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Brain injury glossary

Brain injury terms index

The field of brain injury is so complex that you’re likely to be confronted with a wide variety of terms that you haven’t heard of before.

You might be speaking to a doctor in the immediate aftermath of a traumatic brain injury, or could simply be reading information at home. Either way, this A-Z index of phrases and terminology will ensure that you’re always up to speed on the subject of brain injury.

Click the letters below to jump to the relevant section, or use the search function to find a particular definition.

If you can’t find the definition you’re looking for, or you need any more information on the legal aspect of a traumatic brain injury, simply give us a call or fill out an online enquiry form.

  A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z 


Brain injury glossary – A



Acceleration is a closed head injury which occurs when the brain moves forward or backward inside the skull and impacts the skull wall. Acceleration and deceleration injuries are most common in car accidents and cause damage to the back of the brain and the frontal lobes.


Amnesia is a failure of memory and inability to recall certain information. There are different kinds of amnesia. Retrograde amnesia is the loss of recent memories or learning which occurred before an injury or disease but does not usually affect remote memories. Post traumatic amnesia is the state of confusion which occurs after a traumatic brain injury when a patient may not only be unable to recall the event but other information such as their own name.


Anosmia is the loss of the ability to smell.


An aneurism or aneurysm is the swelling or dilation of an artety.


Anoxia is the complete starvation of oxygen from the brain. In certain traumatic brain injuries, oxygen supply to brain tissue is completely disconnected.


Apathy is a symptom of frontal lobe brain injuries. Frontal lobes govern emotion, motivation and forward planning, when damaged they can affect the personality of the victim.


Aphasia is a symptom of brain injury which causes an inability to understand or use language. Dysphasia, meanwhile, is a partial loss of language skills.


Apraxia, or dyspraxia, is the inability to plan and perform purposeful movements. This is different to paralysis since patients are still able to move and are aware of their movements, yet cannot accomplish certain deliberate actions.

Arterial Line

The arterial line is a catheter (thin tube) which is inserted into an artery to measure blood pressure in addition to the O2 and CO2 levels of the blood.


The arachnoid is a membrane which covers and protects the brain and spinal cord. It is actually found between the dura mater and subarachnoid membrane.


Ataxia is the collective term for abnormal movements caused by loss of co-ordination between muscles.


Athetosis occurs in a large number of brain disorders and can also be caused by a traumatic brain injury. It causes abnormal writhing movements, most commonly affecting the hands.


The axon is the part of a nerve cell which looks like a hair or tentacle. Once nerve cells have received information via the dentrites, they communicate this information by passing electrical signals via the axons which release chemical signals.


Anomia is a symptom of brain injury which causes an inability to name objects or things


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Brain injury glossary – B


Basal ganglia

A basal ganglia is a collection of grey matter which aids the control of movement. It is found deep within the brain, beneath the cerebral cortex. Certain brain injuries may cause damage to the basal ganglia causing Parkinson’s Disease-like symptoms.


Blindsight is a medical phenomenon in which a person who is perceptually blind in a certain area of their visual field may respond to some visual stimuli within.

Brain Stem

The brain stem connects the brain to the spinal cord. It controls many neurological functions which we could not survive without, including the ability to breathe and manage our heart rate. The brain stem is also required to allow a person to be awake and alert.

Brain plasticity

Brain plasticity describes a process by which undamaged brain nerve cells, called neurones, make new connections within the brain or take over the functions of damaged brain cells in the wake of an accident or injury. Our brain plasticity contributes to memory and becomes weaker as we get older.

Broca’s area

The Broca’s area of the brain is integral to the process of language, as well as the production and understanding of speech.


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Brain injury glossary – C


Cardiac arrest

Cardiac arrest occurs when the brain and other organs are quickly starved of oxygen by problems with the circulation of blood within the body.


A catheter is a small tube which is inserted into the body during a medical procedure in order to withdraw or introduce fluids.


The cerebellum is the area below the cerebral hemispheres at the back of the brain which controls movement, co-ordination, posture and balance.


