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Relapses in multiple sclerosis: effects of high‐dose steroids on cortical excitability
Author(s) -
Ayache S. S.,
Créange A.,
Farhat W. H.,
Zouari H. G.,
Mylius V.,
Ahdab R.,
Abdellaoui M.,
Lefaucheur J.P.
Publication year - 2014
Publication title -
european journal of neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.881
H-Index - 124
eISSN - 1468-1331
pISSN - 1351-5101
DOI - 10.1111/ene.12356
Subject(s) - silent period , transcranial magnetic stimulation , medicine , multiple sclerosis , facilitation , remyelination , neuroscience , expanded disability status scale , motor cortex , stimulation , physical medicine and rehabilitation , psychology , central nervous system , myelin , psychiatry
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 ( ISI s), 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 GABA ergic inhibition and glutamatergic facilitation was in favour of weaker inhibition or stronger facilitation, which could lead to improving the motor performance in MS patients.