A

Acetylcholine
A chemical messenger released by cholinergic nerves. Medications that block the action of acetylcholine can help with the symptoms of Parkinson’s disease.

Action Tremor
Rhythmic, involuntary movement of a limb when movement is initiated, i.e., when writing or lifting an object. Not usually seen in the earlier stages of Parkinson's.

Agonist
A chemical or drug that imitates neurotransmitter activity. For example, dopamine agonists used in the treatment of Parkinson’s disease "trick" the brain into thinking that it is dopamine and the brain responds with an improvement in symptoms.

Akinesia
Inability to move (freezing) or difficulty in producing bodily movements.

Amantadine
An antiparkinson medication that stimulates the release of available dopamine in the brain therby improving symptoms. It may be used early in disease or added to levodopa.

Anticholinergics
A class of antiparkinson medications that are mostly useful for tremor.

Ataxia
Loss of balance and decreased coordination.

Athetosis
Dyskinesias in which there are slow, repetitive, involuntary movements especially in the hands.

Atypical Parkinsonisms
Disorders related to Parkinson’s disease in that they are characterized by a slowness of movement, and sometimes rigidity, tremor and balance problems, but have other clinical features and pathology.

Autonomic Nervous System
A part of the nervous system responsible for control of bodily functions that are not consciously directed; (for example: heart rate, blood pressure, sweating, intestinal movements, temperature control).

B

Basal Ganglia
The interconnected cluster of nerve cells deep in the brain that coordinate normal voluntary movements such as walking.

Benign Essential Tremor
A condition characterized by tremor of the hands, head, voice, and sometimes other parts of the body. It is sometimes mistaken for a symptom of Parkinson’s disease. However, this is an action tremor and there is no rigidity or slowness of movement.

Bilateral
Occurring on both sides of the body.

Blood-brain barrier
A thin layer of tightly packed cells, which separate the body’s central nervous system from the blood stream. This layer blocks the ability of many substances, including certain drugs, from entering the brain.

Blepharospasm
Spasmodic blinking or forced closure of the eyelids.

Bradykinesia
Literally “slow movement;” the gradual loss of spontaneous and voluntary movement. This is one of the main symptoms of Parkinson's.

Brainstem
The lowest part of the brain, which merges with the spinal cord.

Bromocriptine
The generic name of a dopamine agonist drug.

C

Carbidopa
A drug used with levodopa, to block the breakdown of levodopa to dopamine in the intestinal tract and in the blood. Carbidopa helps levodopa to be more effective and can be used to reduce the side effects of levodopa and dopamine agonists.

Central Nervous System
A term referring to the brain and spinal cord.

Cerebellum
The largest part of the brain; responsible for thought, reasoning, memory, sensation, voluntary movement.

Chorea
Jerky, random, dance-like involuntary movements, usually seen in Parkinson's disease from too much medication.

Cognitive Function
The ability to think, to remember, to plan and to organize information.

Cogwheel Rigidity
Stiffness in the muscles, with a jerky quality when arm and leg joints are repeatedly moved.

COMT Inhibitor
A new class of antiparkinson drugs that blocks the enzyme catchol-O-methyltransferase (COMT), which prevents the breakdown of levodopa in the intestinal tract. This allows more levodopa to cross into the blood and then into the brain. COMT inhibitors include entacapone (Comtan) and tolcapone (Tasmar).

D

Deep Brain Stimulation (DBS)
A new surgical procedure that has proven to be very effective in treating Parkinson’s disease. The surgery includes the implantation of permanent electrodes in various parts of the brain through which continuous pulses of electricity are given. These are connected to a programmable power source inserted in the chest wall (similar to a cardiac pacemaker).

Delusions
Erroneous beliefs that cannot be altered by rational argument.

Dementia
A progressive decline in mental functions characterized by loss of awareness, reality and confusion.

Dopamine
A chemical produced by the brain, which assists in the effective transmission of messages from one nerve cell to the next. Dopamine helps control the actions of movement, balance and walking. The lack of dopamine is the primary cause of Parkinson's symptoms.

Dopamine Agonist
Drugs that mimic the effects of dopamine and stimulate the dopamine receptors.

Dopamine Receptor
The area of the nerve cell in the striatum that receives the dopamine message from the substantia nigra.

Dopaminergic
An adjective used to describe a chemical or a drug effect related to dopamine.

Dysarthria
Slurred or impaired speech. Dysarthria occurs when the muscles associated with speech are affected.

Disequilibrium.
Unsteadiness or balance problems.

Dyskinesia
Abnormal involuntary movements. A common side effect of many drugs used to treat Parkinson's disease.

Dysphagia
Difficulty or abnormality of swallowing.

Dystonia
In Parkinson's disease, a tightness, spasm or cramping of muscles; may also involve twisting or posturing of muscles.

E

End-of-dose-failure
A loss of benefit from a dose of levodopa, typically at the end of a few hours.

Enzyme
A protein or chemical tool that speeds up the rate of a biological reaction.

Essential Tremor
A fast tremor that is most pronounced when performing an action such as writing.

Etiology
The cause of a disease, or how it is acquired.

F

Festination
Slow, small, shuffling steps.

Freezing
Inability to move or getting “stuck” as if the feet appear to be glued to the floor. This frequently occurs at a boundary such as a doorway or when exiting a car.

G

Gait
The manner in which a person walks.

Globus Pallidus
A part of the basal ganglia; the internal part of the globus pallidus is what is targeted by pallidotomy to treat Parkinson’s disease.