The term cerebral refers to anything which concerns the brain i.e. the cerebral cortex.

Cerebral angiogram

A cerebral angiogram is an X-Ray which depicts the blood vessels within the head. This is accomplished by injecting a drug into the groin artery which outlines the relevant vessels.

Cerebral anoxia

Cerebral anoxia is the total prevention of oxygen supply to the brain.

Cerebral cortex

The cerebral cortex is a folded layer of nerve cells, or grey matter, which can be found on the surface of the brain. It governs higher brain functions, including perception and sensation, in addition to controlling voluntary movement, thought, language and memory.

Cerebral hemispheres

The cerebral hemispheres are the two halves of the cerebrum, to the left and right. During a laboratory examination of the brain, most of the visible brain is made up of the cerebral cortex covering the two cerebral hemispheres.

Cerebral hypoxia

Cerebral hypoxia is the partial interruption of oxygen flow into the brain. This interruption prevents the brain from functioning normally.

Cerebral ischaemia

Cerebral ischaemia describes the inadequate supply of blood to brain tissue. This is caused by an interruption of blood flow, or reduction.

Cerebro-spinal fluid (CSF)

Cerebro-spinal fluid, or CSF, is the liquid which fills the ventricles of the brain. CSF surrounds the brain and spinal cord.


The cerebrum is the largest part of the brain and is made up of the two cerebral hemispheres. It occupies the majority of the skull cavity.


The cerebellum can be found between the cerebrum and the brain stem at the back of the head. It is responsible for coordinating movement and balance; and is also believed to play a part in the process of emotion.


Chorea is the collective term for brief and involuntary jerk movements involving limbs of parts of the face. They are caused by a variety of brain disorders and traumatic brain injuries.

Closed head injury

A closed head injury occurs when the brain is damaged without a penetrating blow through the skull to the brain tissue. Despite no injury to the skull or scalp, a serious injury may have occurred within the brain.


Cognition is the collective term for intellectual functions. It includes thinking, planning, understanding, concentrating, using language and memory.


A concussion is a loss of consciousness following a serious head injury.


Confabulations are verbalisations which have no basis in reality. They might concern people, places or other things but are created purely by the mind.


A coma is a state of deep and sometimes prolonged unconsciousness.

Contra coup

Contra coup is bruising of the brain tissue which occurs not at the point where a blow was struck but on the opposite side of the brain.


Contractures occur when joints and muscles are not used regularly and become stiff or resistant to stretching.

Cortical blindness

Cortical blindness is the loss of vision which occurs when damage is caused to the occipital lobes at the back of the brain.


A craniotomy is the surgical removal of the skull in small pieces.


The cranium is the area of the skull which covers the brain in order to protect it.

Cranial nerves

Two sets of 12 pairs of nerves make up the cranial nerves. They originate in the brain stem and control eye movement, blinking and more.

CT scan

A CT scan, or cat scan, is a series of computerised X-Rays at different levels of the brain.


Cyanosis is caused by a lack of oxygen in the blood. It creates a bluish tinge to skin, which is often most apparent around the lips, mouth and fingertips.


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Brain injury glossary – D



Myelin is the fatty insulator which surrounds nerve axons. Demyelination is the loss of this sheath, which impairs the function of the nerve axons and their ability to conduct electrical nerve impulses.


Dendrites assist the transmission of electrical signals into the nerve cell.

Diffuse brain injury

A diffuse brain injury causes injury to cells in many areas of the brain and not just a single location.


The diencephalon, or midbrain, contains discrete nerve centres such as the hypothalamus. It controls appetite, sexual arousal, thirst and temperature control. It is also believed to be active in elements of memory. The diencephalon is also home to the thalamus, which is known as the body’s sensory gateway to the brain.

Diffuse axonal injury (DAI)

A diffuse axonal injury is the widespread tearing of nerve fibres across the whole of the brain and not a specific area.


Diplopia is the medical term for double vision.


