Is it safe to have Deep Brain Stimulation after MRI-guided focused ultrasound ablation? A report of three cases and review of literature.

Introduction MRI-guided focused ultrasound (MRgFUS) ablation has become increasingly utilised for movement disorders since its approval by the U.S. Food and Drug Administration (FDA) in the treatment of unilateral essential tremor (ET) in 2016. While most patients achieve significant improvement in their symptoms, a proportion of ET patients experience tremor recurrence. Deep brain stimulation (DBS) is a potential rescue therapy post-MRgFUS. However, the safety profile of such scenarios is currently unknown. Case Presentations Here, we report three ET patients who previously underwent MRgFUS of the ventral intermediate nucleus of the thalamus (Vim) and subsequently had DBS insertion due to tremor recurrence. Three patients (ranging from 58 to 85 years of age; one female) presented with a history of refractory ET. Patient 1 had left Vim MRgFUS and then left Vim DBS. However, the tremor control was still inadequate, and he had a further revision DBS surgery where two electrodes were inserted into left Vim. Patient 2 had two MRgFUS procedures in left Vim and then underwent left Vim DBS insertion due to hand tremor recurrence. Patient 3 had left Vim MRgFUS and then bilateral Vim DBS due to midline tremor. Patients 2 and 3 experienced substantial improvement in symptoms after DBS but Patient 1 only had minimal improvement. There were no surgical complications and no readmission within 30 days. Conclusions This case series demonstrates that insertion of DBS electrodes in the vicinity of prior MRgFUS site can be safe. These findings have important implications for pre-operative counseling of patients with ET with high surgical risks, as well as supporting MRgFUS as a first-line therapy in selected patients. Further studies with larger population will delineate the optimal timeline where DBS may be safely performed in this population, as well as the long-term therapeutic effect of such rescue intervention.