P55-F Neurophysiological assessment of rTMS effectiveness in patients with schizophrenia using cortical and cutaneous silent period

Background At this moment there is not a definite consensus on the effectiveness of the rTMS treatment and parameters to be used for the AVH drug resistant patients (Slotema et al., 2012). We aimed to identify changes of intracortical and spinal motoneuronal inhibition measured before and after 10 sessions of 15 min 1 Hz rTMS. Methods In 6 healthy subjects and 10 patients we assessed the APB silent period (SP) to cortical magnetic single pulse stimulation at 140% RMT applied on motor primary cortex region while the participants performed submaximal isometric contraction. Cutaneous SP was recorded after 2nd finger dermatome electrical stimulation using ring electrodes. We compared CSP/CuSP ratio of a healthy subjects group (HS) with pretreatment and after rTMS treatment conditions for a control patients group (CG) receiving sham treatment and a treatment patients group (TG) receiving treatment on T3-P3 scalp location at the beginning of the study, within one week after, one month after and 3 months after the treatment. Results In HS the CSP showed the average duration of 160 ms (SD 20) larger than CuSP duration of 44 ms (SD 4). The average CSP/CuSP ratio was 3,64:1 in HS. CG ratio analyzed in 3 patients increased from 3,92:1 to 4,4:1. TG and CG ratio at one month and 3 months post rTMS analyses are in progress. Conclusion Intracortical inhibition showed larger duration than spinal motoneuronal inhibition in HS, CG and TG. In CG, preliminary data showed slight increment of CSP:CuSP after rTMS.