Quantification of central motor conduction deficits in multiple sclerosis patients before and after treatment of acute exacerbation by methylprednisolone.
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.
Humm
A M
AM
Department of Neurology, University of Berne, Switzerland.
Z'Graggen
W J
WJ
Bühler
R
R
Magistris
M R
MR
Rösler
K M
KM
D000328:Adult; D004305:Dose-Response Relationship, Drug; D019054:Evoked Potentials, Motor / Q000187:drug effects / Q000502:physiology; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D007537:Isometric Contraction / Q000187:drug effects / Q000502:physiology; D008297:Male; D008775:Methylprednisolone / Q000009:adverse effects / Q000627:therapeutic use*; D008875:Middle Aged; D016472:Motor Neuron Disease / Q000188:drug therapy* / Q000503:physiopathology; D020528:Multiple Sclerosis, Chronic Progressive / Q000175:diagnosis / Q000188:drug therapy* / Q000503:physiopathology; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000175:diagnosis / Q000188:drug therapy* / Q000503:physiopathology; D018482:Muscle, Skeletal / Q000294:innervation; D009431:Neural Conduction / Q000187:drug effects* / Q000502:physiology; D009902:Optic Neuritis / Q000188:drug therapy / Q000503:physiopathology; D011712:Pyramidal Tracts / Q000187:drug effects / Q000503:physiopathology; D016896:Treatment Outcome
D008775:Methylprednisolone