Staged Bilateral Magnetic Resonance-Guided Focused Ultrasound for Treating Essential Tremor: Systematic Review and Meta-Analysis.

Essential tremor (ET) is one of the most common movement disorders and frequently causes bilateral action tremor with substantial effects on daily functioning and quality of life., Pharmacological therapy is often inadequate or poorly tolerated, prompting consideration of surgical treatment options., Unilateral magnetic resonance‐guided focused ultrasound (MRgFUS) thalamotomy is a non‐incisional ablative procedure performed with real‐time magnetic resonance (MR) imaging, MR thermometry, and intraoperative clinical testing, and it is now used in routine clinical practice following regulatory approval., , , , MRgFUS is one of several modalities, alongside with deep brain stimulation (DBS), radiofrequency ablation, and γ knife radiosurgery, applied across two main anatomical targets: ventral intermediate nucleus (VIM) of the thalamus and the posterior subthalamic area (PSA), which encompasses the caudal zona incerta and fields of Forel., Growing evidence suggests that PSA targeting may achieve comparable or superior tremor suppression to VIM with a favorable long‐term safety profile., However, many patients remain functionally limited by tremor in the untreated limb, and unilateral intervention may also be insufficient for some axial symptoms such as head or voice tremor. Historically, bilateral lesioning raised concerns about dysarthria, gait ataxia, and other speech‐ and balance‐related adverse effects, which limited adoption. Recent technical developments, including improved imaging, center‐specific targeting refinements, tractography‐informed approaches in some cohorts, and more conservative second‐side lesioning strategies have renewed interest in staged bilateral MRgFUS as a potentially safer approach., , , , , , , , Centers now use more patient‐specific targeting (eg, diffusion‐tractography informed localization and computerized tomography‐based skull modeling/skull density ratio; with minor second‐side adjustments after confirming no persistent first‐side deficits) and more reliable real‐time monitoring with MR thermometry., Early prospective series and a multicenter open‐label trial suggest that a contralateral staged procedure can provide additional tremor reduction, although persistent mild adverse effects remain an important consideration., , , , ,