Background: Deep brain stimulation (DBS) has been introduced as a treatment option for treatment-resistant obsessive-compulsive disorder (OCD). However, the optimal stimulation target and the corresponding stimulation settings remain unclear. Furthermore, there is limited knowledge about the acute effects of DBS.
Methods: In 3 patients with treatment-resistant OCD, DBS electrodes were implanted in the bed nucleus of the stria terminalis (BNST)/internal capsule (IC). On the next day, different electrode pairs (BNST only, IC only, and BNST/IC) were stimulated at different voltages (1, 2, and 3.5 V) for 5 minutes each. Afterwards, patients rated their perceived OCD symptoms and various emotional states on corresponding visual analog scales.
Results: Across locations, low voltage stimulation (1 and 2 V) was associated with reduction of OCD symptoms (i.e., anxiety and tension), in particular when the IC was stimulated. High voltage stimulation (3.5 V), in particular when BNST was involved, led to less reduction of OCD symptoms. Moreover, 3.5-V stimulation of the BNST (BNST only and BNST/IC) induced higher levels of anxiety, tension, and discomfort. Subjects also reported an increase in vegetative sensations.
Conclusions: In summary, we demonstrate that both stimulation site and voltage settings show sweet spots (2 V at IC or BNST/IC) at which OCD symptom severity decreased while negative effects were minimal. Stimulation of IC fibers might be relevant both for acute and chronic effects. Whether acute effects are useful for outcome prediction remains to be shown in future studies.
Keywords: Acute effects; Bed nucleus of stria terminalis; Deep brain stimulation; Neuromodulation; Obsessive-compulsive disorder; Psychiatric neurosurgery; Treatment resistant.
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