The [Christian] message is that there is hope for a ruined humanity – hope of pardon, hope of peace with God, hope of glory – because at the Father’s will Jesus became poor, and was born in a stable so that thirty years later He might hang on a cross.
J.I. Packer

Glossary Of Neurological Terms

Glossary Of Neurological Terms

GLOSSARY OF NEUROLOGICAL TERMINOLOGY

Reprinted with permission from the United Parkinson Foundation, 360 West Superior Street, Chicago, Illinois 60610, (312) 664-2344

  • ANATOMIC TERMS **

BASAL GANGLIA: A group of brain areas that collectively are involved with control of normal movement and walking. The caudate nucleus and putamen (striatum), globus pallidus and substantia nigra are important basal ganglia structures.

GLIA: These are the support cells of the central nervous system. While they do not carry out the brain’s functions as the neurons do, they may play a role in maintaining the health of the neurons, and may be involved in a variety of neurologic disorders.

GLOBUS PALLIDUS: An area of the brain adjacent to the striatum and related in function to the striatum. At one time surgical procedures were performed on the globus pallidus to try to relieve some of the symptoms of Parkinson disease. This surgery was of very limited benefit and is no longer being done. The term pallidum is also used to describe this area of the brain.

NEURON: A nerve cell. A neuron when viewed microscopically is composed of three parts: “dendrites” with receptor sites that a receive information from other cells, a “cell body” that integrates the information from all of the receptor sites, and an “axon” that travels sometimes many feet and from which a neurotransmitter is released to pass on information. Sometimes axons and cell bodies can have receptor sites as well.

STRIATUM: A term used to describe the caudate nucleus and the putamen, important basal ganglia structures richly concentrated with dopamine.

SUBSTANTIA NIGRA: A darkly pigmented region of the brain that normally has a dense concentration of cells that produce dopamine. In Parkinson’s disease, these cells die.

  • CHEMICAL TERMS **

ACETYLCHOLINE: A chemical found in the body and brain that is felt to be important as a neurotransmitter. It appears to counteract many actions of dopamine.

AGONIST: A chemical or drug that enhances neurotransmitter activity. There are two important types of agonists: Indirect agonists act to increase the release of the neurotransmitter or to delay its breakdown. Amantadine (Symmetrel) is an example of an indirect agonist. Direct-acting agonists (bromocriptine, pergolide, lisuride) directly stimulate dopamine receptors and have been used mainly as an ancillary drug for parkinson patients who are helped with moderate doses. Pergolide and lisuride remain investigational drugs, available only at research institutions.

ANTAGONIST: A chemical or drug that diminishes neurotransmitter activity. Antagonists can act to decrease neurotransmitter production, to increase neurotransmitter breakdown or to block receptor sites.

ANTICHOLINERGIC: An adjective used to describe a chemical, a drug or a drug effect that relates to acetylcholine inactivity or blockade.

CATECHOLAMINE: A class of chemicals, two of which are known to be important to brain function. These are dopamine and norepinephrine.

CHOLINERGIC: An adjective used to describe a chemical, a drug or a drug effect that is related to acetylcholine.

DOPAMINE: A chemical found in the body and brain that is felt to be important as a neurotransmitter. Its action in the brain appears important for the facilitation of normal movement. Its highest concentration is in the basal ganglia (striatum).

DOPAMINERGIC: An adjective used to describe a chemical, a drug or a drug effect related to dopamine.

GABA (gamma-amino-butyric acid): A chemical found in the brain that may act to antagonize dopamine activity in specific brain regions. In Huntington’s disease, where dopamine activity may be excessive, there is evidence for a deficiency of GABA. In Parkinson’s disease, where there is already underactivity of dopamine, some patients find they walk worse when they take a GABA-like drug. However, GABA-mimetic drugs such as baclofen (Lioresal) can be helpful in controlling some side effects such as the dystonias or dyskinesias seen in patients being treated chronically for Parkinson’s disease.

NEUROTRANSMITTER: A specialized chemical produced in nerve cells that assists in transmitting information form one nerve cell to another. Examples of probable neurotransmitters include dopamine and acetylcholine.

SYNERGISM: The phenomenon whereby two chemicals or drugs work together to cause an effect that is usually greater as a whole than if the two individual effects were summed individually.

