empowering the severely brain injured and their families via support, understanding and a network of care

Glossary

A

ACCELERATION/DECELERATION

The brain smashes forwards and then backwards against the skull which can cause injury to front and back

AMNESIA

Failure of memory.

ANEURISM / ANEURYSM

Swelling or dilation of an artery due to a weakened wall.

ANOXIA

Complete oxygen starvation. Partial loss of oxygen supply to the tissues is known as HYPOXIA.

ARTERIAL LINE

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

ARACHNOID

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

ATHETOSIS

Abnormal writhing movements, particularly of the hands.

AXON/DENDRITES

Parts of nerve cells in the brain. 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 involved in the control of movement.

BRAIN STEM

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).

BRAIN PLASTICITY

The ability of intact brain nerve cells (neurones) to make new connections and, in some cases, take over functions of damaged cells.

C

CEREBELLUM

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

CEREBRAL ANGIOGRAM

An X-ray picture of the blood vessels inside the head.

CEREBRAL CORTEX

The folded layer of grey matter (made up of nerve cell bodies) on the surface of the brain. It is involved in higher brain functions such as sensation and perception, the control of voluntary movement, thought and reasoning, language and memory.

CEREBRAL HEMISPHERES

The right and left halves of the cerebrum.

CEREBRO-SPINAL FLUID (CSF)

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

CEREBRUM

the largest part of the 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.

CLOSED HEAD INJURY

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

COGNITION

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

CONCUSSION

Unconsciousness after a blow to the head

COMA

A state of deep and often prolonged unconsciousness.

CONTRA COUP

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, in the occipital lobes at the back of the brain.

CRANIECTOMY

Surgical removal of a piece of the skull (a bone flap) to give the brain room to swell. Unlike a craniotomy (see below) the bone flap is generally not replaced, and in such cases reconstruction surgery to fit a metal plate will usually take place at a later date.

CRANIOTOMY

Surgical removal of a piece of the skull (a bone flap) to access the brain. The bone flap is usually replaced when the surgery is completed.

CRANIUM

The bony skull which completely engulfs the brain.

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

Dendrites are branched filaments in nerve cells (neurons).

DIFFUSE BRAIN INJURY

Injury to cells in many areas of the brain as opposed to one specific location.

DIENCEPHALON

The midbrain. This contains discrete nerve centres including the hypothalamus.

DIFFUSE AXONAL INJURY (DAI)

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

DURA

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

DYSPHAGIA

Difficulty with swallowing.

E

ECHOLALIA

Imitation of sounds or words without comprehension.

ELECTROENCEPHALOGRAM (EEG)

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

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.

EPILEPSY

Seizure or fit activity involving parts of or the complete body.

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.

G

GASTROSTOMY

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

GLASGOW COMA SCALE

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 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

H

HAEMATOMA

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

HAEMORRHAGE

Blood loss, bleeding.

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.

HYPERBARIC OXYGEN THERAPY

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.

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.

HYPOXIA

A term applied to that state in which the body tissues have an inadequate supply of oxygen.

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

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 SYNDROME

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

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

A 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.

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

OEDEMA

Increased water content in the brain, causing brain swelling.

OCCIPITAL LOBES

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

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.

PERSISTENT VEGETATIVE STATE (PVS)

After a very severe brain injury, there may be a transition from coma into a persistent 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.

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.

PROPRIOCEPTION

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

R

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.

SPASTICITY

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

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

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.

TRACHEOSTOMY

An operation to insert a plastic tube into the windpipe. 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

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.

W

WERNICKE’S AREA

Located in the temporal lobes, this is an area of the brain concerned with producing speech

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.