Trigeminal Nerve Stimulation for Major Depressive Disorder: An Updated Systematic Review

Trigeminal nerve stimulation (TNS) is a promising non-invasive brain stimulation intervention. The TNS has been proposed for major depressive disorder (MDD) with auspicious results. The aim of this study was to review the literature on TNS for MDD. Systematic review, using MEDLINE and EMBASE, of first articles available until 22nd of April 2016. We included seven studies; six of them were open-label studies and one sham-controlled randomized double-blinded trial. Most studies had small sample sizes. Two studies were on MDD with comorbid posttraumatic stress disorder and one study focused on the elderly population. Two different protocols of stimulation were reported. Studies had interesting positive results for treating MDD. The TNS was reported to be well tolerated, with no severe adverse effect reported, and had impressive results for MDD. This promising, safe and easy-to-use new neuromodulation technique could be a useful tool for MDD treatment. However, the results reported in the studies performed so far must be analyzed under the strict limitations of the study design. Most of the studies on TNS are case studies or open-label trials with very small sample sizes. We acknowledge that it is the time to initiate more rigorous sham-controlled trials to better understand the huge potential involved with this technique, which could lead to the development of more accessible, easy-to-use, safe and non-invasive technology.