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Updated: Oct 18, 2026
MRI-guided Focused Ultrasound Thalamotomy for Patients with Medically-refractory Essential Tremor
Published on: December 13, 2017
Postoperative Changes in Line-Drawing Trajectories After Vim Thalamotomy for Essential Tremor: An Exploratory
Introduction:
Ventral intermediate nucleus (Vim) thalamotomy effectively suppresses essential tremor (ET); however, improvements in tremor severity do not necessarily translate into enhanced upper-limb dexterity or quality of life (QOL). In this study, we aimed to characterize postoperative changes in line-drawing trajectories and explore their functional correlates following Vim thalamotomy.
Methods:
Thirty patients with ET who underwent unilateral Vim thalamotomy and 13 healthy controls (HC) were included. The ET group was assessed preoperatively and at 1 week and 1 month postoperatively using The Essential Tremor Rating Assessment Scale (TETRAS; tremor severity [performance subscale; PS] and activities of daily living [ADL]), Purdue Pegboard Test (PPT), Box and Block Test (BBT), and Quality of Life in Essential Tremor Questionnaire (QUEST [QOL]). Line-drawing trajectories were quantitatively analyzed using the proportion of upward-direction deviation area (upper %) as an exploratory descriptor of trajectory characteristics. Longitudinal changes, comparisons with HC, and regression analyses of QOL were performed.
Results:
Tremor severity and ADL impairment improved significantly after surgery (both p < 0.001), accompanied by significant improvement in QOL (p < 0.001). In contrast, PPT and BBT scores showed no significant postoperative improvement. Upper % was significantly higher at 1 month than at 1 week postoperatively (p = 0.047) and exceeded the level observed in HC (p = 0.034). Sensitivity analysis demonstrated that increases in upper % occurred more frequently than decreases (20 vs. 6 patients, p = 0.009). TETRAS ADL was the only independent predictor of QOL (B = -1.565, p = 0.001).
Conclusion:
Vim thalamotomy improved tremor severity, ADL, and QOL, whereas objective dexterity remained unchanged. Exploratory trajectory analysis identified delayed postoperative alterations in line-drawing characteristics. These trajectory changes may provide complementary information regarding upper-limb performance beyond conventional tremor measures and warrant further longitudinal investigation.
