A diffusion-based connectivity map of the GPi for optimised stereotactic targeting in DBS

Area of Science:

• Neuroscience
• Neurosurgery
• Medical Imaging

Background:

• The globus pallidus internus (GPi) is a key target for Deep Brain Stimulation (DBS) in movement disorders like Parkinson's disease and dystonia.
• Optimal clinical outcomes in DBS depend on accurate electrode placement within the GPi.
• Emerging evidence suggests that axonal fibre tracts, in addition to neurons, contribute to DBS efficacy, necessitating consideration of individual fibre tract trajectories in surgical planning.

Purpose of the Study:

• To investigate the connectivity profile of the GPi.
• To develop a connectivity-based parcellation map of the GPi.

Main Methods:

• Diffusion MRI was utilized in sixteen healthy subjects.
• Connectivity-based parcellation of the GPi was performed using two methods: a hypothesis-driven approach and a data-driven k-means clustering approach.

Main Results:

• The hypothesis-driven method identified five GPi clusters with distinct connections (prefrontal cortex, brainstem, GPe, putamen, thalamus).
• The data-driven method yielded three major GPi parcellation clusters.
• Both parcellation methods showed similar connectivity profiles, with comparable inter-individual variability to thalamic parcellation studies.

Conclusions:

• The data-driven parcellation suggests potential subdivisions of the GPi into sensorimotor, associative, and limbic regions.
• The sensorimotor region, connected to the thalamus, aligns with optimal electrode placement for DBS in movement disorders.
• Further clinical studies correlating DBS electrode positions with this GPi connectivity map are warranted to validate findings.