Traumatic Brain Injury
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.
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.
A moderate head injury is defined as loss of consciousness for between 15 minutes and six 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.
Severe head injury is usually defined as being a condition where the patient has been in an unconscious state for six 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.
What Happens in a Traumatic Brain Injury?
A traumatic brain injury can be seen as a chain of events:
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.
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.
A brain or cerebral aneurysm is where the wall of an artery or blood vessel in the brain is weakened, causing it to swell into a blister-like shape. As aneurysms grow, they put pressure on the surrounding tissue, which can cause a variety of symptoms. If detected, it is vital to seek immediate medical advice as an aneurysm could rupture at any time. This is known as a brain haemorrhage.
Where the wall of an artery or blood vessel in the brain is weakened, it may swell in a blister-like shape and form what is known as a cerebral aneurysm. As aneurysms grow, symptoms can occur as they put pressure on the surrounding tissue. Sometimes, however, no symptoms will occur. An aneurysm can rupture at any time, causing serious bleeding into the surrounding tissue and damaging the brain. This is called a haemorrhage.
Treatment for aneurysm is difficult due to problems accessing parts of the brain, but generally involves surgical clipping, where a section of skull is removed and a clip placed over the neck of the aneurysm to stop blood flowing into it, or coiling, where a series of platinum coils are threaded from the patient’s lower body up into the brain aneurysm, filling it with the platinum and stopping blood flow. Not all treatments are suitable in all cases, and the medical team will be able to advise on this.
A brain haemorrhage is bleeding in or around the brain either as a result of ruptured aneurysm, known as a haemorrhagic stroke, or following a significant blow to the head. This section explains the different types of brain haemorrhage while explaining the long-term effects it can cause.
There are four types of haemorrhage, named according to where the bleeding occurs. These are: subdural haemorrhage, extradural haemorrhage, subarachnoid haemorrhage and intracerebral haemorrhage.
Subdural and extradural haemorrhages are the most common type after TBI, and they are a cause of further brain damage that can lead to more long-term effects.
Subarachnoid and intracerebral haemorrhages are more likely to happen spontaneously. Small blood vessels rupture, often causing loss of consciousness. Sometimes a brain haemorrhage can occur after a seemingly minor head injury. Symptoms can develop rapidly or can take a number of weeks to develop, and urgent investigation and treatment is required. The long-term effects of a brain haemorrhage depend on the type and location, but as with all brain injuries, every person’s recovery is individual.
A brain tumour is an abnormal mass of tissue inside the skull, which is caused by cells dividing at an increased speed.
There are two types of brain tumour: malignant and benign.
Malignant, or cancerous, tumours often invade surrounding tissue and can spread to other parts of the body through the blood stream or lymphatic system. They can also erode ‘healthy’ tissue, as the cells that make up a malignant tumour share very little in common with the healthy cells that surround them.
Because malignant tumours often grow and spread rapidly, early diagnosis can increase the chances of survival. If caught early, they will have had less chance to destroy healthy brain tissue, and are less likely to have spread to other parts of the body. Sometimes, brain tumours are the result of other malignant tumours in other parts of the body that have spread to the brain – these are known as ‘metastases’, or ‘secondary tumours’. These are always malignant.
Benign, or non-cancerous, tumours tend to grow more slowly and do not spread, although people can have more than one benign tumour. A benign brain tumour can put pressure on the brain as it grows inside the enclosed space of the skull, and this may compress and damage healthy tissue.
Modern imaging techniques, such as MRI and CT scans, have made it possible for doctors to accurately judge the size and location of a tumour, making surgery possible where the growth is accessible, and allowing them to estimate how treatable it is. Surgery to remove all or part of a brain tumour is called a craniotomy, where the skull is opened. Where the entire tumour cannot be removed, radiotherapy or anti-cancer drugs may be tried to slow, limit or stop its spread.
The effects of a brain tumour are dependent on the size and location of the tumour and how much it has spread.
What is encephalitis?
Encephalitis is an inflammation of the brain, usually caused by a viral infection. Although rare, it is potentially life-threatening and may lead to permanent brain damage or death.
