Axonal Morphometric Correlates of Evoked Potentials in Experimental Spinal Cord Injury

  • Andrew R. Blight
  • Wise Young
Part of the Neurotrauma book series (NT)


Cortical somatosensory-evoked potentials recorded at a succession of intervals after contusion injury of the cat spinal cord were compared with the numbers of axons surviving in transverse sections of the lesion at 3 months postinjury. In a sample of 25 animals, with injuries varying from ca.87% to 99% loss of myelinated axons in the white matter, there was a significant correlation between chronic axonal survival and the amplitude of the SEP recorded from 30 min to 1 day postinjury. There was little or no correlation between axon numbers and SEPs recorded at 3 months, within this narrow but crucial range of injury intensity. Robust, relatively normal waveforms could be obtained from animals with as few as 2% of the original axon population surviving at the lesion site, and from animals in which all the surviving axons in the dorsal columns were restricted to the outer 100–200 um of tissue. In other cases, repeatable SEPs could not be recorded from animals with >5% survival of axons. SEPs were lost immediately after contusion injury, but partially recovered within the first 4 hours in ca.30% of cases. There was a secondary severe reduction of SEP amplitude within the first day in most examples of early recovery. Most of the final recovery of chronic SEP amplitude occurred within 2–4 weeks.

SEPs from chronic injuries are useful indicators of conduction in spinal cord sensory tracts, though their amplitude cannot be interpreted as a measurement of axonal survival. Acute recovery of the SEP is predictive of chronic functional improvement and indicative of significant axonal survival. Reduction of SEP amplitude is a much more sensitive indicator of acute axonal distress than of chronic axonal loss.


