This study aims to evaluate the safety and effectiveness of simultaneous bilateral radiofrequency thalamotomy for patients with medication-refractory essential tremor (ET). Essential tremor is a common neurological condition that causes involuntary shaking, often affecting the hands and interfering with daily activities such as writing, eating, or using tools. While medications such as propranolol and primidone can help some patients, others experience limited or no benefit. In this study, five adult participants diagnosed with essential tremor that does not respond to standard medications will undergo simultaneous bilateral stereotactic radiofrequency lesioning of the ventral intermediate nucleus (Vim) of the thalamus. This procedure involves precisely targeting both sides of the Vim to reduce tremor in both arms during a single surgical session. Prior to surgery, participants will undergo brain MRI for surgical planning, as well as clinical evaluations including the Clinical Rating Scale for Tremor (CRST), Quality of Life in Essential Tremor Questionnaire (QUEST), the Scale for the Assessment and Rating of Ataxia (SARA), mood scales (BDI, BAI, AES), and cognitive function testing. The surgery will be performed under local anesthesia using a stereotactic frame and intraoperative imaging. Tremor reduction will be assessed postoperatively and at 1, 3, and 6 months. The primary outcome is the improvement in CRST scores at 6 months. Secondary outcomes include quality of life (QUEST), ataxia symptoms (SARA), mood and cognitive changes, and adverse events. This research is being conducted at Tokyo Women's Medical University. The study is IRB-approved and participants will be monitored closely throughout the 6-month follow-up period. Any complications or adverse events, such as temporary speech or swallowing difficulties, will be recorded and managed appropriately. The goal of this study is to explore whether performing thalamotomy on both sides simultaneously is a safe and effective treatment option for patients with severe and medication-resistant essential tremor.