Many different viruses can cause encephalitis, including the herpes simplex virus (HSV – which also causes cold sores) and enteroviruses. In some cases infections are caused by mosquito bites (e.g. Murray Valley encephalitis, also known as Australian encephalitis; equine encephalitis). A milder form of encephalitis can also accompany some of the common childhood diseases such as chicken pox, measles, mumps, and rubella (German measles).
Symptoms of encephalitis
Infectious encephalitis usually begins with a ‘flu-like illness’ or headache followed by more serious symptoms hours to days, or sometimes weeks later. The most serious finding is an alteration in the level of consciousness. This can range from mild confusion or drowsiness, to loss of consciousness and coma. Other symptoms include a high temperature, seizures (fits), aversion to bright lights, inability to speak or control movement, sensory changes, neck stiffness or uncharacteristic behaviour. Autoimmune encephalitis often has a longer onset. Symptoms will vary depending on the type of encephalitis related antibody but may include: confusion, altered personality or behaviour, psychosis, movement disorders, seizures, hallucinations, memory loss, or sleep disturbances.
The after-effects of encephalitis
Nerve cells (neurons) may be damaged or destroyed and this damage is termed acquired brain injury (ABI). No two people affected will have the same outcome. Effects of encephalitis can be long-term. In children, injury to the parts of the brain that are not developed at the time of the illness can manifest later in life, well after the illness with encephalitis. Tiredness, recurring headaches, difficulties with memory, concentration, balance, mood swings, aggression, clumsiness, epilepsy, physical problems (weakness down one side of the body, loss of sensations and of control of bodily functions and movement), speech and language problems, reduced speed of thought and reaction, changes in personality and in the ability to function day-to-day, problems with senses and hormones are reported. The potential impact on social and family relationships should not be underestimated. Returning to work and school can be difficult.
Hydrocephalus is caused by a buildup of fluid inside the skull, which can increase pressure and cause damage to the brain. This section explains the causes and symptoms of hydrocephalus as well as outlining the long-term effects and treatment options available.
The brain and spine are surrounded by cerebrospinal fluid (CSF), which is essential for cushioning the brain, providing nutrients and removing waste products.CSF is mainly produced in the choroid plexus and flows around the sub-arachnoid space surrounding the brain and spinal cord. It then passes through a series of chambers in the brain called ventricles and connecting channels called foramina.We produce about a pint (500ml) of CSF per day but the brain can contain only about 120-150ml. For this reason excess CSF is drained into the bloodstream through a series of valves called the arachnoid villi. The CSF is recycled about three times a day.
Hydrocephalus can occur if the flow of CSF is blocked, if the body produces too much CSF, or if there is a problem with the arachnoid villi which stops CSF being absorbed into the blood. This can cause the ventricles and sub-arachnoid space to swell as the fluid pressure increases, which may lead to permanent brain injury if prompt treatment is not received.
Types of hydrocephalus
There are five main types of hydrocephalus:
- Communicating hydrocephalus occurs despite the fact that there is no obvious blockage or obstruction in the flow of CSF. The term non-obstructive hydrocephalus is also used. It occurs when the reabsorption of the CSF into the bloodstream is impaired, resulting in increased CSF pressure and enlarged ventricles.
- Non-communicating hydrocephalus occurs when there is a blockage in the flow of CSF. It is also known as obstructive hydrocephalus.
- Hydrocephalus ex vacuo is the result of the ventricles enlarging to compensate for loss of brain tissue. This can happen as a result of another form of acquired brain injury, such as a stroke or traumatic injury.
- Arrested hydrocephalus can occur in people who have a minor blockage in the CSF flow. The person may suffer no effects because the CSF production is balanced by absorption and so pressure is normal. However, if the balance is disrupted spontaneously, or after a minor head injury, then the resulting increase in CSF pressure is called arrested hydrocephalus.
- Normal pressure hydrocephalus (NPH) affects older people (average age 70-75) and is often categorized as a form of dementia. This type of hydrocephalus can be difficult to diagnose because it develops over a long period of time so the fluid pressure in the brain may not appear to be high. It can develop after brain injury but in most cases the cause is unknown.
Causes of hydrocephalus
The different types of hydrocephalus can be congenital, acquired or idiopathic.
