Relapses in multiple sclerosis: effects of high-dose steroids on cortical excitability

Authors

  • S. S. Ayache,

    1. EA 4391, Faculté de Médecine de Créteil, Université Paris Est Créteil, Créteil, France
    2. Service de Physiologie, Explorations Fonctionnelles, Hôpital Henri-Mondor, AP-HP, Créteil, France
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  • A. Créange,

    1. EA 4391, Faculté de Médecine de Créteil, Université Paris Est Créteil, Créteil, France
    2. Service de Neurologie, Hôpital Henri-Mondor, AP-HP, Créteil, France
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  • W. H. Farhat,

    1. EA 4391, Faculté de Médecine de Créteil, Université Paris Est Créteil, Créteil, France
    2. Service de Physiologie, Explorations Fonctionnelles, Hôpital Henri-Mondor, AP-HP, Créteil, France
    3. Service de Neurologie, Hôpital Henri-Mondor, AP-HP, Créteil, France
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  • H. G. Zouari,

    1. EA 4391, Faculté de Médecine de Créteil, Université Paris Est Créteil, Créteil, France
    2. Service de Physiologie, Explorations Fonctionnelles, Hôpital Henri-Mondor, AP-HP, Créteil, France
    3. CHU Habib Bourguiba, Service d'Explorations Fonctionnelles, Sfax, Tunisie
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  • V. Mylius,

    1. EA 4391, Faculté de Médecine de Créteil, Université Paris Est Créteil, Créteil, France
    2. Service de Physiologie, Explorations Fonctionnelles, Hôpital Henri-Mondor, AP-HP, Créteil, France
    3. Department of Neurology, Philipps University Marburg, Marburg, Germany
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  • R. Ahdab,

    1. EA 4391, Faculté de Médecine de Créteil, Université Paris Est Créteil, Créteil, France
    2. Service de Physiologie, Explorations Fonctionnelles, Hôpital Henri-Mondor, AP-HP, Créteil, France
    3. Neuroscience Department, University Medical Center Rizk Hospital, Beirut, Lebanon
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  • M. Abdellaoui,

    1. Service de Neurologie, Hôpital Henri-Mondor, AP-HP, Créteil, France
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  • J.-P. Lefaucheur

    Corresponding author
    1. EA 4391, Faculté de Médecine de Créteil, Université Paris Est Créteil, Créteil, France
    2. Service de Physiologie, Explorations Fonctionnelles, Hôpital Henri-Mondor, AP-HP, Créteil, France
    • Correspondence: J.-P. Lefaucheur, Service Physiologie, Explorations Fonctionnelles, Hôpital Henri Mondor, 51 avenue du Maréchal de Lattre de Tassigny, 94010 Créteil Cedex, France (tel.: + 33 1 4981 2694; fax: + 33 1 4981 4660; e-mail: jean-pascal.lefaucheur@hmn.aphp.fr).

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Abstract

Background and purpose

High-dose steroid administration is the usual treatment of multiple sclerosis (MS) relapse, but it remains to determine whether this treatment may act by changing the excitability of cortical circuitry.

Methods

The functional cortical effects of high-dose steroids in 21 MS patients before and after 3 days of intravenous administration of methylprednisolone (1 g/day) for the treatment of MS relapse were studied. Investigations included various clinical scales [Kurtzke Functional System Scale (KFSS), Expanded Disability Status Scale and Fatigue Severity Scale, 10-m walk] and transcranial magnetic stimulation (TMS) tests of cortical excitability [resting motor threshold, recruitment curve of motor evoked potentials, short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF) at various interstimuli intervals (ISIs), cortical silent period and interhemispheric inhibition].

Results

Following steroid administration, clinical improvement was significant for the KFSS pyramidal (motor) and total scores, whilst TMS showed a reduction of SICI (mean and maximum values) and an increase of ICF at 10 ms ISI.

Conclusions

Very rapid functional changes in the excitability of cortical circuits involved in motor control can be induced by steroids, before any process of remyelination or axonal regeneration has time to occur. The net effect of steroids on the balance between intracortical GABAergic inhibition and glutamatergic facilitation was in favour of weaker inhibition or stronger facilitation, which could lead to improving the motor performance in MS patients.

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