Magnetic stimulation of the cauda equina in the spinal canal with a flat, large round coil

J Neurol Sci. 2009 Sep 15;284(1-2):46-51. doi: 10.1016/j.jns.2009.04.003. Epub 2009 May 1.

Abstract

Magnetic round coil stimulation over the spinal enlargement activates the spinal nerves at the neuro-foramina level. However, activation of the cauda equina in the spinal canal has never been described in the literature. This study, for which 40 healthy subjects were recruited, activated the cauda equina using a round 20-cm-diameter coil designated as a Magnetic Augmented Translumbosacral Stimulation (MATS) coil. Magnetic stimulation placing the edge of the coil over the L1 and L3 spinous processes elicited compound muscle action potentials (CMAPs) from the abductor hallucis muscle. The CMAPs were compared with those elicited through high-voltage electrical stimulation. The CMAP latencies to L1 level MATS coil stimulation were not significantly different from those evoked by electrical stimulation at the same level. The CMAP latencies to L3 level MATS coil stimulation were varied in each subject. In fact, the L1 level MATS coil stimulation is considered to activate the cauda equina at the root exit site from the conus medullaris; the L3 level MATS coil stimulation activates some mid-part of the cauda equina or the distal cauda equina by spreading current. The MATS coil facilitates evaluation of spinal nerve conduction in the cauda equina.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials
  • Cauda Equina / physiology*
  • Cauda Equina / physiopathology
  • Diagnostic Techniques, Neurological / instrumentation*
  • Electric Stimulation
  • Evoked Potentials, Motor
  • Female
  • Humans
  • Low Back Pain / etiology
  • Low Back Pain / physiopathology
  • Lumbar Vertebrae
  • Lymphoma, Non-Hodgkin / diagnosis
  • Lymphoma, Non-Hodgkin / physiopathology
  • Magnetics* / instrumentation
  • Male
  • Middle Aged
  • Neural Conduction
  • Peripheral Nervous System Neoplasms / diagnosis
  • Peripheral Nervous System Neoplasms / physiopathology
  • Reaction Time
  • Reference Values
  • Spinal Canal
  • Tibial Nerve / physiology