Extrapyramidal System

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extrapyramidal system

[¦ek·strə‚pir·ə′mid·əl ′sis·təm]
Descending tracts of nerve fibers arising in the cortex and subcortical motor areas of the brain.

Extrapyramidal System


a group of brain structures in the hemispheres and brainstem involved in the central control of movements without the participation of the corticospinal, or pyramidal, system.

From the standpoint of evolution the extrapyramidal system is the most ancient system of motor control. It consists of the basal ganglia, red and interstitial nuclei, tectum, substantia nigra, reticular formation of pons varolii and medulla oblongata, nuclei of the vestibular system, and cerebellum. Some structures of the extrapyramidal system do not proceed directly to the spinal motor centers. Others are connected by conducting pathways to the segmental levels of the spinal cord, where they serve as an essential switching station for impulses traveling from the brain to moto-neurons. The impulses that travel along the fibers of the extrapyramidal system can reach the motoneurons through direct mono-synaptic connections or by switching in the various interneurons of the spinal cord.

The extrapyramidal system plays an important role in the coordination of movements, locomotion, and maintenance of posture and muscle tone. It is closely associated with the control of truncal muscles and proximal portions of the limbs. It is also involved in emotional manifestations, for example, laughing and crying. Injury to the pyramidal system decreases muscle tone and impairs motor functions (causing, for example, hyperkinesia and parkinsonism).


Kostiuk, P. G. Struktura i funktsiia niskhodiashchikh sistem spinnogo mozga. Leningrad, 1973.
Shapovalov, A. I. Neirony i sinapsy supraspinal’nykh motornykh sistem. Leningrad, 1975.


References in periodicals archive ?
1) Clinical features of this syndrome include high fever, extrapyramidal symptoms, and dysfunction in autonomic system such as unstable blood pressure, cardiac arrhythmia, dyspnea, sweating and urinary incontinence.
pneumonia, systemic infection) and untreated or inadequately treated extrapyramidal signs and symptoms (EPS).
The study is among the first to examine the link between extrapyramidal signs and dementia other than Alzheimer's disease, said Woojae Myung, MD, of Sungkyunkwan University School of Medicine in Seoul, South Korea, and his associates.
Both of them did not have any other extrapyramidal or other behavioural disturbances except stimming till the last follow-up (7 years in first child and 2 years in second child.
Aripiprazole###15-30###Lesser propensity to cause sedation, extrapyramidal side effects
The potential risk factors associated with the development of TD were reported as the presence of a past medical history of extrapyramidal symptoms, diabetes mellitus, affective disorders, female gender older age, and long-term therapy with neuroleptics at higher dosages (9).
Extrapyramidal symptoms (EPS) observed during the 6-week LATUDA monotherapy study included akathisia (noted for 8%, 11%, and 2% of patients in the LATUDA 20-60 mg, LATUDA 80-120 mg, and placebo groups, respectively), dystonia (0%, 2%, and 0%), parkinsonism (5%, 8%, and 2%), and restlessness (0%, 3%, and <1%).
Topics cover include: Various forms of cortical dysfunctions, such as seizures, disconnection syndrome, coma, and dementia; The role of prefrontal cortex in behavior and attention, introducing the topic of autism; Up-to-date information on the auditory, vestibular, gustatory, and limbic systems; The neurochemistry of the limbic system, memory and associated disorders, and the structural and neuronal circuitry of the hippocampal gyrus; Structural organization and associated pathways of the extrapyramidal system, demonstrating the neurochemical basis of movement disorders, and more.
Typical antipsychotics are associated with causing more extrapyramidal side effects.
During the first week of treatment her dosage was increased to 10 mg/d but at this dose she experienced akathisia and other extrapyramidal symptoms.
This edition has updates to antipsychotic dosages; restructured information on antipsychotic-induced extrapyramidal side effects and their management; more on dosing recommendations for patients with renal or hepatic impairment; pharmacogenomics information for dementia drugs; new drugs and preparations, such as Forfivo, Gralise, Horizant, and Trokendi XR; more on vilazodone; the addition of synthetic cannabinoids to the drugs of abuse; updates on the psychotropic usage of natural health products; and patient handouts.
1) However, the sign is pathognomonic of WD, being the only MRI feature that distinguishes WD from other early onset extrapyramidal disorders.