Common brain injury terms

This section is designed to provide a glossary of terms, explaining some of the different words you might hear when reading information on, or talking about, brain injury.

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A

Acceleration/deceleration

A CLOSED HEAD INJURY often sustained in car accidents, where the brain smashes forwards and then backwards, rebounding against the walls of the skull, causing damage to both the FRONTAL LOBES and the back of the brain.

Amnesia

Failure of memory.  (also see POST TRAUMATIC AMNESIA) – amnesia following a traumatic event)

Aneurysm

Swelling or dilation of an artery due to a weakened wall. Also spelled 'Aneurism'.

Anomia

The inability to name objects or items.

Anosmia

Loss of sense of smell.

Anoxia

Complete oxygen starvation. A condition in which the oxygen supply to the tissues is cut off completely. Partial loss of oxygen supply to the tissues is known as HYPOXIA.

Apathy

A direct result of brain injury to frontal lobe structures which concern emotion, motivation and forward planning.

Aphasia (Dysphasia)

Difficulty understanding or expressing language as a result of damage to the brain. There are different levels of impairment and the term dysphasia refers to partial loss of language whereas aphasia refers to complete loss of language. However, in practise, the terms are interchangeable.

Apraxia/Dyspraxia

Inability to plan and perform purposeful movements, while still having the ability to move and be aware of movements.

Arachnoid

The middle of the three membranes covering and protecting the brain and spinal cord. The arachnoid membrane lies below the DURA mater and directly above the SUBARACHNOID SPACE.

Arterial line

A very thin tube (catheter) inserted into an artery to allow direct measurement of the blood pressure, the amount of oxygen and carbon dioxide in the blood.

Ataxia

Abnormal movements due to loss of co-ordination of the muscles.

Athetosis

Abnormal writhing movements, particularly of the hands, seen in a number of brain disorders and following brain injury.

Axon/dendrites

Parts of nerve cells in the brain which look like small hair-like tentacles. The cells receive information via the dendrites and communicate with each other by passing electrical signals down the axons and releasing chemical signals at their ends.

B

Basal Ganglia

Collections of grey matter in the deep areas of the brain, below the cerebral cortex. They are involved in the control of movement and injury may produce a disturbance resembling Parkinson's disease.

Blindsight

A phenomenon in which people who are perceptually blind in a certain area of their visual field demonstrate some response to visual stimuli.

Brain plasticity

The ability of intact brain nerve cells (neurones) to make new connections and, in some cases, take over functions of damaged cells. Neuronal plasticity plays a crucial role in memory and diminishes as a person gets older.

Brainstem

The lower extension of the brain where it connects to the spinal cord. Neurological functions located in the brain stem include those necessary for survival (breathing, heart rate) and for arousal (being awake and alert).

Broca's area

An area of the brain crucial to language processing, speech production and understanding. (see also: WERNICKE'S AREA).

C

Cardiac arrest

The heart stops beating and there is no effective circulation of blood to the body, so that the brain and other organs rapidly become starved of oxygen (See also: HYPOXIA or ANOXIA)

Catheter

A tube which is inserted into any body part to withdraw or introduce fluids.

Cerebellum

Area at the back of the brain, below the cerebral hemispheres, involved in the control of movement, co-ordination, posture and balance.

Cerebral

Concerning the brain.

Cerebral angiogram

An X-ray picture of the blood vessels inside the head. A drug is injected via the groin artery to outline these cerebral vessels.

Cerebral anoxia

A complete interruption of the supply of oxygen to the brain.

Cerebral hypoxia

A partial interruption of the supply of oxygen to the brain, which becomes inadequate to maintain normal brain function.

 

Cerebral ischaemia

A deficiency of blood supply to brain tissue, due to an interruption or reduction of arterial blood flow.

Cerebro-spinal fluid (CSF)

Liquid which fills the ventricles of the brain and surrounds the brain and spinal cord.

Cerebrum

This is the largest part of the human brain, which occupies most of the skull cavity. It is made up of the two cerebral hemispheres.

Chorea

Brief, involuntary jerky movements involving the limbs and face, seen in a number of brain disorders and following brain injury.

Closed head injury

Damage to the brain where there is no penetration from the scalp or skull through to brain tissue. Often there is no injury to scalp or skull.

