Abstract|Movement Disorders 3| Volume 357, SUPPLEMENT 1, e57-e58, October 15, 2015

Gamma knife thalamotomy for essential tremor: the first preliminary Chilean experience

      Background: The nucleus ventralis intermedius (VIM) has been widely considered as the preferred target for tremor treatment using different techniques such as radiofrequency ablation (RF), deep brain stimulation (DBS) and more recently gamma knife radiosurgery (GKRS).
      Objective: The purpose of the present study is to present the preliminary experience in Chile with the use of GKRS for the treatment of medically refractory essential tremor (ET).
      Patients and methods/material and methods: Five ET patients underwent Gamma Knife Thalamotomy (GKT). High Resolution Magnetic resonance imaging guidance was used for VIM targeting. A single 4-mm isocenter was used to target a maximum dose of 130 Gray (Gy) to the VIM. Pre and post treatment clinical evaluation was performed using Global (A + B + C) Fahn–Tolosa–Marín tremor rating scale (FTM).
      Results: The mean patient age was 68.2 years (57–80) with a mean follow-up of 18 months (6–28). In four patients (80%) an important clinical improvement was documented (mean pre-treatment FTM = 32.5 and mean post-treatment FTM = 17.9). In one patient no significant effect was observed and a second GKT was performed achieving a FTM score improvement from 28.9 to 11.5. No complication was observed.
      Conclusion: GKT could be considered a safe and effective neurosurgical treatment for medically refractory essential tremor. These results are in agreement with other GKT series published in the literature and are equivalent to those obtained using radiofrequency and deep brain stimulation.