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Journal of Neurology, Neurosurgery, and Psychiatry logoLink to Journal of Neurology, Neurosurgery, and Psychiatry
. 1998 Jul;65(1):80–87. doi: 10.1136/jnnp.65.1.80

Responses of thenar muscles to transcranial magnetic stimulation of the motor cortex in patients with incomplete spinal cord injury

N Davey 1, H Smith 1, E Wells 1, D Maskill 1, G Savic 1, P Ellaway 1, H Frankel 1
PMCID: PMC2170166  PMID: 9667566

Abstract

OBJECTIVE—To investigate changes in electromyographic (EMG) responses to transcranial magnetic stimulation (TMS) of the motor cortex after incomplete spinal cord injury in humans.
METHODS—A group of 10 patients with incomplete spinal cord injury (motor level C3-C8) was compared with a group of 10 healthy control subjects. Surface EMG recordings were made from the thenar muscles. TMS was applied with a 9 cm circular stimulating coil centred over the vertex. The EMG responses to up to 50 magnetic stimuli were rectified and averaged.
RESULTS—Thresholds for compound motor evoked potentials (cMEPs) and suppression of voluntary contraction (SVC) elicited by TMS were higher (p<0.05) in the patient group. Latency of cMEPs was longer (p<0.05) in the patient group in both relaxed (controls 21.3 (SEM 0.5) ms; patients 27.7 (SEM 1.3) ms) and voluntarily contracted (controls 19.8 (SEM 0.5) ms; patients 27.6 (SEM 1.3) ms) muscles. The latency of SVC was longer (p<0.05) in the patients (51.8 (SEM 1.8) ms) than in the controls (33.4 (SEM 1.9) ms). The latency difference (SVC−cMEP) was longer in the patients (25.3 (SEM 2.4) ms) than in the controls (13.4 (SEM 1.6) ms).
CONCLUSION—The longer latency difference between cMEPs and SVC in the patients may reflect a weak or absent early component of cortical inhibition. Such a change may contribute to the restoration of useful motor function after incomplete spinal cord injury.



