rTMS with a two-coil array: Safety and efficacy for treatment resistant major depressive disorder

Abstract

Background: Therapeutic repetitive Transcranial Magnetic Stimulation (rTMS) has emerged as a standard of care for individuals with major depressive disorder (MDD) who do not benefit from, or are unable to tolerate, antidepressant pharmacotherapy. Depth of stimulation is limited with currently approved figure-eight coils and larger coils capable of deeper penetration may be associated with loss of stimulation focality and undesired recruitment of motor cortex. A second generation 2-coil array rTMS system was designed to target converging brain pathways for potentially deeper prefrontal cortex stimulation.

Methods: A randomized, double-blind, sham-controlled trial examined the safety and efficacy of an investigational 2-coil rTMS device. Antidepressant treatment-resistant or treatment-intolerant MDD patients (n = 92) received 20 daily rTMS treatments with coil centers positioned over left dorsolateral prefrontal cortex (dlPFC) and dorsomedial prefrontal cortex (dmPFC). 10 Hz stimulation (maximum summated power for both coils ≤ 120% motor threshold) was delivered. Primary efficacy endpoint was change in HAMD-24 score from baseline to the conclusion of treatments.

Results: Data from n = 75 (per-protocol sample) showed significantly greater improvement (mean HAMD-24 change) over time for the active (n = 38) versus sham (n = 37) group after 20 sessions (F = 7.174; p = 0.008) and also at the one-month follow-up (F = 6.748; p = 0.010). Response rates were 55.3% (active) versus 32.4% (sham) (p = 0.063); remission rates were 26.3% versus 18.9% (p > 0.05). Other secondary outcomes were generally supportive.

Conclusions: The results confirmed safety and acute efficacy of the 2-coil rTMS device. Despite modest sample size, primary outcome was clinically and statistically significant, and the effect size was comparable with those reported for regulatory trials with FDA-cleared devices.

Keywords: Depression; Multiple coil array; Randomized clinical trial; Transcranial magnetic stimulation.