Methods of therapeutic cortical stimulation Méthodes de stimulation corticale thérapeutique

In the nineties, epidural cortical stimulation (ECS) of precentral region has been performed to treat drug-resistant neuropathic pain and repetitive transcranial magnetic stimulation (rTMS) of prefrontal region has shown antidepressant effects in episodes of major depression. These were among the first attempts to treat neurological or psychiatric disorders with cortical stimulation. Actually, a variety of invasive and noninvasive techniques of cortical stimulation could serve therapeutic purpose, including ECS, rTMS, but also transcranial electrical stimulation using pulsed currents (TCES) or direct currents (tDCS). This review presents the methods of therapeutic cortical stimulation that are currently applicable and some of their principles. In particular, it must be emphasized that the site(s) of action can be distant from the site of stimulation because axons with remote projections are more prone to be activated than local cell bodies. Hence, cortical stimulation may activate, inhibit or otherwise interfere with the activity of various cortico-subcortical networks, depending on stimulus frequency and intensity, current polarity, and the configuration of the induced electric field. Functional and clinical effects occur during or beyond the time of stimulation. The existence of after-effects relates to processes of synaptic plasticity induced by the stimulation. Cortical stimulation may also have neuroprotective effects against disease-related excitotoxic phenomena. Considering the multiple techniques and the various potential clinical indications, it is a challenge to determine the place of cortical stimulation in the treatment of neurological and psychiatric diseases, in particular by the side of deep brain stimulation. Résumé Au début des années 1990, la stimulation corticale a été proposée dans le traitement de diverses pathologies neurologiques ou psychiatriques résistant aux médicaments, à savoir : la stimulation corticale épidurale précentrale pour les douleurs neuropathiques et la stimulation magnétique transcrânienne répétitive préfrontale pour les épisodes dépressifs. En fait, dif-férentes techniques invasives et non-invasives de stimulation corticale pourraient être utilisées dans un but thérapeutique, parmi lesquelles la stimulation corticale épidurale et les stimula-tions transcrâniennes magnétiques, électriques et à courant continu. Cette revue présente les Stimulation corticale épidurale ; Stimulation électrique transcrânienne ; Stimulation magnétique transcrânienne ; Stimulation transcrânienne à courant continu méthodes de stimulation corticale thérapeutique qui sont actuellement applicables et certains de leurs principes. En particulier, dans le cadre de la stimulation corticale, il faut souligner que le(s) site(s) d'action peu(ven)t être distant(s) du site de stimulation car les axones se projetant sur des structures plus ou moins éloignées sont bien plus excitables que les corps cellulaires locaux. …