Reduced limbic connections may contraindicate subgenual cingulate deep brain stimulation for intractable depression

Area of Science:

• Neuroscience
• Neurosurgery
• Psychiatry

Background:

• This study investigated deep brain stimulation (DBS) of the subgenual anterior cingulate cortex (SACC) in a patient with bipolar disorder who developed intractable depression after a right thalamic stroke.
• The patient underwent bilateral SACC DBS and died 16 months later. Anatomical connections were assessed preoperatively and postmortem using diffusion tractography (DT).

Observation:

• Diagnostic measures included neuropsychological testing, preoperative and ex vivo DT, and neuropathological assessment.
• Post-DBS depression scores did not improve. In vivo and ex vivo DT revealed significantly reduced limbic projections from the thalamus and SACC to the amygdala in the right, stroke-affected hemisphere.

Findings:

• A selective right mediothalamic lesion correlated with the onset of refractory depression.
• Reduced amygdalar-thalamic and amygdalar-SACC connections were identified in the affected hemisphere.
• The lack of improvement in depression scores suggests these connectivity deficits may be a contraindication for DBS in similar cases.

Implications:

• The study highlights the potential role of specific thalamic and SACC connectivity patterns in treatment-resistant depression.
• Findings suggest that reduced amygdalar-thalamic and amygdalar-SACC connections could contraindicate DBS for depression.
• The strong correspondence between in vivo and ex vivo DT supports the utility of DT as a presurgical planning tool for DBS.