Background Unilateral magnetic resonance-guided focused ultrasound (FUS) thalamotomy is efficacious for the treatment of medically refractory essential tremor (ET). Viability of bilateral FUS ablation is unexplored.
Methods Patients diagnosed with medically refractory ET and previously treated with unilateral FUS thalamotomy at least 5 months before underwent bilateral treatment. The timepoints were baseline (before first thalamotomy) and FUS1 and FUS2 (4 weeks before and 6 months after second thalamotomy, respectively). The primary endpoint was safety. Efficacy was assessed through the Clinical Rating Scale for Tremor (CRST), which includes subscales for tremor examination (part A), task performance (part B) and tremor-related disability (part C).
Results Nine patients were treated. No permanent adverse events were registered. Six patients presented mild gait instability and one dysarthria, all resolving within the first few weeks. Three patients reported perioral hypoesthesia, resolving in one case. Total CRST score improved by 71% from baseline to FUS2 (from 52.3±12 to 15.5±9.4, p<0.001), conveying a 67% reduction in bilateral upper limb A+B (from 32.3±7.8 to 10.8±7.3, p=0.001). Part C decreased by 81% (from 16.4±3.6 to 3.1±2.9, p<0.001). Reduction in head and voice tremor was 66% (from 1.2±0.44 to 0.4±0.54, p=0.01) and 45% (from 1.8±1.1 to 1±0.8, p=0.02), respectively.
Conclusion Bilateral staged FUS thalamotomy for ET is feasible and might be safe and effective. Voice and head tremor might also improve. A controlled study is warranted.
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RM-F and SM contributed equally.
CRB and JAO contributed equally.
Contributors RMF, SM, JAPP, CRB and JAO: conception, organisation and execution of the project, performance of FUS procedures, and writing of the first draft and revisions. LLI, JUMM, FB, RRR, MdA, FHF, MM, LHGQ, LS: execution of the project, performance of FUS procedures and review of manuscript. BW, IO: execution of the project and review of manuscript. GD: project conception and review of manuscript.
Funding This study was supported by the Fundación de Investigación HM Hospitales and InSightec, which provided funding for performance of ultrasound procedures.
Competing interests RMF has received honoraria for lecturing from InSightec. JAPP has received honoraria for lecturing and payment of travel expenses to attend scientific meetings from General Electric. JUMM receives grant support from InSightec. RMF, JAPP, JUMM, MdA, RRR and FHF have received honoraria for teaching in two courses sponsored by InSightec at HM Puerta del Sur (Mostoles, Madrid, Spain). JAO has received honoraria for lecturing and payment of travel expenses to attend scientific meetings from InSightec.
Provenance and peer review Not commissioned; externally peer reviewed.
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