- Congenital hydrocephalus – When hydrocephalus is caused by congenital birth defects the symptoms normally present themselves in childhood. However, they may not appear until adulthood in some cases.
- Acquired hydrocephalus – Hydrocephalus can be acquired at any stage of life due to head injuries, strokes, tumours, meningitis, hemorrhages and other forms of ABI.
- Idiopathic hydrocephalus – This means that there is no known cause and many cases of hydrocephalus, at any stage of life, appear despite no apparent obstruction or impairment of CSF reabsorption.
Hypoxic and anoxic brain injury
About anoxic and hypoxic brain injury
Oxygen is crucial to the brain as it is used to metabolise glucose, which provides energy for all body cells. Brain cells are sensitive to the effects of restricted oxygen supply and can die within minutes of oxygen restriction. The immediate outcome of severe oxygen restriction is often coma and in very severe cases brain death.
- near drowning
- drug overdose
- severe asthma
- accidents involving anaesthesia
- carbon monoxide inhalation and poisoning
- heart attack
Hypoxia can also occur as a secondary injury following a traumatic brain injury, e.g. when there is serious blood loss resulting in low blood pressure, or as a result of brain swelling that restricts oxygen supply to areas of the brain.
Types of anoxic/hypoxic brain injury
Anoxic anoxia occurs when inadequate oxygen is breathed in and absorbed by the body, e.g. altitude sickness or suffocation
Anaemic anoxia is an inadequate oxygen supply due to a decrease in total haemoglobin or change in the haemoglobin’s ability to carry oxygen
Stagnant hypoxia is inadequate oxygen supply to the brain due to the reduction of cerebral blood flow or pressure, e.g. stroke, heart attack
Toxic anoxia occurs when toxins or substances interfere with oxygen supply, e.g. carbon monoxide, cyanide, narcotics, alcohol.
Effects of anoxic and hypoxic brain injury
The overall effects of a hypoxic/anoxic brain injury vary depending upon the severity of damage. Areas of the brain particularly vulnerable to lack of oxygen include those responsible for coordination, movement and memory. A significant hypoxic brain injury can result in coma and possibly post-coma unresponsiveness.
Symptoms following a return to consciousness can include memory difficulties, abnormal movements, weakness in arms and legs, lack of coordination and visual problems. Movement disorders are quite common, including lack of coordination, spasticity (involuntary muscle tightness), tremors and an impaired ability to adjust the body’s position.
As with other types of brain injury, people can develop challenging behaviours and emotional problems, such as depression, agitation or a reduced ability to tolerate stress and frustration.
Outcomes and recovery
Recovery is similar to that of other types of brain injury, but because a hypoxic injury usually results in widespread injury to the brain, outcomes are likely to be lower than other brain injuries.
A holistic level of support is important, e.g. a physiotherapist and occupational therapist for movement disorders, speech pathologist for communication difficulties, and a neuropsychologist to assess for cognitive deficits. Support from a good team of specialists and family and friends will ensure the best recovery possible.
What is Meningitis?
Meningitis is a bacterial, viral or fungal infection that can cause inflammation of the protective membranes that line the brain (the meninges).
Causes of Meningitis
Meningitis can be bacterial, viral or sometimes fungal, although bacterial meningitis (caused by the meningococcal bacteria) is more serious than viral or fungal meningitis and requires rapid treatment. The infection can pass through the brain’s natural barrier and infect the meninges, causing them to swell as they attempt to stop the infection from spreading. Meningitis can also infect the cerebrospinal fluid (CSF), leading to a rise in intracranial pressure. Inflammation and increased pressure around the brain can cause serious injury if left untreated.
Diagnosis and treatment of meningitis
Meningitis can be recognised by a rapid onset of flu-like symptoms and a characteristic purple rash, although the rash does not always appear. Tests to diagnose meningitis can take a number of hours to complete, so treatment will usually be offered immediately if meningitis is suspected. A diagnosis can also be made using a blood test, lumbar puncture, a CT scan or a chest X-ray. Antibiotics are used to treat bacterial meningitis and serious viral meningitis. Mild viral meningitis can usually be treated at home with plenty of rest.
