A pilot study of focused ultrasound thalamotomy for essential tremor.
BACKGROUND
Recent advances have enabled delivery of high-intensity focused ultrasound through the intact human cranium with magnetic resonance imaging (MRI) guidance. This preliminary study investigates the use of transcranial MRI-guided focused ultrasound thalamotomy for the treatment of essential tremor.


METHODS
From February 2011 through December 2011, in an open-label, uncontrolled study, we used transcranial MRI-guided focused ultrasound to target the unilateral ventral intermediate nucleus of the thalamus in 15 patients with severe, medication-refractory essential tremor. We recorded all safety data and measured the effectiveness of tremor suppression using the Clinical Rating Scale for Tremor to calculate the total score (ranging from 0 to 160), hand subscore (primary outcome, ranging from 0 to 32), and disability subscore (ranging from 0 to 32), with higher scores indicating worse tremor. We assessed the patients' perceptions of treatment efficacy with the Quality of Life in Essential Tremor Questionnaire (ranging from 0 to 100%, with higher scores indicating greater perceived disability).


RESULTS
Thermal ablation of the thalamic target occurred in all patients. Adverse effects of the procedure included transient sensory, cerebellar, motor, and speech abnormalities, with persistent paresthesias in four patients. Scores for hand tremor improved from 20.4 at baseline to 5.2 at 12 months (P=0.001). Total tremor scores improved from 54.9 to 24.3 (P=0.001). Disability scores improved from 18.2 to 2.8 (P=0.001). Quality-of-life scores improved from 37% to 11% (P=0.001).


CONCLUSIONS
In this pilot study, essential tremor improved in 15 patients treated with MRI-guided focused ultrasound thalamotomy. Large, randomized, controlled trials will be required to assess the procedure's efficacy and safety. (Funded by the Focused Ultrasound Surgery Foundation; ClinicalTrials.gov number, NCT01304758.).
Department of Neurosurgery, University of Virginia Health Sciences Center, Charlottesville, VA 22908, USA. wje4r@virginia.edu
W Jeffrey
WJ
Elias
Diane
D
Huss
Tiffini
T
Voss
Johanna
J
Loomba
Mohamad
M
Khaled
Eyal
E
Zadicario
Robert C
RC
Frysinger
Scott A
SA
Sperling
Scott
S
Wylie
Stephen J
SJ
Monteith
Jason
J
Druzgal
Binit B
BB
Shah
Madaline
M
Harrison
Max
M
Wintermark
D000368:Aged; D001931:Brain Mapping; D020329:Essential Tremor / Q000628:therapy*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D013238:Stereotaxic Techniques; D014464:Ultrasonic Therapy / Q000009:adverse effects / Q000379:methods; D020651:Ventral Thalamic Nuclei / Q000473:pathology