| central nervous system agents | A class of drugs producing both physiological and psychological effects through a variety of mechanisms. They can be divided into "specific" agents, e.g., affecting an identifiable molecular mechanism unique to target cells bearing receptors for that agent, and "non-specific" agents, those producing effects on different target cells and acting by diverse molecular mechanisms. Those with non-specific mechanisms are generally further classed according to whether they produce behavioural depression or stimulation. Those with specific mechanisms are classed by locus of action or specific therapeutic use. (12 Dec 1998) |
|---|---|
| central nervous system depressants | A very loosely defined group of drugs that tend to reduce the activity of the central nervous system. The major groups included here are ethyl alcohol, anaesthetics, hypnotics and sedatives, narcotics, and tranquillising agents (antipsychotics and antianxiety agents). (12 Dec 1998) |
| central nervous system infections | Diseases of the central nervous sytem collectively, caused by pathogenic organisms. (12 Dec 1998) |
| central nervous system neoplasms | Neoplasms located in the brain, spinal cord, or meninges. (12 Dec 1998) |
| central nervous system stimulants | A loosely defined group of drugs that tend to increase behavioural alertness, agitation, or excitation. They work by a variety of mechanisms, but usually not by direct excitation of neurons. The many drugs that have such actions as side effects to their main therapeutic use are not included here. (12 Dec 1998) |
| central neuritis | Inflammation of the nervous substance proper, the axons, and myelin. Synonym: axial neuritis, central neuritis. (05 Mar 2000) |
| central obesity | The deposition of obesity around the trunk sparing the limbs. (27 Sep 1997) |
| central ossifying fibroma | <tumour> A painless, slow-growing, expansile, sharply circumscribed benign fibro-osseus tumour of the jaws that is derived from cells of the periodontal ligament; presents initially as a radiolucency that becomes progressively more opaque as it matures. See: central cementifying fibroma. (05 Mar 2000) |
| central osteitis | <pathology> Inflammation of bone caused by a pyogenic organism. It may remain localised or may spread through the bone to involve the marrow, cortex, cancellous tissue and periosteum. Origin: Gr. Myelos = marrow (18 Nov 1997) |
| central palmar space | The more medial of the central palmar spaces, bounded medially by the hypothenar compartment; related distally to the synovial tendon sheaths of digits 3 and 4 and proximally to the common flexor sheath. Synonym: medial midpalmar space, middle palmar space. (05 Mar 2000) |
| central paralysis | Paralysis due to a lesion in the brain or spinal cord. (05 Mar 2000) |
| central pit | A depression in the centre of the macula retinae containing only cones and lacking blood vessels. Synonym: fovea centralis retinae, central pit. (05 Mar 2000) |
| central placenta previa | Placenta previa in which the placenta entirely covers the internal os of the cervix. Synonym: central placenta previa, total placenta previa. (05 Mar 2000) |
| central pneumonia | A form of pneumonia in which exudation is confined for a time to the central portion of a lobe or the hilar region. Synonym: core pneumonia. (05 Mar 2000) |
| central pontine myelinolysis | <neurology> A condition characterised by damage to the myelin (sheath) layer of nerve cells in the pons (brainstem). The destruction of myelin inhibits the conduction of a nerve impulse along a nerve cell. The most common cause for exacerbating this condition is a rapid correction of hyponatraemia (low blood sodium level). Some conditions such as Wernicke-Korsakoff syndrome and alcoholism can predispose to loss of myelin. Symptoms can include weakness, double vision, muscle spasms, speech difficulty, delirium, sleepiness, hallucinations, tremors and uncontrolled eye movements. An MRI scan of the brain can demonstrate the abnormality. A more slow controlled correction of serum sodium levels is necessary in these patients. There is no definitive treatment for the underlying disorder. (12 Jan 1998) |