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Quantification of central motor conduction deficits in multiple sclerosis patients before and after treatment of acute exacerbation by methylprednisolone
  1. A M Humm1,
  2. W J Z’Graggen1,
  3. R Bühler1,
  4. M R Magistris2,
  5. K M Rösler1
  1. 1Department of Neurology, University of Berne, Berne, Switzerland
  2. 2Department of Neurology, University of Geneva, Geneva, Switzerland
  1. Correspondence to:
 Professor K M Rösler
 Department of Neurology, Inselspital, CH-3010 Bern, Switzerland; kai-michael.roesler{at}


Objective: To compare the effects of intravenous methylprednisolone (IVMP) in patients with relapsing-remitting (RR-MS), secondary progressive (SP-MS), and primary progressive multiple sclerosis (PP-MS).

Methods: Clinical and neurophysiological follow up was undertaken in 24 RR-MS, eight SP-MS, and nine PP-MS patients receiving Solu-Medrol 500 mg/d over five days for exacerbations involving the motor system. Motor evoked potentials (MEPs) were used to measure central motor conduction time (CMCT) and the triple stimulation technique (TST) was applied to assess conduction deficits. The TST allows accurate quantification of the number of conducting central motor neurones, expressed by the TST amplitude ratio.

Results: There was a significant increase in TST amplitude ratio in RR-MS (p<0.001) and SP-MS patients (p<0.02) at day 5, paralleling an increase in muscle force. TST amplitude ratio and muscle force remained stable at two months. In PP-MS, TST amplitude ratio and muscle force did not change. CMCT did not change significantly in any of the three groups.

Conclusions: In RR-MS and SP-MS, IVMP is followed by a prompt increase in conducting central motor neurones paralleled by improvement in muscle force, which most probably reflects partial resolution of central conduction block. The lack of similar clinical and neurophysiological changes in PP-MS corroborates previous clinical reports on limited IVMP efficacy in this patient group and points to pathophysiological differences underlying exacerbations in PP-MS.

  • CMCT, central motor conduction time
  • EDSS, extended disability scale score
  • IVMP, intravenous methylprednisolone
  • MEP, motor evoked potential
  • PP-MS, primary progressive multiple sclerosis
  • RR-MS, relapsing-remitting multiple sclerosis
  • SP-MS, secondary progressive multiple sclerosis
  • TMS, transcranial magnetic stimulation
  • TST, triple stimulation technique
  • multiple sclerosis
  • steroid treatment
  • transcranial magnetic stimulation
  • triple stimulation technique

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  • Published Online First 20 September 2005

  • Competing interests: none declared