Resident Department of Neurosurgery, Tokyo Women's Medical University, Tokyo
Introduction: The pallidothalamic tract (PTT) has emerged as a promising target for treating cervical dystonia, with Forel’s Field H identified as a critical region for achieving symptom relief. Recent advances in MR-guided Focused Ultrasound (MRgFUS) have heightened interest in PTT targeting. However, the relationship between lesion localization within the PTT and both clinical outcomes and adverse events remains underexplored. This study aims to utilize probabilistic mapping to determine optimal lesion sites within the PTT that maximize therapeutic efficacy while minimizing side effects.
Methods: We retrospectively analyzed 60 patients who underwent unilateral PTT targeting with either Radiofrequency Ablation (RF) or MRgFUS at Tokyo Women's Medical University Hospital and Sanai Hospital from July 2017 to December 2023. Symptom severity was evaluated using the Burke-Fahn-Marsden Dystonia Rating Scale-Movement Scale (BFMDRS) preoperatively, at 3 months postoperatively, and at final follow-up. Adverse events were assessed solely at the final follow-up to determine long-term postoperative complications. Probabilistic mapping was conducted on postoperative T1-weighted images to correlate lesion locations with clinical improvement and adverse events. Additionally, diffusion tensor imaging (DTI) was utilized preoperatively to analyze the PTT fibers most associated with symptom alleviation.
Results: Unilateral PTT targeting led to a 53% improvement in BFMDRS neck scores at final follow-up, with probabilistic mapping revealing that lesion sites in the medial region above the subthalamic nucleus (STN) were most strongly associated with symptom relief. Notably, weight gain was identified as a postoperative adverse event, with mapping indicating that lesions contributing to this effect were located medially relative to the STN.
Conclusion : This study provides refined insights into optimal PTT lesioning for cervical dystonia by leveraging probabilistic mapping techniques. Targeting the medial PTT region above the STN may enhance symptom relief, while preoperative tractography could aid in avoiding regions associated with adverse effects such as weight gain. Implementing these findings into RF or MRgFUS treatment planning holds potential for advancing patient outcomes and refining dystonia management strategies.
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