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Extrapyramidal System/Symptoms/Signs Should Be Retired Abhishek Lenka, MD, PhD, and Joseph Jankovic, MD Neurology: Clinical Practice 2024;14:e200308. doi:10.1212/CPJ.$7.99
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Extrapyramidal System/Symptoms/Signs Should Be Retired Abhishek Lenka, MD, PhD, and Joseph Jankovic, MD Neurology: Clinical Practice 2024;14:e200308. doi:10.1212/CPJ.
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Extrapyramidal System/Symptoms/Signs Should
Be Retired
Abhishek Lenka, MD, PhD, and Joseph Jankovic, MD
Neurology: Clinical Practice 2024;14:e200308. doi:10.1212/CPJ.
Extrapyramidal System/Symptoms/Signs Should
Be Retired
Abhishek Lenka, MD, PhD, and Joseph Jankovic, MD Correspondence
Dr. Jankovic
Neurology: Clinical Practice 2024;14:e200308. doi:10.1212/CPJ.0000000000200308 josephj@bcm.edu
Abstract
The term “extrapyramidal system/symptoms/signs” and the acronym “EPS” have been
abundantly used in neurology and psychiatry literature for more than a century. However, EPS
has been increasingly criticized, especially by movement disorder neurologists, for its lack of
clinical, anatomical, and physiologic definition. Contrary to traditional assumptions, pyramidal
and extrapyramidal systems are not mutually exclusive. The acronym EPS, commonly used to
denote drug-induced movement disorders, lacks specificity in conveying the nature and severity
of these and other movement disorders. Consequently, we propose that the term is retired from
scientific literature and that clinicians use specific phenomenologic descriptors for the various
hypokinetc and hyperkinetic movement disorders.
Introduction
The term “extrapyramidal system/symptoms/signs” (EPS) has been extensively used in psy-
chiatric and neurologic literature spanning several decades. A PubMed search using the keyword
“extrapyramidal” revealed consistent usage in approximately 250 publications annually over the
last 2 decades, albeit with a subtle decrease in recent years. Despite its traditional use, this term has
never been adequately defined and has been increasingly criticized for many diverse reasons.1,2
This article revisits the key historical underpinnings of the term “extrapyramidal,” reassesses its
use as a descriptor of motor or movement disorders, and underscores the reasons for advocating
its discontinuation in both literature and clinical practice.
The History of “Extrapyramidal System”
Downloaded from https://www.neurology.org by Boston University on 16 May 2024
Johann Prus coined the term “extrapyramidal” in 1898, while describing his transectional
experiments in dogs speculating on the existence of a motor pathway crucial for dual motor
control outside the pyramidal tracts.3 His major interest was in exploring the possibility that
pyramidal tracts were responsible in transmitting experimentally induced epileptic activity
from the cortex to the spinal cord. However, even after transecting pyramidal tracts of dogs in
multiple anatomical points (internal capsule, peduncle, pons, pyramid, and spinal cord)
unilaterally as well as bilaterally, he observed that the epileptic activities still propagated to the
muscles. He wrote, “In view of the fact that bilateral transection of the pyramidal tracts does
not prevent the appearance of bilateral epileptic attacks, i.e., the transmission of excitation
from the cortex to the muscles, it is established beyond doubt that in the case of transection of
the pyramidal tracts the pathways by means of which transmission of cortical epilepsy is
effected must lie outside the pyramidal tracts and outside the so-called pontine tracts. To
distinguish these apparently motor pathways from pyramidal and pontine tracts we shall call
them extrapyramidal tracts.”3 Later, Prus made several incisions in the midbrain tegmentum at
the level of the posterior quadrigeminal plate avoiding the pyramidal and corticopontine
tracts and that resulted in cessation of epileptic activities. He postulated, “conduction of
cortical epilepsy takes place via centrifugal motor pathways which lie outside the pyramidal, as
Parkinson’s Disease Center and Movement Disorders Clinic, Department of Neurology, Baylor College of Medicine, Houston, TX
Funding information and disclosures are provided at the end of the article. Full disclosure form information provided by the authors is available with the full text of this article at
Neurology.org/cp.
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