GLOSSARY

Underlined terms are defined elsewhere in the glossary

Akinetic-rigid syndrome: A syndrome, or collection of systems, consisting of lack of movement (akinesia) or reduced movements (hypokinesia), slow movements (bradykinesia), and stiffness or rigidity (involuntary resistance to movement). The rigidity is of a type called cogwheel rigidity.

Basal ganglia: A group of nuclei, or clusters of nerve cells, near the base of the brain that is important in regulating both movements and emotions.

Bradykinesia, hypokinesia & akinesia: Bradykinesia means slow movements. Hypokinesia means reduced movements and generally refers to making smaller movements than intended, such as the small steps seen when a Parkinsons patient walks, or the small size of a Parkinsons patient's handwriting (called micrographia). Akinesia means lack of movement.

Cogwheel rigidity: " A type of rigidity in which, when a patient's limb is moved by the examiner, it resists and gives way in small, step-like movements as if it was being controlled by a cog-wheel.

Dopamine: One of a number of chemicals used by nerve cells as neurotranmitters. Messages are carried electrically along individual nerve cells but signalling from one nerve cell to another is usually accomplished by releasing a neurotransmitter chemical. Dopamine is the main neurotransmitter of the nerve cells which die off in Parkinson's disease.

Dysarthria:  soft voice or inarticulate speech.

Dyskinesia:  Abnormal writhing movement of voluntary muscles.

Dystonia:  Involuntary spasms of muscle contraction that cause abnormal movement and posture.

Epidemiological studies: Statistical studies of the occurence of diseases in populations and environments.

Familial Parkinsons: Some unusual forms of Parkinson's disease run in a few families. Abnormal genes have been identified in some of these families, but abnormalities in these genes are NOT found in most patients with Parkinson's disease. Alpha-synuclein and parkin are the proteins coded for by genes identified as being abnormal in some familial forms of atypical Parkinson's disease. Normal alpha-synuclein is also the major protein in Lewy bodies, the pathologic inclusions found in typical Parkinson's disease. The normal functions of alpha-synuclein and parkin are not yet clearly established.

Freezing:  Temporary inability to move.

Levodopa:  Levodopa was the first major breakthrough in the treatment of Parkinson's disease.  Levodopa is used by the brain to produce the chemical dopamine, which is deficient in persons with PD. The neurotransmitter is converted by the neurons in the brain into dopamine, which is stored within the cells until needed by the body.

Neurodegenerative Disease: A disease in which nerve cells in the brain or spinal cord (central nervous system, CNS) progressively die or degenerate.

Neuron:  a cell that generates or conducts electrical impulses to carry information from one part of the brain to another.

On-off phenomena:  sudden, unpredictable changes in motor performance by people on levodopa therapy.

Parkinson's Plus diseases: These are neurodegenerative diseases which cause the akinetic-rigid syndrome or parkinsonism PLUS additional symptoms not usually seen in Parkinson's disease. These diseases are progressive supranuclear palsy or PSP, corticobasilar ganglionic degeneration or CBGD, and multiple system atrophy or MSA, which includes Shy-Drager Syndrome, olivopontocerebellar atrophy or OPCA, and striato-nigral degeneration.

Pathology of Parkinson's disease: Examination of brain tissue from Parkinson's disease patients under the microscope shows loss of the dark-colored dopamine-producing nerve cells in the substantia nigra pars compacta and appearance of Lewy bodies, abnormal small round clumps of protein and other materials which are rarely seen except in Parkinson's disease.

Postural reflexes: Postural reflexes are the involuntary movements people automatically make to maintain their balance when standing and walking. Impairment of the postural reflexes causes poor balance and a tendency to fall.

Resting tremor: Tremor is a rythmic movement or shaking of any part of the body. The tremor of Parkinson's disease is called a "resting tremor" because it is present when a limb is at rest and may be reduced or go away when the limb is held up or otherwise used by the patient. Most other types of tremor are reduced or absent when the limb is at rest and relaxed.

Striatum: A region of the brain made up of two nuclei, or clusters of nerve cells, the globus pallidus (which means "white ball") and caudate (which means "tailed"). These two nuclei are part of a group of nuclei called the basal ganglia, which is important in regulating both movements and emotions.

Substantia nigra: This literally means "the black substance" and is a region in the brainstem (where the spinal cord joins the brain) where there is a group of dopamine-producing nerve cells, which appear darker than the surrounding tissue. The dopamine-producing nerve cells are in the pars compacta (meaning "compact or dense part"). There is another part called the pars reticulata ("speckled part").

Edwin B. George, MD, PhD., Wayne State University School of Medicine, 2003