  • DRUGS USED FOR PARKINSON’S DISEASE AND OTHER NEUROLOGICAL DISORDERS **

AMANTADINE (Symmetrel): A drug which is believed to help parkinson’s patients by decreasing the rate of dopamine breakdown. Amantadine is a dopaminergic agonist which allows dopamine to remain in the synapse region to activate receptor sites.

ANTICHOLINERGIC DRUGS (Artane, Benedryl, Cogentin, etc.): These agents diminish the effect of acetylcholine, a neurotransmitter that in many ways counteracts the effect of dopamine in the brain. These agents are used as ancillary drugs in the treatment of the symptoms of Parkinson’s disease and their side effects include dry mouth, blurred vision, difficulty with urination and occasional personality changes.

BACLOFEN (Lioresal): An agent that presumably increases GABA activity. It has been used to help control some side effects of chronic dopaminergic therapy, especially dystonias.

BETA-BLOCKERS: Drugs which block one of the two types of receptors for neurotransmitter norepinephrine (noradrenaline). The major use of these drugs is in the treatment of hypertension and heart disease, but they are also frequently used in the treatment of benign, essential tremor. The best known of these is Inderal (propranolol).

CARBIDOPA: This drug prevents levodopa from being broken down by enzymes in the body and excreted before it reaches the brain. With carbidopa, a higher percentage of ingested levodopa can arrive at the brain and be converted to dopamine which acts at the striata receptor sites where it is needed. Carbidopa combined with levodopa is marketed as Sinemet and is presently the drug of choice for most patients.

CHOLINE: A natural compound that may be used by the body to make acetycholine. Increasing acetylcholine concentrations in the brain could possibly be useful in controlling Huntington’s disease, levodopa-induced dyskinesias, tardive dyskinesia and certain problems related to dementia. Increasing acetycholine concentration is hazardous to patients with Parkinson’s disease.

DEPRENYL: An inhibitor of the enzyme monoamine-oxidase type B. This enzyme normally acts to degrade dopamine so that it is no longer active to stimulate brain dopamine receptors. Deprenyl, by antagonizing this breakdown sequence, has been used in an attempt to prolong dopamine activity.

LECITHIN (Phosphatidylcholine): Like choline, this substance may be a dietary precursor to acetylcholine and may be useful in the conditions mentioned above, where choline is being studied.

LEVODOPA (L-dopa): A natural compound found in the body and brain that is converted into dopamine by special enzymes. When nerve cells die and no longer produce dopamine, levodopa may be given as a medication which is absorbed from the stomach and intestines into the blood stream and eventually passes to the brain where the special enzymes can convert it into dopamine.

NEUROLEPTIC DRUGS: This class of drugs is used for treating a wide variety of conditions and act as dopamine antagonists. They block post-synaptic dopaminergic receptor sites and will usually aggravate the symptoms of Parkinson’s disease. The phenothiazine drugs such as Triavil, Thorazine, Stelazine, Compazine and Prolixin are the largest class of neuroleptics.

  • CLINICAL TERMS **

ALZHEIMER’S DISEASE is a generative disorder of the brain. It usually begins in middle or late adult life and produces a progressive deterioration of mentation. While often attributed in ignorance to a hardening of the arteries, there is no known relationship between AD and ANY vascular disorder. While occasionally familial, in most instances it is not, and the cause remains entirely unknown. (For more information on this disorder, choose “Alzheimer” as your search term in the Rare Disease Database.)

AMYOTROPHIC LATERAL SCLEROSIS (ALS) is a degenerative disorder of the central nervous system (CNS) which involves the major motor pathway. The cause is unknown and the disease usually begins in middle or late adult life. The patients develop progressive weakness, spasticity and loss of muscle tissue. There is no known treatment; the disease significantly decreases life expectancy. (For more information on this disorder, choose “ALS” as your search term in the Rare Disease Database.)

BLEPHAROSPASM: Uncontrolled closure of the eyelids. These movements are seen in a variety of movement disorders including, at times, Parkinson’s disease. (For more information on this disorder, choose “Blepharospasm” as your search term in the Rare Disease Database.)

BRADYKINESIA: Often used interchangeably with akinesia, the term means a difficulty in initiating, or a lack of movement: it is one of the four hallmarks of parkinsonism.

