Focused Ultrasound as Rescue Treatment of Essential Tremor After Deep Brain Stimulation: 2 Case Reports.

Approximately 25% to 55% of patients with essential tremor will eventually develop medication-refractory tremor. Currently, the standard surgical treatment for this condition is deep brain stimulation (DBS) of the ventralis intermedius nucleus of the thalamus and, more recently, the posterior subthalamic area. However, MRI-guided focused ultrasound (FUS) thalamotomy has shown promising results in improving tremor in patients with refractory essential tremor. We present 2 cases of patients with a disabling action tremor, recurring after DBS. A 55-year-old right-handed male and a 52-year-old woman presented with bilateral medically refractory action tremor, which began in their second decade of life. Both underwent bilateral DBS-ventralis intermedius, with the first patient showing a good initial response but the second patient showing a suboptimal response within the first year after DBS. In both cases, the DBS system was removed and the patients subsequently underwent left-sided FUS thalamotomy with a dramatic improvement of their tremor. These cases demonstrate the feasibility of performing FUS thalamotomy as a rescue treatment for disabling tremor after DBS.