Spinal Cord Injury Myelinated Axon Dorsal Column Secondary Loss Contusion Injury 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    Allen, A.R.: Surgery of experimental lesion of spinal cord equivalent to crush injury of fracture dislocation of spinal column: a preliminary report. J. Am. Med. Assn. 57:878–880, 1911.CrossRefGoogle Scholar
  2. 2.
    Alpsan, D.: The effect of the selective activation of different peripheral nerve fiber groups on the somatosensory-evoked potentials in the cat. Electroen-cephalogr. Clin. Neurophysiol. 51:589–598, 1981.CrossRefGoogle Scholar
  3. 3.
    Berenstein, A., Young, W., Ransohoff, J., Benjamin, V. and Merkin, H.: Somatosensory-evoked potentials (SEP) during spinal angiography and therapeutic transvascular embolization. J. Neurosurg. 60:777–785, 1983.Google Scholar
  4. 4.
    Blight, A.R.: Cellular morphology of chronic spinal cord injury in the cat: analysis of myelinated axons by line sampling. Neuroscience 10:521–543, 1983a.PubMedCrossRefGoogle Scholar
  5. 5.
    Blight, A.R.: Axonal physiology of chronic spinal cord injury in the cat: intracellular recording in vitro. Neuroscience 10:1471–1486 1983b.PubMedCrossRefGoogle Scholar
  6. 6.
    Blight, A.R.: Delayed demyelination and macrophage invasion: a candidate for “secondary” cell damage in spinal cord injury. Cen. Nerv. Syst. Trauma 2:299–315, 1985.Google Scholar
  7. 7.
    Blight, A.R.: Motor evoked potentials in CNS trauma. Cen. Nerv. Syst. Trauma 3:207–214, 1986.Google Scholar
  8. 8.
    Blight, A.R.: Mechanical aspects of experimental spinal cord trauma. J. Amer. Paraplegia Soc, in press, 1988.Google Scholar
  9. 9.
    Blight, A.R. and De Crescito, V.: Morphometric analysis of experimental spinal cord injury in the cat: the relation of injury intensity to survival of myelinated axons. Neuroscience 19:321–341, 1986.PubMedCrossRefGoogle Scholar
  10. 10.
    Blight, A.R. and Gruner, J.A.: Augmentation by 4-aminopyridine of vestibulospinal free fall responses in chronic spinal-injured cats. J. Neurol. Sci. 82:145–159, 1987.PubMedCrossRefGoogle Scholar
  11. 11.
    Carpenter, M.B., Stein, B.M. and Shriver, J.E.: Central projections of spinal dorsal roots in the monkey. II, Lower thoracic, lumbosacral and coccygeal dorsal roots. Am. J. Anat. 123:75–118, 1968.PubMedCrossRefGoogle Scholar
  12. 12.
    Cohen, A.R., Young, W. and Ransohoff, J.: Intraspinal localization of somatosensory-evoked potential. Neurosurgery 9:157–162, 1981.PubMedCrossRefGoogle Scholar
  13. 13.
    D’Angelo, C.M., Van Gilder, J.C. and Taub, A.: Evoked cortical potentials in experimental spinal cord trauma. J. Neurosurg. 38:332–336, 1973.PubMedCrossRefGoogle Scholar
  14. 14.
    Dorfman, L.J., Perkash, I., Bosley, T.M. and Cummins, K.L.: Use of cerebral evoked potentials to evaluate spinal somatosensory function in patients with traumatic and surgical myelopathies. J. Neurosurg. 52:654–660.Google Scholar
  15. 15.
    Gardner, E.P., Hamalainen, H.A., Warren, S., Davis, J. and Young, W.: Somatosensory-evoked potentials (SEPs) and cortical single unit responses elicited by mechanical tactile stimuli in awake monkeys. Electroen-cephalogr. Clin. Neurophysiol. 58:537–552, 1984.CrossRefGoogle Scholar
  16. 16.
    Martin, H.F., Katz, S. and Blackburn, J.G.: Effects of spinal cord lesions on somatic evoked potentials altered by interactions between afferent inputs. Electroenceph. Clin. Neurophysiol. 50:186–195, 1980.PubMedCrossRefGoogle Scholar
  17. 17.
    Martin, S.H. and Bloedel, J.R.: Evaluation of experimental spinal cord injury using cortical evoked potentials. J. Neurosurg. 39:75–81, 1973.PubMedCrossRefGoogle Scholar
  18. 18.
    Perot, P.L. and Vera, C.L.: Scalp-recorded somatosensory-evoked potentials to stimulation of nerves in the lower extremities and evaluation of patients with spinal cord trauma. Ann. N.Y. Acad. Sci. 388:359–368, 1982.PubMedCrossRefGoogle Scholar
  19. 19.
    Rowed, D.W., McLean, J.A.G., and Tator, C.H.: Somatosensory-evoked potentials in acute spinal cord injury: Prognostic value. Surg. Neurol. 9:203–210, 1978.PubMedGoogle Scholar
  20. 20.
    Schramm, J.: Spinal cord monitoring: Current status and new developments. Cen. Nerv. Syst. Trauma 2:207–227, 1985.Google Scholar
  21. 21.
    Shriver, J.E., Stein, B.M. and Carpenter, M.B.: Central projections of spinal dorsal roots in the monkey I. Cervical and upper thoracic dorsal roots. Am. J. Anat. 123:27–74, 1968.PubMedCrossRefGoogle Scholar
  22. 22.
    Simpson, R.K. Jr., Blackburn, J.G., Martin, H.F. III, and Katz, S.: Peripheral nerve fiber and spinal cord pathway contributions to the somatosensory-evoked potential. Exp. Neurol. 73:700–715, 1981.PubMedCrossRefGoogle Scholar
  23. 23.
    Walker, A.E. and Weaver, T.A. Jr.: The topical organization and termination of the fibers of the posterior columns in Macaca mulatta. J. Comp. Neurol. 76:145–158, 1942.CrossRefGoogle Scholar
  24. 24.
    Whitsel, B.L., Petrucelli, L.M., Sapiro, G. and Ha, H.: Fiber sorting in the fasciculus gracilis of squirrel monkeys. Exp. Neurol. 29:227–242, 1970.PubMedCrossRefGoogle Scholar
  25. 25.
    Young, W.: Correlation of somatosensory-evoked potentials and neurological findings in spinal cord. In: Tator, C.H. (ed) Early Management of Acute Spinal Cord Injury. Raven Press, New York, pp. 153–165, 1982.Google Scholar
  26. 26.
    Young, W.: Somatosensory-evoked potentials (SEPs) in spinal cord injury. In: J. Schramm and S.J. Jones (Eds.), Spinal Cord Monitoring, Springer Verlag, Berlin, pp. 127–142, 1985.CrossRefGoogle Scholar
  27. 27.
    Young, W.: Blood flow, metabolic and neurophysiological mechanisms in spinal cord injury. In Becker, D. and Povlishock, J. (Eds) CNS Trauma Status Report. NIH/NINCDS, William Byrd Press, Virginia, pp. 463–473, 1985.Google Scholar
  28. 28.
    Young, W., Cohen, A.R., Hunt, C.D. and Ransohoff, J.: Acute physiological effects of ultrasonic vibrations on nervous tissue. Neurosurgery 8:689–694, 1981.PubMedCrossRefGoogle Scholar
  29. 29.
    Young, W. and Koreh, I.: Potassium and calcium changes injured spinal cords. Brain Res. 365:42–53, 1986.PubMedCrossRefGoogle Scholar
  30. 30.
    Young, W., Koreh, I. and Lindsay, A.: Effect of sympathectomy on extracellular potassium ionic activity and blood flow in experimental spinal cord contusion. Brain Res. 253:115–124, 1982.PubMedCrossRefGoogle Scholar
  31. 31.
    Ziganow, S.: Neurometric evaluation of the cortical somatosensory-evoked potential in acute incomplete spinal cord injuries. Electroencephalogr. Clin. Neurophysiol. 65:86–93, 1986.PubMedCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 1990

Authors and Affiliations

  • Andrew R. Blight
    • 1
  • Wise Young
    • 1
  1. 1.Departments of Neurosurgery and Physiology and BiophysicsNYU Medical CenterNew YorkUSA

Personalised recommendations