CENTRAL NERVOUS SYSTEM: Consists of the brain and spinal cord with their nerves which control voluntary acts, consciousness and mental activities. (For information on central nervous system disorders available in the Rare Disease Database, choose “nervous” as your search term in the database.)

CHOREA: A movement abnormality that can be seen in many diseases. It is characterized by fidgety irregular movements of the extremities and trunk, and often involves the lip and facial muscles. Chorea can be seen as a reversible side effect of chronic dopaminergic therapy in patients with Parkinson’s disease, and it is symptomatic of Huntington’s disease and Sydenham’s chorea.

DRUG-INDUCED PARKINSONISM: In patients receiving neuroleptic drugs, the dopaminergic system is underactive because of drug-induced receptor site blockade. In patients receiving reserpine for hypertension (high blood pressure), the dopaminergic system is underactive because this drug depletes the brain of dopamine. All of these agents will cause parkinsonism that is usually reversible when the offending medication is stopped. Patients with drug-induced parkinsonism look the same as patients with Parkinson’s disease, but the cause and treatment of the two conditions are different.

DYSKINESIA: Abnormal, rapid, involuntary movement(s) most commonly appearing as protrusions of the tongue or mouthing movements of the lips, but which may involve any part of the body. Like the word parkinsonism, dyskinesia is a descriptive term, and may be due to many factors including levodopa-induced dyskinesias and tardive dyskinesia. Dyskinesias appear to relate to the dopaminergic system and may relate to altered sensitivity of receptor sites in the brain to neurotransmitters.

DYSTONIA is a motor disorder consisting of forceful, spasmodic twisting or jerking movements. It frequently worsens during motor activity or emotional stress, subsiding when the patient sleeps. Dystonic posture may occur as part of a neurologic disease or as a reaction to drug treatment or as a result of an injury or trauma. If confined to the muscles of the neck with onset occurring in middle life, it is usually called spasmodic torticollis. Present medical therapy is erratic and of limited clinical value. (For more information on this disorder, choose “Spasmodic Torticollis” as your search term in the Rare Disease Database.)

ESSENTIAL TREMOR (benign, familial tremor): This sort of tremor differs from the tremor of Parkinson’s disease in that it is usually minimal or not present at rest and is increased when the patient moves his hands, especially in writing. The handwriting of a patient with essential tremor is usually large and sloppy as opposed to the micrographic handwriting of a patient with Parkinson’s disease. Essential tremor is often associated with head-shaking and may also be associated with walking difficulties (titubation). These walking problems differ from those of parkinson’s patients who walk with their feet close together, while those with essential tremor may walk with their legs far apart (ataxia). Essential tremor occuring in families is termed specifically familial tremor. (For more information on this disorder, choose “Benign Essential Tremor Syndrome” as your search term in the Rare Disease Database.)

FESTINATION: A tendency to take shorter, quicker steps in walking. Like micrographia (handwriting becoming smaller in a sentence), it is a sign of Parkinson’s disease.

HUNTINGTON’S DISEASE is a degenerative disorder of the basal ganglia in which the striatum becomes shrunken. It is characterized by chronic, progressive motor disability including chorea and/or rigidity, plus mental deterioration terminating in dementia. Except for very rare mutations, the disease is inherited from an afflicted parent. (For more information this disorder, choose “Huntington” as your search term in the Rare Disease Database.)

IDIOPATHIC: Without known cause. There are two major types of Parkinson’s disease; the post-encephalitic variety associated with an attack of encephalitis, and the idiopathic variety, without apparent cause.

LEVODOPA-INDUCED DYSKINESIAS: Abnormal, involuntary movements which appear after patients have been treated for prolonged periods with dopaminergic agents. At early stages of the disorder these can often be alleviated by a reduction in the amount of drug taken. This side effect can be alleviated by a reduction in the amount of drug taken. This side effect differs from the “on-off” phenomenon and end-of-dose akinesia (see ON-OFF PHENOMENON below).

MEIGE’S SYNDROME occurs in middle to late adult life, of unknown cause, and consists of forceful blepharospasms and dystonic movements of the lower face. (For more information on this disorder, choose “Meige” as your search term in the Rare Disease Database.)

