BACKGROUND AND OBJECTIVES

1. LPMP U894 Institut national de la santé et de la recherche médicale Poster 18-019 Theta-Burst Repetitive Transcranial Magnetic Stimulation of The Motor Cortex Improves Obsessive Compulsive Disorder: Preliminary findings of an open-label study A. Radtchenko¹, M.A. Gorsane², M. Soufia², C. Benamor², H. Benbetka³, Q. Debray¹, S Kindynis¹, B Granger¹, B. Gueguen³, M.O. Krebs², F.J. Baylé², A. Galinowski² ¹Psychiatric Department, Corentin Celton Hospital, Issy-les Moulineaux, France ²Psychiatric Department SHU, Sainte-Anne Hospital, Paris, France INSERM, Pathophysiology of psychiatric diseases, U894, Paris, France ; University Paris Descartes, Paris, France ³Neurophysiologic Department, Sainte-Anne Hospital, Paris, France Hôpital CORENTIN CELTON BACKGROUND AND OBJECTIVES • Few studies focused on rTMS in the treatment of obsessive-compulsive disorder (OCD). Fast or low-frequency rTMS failed to produce significant improvement. We know only one positive study using left DLPFC rapid (10 Hz) or right DLPFC low-frequency (1 Hz) rTMS for patients with drug-resistant OCD. • Deep brain stimulation (DBS), especially of subthalamic nuclei, seems to be a promising method to improve treatment-refractory obsessive-compulsive disorder. We hypothesize, that rTMS over the motor cortex may improve OCD symptoms via neuronal pathways between M1 and subthalamic nuclei. • Recently Huang et al. proposed the rTMS version of the theta burst stimulation (TBS) protocol in order to induce a LTP/LTD ratio modification in brain slices. Compared to the “classic” rTMS, TBS produces a long-lasting and powerful effect on motor cortex physiology and we proposed to apply TBS over the bilateral motor cortex.  SUBJECTS AND METHODS Nine patients with OCD symptoms were included between September 2007 and January 2009 and treated with TBS. The TBS protocol consisted of 15 sessions of intermittent TBS (iTBS) over the right and left motor cortex (hand area, M1), 100% of active motor threshold, 10 bursts of 3 stimuli at 50 Hz, repeated at intervals of 200 ms (5 Hz), followed by 8 second pause. The total number of 3-bursts was 350 over each M1 cortex (1050 pulses/ each motor cortex/day). The medications remained unchanged. All OCD evaluations were made blindly by the same psychologist trained for the Y-BOCS administration. HYPOTHESES The theta burst stimulation (TBS) was proposed as a rTMS version producing a more long-lasting and powerful effect. rTMS of the motor cortex and DBS improves some advanced forms of Parkinson's disease and the DBS seems to bee also a promising method to improve OCD. We hypothesized, that rTMS over the motor cortex would be able to improve the OCD symptoms and proposed to apply the intermittent (iTBS), stimulating mode of TBS, over the bilateral motor cortex. RESULTS Clinical improvement and YBOCS scores decrease were meaningful for most of patients.The treatment was well tolerated and without any side effects. CONCLUSIONS These preliminary clinical results seems to bee very interesting for some individuals suffering from chronic treatment-resistant OCD. iTBS appears as a new, effective, safe and well tolerated method to treat resistant OCD, inducing a rapid clinical response with the a decrease of the Y-BOCS scores (lowering for 29% of the total score, for 25% of the OS and 34% of the CS), at least comparable with DBS results. LimitationsThe main limitations of this study was its open design without comparison sham treatment. REFERENCES • Couturier JL. Efficacy of rapid-rate repetitive transcranial magnetic stimulation in the treatment of depression: a systematic review and meta-analysis. J Psychiatry Neurosci 2005; 30:83-90. • Martin JL, Barbanoj MJ, Perez V, Sacristan M. 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