Subcaudate Tractotomy White Matter Anatomy and Variability: A Diffusion Tensor Imaging Study

Abstract

Background: Subcaudate tractotomy is a functional ablative procedure performed for treatment-resistant psychiatric disease, targeting the white matter tracts ventral to the head of the caudate nucleus. The white matter anatomy of this region has extensive interindividual variability, and this is thought to impact upon the treatment response to ablative and deep brain stimulation procedures. Objective: We aim to assess in detail the white matter tract anatomy and topographic variability underlying subcaudate tractotomy. Methods: 74 non-depressed adult volunteers underwent MRI including diffusion tensor imaging. Individualized regions of interest were formed in both hemispheres using native non-normalized data to simulate a subcaudate tractotomy. Tractography and analysis were performed and the exact tract locations measured including mean distances and standard deviations to assess variability. Results: The cingulum bundle, uncinate fasciculus, corticostriatal fibres, and corticothalamic fibres were consistently demonstrated. The location of the cingulum bundle was consistent across subjects, but there was extensive interindividual variability in the topographic location of the other tracts. Conclusion: We have demonstrated a detailed analysis of the white matter tracts and their anatomical variability underlying subcaudate tractotomy. This has significant implications for neurosurgical targeting.