Cognition

General term used to cover all areas of intellectual functioning. Includes skills such as thinking, remembering, planning, understanding, concentrating and using language.

Coma

A state of deep and often prolonged unconsciousness.

Concussion

Unconsciousness after a blow to the head.

Confabulation

Verbalisations about people, places or events with no basis in reality.

Contracoup

Bruising of the brain tissue in the side opposite to where the blow was struck.

Contractures

Joints and muscles which are not used regularly quickly becoming stiff, and rendering them resistant to stretching.

Cortical blindness

Loss of visual function resulting from damage to the main visual areas, which are located in the occipital lobes at the back of the brain.

Cranial nerves

A set of 12 pairs of nerves originating in the brainstem, the oldest part of the brain. Functions of the cranial nerves include control of eye movement and blinking.

Craniotomy

Surgical removal of the skull in small pieces.

CT scan/CAT scan

Computerised tomography. A series of X-rays at different levels of the brain. (Tomography is a technique using X-rays to build up a focused image of a "slice" through the body at a given level).

Cyanosis

A bluish tinge to the skin, caused by a deficiency of oxygen in the blood, and often most apparent around the lips and mouth and in the fingertips.

D

Demyelination

Loss of the fatty insulating sheath (myelin) surrounding nerve axons, which impairs their function by interfering with their ability to conduct electrical nerve impulses normally.

Dendrite

(see AXON)

Diencephalon

The midbrain. This contains discrete nerve centres including the hypothalamus, which controls appetite regulation, sexual arousal, thirst and temperature control, and some aspects of memory. The diencephalon also contains the thalamus, the body's sensory gateway to the brain.

Diffuse axonal injury

Widespread tearing of nerve fibres across the whole of the brain.

Diffuse brain injury

Injury to cells in many areas of the brain rather than in one specific location. 

Diplopia

Double vision

Diplopia (1)

Double vision

Disinhibition

Difficulty in controlling urges and impulses to speak, act or show emotions.

Dura

Outermost of the three membranes protecting the brain and spinal cord.

Dysarthria

Difficulty speaking because of weakness and lack of co-ordination of the muscles for speech.

Dysphagia

Difficulty with swallowing.

Dysphasia

See APHASIA.

Dyspraxia

Inability to plan and perform purposeful movements, while still having the ability to move and be aware of the movement.

E

Echolalia

Imitation of sounds or words without comprehension. This is a normal stage of language development in infants but is abnormal for adults.

Electroencephalogram (EEG)

EEG is a test used to record any changes of electrical activity in the brain by placing electrodes on the scalp.

Emotional lability

Rapid and drastic changes in emotional state (such as laughing, crying or anger) that are inappropriate.

Epilepsy

There are many varied presentations. Seizure or fit activity involving parts of or the complete body.

Evoked potentials

Electrical responses of the brain to stimulation, recorded from the scalp.

Executive functions

The ability to think and reason, to synthesize and integrate complex information and make considered judgements and decisions about what to do in a particular situation.

F

Focal brain injury

Injury restricted to one region (as opposed to diffuse).

Frontal lobes

The largest lobes of the brain, occupying the front part of the cerebral hemispheres. As well as containing the areas controlling voluntary movement and speech production, the frontal lobes are involved in the executive functions of thinking and reasoning, the integration of complex information, judgement, decision-making and planning for the future. They also have an important role in social behaviour, personality and emotion.

G

Gastrostomy

The creation of an opening into the stomach for the administration of foods and fluids when swallowing is impossible.

Glasgow Coma Scale (GCS)

A score given to head injured patients starting immediately after the head injury to measure the degree of unconsciousness. A score of 7 or less indicates that the person is in a coma. A maximum score of 15 indicates that the person can speak coherently, obey commands to move, and can spontaneously open their eyes.

Glutamate

The major excitatory neurotransmitter in the brain. Excessive glutamate release (or cascade) following TBI can be a major cause of nerve cell death in the second injury.

Grey matter

Nerve cell bodies in the brain, which have a greyish appearance and make up the cerebral cortex.

Gyrus (pl. gyri)

A ridge of the cerebral cortex (also see SULCUS).

H

Haematoma

A collection of blood forming a definite swelling which compresses and damages the brain around it.

Haemoglobin

A substance in the red blood cells, which takes up oxygen in the lungs and transports it to the tissues of the body.

