Objective: To evaluate whether diffusion MRI markers of callosal integrity, together with baseline clinical vulnerability, are associated with cognitive trajectory after functional neurosurgical treatment in Parkinson’s disease.

Background: Cognitive outcomes after functional neurosurgical treatment in Parkinson’s disease (PD) vary across patients. Baseline clinical vulnerability, including age, disease duration, motor severity, and cognitive status, may influence postoperative trajectories. Diffusion MRI measures of interhemispheric white-matter integrity may complement these clinical markers in estimating neural reserve.

Method: We analyzed 98 PD patients undergoing functional neurosurgical treatment with 18-month follow-up. Patients received deep brain stimulation (DBS, n=49) or radiofrequency lesioning (RF, n=49) according to clinical indication. Mean age was 64.8 ± 7.9 years and disease duration 11.3 ± 3.8 years. Baseline motor severity averaged UPDRS-III 50.3 ± 11.4 and baseline MoCA 26.1 ± 2.3. Motor phenotype (tremor-dominant vs PIGD) was recorded. Diffusion MRI metrics were obtained from the genu and splenium of the corpus callosum. Cognitive decline was defined as ≥1-point reduction in MoCA at 18 months.

Results: Cognitive decline occurred in 26 patients (26.5%), while 72 (73.5%) remained stable. The decline group showed slightly higher age (66.1 ± 8.5 vs 64.3 ± 7.6 years, p<0.05), longer disease duration (12.4 ± 4.1 vs 10.9 ± 3.5 years, p<0.05), and lower baseline MoCA (25.0 ± 2.5 vs 26.5 ± 2.1, p<0.05). Callosal FA was modestly lower in this group (genu 0.7097 ± 0.011 vs 0.7145 ± 0.010; splenium 0.7905 ± 0.010 vs 0.7957 ± 0.009). Mean FA difference was approximately 0.004–0.005. Similar FA distributions were observed across DBS and RF treatments.

Conclusion: Lower fractional anisotropy in callosal segments was modestly associated with cognitive decline over 18 months. Older age and longer disease duration were also associated with worse cognitive trajectoryTogether, these findings support the concept that structural connectivity and clinical vulnerability may jointly reflect cognitive neural reserve in PD, potentially informing patient selection and prognostic assessment.

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References: • Jian Y, Peng J, Wang W, Hu T, Wang J, Shi H, et al. Prediction of cognitive decline in Parkinson’s disease based on MRI radiomics and clinical features: A multicenter study. CNS Neurosci Ther. 2024;30(6):e14789. doi: 10.1111/cns.14789.
• Liao TW, Wang JJ, Tsai CC, Wang PN, Chen YL, Wu YM, et al. A fixel-based analysis of white matter reductions early detects Parkinson disease with mild cognitive impairment. Biomed J. 2024;47(5):100678. doi: 10.1016/j.bj.2023.100678.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/diffusion-mri-markers-of-neural-reserve-interaction-between-callosal-integrity-and-clinical-vulnerability-after-functional-neurosurgery-in-parkinsons-disease/