Objective: To identify structural MRI factors that correlate with variations in motor outcomes for essential tremor (ET) patients after Gamma Knife thalamotomy (GKT).

Background: Stereotactic radiosurgery is an important non-invasive treatment for contralateral tremor relief and control in the elderly and those considered high risk for deep brain stimulation and radiofrequency ablation. Individuals with ET undergoing GKT do not consistently experience relief from motor symptoms, even when the procedure is without complications. MRI provides ways to examine structural factors that could potentially forecast post-GKT clinical motor outcomes.

Method: 10 non-demented ET patients with 3T brain MRIs were analyzed. Cortical reconstruction and volumetric segmentation were performed with the FreeSurfer image analysis software. Patients were re-assessed 12 months after GKT.

Results: The age at diagnosis and Fahn-Tolosa-Marin tremor score were positively correlated, indicating that patients who are older at the time of diagnosis tend to have more severe tremors. We found significant associations between higher pre-treatment tremor scores and cortical atrophic changes in widespread areas, including left entorhinal, left lingual, left posterior cingulate, right middle frontal, right entorhinal, right isthmus of the cingulate, right lateral orbitofrontal, right parahippocampal, and right posterior cingulate. The data indicates that there was a significant reduction in the mean tremor score among the patients, dropping from 3.7 ± 0.52 to 1.3 ± 1.21.

Conclusion: According to existing literature, structural changes in the brain, such as cortical thinning or volume loss in specific regions, could be linked to the severity and progression of motor symptoms in ET and other movement disorders. The positive correlation between age at diagnosis and tremor severity is also consistent with what is known about many neurodegenerative diseases: that symptoms can worsen or become more apparent with age. Our results suggest that younger patients with refractory ET may respond better to surgical interventions. However, the MR imaging data collected did not show a consistent pattern or changes that could be used to forecast the level of improvement in motor function that a patient might experience following GKT.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/predictive-value-of-brain-structural-changes-on-motor-outcomes-following-vim-thalamotomy-in-essential-tremor-preliminary-results/