Haemorrhage

Blood loss, bleeding

Head injury - mild/minor

May causes brief loss of consciousness for 15 minutes or less with a period of post-traumatic amnesia of less than 1 hour.

Head injury - moderate

Defined as being a condition where the patient has been in a coma for 6 hours, and a period of post-traumatic amnesia of up to 24 hours.

Head injury - severe

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.

Hippocampus

A structure on the inner surface of the temporal lobes, which is made up mainly of grey matter and has an important role in memory processes. Damage to the hippocampus may lead to memory problems.

Homeostasis

The ability or tendency of an organism or cell to maintain internal equilibrium by adjusting its physiological processes. For example, sweating when hot in order to keep the core body temperature at 98.6 degrees maintains homeostasis.

Hyperbaric oxygen therapy (HOT)

A specialized treatment sometimes used in severe anoxic states - particularly after carbon monoxide poisoning - which involves giving pure oxygen at increased pressure in a hyperbaric chamber.

Hypopituitarism

The condition in which the pituitary gland doesn't produce adequate levels of one or more hormones.

Hypothalamus

A small structure just above the brain stem. The hypothalamus detects levels of hormones in the blood and controls the pituitary gland's release of hormones in order to keep the levels stable (also see pituitary gland).

Hypoxia

A term applied to that state in which the body tissues have an inadequate supply of oxygen. This may be because the blood in the lungs does not receive enough oxygen, or because there is not enough blood to receive oxygen, or because the blood stagnates in the body.

Hypoxic-ischaemic injury

Damage caused by an interruption of oxygen supply (hypoxia) linked with a reduction in the blood flow to the brain (ischaemia), such as occurs when the heart stops beating in a cardiac arrest.

I

Impulsivity

A tendency to rush into something without reflecting or thinking first.

Infarction

Death of brain cells resulting from an interruption of their blood supply, as occurs in a stroke.

Intracranial pressure (ICP) monitor

A monitoring device to determine the pressure within the brain. It consists of a small tube (catheter) in contact with the pulsing brain or the fluid cavity within it. ICP is measured by means of a metal screw or a plastic catheter connected to an electronic measuring device.

L

Limbic system

A group of deep cortical structures connected to the hypothalamus, governing memory, emotions and basic drives, including sex drive.

Locked in system

A condition in which the patient is awake and retains the ability to sense and perceive, but is unable to communicate except by limited eye movements. This is due to the motor nervous system being paralysed. It can sometimes be confused with persistent vegetative state.

M

Magnetic resonance imaging (MRI)

A scanning technique for producing high resolution images of the brain, which give much better detail than CT scans. MRI uses a strong magnetic field rather than X-rays to produce the images.

Mannitol

A solution which removes water from the brain by accelerating urinary excretion and thus reduces raised intracranial pressure.

Minimally conscious state (MCS)

A state of profoundly altered consciousness seen following a severe brain injury, in which there is some evidence of minimal awareness, although this is far removed from anything approaching normal appreciation of the surroundings or of what is happening.

Motor cortex

The part of the brain involved in planning and executing voluntary movements. The primary motor cortex lies directly in front of the primary SENSORY CORTEX on the upper surface of the brain.

Myelin

A fatty insulating sheath, which surrounds nerve axons and improves the efficiency of transmission of the electrical nerve impulses along them.

Myoclonus

Sudden, shock-like muscle twitches or jerks, seen in various brain disorders and quite common following severe cerebral anoxia.

N

Nasogastric tube

This is the very thin tube that is threaded through the nose and throat into the stomach for giving liquid food and pureed meals. Used if there are swallowing difficulties.

Nerve call bodies

The largest part of a nerve cell. The cell body holds all of the general parts of a cell as well as the nucleus, which is the control centre.

Neurogenic diabetes insipidus

A condition which causes thirst and excessive production of dilute urine due to the pituitary gland not producing enough of the hormone vasopressin (anti-diuretic hormone).

Neuron

A nerve cell.

Neuro-transmitters

Chemicals made in the nervous system that serve as messengers, aiding or interfering with the functions of the nerve cells.

O

Occipital lobes

Area at the back of the cerebral hemispheres, containing the main visual centres.

Oedema

Increased water content in the brain, causing brain swelling.

Open head injury

An injury where there is penetration of the scalp and skull through to brain tissue.

