jabbrv-ltwa-all.ldf jabbrv-ltwa-en.ldfDiscussion
In this case report, we describe the short- and long-term treatment responses from DBS in the BNST and MFB areas in two patients with treatment-resistant depression and severe and disabling anxiety manifested as GAD. Both patients achieved remission from depression following short-term DBS in the BNST, and one of the patients had a major reduction in anxiety symptoms. However, DBS in the MFB area showed no clear short-term effects on depressive or anxiety symptoms. During the open-label phase, both patients continued to receive BNST-DBS. One of the patients had several trials of DBS in the MFB area but did not experience any additive effect on depression, in addition to the anxiolytic effect of DBS in BNST. After four to five years, stable reductions in depressive and anxiety symptoms were recorded in both patients and the level of global functioning had increased.
In line with our findings, reduced anxiety or depressive symptoms have been previously reported in DBS studies on treatment-resistant depression (16,18,23), in OCD (12,13,24,25), and in two case reports on patients with comorbid anorexia nervosa, depression, and GAD (7,8). In the studies mentioned above, brain targets in the anxiety regulation network were stimulated (9). Thus, we speculate that DBS in areas believed to affect the anxiety regulation network might be more effective in treatment-resistant depression with a clear anxiety component.
The absence of a short-term antidepressant effect from DBS in the MFB area in the two cases could be due to several factors, such as a suboptimal placement of the electrodes, or a too-short stimulation period to achieve a sufficient antidepressant effect as previously discussed (26). In this report, the target area of the MFB was identified on a T2 MRI, based on the visualization of the subthalamic nucleus, red nucleus, and corpora mammillaria. However, it has been suggested that tractography (27,28) or intracranial electrophysiology recordings (29) are more precise methods to determine the electrode position.