500 people in Sweden every year are affected by traumatic brain injuries following exposure of the head to force. Younger men are affected most, but the elderly are also over-represented. The most common causes of traumatic brain injury are road traffic accidents, falls and assault. The injury causes pressure on or wearing of the brain tissue. Injuries to the blood vessels in the brain may also occur, resulting in haemorrhages. The injury may range from very mild and temporary following slight concussion to very severe, where the affected person never regains consciousness.
What does the brain look like?
The brain (encephalon) has a rounded shape with a large folded surface area and weighs just under 1.5 kg. It has a gelatinous consistency. It requires a large amount of energy, and around 20% of the blood flow goes to the brain. It is fragile but is well protected inside the cranium.
The brain can be roughly divided into the cerebrum, cerebellum and the brain stem (truncus encefali). The cerebrum consists of two halves, hemispheres, which are largely mirror images of each other (telencephalon) and a deeper-lying part, the between-brain (diencephalon). The midbrain (mesencephalon), which is actually the top part of the brain stem, is sometimes also included. The brain stem also includes the pons and the medulla oblongata. Each hemisphere is divided into four lobes. The frontal lobe is furthest forward. Behind this is the temporal lobe and the parietal lobe, and furthest to the rear is the occipital lobe. The diencephalon merges into the brain stem, which in turn merges via the medulla oblongata into the spinal cord which is contained inside the spine. The cerebellum lies behind the brain stem and beneath the cerebrum. The brain and spinal cord form the central nervous system from which the peripheral nervous system, the nerves to and from the body, depart.
How does the brain function?
The parts of the brain have different functions. A difference can broadly be seen between the anterior, posterior and central parts and between the left and right sides.
The anterior (front) parts have a overarching and controlling function. They are crucial to our ability to move our body, remember, experience feelings and think.
The diencephalon and brain stem deal with breathing, wakefulness and feelings of desire. The posterior (rear) parts receive, sort, analyse and store information.
The right half of the brain controls the left side of the body and vice-versa. The two halves are otherwise quite unlike each other in terms of function and in part fulfil different tasks.
The lobes of the brain also have different tasks:
The left half of the brain is responsible for language, for example the ability to speak and write, and new language learning, as well as logical thinking.
The right half of the brain deals with spatial perception, melodies, wholeness and intuition.
The occipital lobe receives and processes sensory impressions, the temporal lobe sound and the parietal lobe emotion.
The frontal lobe is responsible for initiative, personality, social behaviour and ability to plan and organise. Our movements also controlled from here.
The cerebellum’s principal task is to coordinate muscle so that we can carry out appropriate movements.
Many functions are thus localised in particular parts of the brain, while many other functions, for example long-term memory, are distributed throughout the brain. The various parts of the brain additionally collaborate intensively in what are known as networks.
Communication within the brain and between the brain and the rest of the body takes place partly via electrical signals in thin nerve fibres and partly via chemical signals. It is thus not just through nerves that the brain controls the body. The lower appendage of the brain (the pituitary) is the master gland which, through its hormones, among other things controls metabolism and the menstrual cycle.
How can brain injury be manifested?
When our brain is injured, there is an effect on our ability to perceive and understand ourselves and those around us, specifically human characteristics, our ability to perceive ourselves specifically as humans The brain is the part of our body that handles impressions from inside ourselves and from our environment. When we have been exposed to stresses and face problems, the brain helps us to take these in and process them so that we can find a way of coping with them.
Being affected by brain injury a problem that the injured brain has to deal with.
Brain injury can result in much different functional impairment. These can be both visible and invisible, regardless of where in the brain the injury is located. Anything from clear motor and sensory loss to difficulty in concentrating, memory problems, increased fatigue, difficulty in keeping several balls in the air, irritability and sensitivity to sound and light can occur. Varying degrees of depression are common, but euphoria also occurs. Many people have problems keeping their emotions in check, are easily moved, and sometimes cry without reason.
If injury occurs in the left half of the cerebrum, control of motor responses and emotion on the right side may be impaired and ability to see objects in the right visual field may be reduced, with aphasia. Aphasia may be manifested as difficulty in speaking and understanding spoken language, as well as in writing and reading. Arithmetical ability may also be impaired. If injury occurs to the right half of the cerebrum, there may be reduced control of motor function and feeling on the left side and reduced ability to see objects in the left visual field. There may additionally be difficulty in planning and organising, as well as problems with perception of space and time. Impaired ability to perceive impressions from the left side, both from the person’s own body and from objects outside, is also common. The person may also have problems in fully understanding and appreciating what symptoms they actually have. The above applies to virtually all who are right-handed and the majority of left-handed people. In around 25% of left-handed people language is wholly or partially localised in the right half of the brain, and the picture of injury may consequently look different.
In the case of injury in the anterior part of the cerebrum, the part of the brain that is most complex and least researched, impaired ability to take the initiative and get started on something and to plan and organise is common. There may be a loss of inhibitions, the scrupulous person becomes slovenly, and the person does not know, for example, what is socially acceptable. It may also be manifested as impaired ability to think abstractly and change thought patterns. If there is injury to the cranial nerves, the nerves that depart directly from the brain, the person may, for example, be affected by double vision or impaired sense of smell, sight and hearing.
Cerebellar injury can cause reduced ability to coordinate movements, leading to shaky movements and impaired balance, a collective term for all these impairments being ataxia. Another symptom is halting speech, also known as dysarthria. Difficulty in taking part in social life is quite common in brain injury. Complex activities in life such as working, looking after the home and dealing with finances are affected. The injury can cause difficulties in social situations and relationships with friends and family are often affected. In more severe cases there may be problems in looking after oneself, moving from one place to another and taking in important information. Some people with brain injury end up suffering exclusion and, in the worst case, social destitution.
To conclude, the brain is an extremely complex organ which we, with our own very limited brains, as complex as they are, find it difficult to understand. However, knowledge of the function of the brain has markedly increased, contributing to our ever improving understanding of how brain injury is manifested. Our knowledge is nonetheless still limited with regard to how the brain, despite low ability for new formation, heals injury and how we can best contribute to this healing taking place. It is just as important, however, that we learn to live a full and meaningful life despite brain injury.
Written by: Björn Johansson, Tiina Saarela, Staffan Stenson, Rehabilitation klinik, Uppsala University Hospital
Factual information checked by Jörgen Borg, professor in rehabilitation medicin