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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Ackermann H., Thomas C., Guschlbauer B., Dichgans J. Neurophysiological evaluation of sensorimotor functions of the leg: comparison of evoked cortical potentials following electrical and mechanical stimulation, long-latency muscle responses, and transcranial magnetic stimulation. J Neurol. 1992 Apr;239(4):218–222. doi: 10.1007/BF00839143. [DOI] [PubMed] [Google Scholar]
  2. Bawa P., Lemon R. N. Recruitment of motor units in response to transcranial magnetic stimulation in man. J Physiol. 1993 Nov;471:445–464. doi: 10.1113/jphysiol.1993.sp019909. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Bennett K. M., Lemon R. N. The influence of single monkey cortico-motoneuronal cells at different levels of activity in target muscles. J Physiol. 1994 Jun 1;477(Pt 2):291–307. doi: 10.1113/jphysiol.1994.sp020191. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Berardelli A., Inghilleri M., Cruccu G., Mercuri B., Manfredi M. Electrical and magnetic transcranial stimulation in patients with corticospinal damage due to stroke or motor neurone disease. Electroencephalogr Clin Neurophysiol. 1991 Oct;81(5):389–396. doi: 10.1016/0168-5597(91)90028-v. [DOI] [PubMed] [Google Scholar]
  5. Brasil-Neto J. P., Cohen L. G., Pascual-Leone A., Jabir F. K., Wall R. T., Hallett M. Rapid reversible modulation of human motor outputs after transient deafferentation of the forearm: a study with transcranial magnetic stimulation. Neurology. 1992 Jul;42(7):1302–1306. doi: 10.1212/wnl.42.7.1302. [DOI] [PubMed] [Google Scholar]
  6. Brouwer B., Bugaresti J., Ashby P. Changes in corticospinal facilitation of lower limb spinal motor neurons after spinal cord lesions. J Neurol Neurosurg Psychiatry. 1992 Jan;55(1):20–24. doi: 10.1136/jnnp.55.1.20. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Burke D., Hicks R. G., Stephen J. P. Corticospinal volleys evoked by anodal and cathodal stimulation of the human motor cortex. J Physiol. 1990 Jun;425:283–299. doi: 10.1113/jphysiol.1990.sp018103. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Chang C. W., Lien I. N. Estimate of motor conduction in human spinal cord: slowed conduction in spinal cord injury. Muscle Nerve. 1991 Oct;14(10):990–996. doi: 10.1002/mus.880141010. [DOI] [PubMed] [Google Scholar]
  9. Clarke C. E., Modarres-Sadeghi H., Twomey J. A., Burt A. A. Prognostic value of cortical magnetic stimulation in spinal cord injury. Paraplegia. 1994 Aug;32(8):554–560. doi: 10.1038/sc.1994.87. [DOI] [PubMed] [Google Scholar]
  10. Cohen L. G., Bandinelli S., Findley T. W., Hallett M. Motor reorganization after upper limb amputation in man. A study with focal magnetic stimulation. Brain. 1991 Feb;114(Pt 1B):615–627. doi: 10.1093/brain/114.1.615. [DOI] [PubMed] [Google Scholar]
  11. Colachis S. C., 3rd, Clinchot D. M. Autonomic hyperreflexia associated with recurrent cardiac arrest: case report. Spinal Cord. 1997 Apr;35(4):256–257. doi: 10.1038/sj.sc.3100359. [DOI] [PubMed] [Google Scholar]
  12. Davey N. J., Puri B. K., Lewis H. S., Lewis S. W., Ellaway P. H. Effects of antipsychotic medication on electromyographic responses to transcranial magnetic stimulation of the motor cortex in schizophrenia. J Neurol Neurosurg Psychiatry. 1997 Oct;63(4):468–473. doi: 10.1136/jnnp.63.4.468. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Davey N. J., Romaiguère P., Maskill D. W., Ellaway P. H. Suppression of voluntary motor activity revealed using transcranial magnetic stimulation of the motor cortex in man. J Physiol. 1994 Jun 1;477(Pt 2):223–235. doi: 10.1113/jphysiol.1994.sp020186. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Donoghue J. P., Sanes J. N. Organization of adult motor cortex representation patterns following neonatal forelimb nerve injury in rats. J Neurosci. 1988 Sep;8(9):3221–3232. doi: 10.1523/JNEUROSCI.08-09-03221.1988. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Donoghue J. P., Suner S., Sanes J. N. Dynamic organization of primary motor cortex output to target muscles in adult rats. II. Rapid reorganization following motor nerve lesions. Exp Brain Res. 1990;79(3):492–503. doi: 10.1007/BF00229319. [DOI] [PubMed] [Google Scholar]
  16. Edgley S. A., Eyre J. A., Lemon R. N., Miller S. Excitation of the corticospinal tract by electromagnetic and electrical stimulation of the scalp in the macaque monkey. J Physiol. 1990 Jun;425:301–320. doi: 10.1113/jphysiol.1990.sp018104. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Ferbert A., Priori A., Rothwell J. C., Day B. L., Colebatch J. G., Marsden C. D. Interhemispheric inhibition of the human motor cortex. J Physiol. 1992;453:525–546. doi: 10.1113/jphysiol.1992.sp019243. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Fuhr P., Cohen L. G., Dang N., Findley T. W., Haghighi S., Oro J., Hallett M. Physiological analysis of motor reorganization following lower limb amputation. Electroencephalogr Clin Neurophysiol. 1992 Feb;85(1):53–60. doi: 10.1016/0168-5597(92)90102-h. [DOI] [PubMed] [Google Scholar]
