Background: A significant proportion of patients with obsessive-compulsive disorder (OCD) fail to improve with standard medication and cognitive behavior therapy. Repetitive transcranial magnetic stimulation (rTMS) has been investigated for its role in treating OCD. Low-frequency rTMS over the presupplementary motor area (pre-SMA) has shown mixed results. Moreover, it has not been studied in highly treatment refractory OCD. We analyzed the outcome of low-frequency rTMS over pre-SMA in OCD patients refractory to multiple serotonin reuptake inhibitors (SRIs), augmenting agents, and cognitive behavior therapy.
Methods: Low-frequency (1-Hz stimulus at 100% motor threshold) rTMS was delivered over the pre-SMA using a previously described protocol. At least 25% reduction Yale-Brown Obsessive Compulsive Scale scores and 2-point reduction in Clinical Global Impression-Severity of Illness scores were used to assess treatment response.
Results: Seventeen patients were initiated on rTMS. Three of them dropped out within 9 sittings. Only 1 patient met the criteria for response after 1 month of treatment initiation. No major adverse effects were observed in any of them.
Limitations: The study is a retrospective analysis of outcomes when rTMS was administered as part of routine clinical care. Assessments of the patients were done by trained but different raters, and interrater reliability was not measured.
Conclusions: Low-frequency rTMS over the pre-SMA may not be effective in treatment refractory OCD. Further studies, taking note of the possible reasons for ineffectiveness discussed in the study, may help elucidate the role of rTMS in OCD.