Parkinson's disease: glossary of terms
Acetylcholine
The chemical messenger (neurotransmitter) released by cholinergic nerves.
Action tremor
A tremor that develops or increases when limbs or body are moving voluntarily.
Agonist
A chemical or drug that enhances neurotransmitter activity.
Akinesia
Slowness or absence of muscle movements.
Amantadine (e.g. Symmetrel)
A drug that causes an increase in dopamine release in the brain.
Antagonist
A substance that diminishes neurotransmitter activity.
Anticholinergic
A substance that opposes the naturally occurring chemical messenger called acetylcholine.
Antioxidant
An agent that prevents the loss of oxygen in chemical reactions.
Artane
A brand of anticholinergic drug.
Ataxia
Loss of co-ordination of movement.
Athetosis
Slow, involuntary movements of the arms, head and/or legs.
Autonomic nervous system
The part of the nervous system that regulates involuntary vital function, including the activity of the cardiac muscle, smooth muscle (e.g. uterus) and glands (e.g. adrenal).
Axon
The long, hair-like extension of a nerve cell that carries a message to another nerve cell.
Basal ganglia
The large grey masses in the base of the brain — concerned with the programming of normal movements.
Blood-brain barrier
The membrane that separates the blood from brain cells.
Benign essential tremor
A condition characterised by tremor of hands, head, vocal chords and, at times, other parts of the body — sometimes mistaken for Parkinson's disease.
Bradykinesia
Slowness in initiating and executing movement and difficulty in performing repetitive movements.
Bromocriptine (e.g. Parlodel)
A dopamine agonist — a drug.
Carbidopa
A drug that prevents the breakdown of levodopa in the body before it reaches the brain. In combination with levodopa it allows more levodopa to reach the brain, where it is converted into dopamine.
Cogwheeling
Slow, jerking movements — a feature of the rigidity present, (especially noted when testing passive movement).
Chorea
Abnormal jerky, rapid involuntary movements of the body.
Decarboxylase inhibitor
A drug that hinders the conversion of dopa to dopamine.
Deep brain stimulation
A reversible therapy that uses small electric impulses to block the brain signals that cause tremor.
Dendrite
A thread-like extension of a nerve cell that serves as an antenna to receive messages from the axon of other nerve cells.
DOPA
A short name for dihydroxyphenylalanine, an amino acid.
Dopa decarboxylase
An enzyme found in nerve tissue and blood — controls conversion of DOPA to dopamine.
Dopa decarboxylase inhibitors
Drugs (e.g. carbidopa) that block the conversion of levodopa to dopamine outside the brain (so that more DOPA can reach the brain).
Dopamine
A chemical produced by the brain — functions in the nervous system as a messenger transmitting impulses from one nerve cell to the next. It governs actions of movement, balance and walking. It is deficient in Parkinson's patients.
Dopamine agonist
A drug that mimics the effects of dopamine and stimulates the dopamine receptors.
Dysarthria
Difficult, poorly articulated speech, sometimes slurred.
Dyskinesia
An impairment of the ability to execute voluntary movements.
Dysphagia
Difficulty in swallowing.
Dystonia
Slow, twisting or writhing involuntary movements.
Enzyme
A substance that speeds up a chemical reaction.
Extrapyramidal system
The system of nerve cells, nerve tracks and pathways that connects the cerebral cortex, basal ganglia, thalamus, cerebellum, reticular formation and spinal neurones — responsible for the regulation of reflex movements such as balance and walking. The extrapyramidal system is damaged in Parkinson's disease.
Festination
Rapid short, shuffling, hesitant steps when walking.
Freezing
Temporary, involuntary inability to move.
Idiopathic
Disease of unknown origin or without apparent cause.
Levodopa (L-dopa)
A naturally occurring compound found in the body and brain. A particularly effective anti-Parkinson's drug that is changed into dopamine in the brain.
Lewy bodies
Pink staining spheres, found in nerve cells — considered to be a marker for Parkinson's disease.
Micrographia
Change in handwriting where script becomes small.
Monoamine oxidase inhibitors
Drugs that enhance the effect of certain chemical transmitters such as dopamine, by inhibiting the function of enzymes that oxidise them (break them down).
MPTP
A toxic chemical produced during an attempt to make a synthetic narcotic. MPTP destroys the cells of the substantia nigra and produces a condition that leads to parkinsonism.
Neurone
A nerve cell.
Neurotransmitter
A chemical messenger produced in nerve cells and permitting communication from the brain to other parts of the body.
Norepinephrine
A chemical transmitter involved in governing the involuntary nervous system.
'On-off' phenomena
A term used to describe abrupt and often unpredictable changes in the clinical state of a patient with Parkinson's disease.
Orthostatic hypotension
A rapid decrease in blood pressure upon standing. It may cause fainting.
Pallidotomy
A type of brain surgery sometimes performed to reduce symptoms of bradykinesia, rigidity, and drug-induced side-effects.
Palsy
Paralysis of a muscle or group of muscles.
Parkinsonism
A clinical state characterised by tremor, rigidity, bradykinesia, stooped posture and shuffling gait.
Parlodel (bromocriptine)
A dopamine agonist — a drug.
Pergolide (e.g. Permax)
A dopamine agonist — a drug.
Resting tremor
Tremor of the limb(s) or body while the body is at rest.
Rigidity
Increased resistance to the passive movement of a limb. When constant it is known as 'lead pipe rigidity'.
Selegiline (e.g. Eldepryl)
A drug that inhibits the enzyme that destroys dopamine. It has been used in an effort to smooth the response to levodopa.
Sinemet
A combination of an inhibitor (carbidopa) with levodopa — a drug. The carbidopa blocks the conversion of levodopa to dopamine outside the brain.
Sinemet CR
A slow-release form of Sinemet.
Striatum
An area of the brain controlling movement, balance and walking; connects to and receives impulses from the substantia nigra.
Substantia nigra
The area of the brain where cells produce dopamine.
Symmetrel (amantadine)
Releases dopamine from substantia nigra cells — a drug.
Thalamotomy
A surgical procedure whereby a small region of the thalamus is destroyed.
Tremor
A rhythmical shaking of a limb, mouth, tongue or other part of the body.
'Wearing off' phenomena
Waning of the effect of previously administered levodopa, associated with abrupt changes in performance.
Acknowledgements: Parkinson's Association of WA (Inc.) and American P.D. Association.
Last Reviewed: 18 July 2002
