DBS and Ablation Surgery for Movement Disorders

Abstract

  Recent technical advances in functional neurosurgery have brought notable changes and developments in the treatment of movement disorders. One of these changes is that the end of deep brain stimulation (DBS) all-around era and reevaluation of ablation surgery. This can be seen in the revised third edition of the Japanese Treatment Guidelines for Stereotactic and Functional Neurosurgery (2019). Evidently, this has accelerated the development of focused ultrasound surgery (FUS). Another topic is the clinical application of adaptive (closed-loop) DBS (aDBS). Here, aDBS for Parkinson's disease (PD), which is the only target disease of aDBS currently approved by the Japanese health insurance at the present, is discussed. Until the second edition of the guidelines, ablation surgery was not recommended for most diseases. However, the revised guidelines have been reevaluated in all items of movement disorders, such as PD, essential tremor, and dystonia. Many of them are listed as options to be considered in situations where DBS cannot be performed, except for writer's cramp (occupational dystonia), for which there is no disclaimer on the choice of DBS and ablation surgery. In addition, bilateral ablation surgery has been cited as an option even when bilateral pallidotomy is a principle, such as generalized dystonia and spasmodic torticollis. aDBS is an epoch-making therapeutic technique that enables dynamic neuromodulation of the basal ganglia by feeding back the field potential around the electrode in real time. In November 2020, a fully implantable pulse generator (IPG) equipped with aDBS function was launched in Japan. In PD, the subthalamic nucleus beta-band activity (13-35Hz), which correlates with bradykinesia-rigidity, is used for feedback control. Although aDBS by new IPG is shallow and difficult to evaluate at present, previous research suggests that aDBS has at least the same effect as conventional DBS and is effective in suppressing dyskinesia. Prospects and issues to be resolved in the field of functional neurosurgery are 1) Can bilateral ablation surgery (including FUS) be performed safely using modern surgical techniques? 2) Verification of the reliability and long-term effectiveness of aDBS sensing features. 3) Data accumulation of data on PD tremor, which is considered difficult to control by aDBS.