Hypoactivity in the Paraterminal Gyrus Following Bilateral Anterior Capsulotomy

Abstract

Objective: Bilateral anterior capsulotomy (BAC) is one of the ablative neurosurgical procedures used to treat major depressive disorder or obsessive-compulsive disorder when all other therapies fail. Tristolysis, a reduction in sadness, is the most striking clinical effect of BAC and is seen in the first 1 to 2 weeks after surgery. This retrospective study measured regional cerebral blood flow (rCBF) following surgery to identify which cortical regions were impacted and could account for this clinical effect. Methods: All patients had their capsulotomies done in Vancouver by the same team. Pre- and postoperative single-photon emission computed tomography perfusion scans were analyzed for 10 patients with major depressive disorder and 3 with obsessive-compulsive disorder. rCBF was measured semiquantitatively by calculating the ratio between an identified region of interest and a whole brain reference area. Results: Decreased rCBF was found in the paraterminal gyri. Increased rCBF was found in the dorsolateral prefrontal cortices and in the left lateral temporal lobe. Conclusions: BAC causes hypoactivity in the paraterminal gyri and is the most likely explanation for its tristolytic effect, suggesting that the paraterminal gyrus is the limbic cortical locus for the emotion of sadness. Increased activity in the dorsolateral prefrontal cortices may be occurring via connectional diaschisis, and suppression by overactive paraterminal gyri during depression may account for some of the neurocognitive deficits observed during depressive episodes.

Ablation Surgeries for Treatment-Resistant Depression: A Meta-Analysis and Systematic Review of Reported Case Series

“…After applying our inclusion criteria, ten unique studies [31][32][33][34][35][36][37][38][39] remained to be used for meta-analysis. Four studies [15,19,40,41] contained duplicate data and this information was extracted and included when missing from the original studies, as shown in online supplementary C-Table 1 [50][51][52][53][54][55][56][57][58][59][60][61].…”

“…Like the Vancouver group, they also noted the tristolytic effect. Tristolysis is a rapid reduction in depression surfacing as early as 1-week post-ablation when BAC is used to treat TRD, which may be the marker of an effective capsulotomy [19, 41].…”

“…There is also now good evidence that benefits come from ablating the ventral half of the ALIC as seen in the coronal plane [17, 31, 66, 68]. The BAC lesion can now be personalized to a given patient with no loss of benefit using presurgical tractography to target limbic pathways where the likely target is thalamic fibers that project to the paraterminal gyrus [19, 31, 68]. This technique avoids damaging the dorsal associative pathways in the ALIC responsible for executive abilities.…”

“…Key terms grossly included depression/depressive disorders/treatment-resistant, capsulotomy, cingulotomy, tractotomy, leukotomy/leucotomy, radiofrequency or radiofrequency lesion/ablation/ablative/thermocoagulation, focused ultrasound, stereotactic radiosurgery, undercutting, and focused ultrasound thermal ablation (MR-guided focused ultrasound). For the selection of key terms, we have reviewed peer-reviewed neurosurgical seminal works [10, 15], and referred to our team expertise [19].…”

Interventional Neurorehabilitation for Promoting Functional Recovery Post-Craniotomy: A Proof-of-Concept

“…An increasing line of evidence suggests that increasing the motivation to expend cognitive effort, rather than enhancing cognitive networks themselves, would be more effective in bolstering goal-directed behaviour [33] . Thus, if frontostriatal circuitry can be mapped and effectively modulated post-craniotomy, this would be a significant advancement and become important for other areas of neurosurgery, such as limbic surgery [34] .…”