¹Medical University of Vienna, Department of Psychiatry and Psychotherapy, Vienna, Austria, ²Medical University of Vienna, Department of Neurosurgery, Vienna, Austria

Background: Recent results from the largest sham-controlled trial of antidepressant VNS, (N=493) have indicated that quality of life after VNS vs. sham improved, especially in patients with severe and chronic depression (Rush et al., 2025). On the other hand, randomized sham-controlled trials (RCTs) with deep brain stimulation (DBS) in psychiatric populations are scarce with the largest sham-controlled trial in treatment resistant depression demonstrating similar effects in the active as well as in the sham group (Holtzheimer et. al, 2017). In addition, controlled studies for DBS demonstrate clinical efficacy in obsessive-compulsive disorder (OCD). However, numbers of included patients in these studies are significantly smaller than in comparable studies in the field of movement disorders.

Aims & Objectives: In the talk in this session, the audience will hear about current use of VNS and DBS as approved invasive neuromodulatory procedures in psychiatric patients. The focus will be set on how to use these procedures in the fields of patient selection, imaging of target engagement in DBS and neurophysiological markers of response in VNS.

Method: We are conducting studies with DBS for patients with severe OCD and VNS for patients with chronic and difficult-to-treat depression. For both methods, we detail the patient selection process, which is important for the audience to learn in order to refer patients to specialized centers.
For DBS in OCD we collect data from the patient screening and selection process (N=16) such as disease duration, symptom dimensions of OCD, indication-specific scores, comorbidities and previous treatments as well as perioperative imaging with structural magnetic resonance imaging. Reconstruction of electrode location was conducted with LEAD-DBS as implemented in MATLAB. Electrode localization in the anterior limb of the internal capsule was compared to normative tractography by visual inspection.
For VNS, we included data from a ongoing EEG experiment with auditory evoked potentials (p300) aiming to replicate previous results on antidepressant response prediction (Neuhaus et al, 2007).

Results: For patients treated with DBS and severe OCD, mean illness duration was 21.3 years, average YBOCS: 32 (±1.2), MADRS: 17.7 (± 6) and mean age at DBS: 36 years (±8.07). All, but one patient screened for DBS had major depressive disorder as a comorbidity, others were autism spectrum disorder, post-traumatic stress disorder and attention-deficit and hyperactive disorder. Electrode placement of 6 implanted patients was well placed in the bilateral ALIC as demonstrated by individual and normative tractography.
Patients treated with VNS exhibited a mean latency of P300 at baseline was 377.4 ms (± 32.5). No significant changes were found at day 1 (+30.8ms, p=0.47) and day 30 (+38.9 ms, p=0.35). However, at day 180 there was a significant decrease in latency compared to baseline (-190.0 ms, p=0.0025, 95% CI: 302.5 to -77.5 ms).

Discussion & Conclusions: Invasive neuromodulation techniques such as DBS or VNS are suited for improving the lives of patients with severe forms psychiatric diseases. However, due to the invasive surgery needed, risks and benefits need to be carefully considered. ​After ​attending the talk, the audience will learn how to use DBS and VNS for severely sick patients.