A critical reappraisal of corticospinal tract somatotopy and its role in traumatic cervical spinal cord syndromes

Allan D. Levi, Jan M. Schwab

Research output: Contribution to journalReview articlepeer-review

Abstract

The corticospinal tract (CST) is the preeminent voluntary motor pathway that controls human movements. Consequently, long-standing interest has focused on CST location and function in order to understand both loss and recovery of neurological function after incomplete cervical spinal cord injury, such as traumatic central cord syndrome. The hallmark clinical finding is paresis of the hands and upper-extremity function with retention of lower-extremity movements, which has been attributed to injury and the sparing of specific CST fibers. In contrast to historical concepts that proposed somatotopic (laminar) CST organization, the current narrative summarizes the accumulated evidence that 1) there is no somatotopic organization of the corticospinal tract within the spinal cord in humans and 2) the CST is critically important for hand function. The evidence includes data from 1) tract-tracing studies of the central nervous system and in vivo MRI studies of both humans and nonhuman primates, 2) selective ablative studies of the CST in primates, 3) evolutionary assessments of the CST in mammals, and 4) neuropathological examinations of patients after incomplete cervical spinal cord injury involving the CST and prominent arm and hand dysfunction. Acute traumatic central cord syndrome is characterized by prominent upper-extremity dysfunction, which has been falsely predicated on pinpoint injury to an assumed CST layer that specifically innervates the hand muscles. Given the evidence surveyed herein, the pathophysiological mechanism is most likely related to diffuse injury to the CST that plays a critically important role in hand function.

Original languageEnglish (US)
Pages (from-to)653-659
Number of pages7
JournalJournal of Neurosurgery: Spine
Volume36
Issue number4
DOIs
StatePublished - Apr 2022
Externally publishedYes

Keywords

  • central cord syndrome
  • corticospinal tract
  • human
  • somatotopic localization
  • spinal cord injury
  • trauma

ASJC Scopus subject areas

  • Surgery
  • Neurology
  • Clinical Neurology

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