H

Hallucinations
False perception of something that is not really there. In Parkinson's disease, they are usually things or people that patients see, but occasionally hallucinations can be things patients hear or feel.

High-dopa dyskinesias
Abnormal movements that occur when the levodopa in the blood is at its highest level.

Hypokinesia
Abnormally diminished motor activity

Hypomimia
The mask-like expression typical of Parkinson's disease

I

Idiopathic
An adjective meaning “of unknown cause.” The usual form of Parkinson's disease is idiopathic.

Intention Tremor
A tremor that occurs when a person attempts voluntary movement.

L

Levodopa (L-DOPA)
The international generic name for a drug that is changed into dopamine in the brain. This is most commonly administered and the most effective drug for the treatment of PD. (The brand name is Sinemet in the United States). Levodopa helps restore the levels of dopamine in the brain.

Lewy Bodies
Abnormal pink staining spheres found in dead or dying dopamine-producing cells. They are frequently the most precise way to diagnose Parkinson's disease.

Low-Dopa Dyskinesias
Abnormal movements that occur when doses of levodopa are wearing off, or when the levodopa in the blood is at a low or falling level.

M

Mentation
Mental or cognitive function.

Micrographia
The tendency to have very small, cramped handwriting due to difficulty with fine motor movements in Parkinson's disease.

Monoamine Oxidase-B (MAO-B)
An enzyme that breaks down dopamine in the area of the dopamine receptor.

Monoamine Oxidase-B (MAO-B) Inhibitors
A class of antiparkinson drugs (for example selegiline) that blocks the enzyme MAO-B, preventing the breakdown of dopamine in the area of the dopamine receptor.

Motor Fluctuations
The complications of the treatment of Parkinson’s disease affecting ability to move; examples are wearing-off of dose , on-off phenomena and dyskenesias.

Myoclonus
Jerking involuntary movements of arms and legs, usually occurring during sleep.

N

Neurodegenerative
Refers to conditions such as Parkinson's, which are characterized by a loss of cells in the central nervous system.

Neurotransmitter
A specialized chemical produced in nerve cells that carry impulses from one nerve cell to another; a chemical messenger; dopamine is a neurotransmitter.

Norepinephrine
A neurotransmitter.

O

On-Off Phenomenon
Unpredictable, usually abrupt oscillations in motor state.

Off
The state of re-emergence of Parkinsonian signs and symptoms when the medication’s
effect has waned.

On
Improvement in Parkinsonian signs and symptoms when the medication is working optimally.

P

PD
Abbreviation for Parkinson’s disease.

Palilalia
Stuttering or stammering speech in Parkinson’s disease.

Pallidotomy
Surgical destruction of a small group of cells in the internal globus pallidus, the major area from which information leaves the basal ganglia, in order to relieve dyskinesias and other symptoms of advanced Parkinson’s disease.

Paranoia
An irrational belief that others are “out to get” an individual, making the patient suspicious and untrusting.

Parkinson’s Mask
A stolid, mask-like facial expression with infrequent blinking; characteristic of PD.

Parkinsonian Syndromes
Disorders related to PD in that they are characterized by bradykinesia and sometimes rigidity, tremor and balance problems, but have other clinical features and other pathology.

Parkinsonism
The clinical term referring to the group of conditions that characterize the most typical Parkinson’s symptoms: rigidity, bradykinesia, tremor, shuffling gait and difficulty with balance.

Pathogenesis
The abnormal processes in the body that produce the signs and symptoms of a disease.

Pathology
The study of a disease process, including what is affected and what it looks like under a microscope.

Postural Instability
Difficulty with balance.

Postural Tremor
A tremor that increases when a patient’s hands are stretched out in front of them.

Prognosis
A forecast of the probable course and outcome of a disease.

Propulsion
Propelling forward as the patient accelerates with rapid, short steps.

Psychosis
A mental syndrome in which the patient loses contact with reality; psychotic manifestations include delusions, hallucinations and paranoia.

R

Range of Motion
The extent that a joint will move from being fully straightened to completely bent.

Resting Tremor
A shaking that appears in the limbs when they are relaxed.

Retropulsion
Stumbling or falling backwards.

Rigidity
A tightness or increase in muscle tone at rest or throughout the entire range of motion of a limb; it may be felt as a stiffness by the patient.

S

Serotonin
A neurotransmitter.

Shaking Palsy
The term initially used by James Parkinson to describe the disorder we now call Parkinson’s disease.

Sialorrhea
Drooling.

Side Effect
A drug’s effect that is different from the beneficial effect for which the drug is being taken.

Striatum
Part of the basal ganglia circuit in the brain; it receives connections from the substantia nigra and contains the dopamine receptors. It is the largest component of the basal ganglia and controls movement, walking and balance.

Substantia Nigra
Meaning “dark substance,” the part of the brainstem that produces dopamine and that degenerates in PD.

T

Thalamic (or Pallidal) Stimulation
Electrical stimulation of cells in the thalamus (or internal globus pallidus) to treat tremor (or other signs of PD) instead of destroying them.

Thalmatomy
Surgical destruction of a small group of cells in the thalamus in order to abolish tremor on the side of the body opposite the surgery.

Thalamus
A major area of the brain that receives information from the basal ganglia.

Tremor
Rhythmic shaking, usually of the hand (but may also affect the legs, lips, or jaw) that occurs at rest in PD. It may occur less commonly on holding up the hands or when moving a limb.

W

Wearing-Off
A loss of benefit from a dose of levodopa, typically at the end of a few hours.