Disinhibition is a symptom of brain injury which creates difficult controlling urges, impulses to speak, behave a certain way or show emotions.


The dura is the outermost membrane which protects the brain and spinal cord.


Dysarthia is a weakness and lack of co-ordination of the muscles used to speak. This creates speech difficulties and can occur in the aftermath of a traumatic brain injury.


Dysphagia is the medical term for difficulty swallowing.


Dyphasia is a partial loss of language skills, including speech and interpretation.


Dyspraxia is the inability plan and carry out certain movements. Importantly, patients do have the ability to move and are aware of movement.


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Brain injury glossary – E



Echolalia concerns the imitation of sounds or words without understanding. While this is normal in the development of a small child it is abnormal in adults.

Electroencephalogram (EEG)

An electroencephalogram, or EEG, is a test used to record changes in electrical activity within the brain. It is accomplished by placing electrodes on the scalp.

Emotional lability

Emotional lability creates fast and extreme changes in emotional state which are not appropriate. This could include anger, laughter or crying.

Evoked potentials

Evoked potentials are the electrical responses of the brain to a stimulus, as recorded via the scalp.

Executive functions

Executive functions allow us to make decisions on what to do in certain situations. They include the ability to think, reason, synthesize and integrate complex information in order to make an appropriate judgement.


Epilepsy is a seizure or fit which involve all or part of the body.


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Brain injury glossary – F


Focal brain injury

A focal brain injury is one that is confined to a particular area of the brain.

Frontal lobes

The frontal lobes are the largest lobes in the brain and are located in the front of the cerebral hemisphere. They contain the areas of the brain which control voluntary movement, speech and executive functions. They play a role in social behaviour, personality and emotion.


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Brain injury glossary – G



A gastrostomy is the surgical procedure by which a hole is created into the stomach for administering foods and fluids. This is necessary when swallowing is impossible.

Glasgow coma scale

The Glasgow Coma Scale is a scoring scale to measure the degree of unconsciousness in head injury patients. Scores of 1-7 signify that the patient is in a coma, while a score of 15 indicated that the patient can speak, obey commands to move and open their eyes spontaneously.


Glutamate is the human brain’s major excitatory neurotransmitter. In the event of a traumatic brain injury, an excess of glutamate can be released. This is known as a cascade and can cause the death of nerve cells in the brain.

Grey matter

The grey coloured nerve cell bodies in the brain make up the cerebral cortex and are known as the brain’s grey matter.


The gyrus is a ridge in the cerebral cortex.


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Brain injury glossary – H



A haematoma is the collection of blood which forms a swelling that damages the brain.


Haemoglobin is a substance in red blood cells which collects oxygen in the lungs and transports it to the rest of the tissues in the body.


A haemorrhage is the medical term for bleeding or loss of blood.

Head injury (Mild or Minor)

A mild or minor head injury causes a brief loss of consciousness, which lasts for 15 minutes or less; along with post-traumatic amnesia of less than an hour.

Head injury (Moderate)

A moderate head injury causes a coma state of around 6 hours and a period of post traumatic amnesia of around 24 hours.

Head injury (Severe)

A severe head injury causes a coma of more than 6 hours and post traumatic amnesia of 24 hours or more.


The hippocampus is a structure on the inner surface of the temporal lobes. It is composed predominantly of grey matter and plays a crucial role in the process of memory. Damage to the hippocampus can cause memory problems.


Homeostasis is the ability or tendency of an organism or cell to maintain internal equilibrium by making changes to key physiological processes. Sweating is an example of homeostasis, since the body creates sweat to keep the core temperature within at 98.6 degrees.

Hyperbaric oxygen therapy

Hyperbaric Oxygen Therapy is a specialist treatment used in severe anoxic states. Pure oxygen is delivered at increased pressure within a hyperbaric chamber. The process is most often used after a patient has suffered carbon monoxide poisoning.


The hypothalamus is a small structure which resides above the brain stem. It is used to detect hormone levels in the blood and control the release of hormones by the pituitary gland to keep these levels stable.


