Enhancement of bilateral cortical somatosensory evoked potentials to intact forelimb stimulation following thoracic contusion spinal cord injury in rats

Faith A. Bazley, Anil Maybhate, Chuen Seng Tan, Nitish V. Thakor, Candace Kerr, Angelo H. All

Research output: Contribution to journalArticle

Abstract

The adult central nervous system is capable of significant reorganization and adaptation following neurotrauma. After a thoracic contusive spinal cord injury (SCI) neuropathways that innervate the cord below the epicenter of injury are damaged, with minimal prospects for functional recovery. In contrast, pathways above the site of injury remain intact and may undergo adaptive changes in response to injury. We used cortical somatosensory evoked potentials (SSEPs) to evaluate changes in intact forelimb pathways. Rats received a midline contusion SCI, unilateral contusion SCI, or laminectomy with no contusion at the T8 level and were monitored for 28 days post-injury. In the midline injury group, SSEPs recorded from the contralateral forelimb region of the primary somatosensory cortex were 59.7% (CI 34.7%, 84.8%; c2=21.9;dof=1;p=2.9×10-6) greater than the laminectomy group; SSEPs from the ipsilateral somatosensory cortex were 47.6% (CI 18.3%, 77%;c2=10.1;dof=1;p=0.001) greater. Activation of the ipsilateral somatosensory cortex was further supported by BOLD-fMRI, which showed increased oxygenation at the ipsilateral hemisphere at day seven post-injury. In the unilateral injury group, ipsilesional side was compared to the contralesional side. SSEPs on day 14 (148%; CI 111%, 185%) and day 21 (137%; CI 110%, 163%) for ipsilesional forelimb stimulation were significantly increased over baseline (100%). SSEPs recorded from the hindlimb sensory cortex upon ipsilesional stimulation were 33.9% (CI 14.3%, 53.4%; c2=11.6;dof=1;p.=0.0007) greater than contralesional stimulation. Therefore, these results demonstrate the ability of SSEPs to detect significant enhancements in the activation of forelimb sensory pathways following both midline and unilateral contusive SCI at T8. Reorganization of forelimb pathways may occur after thoracic SCI, which SSEPs can monitor to aid the development of future therapies.

Original languageEnglish (US)
Article number6807805
Pages (from-to)953-964
Number of pages12
JournalIEEE Transactions on Neural Systems and Rehabilitation Engineering
Volume22
Issue number5
DOIs
StatePublished - Sep 1 2014

Keywords

  • Contusion spinal cord injury
  • Cortical plasticity
  • Electrophysiology
  • Somatosensory evoked potentials
  • Unilateral spinal cord injury

ASJC Scopus subject areas

  • Internal Medicine
  • Neuroscience(all)
  • Biomedical Engineering

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