Anesthesia considerations of magnetic resonance imaging-guided focused ultrasound thalamotomy for essential tremor: a case series

Abstract

Purpose: Essential tremor (ET) is a common movement disorder with disability in voluntary actions such as eating and writing. First-line treatment involves pharmacological agents, although efficacy is limited by side effects. In these patients, functional neurosurgery can be considered. Magnetic resonance imaging-guided focused ultrasound (MRgFUS) thalamotomy offers a non-invasive solution for treatment. This paper examines an original cohort of ET patients undergoing MRgFUS thalamotomy and discusses the anesthetic management of these cases. Methods: We retrospectively reviewed the anesthetic records of all MRgFUS thalamotomy cases from 15 May 2012 to 16 July 2015 at our centre (Sunnybrook Health Sciences Centre, Toronto, Canada) to expand a data set provided by the focused ultrasound system manufacturer (Insightec, Tirat Carmel, Israel) from a prior phase-II regulatory approval study. Specific drug and procedural details were listed including aspects of the patients’ experience. Results: A total of 82 patients were included in the analysis, 78 from a phase-II trial (16 were from the local site) and four local non-trial cases. No patient required general anesthesia and only 29% of cases required sedation to tolerate the procedure. The most frequent medications required were antiemetics and analgesics. Headache (31%) was the most frequent perioperative symptom. Transient intra-procedural paresthesia symptoms were a common occurrence (32%). Conclusions: The use of MRgFUS for thalamotomy provides a non-invasive and well-tolerated method for treating ET, which usually only requires monitored anesthesia care sedation. Nevertheless, there are several predictable side effects that require contingency planning including the personnel and means to resolve them.