Hypopituitarism is a condition which causes the pituitary gland to fail to produce adequate levels of one or more hormones.


Hypoxia refers to the inadequate supply of oxygen to body tissues. It occurs when blood does not receive oxygen in the lungs, or there is not enough blood to receive the oxygen, or because the heart does not transmit the blood around the body and it stagnates.

Hypoxic-ischaemic injury

A hypoxic-ischaemic injury refers to damage caused by the interruption of oxygen supply, when this is caused by a reduction in blood flow to the brain. One cause of hypoxic-ischaemic injury is a cardia arrest.


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Brain injury glossary – I



Impulsivity refers to a tendency to rush into something without due thought or reflection.


Infarction is the death of brain cells caused by the interruption of blood supply. This occurs during a stroke.

Intracranial pressure (ICP) monitor

An intracranial pressure monitor is a device which determines the pressure levels within the brain. A small tube, or catheter, is placed in contact with the pulsing brain or the fluid cavity within it. This is connected to an electronic measuring device.


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Brain injury glossary – L


Limbic system

The limbic system is a group of deep cortical structures which are connected to the hypothalamus. They are used to control memory, emotion and other drives such as sex drive.

Locked in syndrome

Locked in syndrome is a condition in which a patient is awake and also able to sense and perceive but does not have the ability to move or communicate; other than via limited eye movements. This is because the motor nervous system is paralysed. Locked-in-syndrome can be confused with a persistent vegetative state.


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Brain injury glossary – M


Magnetic resonance imaging (MRI)

Magnetic resonance imaging, or MRI, is a technique of scanning used to produce high resolution images of the brain. MRI scans provide much greater detail than a CT scan. MRI is accomplished using strong magnetic fields instead of X-Rays.


Mannitol is a solution which removes water from the brain by accelerating urinary excretion. This is used to reduce intracranial pressure.

Minimumally conscious state

A minimumally conscious state is a period of profoundly altered consciousness which occurs after a severe brain injury. During this period there is minimal awareness of surroundings or what is currently happening.

Motor cortex

The motor cortex is the part of the brain which is used to plan and execute voluntary movements. The primary motor cortex resides directly in front of the sensory cortex on the upper surface of the brain.


Myelin is the fatty insulation which surrounds nerve axons and improves the transmission of electrical nerve impulses across them.


Myoclonus refers to the sudden twitches or jerks of muscles which appear like shocks. They are caused by various brain disorders and are commonplace after severe cerebral anoxia.


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Brain injury glossary – N


Nasogastric tube

The nasogastric tube is a very thin tube which is threaded into the stomach via the nose and throat in order to provide liquid food and pureed meals. The tube is used on patients with swallowing difficulties.

Nerve cell bodies

The nerve cell bodies are the largest part of the nerve cell. The body holds all of the other cell parts together, including the nucleus which controls the cell.

Neurogenic diabetes insipidus

Neurogenic diabetes insipidus is a condition which causes thirst and subsequent excesses of dilute urine. The condition is caused by a lack of vasopressin hormone from the pituitary gland.


A neuron is a nerve cell.


Neuro-transmitters are chemicals produced within the nervous system which act as messengers. Neuro-transmitters can help or hinder the function of nerve cells.


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Brain injury glossary – O



Oedema is increased water content in the brain which causes swelling.

Occipital lobes

The occipital lobes are the area at the back of the cerebral hemispheres which contain the primary visual centres of the brain.

Open Head Injury

An open head injury occurs when a foreign object penetrates the skull, into the brain.


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Brain injury glossary – P


Parietal lobes

The parietal lobes help with perception and the brain’s interpretation of sensation and movement.

Parkinson’s disease

Parkinson’s Disease is the slow and progressive brain disease which causes reduced movement and tremors. The disease involves the basal ganglia and when the basal ganglia are injured, such as when cerebral anoxia occurs, symptoms can seem like Parkinson’s Disease.


Preservation is described as the unnecessary continuation of a response to a task, which is not appropriate to the current task, but was appropriate to a former task. There are instances of verbal preservation and motoric preservation.

