The purpose of this study is to evaluate the safety and feasibility of deep brain stimulation (DBS) in the deep cerebellar nuclei (DCN) in patients with Spinocerebellar Ataxia (SCA) types 1 and 3.
Primary Objective: The incidence and nature of treatment-related adverse events across the entire study, including serious treatment-related adverse events such as intracerebral hemorrhage, infection, and serious or unanticipated adverse device effects (SADEs and UADEs).
Secondary/Exploratory Objectives:
* Evaluation of the effect of Dentate Nucleus (DN) - Deep Brain Stimulation (DBS). Ataxia severity will be quantified using the Scale of Assessment and Rating of Ataxia (SARA), Patient-Reported Outcome Measure of Ataxia (PROM-Ataxia), and kinematics.
* To characterize electrophysiological activity across the cerebellothalamocorticomuscular (CTCM) network at rest and during motor behaviors.
* To examine how DN-DBS modulates oscillatory activity and coupling across the CTCM circuit in relation to improvements in controlling ataxia.