Clinical effects of low frequency rTMS over the left- and right temporo-parietal cortex on

Abstract

Background: Several studies have reported that low frequency repetitive transcranial magnetic stimulation (rTMS) diminishes medication-resistant auditory verbal hallucinations (AVH). However contra dictionary findings have also been reported. Until now the sham condition has been an inactive control. Furthermore little neuroimaging research at the effect of rTMS has been done. This study aims to investigate whether low frequency rTMS on the language related areas will lead to reduction in auditory verbal hallucinations on short term compared to an active control site and to investigate correlated changes in the EEG. Method: Sixteen patients with schizophrenia spectrum disorder and medication-resistant AVH underwent three rTMS treatments in random order on the left temporo-parietal cortex, right temporo-parietal cortex and the active control site Oz. Stimulation was conducted once a week over two weeks, for 20 minutes, at 90% of the motor threshold. Effect measures included the AVH presence, Auditory Hallucination Rating Scale (AHRS), Hallucination Change Scale and EEG power. Results: All three treatments showed improvement in AVH presence, however a significant reduction was found only for the active control site. All three treatments showed improvement on the AHRS, however a significant reduction was found only for the active control site. There was a significant decrease on the HCS between locations; namely the right temporo-parietal cortex and active control site. The EEG showed significant reduction in alpha power of the whole head after active control site stimulation. Conclusion: Low frequency rTMS leads to reduction in duration and severity after stimulation on the left temporo-parietal cortex, right temporo-parietal cortex and active control site Oz. However this is only significant for the active control site Oz. The EEG relates to these findings by showing decreased alpha power after stimulation on the active control site.