Persistent vegetative state (PVS)

Severe brain injuries can lead to a persistent vegetative state, once a patient transitions out of a coma. In a persistent vegetative state, basic functions like breathing and circulation continue but the patient does not exhibit any evidence of consciousness. They give no response to the environment around them and to not have the ability to communicate.


The Pia is one of the three membranes which protect the brain and the spinal cord. It resides below the subarachnoid space and directly contacts the surface of the nerve tissue.

Pituitary gland

The pituitary gland releases hormones from the base of the brain and these hormones control the other hormone glands within the body.

Post concussion syndrome

The symptoms which occur after a minor head injury can persist for any number of days, weeks or months and are known as post concussion syndrome.

Post traumatic amnesia (PTA)

Post traumatic amnesia is a period of confused behaviour after being knocked unconscious and the loss of continuous memory of day to day events.


Proprioception is our sensory awareness of the position of body.


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Brain injury glossary – R



Rigidity is stiffness and resistance to natural movements.

Respiratory arrest

Respiratory arrest occurs when breathing stops and lungs are unable to supply fresh oxygen to the blood stream. Respiratory arrest is quickly followed by cardiac arrest since the heart is equally starved of oxygen.

Retrograde amnesia

Retrograde amnesia is memory loss concerning events prior to an injury.


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Brain injury glossary – S


Sensory cortex

The sensory cortex deals with the sensations which are experienced in different parts of the body. It is situated on the upper surface of the cerebrum, behind the motor cortex.


A shunt is a tube which runs from the ventricles in the brain to draw off excess fluid, which is deposited into the abdominal cavity, heart or neck.

Somatosensory evoked potentials (SSEPs)

Somatosensory Evokd Potentials, or SSEPs, are the electrical responses of the brain which are recorded from the scalp following stimulation of nerves in the limbs. If these responses cannot be obtained from somebody in a coma, after an anoxic brain injury, the outcome is considered to likely be poor.


Spasticity is the involuntary increase in muscle tone. It occurs after a brain injury and can produce stiffness or tightness of the limb muscles. This can make walking or other movements impossible.

Subarachnoid space

The subarachnoid space is the area between the arachnoid and pia membranes. It is filled with fluid.

Sulcus (Sulci)

The sulcus is a groove in the cerebral cortex.


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Brain injury glossary – T


Temporal lobes

The temporal lobes are located under the frontal and parietal lobes. They have a range of functions, including aspects of hearing, auditory processing, language and visual perception. Temporal lobes also play a role in memory and emotion.

Therapeutic hypothermia

Therapeutic hypothermia is a controversial concept. Lowering the core body temperature reduces the metabolism of brain cells and decreases the amount of oxygen they need; so therapeutic hypothermia is suggested to have a protective effect on the brain after an anoxic injury, such as cardiac arrest.


A tracheostomy is a surgical procedure which involves inserting a plastic tube into the neck below the Adam’s apple, so that air flow can continue into the lungs. Sometimes, it is necessary to leave the tube in the windpipe for an extended time.

Traumatic brain injury

A traumatic brain injury is a head injury which causes damage to the brain.


A tremor is a regular repetitive movement, which can worsen during rest or during a different attempted movement.


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Brain injury glossary – V



A ventilator is a machine which breathes for an unresponsive patient, delivering humidified air, containing the right amount of oxygen, and delivering it at the right rate and pressure.


Ventricles are spaces in the brain which contain cerebro spinal fluid.


The vestibular sits in the middle of the ear and senses movement. When the vestibular is injured the patient can experience dizziness.

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Brain injury glossary – W


Wernicke’s area

Wernicke’s area is located in the temporal lobes. It is the area of the brain which governs speech.

White matter

White matter is nerve tissue made up of axons which are covered in myelin. The white matter transmits electrical signals through the nervous system. It resides under grey matter in the cerebral cortex, while white matter tracts continue throughout the brain stem and the spinal cord.

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