Introduction: DBS is an FDA-approved treatment for essential tremor (ET). Due to difficulty visualizing the ventral intermediate nucleus (Vim) of the thalamus on MRI, targeting traditionally uses indirect stereotactic methods with intraoperative awake testing to optimize placement. Advances in neuroimaging, like tractography, have enabled direct targeting, allowing DBS to be safely conducted with patients asleep. However, asleep DBS delays clinical confirmation until the initial programming session, limiting its clinical adoption. This study compares clinical outcomes of asleep (tractography-based) versus awake (indirect targeting with intraoperative testing) Vim DBS for treatment-refractory ET.
Methods: This retrospective study reviewed clinical outcomes of ET patients who underwent awake or asleep Vim DBS from 2017 to 2024 at a single institution. Tremor severity was assessed with TETRAS at baseline and six months post-implantation. Secondary outcomes included total electrical energy delivered (TEED), stimulation-related side effects, and anti-tremor medication reduction.
Results: Among 23 awake and 14 asleep patients, both groups had significant six-month TETRAS reductions, with mean improvements of 49.5% (95% CI: 42.5%–56.5%) in the awake group and 56.0% (95% CI: 39.1%–72.9%) in the asleep group, with no significant difference (p = 0.390, two-sample t-test). TEED values were higher in the awake group (1.56 x 10⁻⁴ vs. 8.76 x 10⁻⁵, p=0.006, Mann-Whitney U Test). Side effects showed comparable safety profiles, including: paresthesia (85.7% vs. 69.6%, p = 0.434), speech (42.9% vs. 56.5%, p = 0.508), gait (35.7% vs. 43.5%, p = 0.738), and capsular effects (35.7% vs. 39.1%, p = 1), all Fisher's exact test. Medication usage showed no overall differences.
Conclusion : Asleep Vim DBS for ET offers outcomes comparable to awake DBS, with lower TEED values suggesting improved electrode accuracy. These findings support asleep DBS as a safe and effective alternative for ET patients.
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