title: Unilateral magnetic resonance guided focused ultrasound thalamotomy for essential tremor: practices and clinicoradiological outcomes.
abstract: BACKGROUND
  Several options exist for surgical management of essential tremor (ET), including radiofrequency lesioning, deep brain stimulation and γ knife radiosurgery of the ventralis intermedius nucleus of the thalamus. Recently, magnetic resonance-guided focused ultrasound (MRgFUS) has been developed as a less-invasive surgical tool aimed to precisely generate focal thermal lesions in the brain.
  
  
  METHODS
  Patients underwent tremor evaluation and neuroimaging study at baseline and up to 6 months after MRgFUS. Tremor severity and functional impairment were assessed at baseline and then at 1 week, 1 month, 3 months and 6 months after treatment. Adverse effects were also sought and ascertained by directed questions, neuroimaging results and neurological examination.
  
  
  RESULTS
  The current feasibility study attempted MRgFUS thalamotomy in 11 patients with medication-resistant ET. Among them, eight patients completed treatment with MRgFUS, whereas three patients could not complete the treatment because of insufficient temperature. All patients who completed treatment with MRgFUS showed immediate and sustained improvements in tremors lasting for the 6-month follow-up period. Skull volume and maximum temperature rise were linearly correlated (linear regression, p=0.003). Other than one patient who had mild and delayed postoperative balance, no patient developed significant postsurgical complications; about half of the patients had bouts of dizziness during the MRgFUS.
  
  
  CONCLUSIONS
  Our results demonstrate that MRgFUS thalamotomy is a safe, effective and less-invasive surgical method for treating medication-refractory ET. However, several issues must be resolved before clinical application of MRgFUS, including optimal patient selection and management of patients during treatment.
authors.affiliation: Department of Neurosurgery, Brain Research Institute, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Won Seok
authors.initials: WS
authors.lastname: Chang
authors.affiliation: Department of Neurosurgery, Brain Research Institute, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Hyun Ho
authors.initials: HH
authors.lastname: Jung
authors.affiliation: Department of Neurosurgery, Brain Research Institute, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Eun Jung
authors.initials: EJ
authors.lastname: Kweon
authors.affiliation: Insightec, Ltd., Tirat Carmel, Israel.
authors.forename: Eyal
authors.initials: E
authors.lastname: Zadicario
authors.affiliation: Insightec, Ltd., Tirat Carmel, Israel.
authors.forename: Itay
authors.initials: I
authors.lastname: Rachmilevitch
authors.affiliation: Department of Neurosurgery, Brain Research Institute, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Jin Woo
authors.initials: JW
authors.lastname: Chang
mesh_terms: D000328:Adult; D000368:Aged; D001931:Brain Mapping; D004185:Disability Evaluation; D020329:Essential Tremor / Q000175:diagnosis* / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053783:Magnetic Resonance Imaging, Interventional / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009460:Neurologic Examination; D014464:Ultrasonic Therapy / Q000379:methods*; D020651:Ventral Thalamic Nuclei / Q000601:surgery*; D055815:Young Adult
keywords: MRI; Surgery; Tremor; Ultrasound