MYOCLONUS: An involuntary, lightning-like muscle contraction or jerk that is marked enough to move a joint. Only one limb may be involved or the whole body may jerk as though suddenly startled. This condition is seen in a variety of illnesses, but is also a normal phenomenon when people are falling asleep. Attempts to control abnormal myoclonus usually focus on influencing the serotonergic system with various agents. (For more information on this disorder, choose “Myoclonus” as your search term in the Rare Disease Database.)

NIGRO-STRIATAL DEGENERATION: Degeneration of the nerve pathways traveling from the substantia nigra to the striatum. These pathways are normally rich in dopamine and are the pathways that are diseased in Parkinson’s disease.

OLIVO-PONTO-CEREBELLAR DEGENERATION: A degenerative disease related to Parkinson’s disease but with other features in addition to parkinsonian signs and symptoms. The added problems include intention tremors and cerebellar ataxia. It is the occurrence of these other features which differentiate OPC from Parkinson’s disease.

ON-OFF PHENOMENON: A widely-occurring side effect of chronic levodopa therapy which is usually seen in patients who have had abnormal involuntary movements previously. Alternately dyskinetic and akinetic phases occur rapidly, literally within minutes, i.e., the patient will switch from satisfactory motility with some orofacial dyskinesias, to a rigid akinetic state without dyskinesias. The reappearance of the dyskinesias signals the end of the episode, which may last from a few minutes to an hour. In some patients, this phenomenon merges slowly into end-of-dose akinesia (the complete reemergence of the symptoms of Parkinson’s disease), which commonly occurs progressively earlier after each dose in patients on long-term levodopa therapy.

PARKINSONISM is a condition that is marked by four important hallmarks: resting tremor, akinesia (bradykinesia), rigidity, and a loss of postural reflexes (usually manifested by falling.) Parkinsonism may relate to decreasing activity of the striatal/dopaminergic system but be due to many factors: Parkinson’s disease (nigro-striatal degeneration), stiato-nigral degeneration and drug-induced parkinsonism are all examples of Parkinsonism, but each is due to a different problem. (For more information on this disorder, choose “Parkinson” as your search term in the Rare Disease Database.)

PROGRESSIVE SUPRANUCLEAR PALSY is a degenerative disease of the brain which shares many features with PD and is often confused with PD, since most patients have rigidity and akinesia, and in many, balance problems are a prominent feature. Unlike PD patients, those with PSP have progressive difficulty moving their eyes and also have a dystonia of the neck in which the neck arches backward. PSP does not respond as well as PD does to available medications. (For more information on this disorder, choose PSP as your search term in the Rare Disease Database.)

PSEUDO-BULBAR PALSY is a syndrome which is usually the result of multiple strokes (transient ischemic attacks or TIAs) or ALS. In this disorder the patient has severe difficulty in swallowing and talking. He often smiles, laughs or cries uncontrollably at inappropriate times. (For more information on this disorder, choose “ALS” as your search term in the Rare Disease Database.)

SHY-DRAGER SYNDROME is a condition in which the prominent features are abnormalities in motor function and failure of the autonomic motor system (that portion of the nervous system which controls blood pressure and bladder and bowel control). These patients have extremely low blood pressure when standing and often have parkinsonian symptoms as well. They are treated with antiparkinson medications plus drugs, diet or special garments to increase the blood pressure. (For more information on this disorder, choose “Shy” as your search term in the Rare Disease Database.)

STRIATO-NIGRAL DEGENERATION: Degeneration of the nerve pathways traveling from the striatum to the substantia nigra. Patients with this degeneration also appear parkinsonian, but have different responses to drug therapy than patients with the more common nigro-striatal disease.

TARDIVE DYSKINESIA is a movement disorder associated with long-term administration of neuroleptic drugs. The movements of tardive dyskinesia are similar in appearance to those of levodopa-induced dyskinesias, but the causes of the two conditions are different.

TOURETTE SYNDROME is a condition that begins in childhood and involves rapid abnormal involuntary movements (tics) and uncontrollable sounds. These sounds may be squeaks or peeps, or may be words, sentences or even involuntary swearing. Some individuals with these symptoms during childhood and adolescence may outgrow them, in which case the term “multiple tic of childhood” is used. If the disorder persists into adult life it is called TS. A similar clinical syndrome may be acquired in later life due to chronic use of psychotropic drugs (neuroleptics, antidepressants and amphetamines) or from encephalitis. (For more information on this disorder, choose “Tourette” as your search term in the Rare Disease Database.)