  19. Hall E. J., Flament D., Fraser C., Lemon R. N. Non-invasive brain stimulation reveals reorganized cortical outputs in amputees. Neurosci Lett. 1990 Aug 24;116(3):379–386. doi: 10.1016/0304-3940(90)90105-i. [DOI] [PubMed] [Google Scholar]
  20. Inghilleri M., Berardelli A., Marchetti P., Manfredi M. Effects of diazepam, baclofen and thiopental on the silent period evoked by transcranial magnetic stimulation in humans. Exp Brain Res. 1996 Jun;109(3):467–472. doi: 10.1007/BF00229631. [DOI] [PubMed] [Google Scholar]
  21. Kaneko K., Kawai S., Fuchigami Y., Shiraishi G., Ito T. Effect of stimulus intensity and voluntary contraction on corticospinal potentials following transcranial magnetic stimulation. J Neurol Sci. 1996 Jul;139(1):131–136. [PubMed] [Google Scholar]
  22. Kaplan J. E., Litchfield B., Rouault C., Lairmore M. D., Luo C. C., Williams L., Brew B. J., Price R. W., Janssen R., Stoneburner R. HTLV-I-associated myelopathy associated with blood transfusion in the United States: epidemiologic and molecular evidence linking donor and recipient. Neurology. 1991 Feb;41(2 ):192–197. doi: 10.1212/wnl.41.2_part_1.192. [DOI] [PubMed] [Google Scholar]
  23. Kujirai T., Caramia M. D., Rothwell J. C., Day B. L., Thompson P. D., Ferbert A., Wroe S., Asselman P., Marsden C. D. Corticocortical inhibition in human motor cortex. J Physiol. 1993 Nov;471:501–519. doi: 10.1113/jphysiol.1993.sp019912. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Levy W. J., Jr, Amassian V. E., Traad M., Cadwell J. Focal magnetic coil stimulation reveals motor cortical system reorganized in humans after traumatic quadriplegia. Brain Res. 1990 Feb 26;510(1):130–134. doi: 10.1016/0006-8993(90)90738-w. [DOI] [PubMed] [Google Scholar]
  25. Machida M., Yamada T., Krain L., Toriyama S., Yarita M. Magnetic stimulation: examination of motor function in patients with cervical spine or cord lesion. J Spinal Disord. 1991 Jun;4(2):123–130. [PubMed] [Google Scholar]
  26. Merzenich M. M., Jenkins W. M. Reorganization of cortical representations of the hand following alterations of skin inputs induced by nerve injury, skin island transfers, and experience. J Hand Ther. 1993 Apr-Jun;6(2):89–104. doi: 10.1016/s0894-1130(12)80290-0. [DOI] [PubMed] [Google Scholar]
  27. Milanov I. G. Mechanisms of baclofen action on spasticity. Acta Neurol Scand. 1992 May;85(5):305–310. doi: 10.1111/j.1600-0404.1992.tb04048.x. [DOI] [PubMed] [Google Scholar]
  28. Nakamura H., Kitagawa H., Kawaguchi Y., Tsuji H., Takano H., Nakatoh S. Intracortical facilitation and inhibition after paired magnetic stimulation in humans under anesthesia. Neurosci Lett. 1995 Oct 20;199(2):155–157. doi: 10.1016/0304-3940(95)12031-x. [DOI] [PubMed] [Google Scholar]
  29. Rausell E., Jones E. G. Extent of intracortical arborization of thalamocortical axons as a determinant of representational plasticity in monkey somatic sensory cortex. J Neurosci. 1995 Jun;15(6):4270–4288. doi: 10.1523/JNEUROSCI.15-06-04270.1995. [DOI] [PMC free article] [PubMed] [Google Scholar]
  30. Ridding M. C., Inzelberg R., Rothwell J. C. Changes in excitability of motor cortical circuitry in patients with Parkinson's disease. Ann Neurol. 1995 Feb;37(2):181–188. doi: 10.1002/ana.410370208. [DOI] [PubMed] [Google Scholar]
  31. Rossini P. M., Barker A. T., Berardelli A., Caramia M. D., Caruso G., Cracco R. Q., Dimitrijević M. R., Hallett M., Katayama Y., Lücking C. H. Non-invasive electrical and magnetic stimulation of the brain, spinal cord and roots: basic principles and procedures for routine clinical application. Report of an IFCN committee. Electroencephalogr Clin Neurophysiol. 1994 Aug;91(2):79–92. doi: 10.1016/0013-4694(94)90029-9. [DOI] [PubMed] [Google Scholar]
  32. Rossini P. M., Martino G., Narici L., Pasquarelli A., Peresson M., Pizzella V., Tecchio F., Torrioli G., Romani G. L. Short-term brain 'plasticity' in humans: transient finger representation changes in sensory cortex somatotopy following ischemic anesthesia. Brain Res. 1994 Apr 11;642(1-2):169–177. doi: 10.1016/0006-8993(94)90919-9. [DOI] [PubMed] [Google Scholar]
  33. Rothwell J. C., Thompson P. D., Day B. L., Boyd S., Marsden C. D. Stimulation of the human motor cortex through the scalp. Exp Physiol. 1991 Mar;76(2):159–200. doi: 10.1113/expphysiol.1991.sp003485. [DOI] [PubMed] [Google Scholar]
  34. Topka H., Cohen L. G., Cole R. A., Hallett M. Reorganization of corticospinal pathways following spinal cord injury. Neurology. 1991 Aug;41(8):1276–1283. doi: 10.1212/wnl.41.8.1276. [DOI] [PubMed] [Google Scholar]
  35. Wassermann E. M., Fuhr P., Cohen L. G., Hallett M. Effects of transcranial magnetic stimulation on ipsilateral muscles. Neurology. 1991 Nov;41(11):1795–1799. doi: 10.1212/wnl.41.11.1795. [DOI] [PubMed] [Google Scholar]
  36. Widmer C. G., Lund J. P. Evidence that peaks in EMG averages can sometimes be caused by inhibition of motoneurons. J Neurophysiol. 1989 Jul;62(1):212–219. doi: 10.1152/jn.1989.62.1.212. [DOI] [PubMed] [Google Scholar]
  37. Ziemann U., Lönnecker S., Steinhoff B. J., Paulus W. Effects of antiepileptic drugs on motor cortex excitability in humans: a transcranial magnetic stimulation study. Ann Neurol. 1996 Sep;40(3):367–378. doi: 10.1002/ana.410400306. [DOI] [PubMed] [Google Scholar]

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