P

Parietal lobes

The part of each cerebral hemisphere primarily concerned with the perception and interpretation of sensation and movement.

Parkinson's disease

A slowly progressive brain disease involving the basal ganglia and causing reduced movement, rigidity and tremor. Damage to the basal ganglia - which can occur in cerebral anoxia - may produce symptoms resembling spontaneously occurring Parkinson's disease.

Perseveration

The inappropriate persistence of a response in a current task which may have been appropriate for a former task. Perseveration may be verbal or motoric.

Pia

One of the three membranes surrounding and protecting the brain and spinal cord. The pia lies below the SUBARACHNOID SPACE in direct contact with the surface of the nerve tissue.

Pituitary gland

A small structure at the base of the brain which releases a wide variety of hormones that, in turn, control the activity of the body's other hormone glands.

Post-concussion syndrome

A group of symptoms occurring after minor head injury that may persist for days, weeks or months.

Post-traumatic amnesia (PTA)

The period after being unconscious when there may be confused behaviour and no continuous memory of day to day events.

Proprioception

The sensory awareness of the position of body parts with or without movement.

R

Respiratory arrest

Breathing stops and there is no effective supply of fresh oxygen to the blood from the lungs. If breathing is not restored, cardiac arrest will quickly follow, as the heart muscle becomes starved of oxygen.

Retrograde amnesia

The loss of memory of events for a period prior to the injury.

Rigidity

This simply means stiffness, resistance to movement.

S

Sensory cortex

The primary sensory cortex is situated on the upper surface of the cerebrum, directly behind the MOTOR CORTEX. Different areas of the sensory cortex specifically deal with the sensations experienced in different parts of the body.

Shunt

A devise to draw off excess fluid in the brain. A surgically placed tube runs from the ventricles and deposits fluid into either the abdominal cavity, heart or large veins in the neck.

Somatosensory evoked potentials (SSEPs)

Electrical responses of the brain recorded from the scalp following stimulation of nerves in the limbs. Failure to obtain SSEPs in someone in coma following an anoxic brain injury is associated with a poor outcome.

Spasticity

An involuntary increase in muscle tone following brain injury, which may produce tightness or stiffness of the limb muscles and interfere with movement and walking.

Subarachnoid space

The space between the ARACHNOID membrane and PIA mater. The subarachnoid space is filled with fluid (see: CSF).

Sulcus (pl. sulci)

A groove of the cerebral cortex (also see GYRUS).

T

Temporal lobes

The part of the cerebral hemispheres located under the frontal and parietal lobes, lying inwards of the ears. It has a range of important functions and is involved with hearing and some complex aspects of auditory, language and visual perception, as well as memory and emotion.

Therapeutic hypothermia

Artificial cooling may be used to lower the core body temperature, as a means of reducing the metabolism of brain cells and decreasing their oxygen requirement. There is some evidence that this may have a protective effect on the brain following cardiac arrest and in other anoxic states, although this remains controversial.

Tracheostomy

An operation to insert a plastic tube in the neck just below the Adam's apple. Through this tube, an adequate air passage can be maintained. It may be necessary to leave the tube in the windpipe for a prolonged period.

Traumatic brain injury

Damage to the brain resulting from a head injury.

Tremor

Regular repetitive movements which may be worse either at rest or on attempted movement.

V

Vegetative state (VS)

After a very severe brain injury, there may be a transition from coma into a vegetative state. Basic functions such as breathing and maintaining the heartbeat and blood pressure all continue, but without evidence of consciousness in any meaningful sense and with no response to the environment and no ability to communicate.

Ventilator

A machine that does the breathing work for the unresponsive patient. It delivers moistened (humidified) air with the appropriate percentage of oxygen and at the appropriate rate and pressure.

Ventricles

Cavities (spaces) inside the brain which contain cerebro-spinal fluid.

Vestibular

System in the middle of the ear which senses movement. Injury can lead to dizziness.

W

Wernicke's Area

Located in the temporal lobes, this is an area of the brain concerned with producing speech (See also BROCA'S AREA).

White matter

White coloured nerve tissue in the brain made up of myelin covered axons, which transmit electrical signals through the nervous system. The white matter lies underneath the grey matter of the cerebral cortex and white matter tracts travel down through the brainstem and into the spinal cord.