What is a stroke?
A stroke is an emergency condition, in which there is a disruption of blood supply to part of the brain, leading to brain injury. There are two types of stroke:
Ischemic stroke: A blood clot in a blood vessel causes a blockage of blood flow
Haemorrhagic stroke: A weakened blood vessel bursts, causing blood to leak into the brain. Also see section Brain haemorrhage.
The occurrence of stroke can be identified by the onset of the following symptoms:
F – Face Part of the person’s face starts to droop, making it difficult for them to smile.
A – Arms The person is unable to fully lift their arms.
S – Speech The person has difficulties with speech, which becomes slurred.
T – Time It is time to call 000. A person displaying these symptoms must immediately be taken to an emergency department for treatment.
A person experiencing a stroke might also have a sudden headache, confusion, dizziness, problems with communicating or problems with their vision.
How does a stroke lead to brain injury?
The brain relies on a rich supply of oxygen to keep brain cells working; this is supplied by an intricate network of blood vessels that pump oxygen-rich blood around the brain. When this blood flow is disrupted by either a blood clot or a burst blood vessel, the brain cells are starved of oxygen and they begin to die. This results in brain injury.
What is a TIA?
TIA stands for ‘Transient Ischemic Attack’; these are mini strokes that can occur in the brain. A TIA occurs when there is a temporary disruption to the blood supply to the brain due to a blocked blood vessel. The symptoms of a TIA are the same as a stroke, but they only last for a few minutes or hours. However, medical attention should always be sought as soon as these symptoms are recognised, as they can be an indication of a stroke occurring. Even if the symptoms of a TIA improve or disappear by the time an ambulance arrives, it may still be necessary to carry out a medical assessment, as TIAs indicate a risk of experiencing a stroke in the future.
Causes of stroke
Sometimes the disruption to the blood supply to the brain can be due to natural causes, such as weakening of blood vessels over time or a genetic condition that increases the risk of experiencing a stroke.
However, there are some factors that can increase the risk of experiencing a stroke; these include:
- Drinking too much alcohol
- Being overweight
- Not exercising enough
- Eating too much food
There are some blood-related medical conditions that also increase the risk of having a stroke. These include:
- High blood pressure
- Atrial fibrillation
- High cholesterol
Receiving appropriate treatment for any medical condition can reduce the chance of experiencing a stroke.
Diagnosis and treatment of stroke
Upon arrival at a hospital, a person suspected of experiencing a stroke will usually undergo a number of tests to confirm the diagnosis. Tests can include:
- Brain scans – these can help with confirming diagnosis of the type of stroke that has occurred and also whereabouts in the brain it has taken place. This can help with guiding treatment at the next stage. The most common types of brain scans used are computerised tomography (CT) and magnetic resonance imaging (MRI) scans.
- Blood tests – these are carried out to get more detail about the person’s blood, such as blood pressure and blood sugar levels, which can help with confirming a diagnosis of stroke and identifying the cause.
- Heart tests – these tests take images of the heart and blood vessels to identify the cause of the stroke. The most common types of tests used are echocardiograms and ultrasound scans.
- Swallowing tests – a person experiencing a stroke usually has problems with speech and swallowing. A test that assesses how much a person is able to swallow can help to confirm a diagnosis of stroke.
- Other assessments – a stroke can lead to a number of different issues, such as problems with mobility and cognitive (thinking) problems. A range of other assessments can be used to identify what particular issues the person is having, which can help with treatment at the next stage.
Strokes are treated differently depending on whether they are ischemic or haemorrhagic.
Ischemic strokes are often treated with medication. Various medications can be used to reduce the chance of blood clots forming to prevent future blockage of the brain’s blood flow. Other medications can be offered to reduce high blood pressure or the amount of cholesterol in the person’s blood. Alternatively, a surgical procedure known as carotid endarterectomy can be performed to remove blockage in a blood vessel.
Haemorrhagic strokes can be treated with medication as well; medication can also be used to prevent the occurrence of future blood vessel bursts. A surgical procedure known as a craniotomy might be performed to remove leaked blood from the brain and repair any blood vessels that have already burst.