Adjuvant intermittent theta burst stimulation over dorsomedial prefrontal cortex in treatment-resistant obsessive-compulsive disorder type: Letter to the editor

Abstract

Repetitive transcranial magnetic stimulation (rTMS) holds promise in the treatment of resistant obsessive-compulsive disorder (OCD). Advances in technology have enabled the stimulation of deeper brain structures such as dorsomedial prefrontal cortex (dmPFC) and anterior cingulate cortex(ACC), which are components of corticoestriatoethalamoecortical pathway (CSTC), implicated in OCD [1]. A multisite RCT using the H7 coil demonstrated the efficacy and tolerability of high frequency rTMS over ACC/ dmPFC [2]. This led to the United States Food and Drug Administration (FDA) approval and the Conformit e Europ eene (CE) certification for the device. The double cone coil is a less expensive alternative, which is capable of stimulating the dmPFC and has shown encouraging results in open-labeled trials [1,3]. Further, the MagventureTM DB-80 double-cone coil has received FDA clearance for OCD due to its substantial equivalence to the H7 coil [4]. However, there is no published evidence on the use of the novel theta burst stimulation (TBS) protocols using deep coils in OCD. Intermittent TBS (iTBS) is purported to have similar but possibly more robust neurophysiological effect over the targeted cortical region as compared to high frequency rTMS (HF-rTMS) [5]. TBS has the advantage of shorter duration of intervention and lower intensity of stimulation, which may improve the acceptability and tolerability. In this background, we report our experience of treating 12 patients with treatment-resistant OCDwith intermittent TBS (iTBS) using D-B80 double cone coil over bilateral dmPFC-ACC. Twelve patients receiving treatment for OCD from a tertiary care center in India were administered deep rTMS as an add-on treatment (Table1). Symptom severity was assessed using YaleBrown Obsessive compulsive scale (YBOCS) [6] before and after the iTBS treatment course. Based on the evidence suggesting dmPFC/ACC dysfunction in OCD and demonstrated efficacy of high frequency rTMS (HFrTMS) over this target [1], all the patients were treated with iTBS. Each patient received 600magnetic pulses per hemisphere per session delivered in 20 trains with 8 second inter-train interval. Each train consisted of 10 bursts of three biphasic pulses delivered at 50 Hz, bursts repeated at 5Hz. The intervention was administered using MagPro X100 (MagVenture, Farum, Denmark) device with cool MagVenture D-B80 coil. In two patients, dmPFC was localized via structural MRI-guided neuronavigation using BrainSight frameless stereotaxic system (Rogue Research, Montreal, Canada) based on the MNI coordinates of x0, yþ30, zþ30 [1]. In the remaining