The role of MRI tractography in stereotactic targeting for surgical treatment of Parkinson’s disease

Abstract

Objective: To evaluate the clinical efficacy of surgical treatment of tremor-dominant Parkinson’s disease (PD) with regard to stereotactic target determination based on MRI tractography data, and to compare the outcomes of stereotactic radiofrequency (RF) thalamotomy of the ventral intermediate nucleus (Vim) with tractography-assisted lesioning of the dentatorubrothalamic tract (DRTT).

Materials and methods: This retrospective study included 25 patients with PD who underwent surgery between 2018 and 2025. Inclusion criteria were tremor-dominant clinical presentation, a progressive disease course, and insufficient response to pharmacological therapy. Patients were divided into two groups: the Vim group (n=19), in which stereotactic RF thalamotomy was performed using indirect target calculation, and the DRTT group (n=6), in which the surgical target was determined using MRI tractography based on diffusion tensor imaging (DTI). Surgical planning was performed using Element software (Brainlab, Germany). Clinical efficacy was assessed preoperatively and 12 months postoperatively using the Unified Parkinson’s Disease Rating Scale (UPDRS, part III), the Clinical Rating Scale for Tremor (CRST, parts A and C).

Results: In all patients, tremor of the contralateral limb was completely abolished immediately after surgery. At 12 months, the mean UPDRS III score decreased by 44%, from 83.2±8.7 to 46.7±4.18 points (p=0.04). A statistically significant improvement in UPDRS III scores was observed in the DRTT group (p=0.032), whereas the difference in the Vim group did not reach statistical significance. Tremor regression assessed by CRST-A and CRST-C was observed in both groups but was more pronounced in patients who underwent tractography-assisted lesioning. Postoperatively, a reduction in daily levodopa dosage was noted: by 23.4% in the Vim group and by 27.7% in the DRTT group. No intraoperative complications were recorded. Transient neurological adverse effects occurred more frequently in the Vim group and resolved completely during the early postoperative period.

Conclusions: The use of MRI tractography for stereotactic target selection in ablative surgery for PD enables individualized surgical planning and provides more precise targeting of pathophysiologically relevant neural pathways. Tractography-assisted lesioning of the DRTT is associated with more stable tremor control, a tendency toward greater improvement of accompanying motor symptoms, and a potentially lower risk of neurological adverse effects.