Dmitry M. Arbuck, MD President and Medical Director Indiana Polyclinic Carmel, Indiana
Ali A. Farooqui, MD Integrative Psychiatry, PLLC Clinical Faculty Department of Psychiatry University of Louisville School of Medicine Louisville, Kentucky
Rif S. El-Mallakh, MD Professor and Director, Mood Disorders Research Program Department of Psychiatry and Behavioral Sciences University of Louisville School of Medicine Louisville, Kentucky
Disclosures Dr. Farooqui is a speaker for AbbVie and BioXcel. Dr. El-Mallakh is a speaker for Axsome, Idorsia, Intra-Cellular Therapies, Janssen, Lundbeck, Myriad, Noven, Otsuka, and Teva, and has received research support from Sunovion. Dr. El-Mallakh is Current Psychiatry’s Section Editor, Clinical Neuroscience. Dr. Arbuck reports no financial relationships with any companies whose products are mentioned in this article, or with manufacturers or competing products.
A critical review of 23 trials and case reports of DBS as a treatment for OCD demonstrated a 47.7% mean reduction in score on the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) and a mean response percentage (minimum 35% Y-BOCS reduction) of 58.2%.49 Most patients regained a normal quality of life after DBS.49 A more rigorous review of 15 meta-analyses of DBS found that conclusions about its efficacy or comparative effectiveness cannot be drawn.50 Because of the nature of neurosurgery, DBS has many potential complications, including cognitive changes, headache, infection, seizures, stroke, and hardware failure.
Vagus nerve stimulation
VNS, in which an implanted device stimulates the left vagus nerve with electrical impulses, was FDA-approved for treating chronic TRD in 2005.51 It had been approved for treatment-resistant epilepsy in 1997. In patients with epilepsy, VNS was shown to improve mood independent of seizure control.52 VNS requires a battery-powered pacemaker device to be implanted under the skin over the anterior chest wall, and a wire tunneled to an electrode is wrapped around the left vagus nerve in the neck.53 The pacemaker is then programmed, monitored, and reprogrammed to optimize response.
VNS is believed to stimulate deep brain nuclei that may play a role in depression.54 The onset of improvement is slow (it may take many months) but in carefully selected patients VNS can provide significant control of TRD. In addition to rare surgery-related complications such as a trauma to the vagal nerve and surrounding tissues (vocal cord paralysis, implant site infection, left facial nerve paralysis and Horner syndrome), VNS may cause hoarseness, dyspnea, and cough related to the intensity of the current output.51 Hypomania and mania were also reported; no suicidal behavior has been associated with VNS.51
Noninvasive vagus nerve stimulationIn noninvasive vagus nerve stimulation (nVNS) or transcutaneous VNS, an external handheld device is applied to the neck overlying the course of the vagus nerve to deliver a sinusoidal alternating current.55 nVNS is currently FDA-approved for treating migraine headaches.55,56 It has demonstrated actions on neurophysiology57 and inflammation in patients with MDD.58 Exploratory research has found a small beneficial effect in patients with depression.59,60 A lack of adequate reproducibility prevents this treatment from being more widely recommended, although attempts to standardize the field are evolving.61
Cranial electrical stimulation
Cranial electrical stimulation (CES) is an older form of electric stimulation developed in the 1970s. In CES, mild electrical pulses are delivered to the ear lobes bilaterally in an episodic fashion (usually 20 to 60 minutes once or twice daily). While CES can be considered a form of neuromodulation, it is not strictly interventional. Patients self-administer CES. The procedure has minimal effects on improving sleep, anxiety, and mood.62-66 Potential adverse effects include a tingling sensation in the ear lobes, lightheadedness, and fogginess. A review and meta-analysis of CES for treating addiction by Kirsch67 showed a wide range of symptoms responding positively to CES treatment, although this study was not peer-reviewed. Because of the low quality of nearly all research that evaluated CES, this form of electric stimulation cannot be viewed as an accepted treatment for any of its listed indications.
