Deep Brain Stimulation for Spinocerebellar Ataxia

Inclusion Criteria:

1. A diagnosis of SCA6 by a Movement Disorders specialist following established criteria recommended by the Movement Disorders Society.
2. A positive genetic test for SCA6.
3. A total scale ≥ 8 on the Scale of the Assessment and Rating of Ataxia (SARA) rating scale.
4. Ability to walk with or without support (score \< 8 on the 'gait' subsection of the SARA rating scale).
5. Age ≥ 21 years and \< 89 years.
6. Ability to give informed consent for the study.
7. Be able to understand the study protocol.

Exclusion Criteria:

1. Inability or unwillingness to comply with the study protocol.
2. History of previously implanted neurostimulators, pacemakers, defibrillators, or metallic head implants.
3. Severe cognitive impairment or dementia, defined as a score \< 21 on the Montreal Cognitive Assessment (MoCA).
4. Evidence of ataxia due to other etiologies, including but not limited to:

   1. Genetic/inherited disorders other than SCA6.
   2. Acquired causes: tramautic brain injury, multiple sclerosis, paraneplastic cerebellar degeneration, infections or post-infectious cerebellitis, autoimmune ataxias (e.g., anti-GAD, gluten ataxia).
   3. Toxic/metabolic causes: alcoholic cerebellar degeneration, vitamin deficiencies.
   4. Structural, vascular, or neoplastic causes: cerebellar stroke, tumors, congenital malformations.
   5. Suspected multiple system atrophy-cerebellar type (MSA-C).
5. The presence of active and untreated psychiatric illness, severe depression (Beck Depression Inventory ≥ 21), or personality disorder at the discretion of the study team.
6. Coagulopathy, uncontrolled epilepsy, or other medical condition considered to place the patient at elevated risk for surgical complications. Presence of a concomitant medical condition that, in the investigator's opinion, may interfere with the study participation or gait/balance, for example, severe arthritis.
7. Presence of a concominant medical condition that, in the investigator's opinion, may interfere with the study participation or gait/balance, for example, severe arthritis.
8. Requirement of diathermy, electroconvulsive therapy, or transcranial magnetic stimulation.
9. Pregnancy or lactation.
10. Active suicidal ideation, defined as fined as a "Yes" response to questions #2-5 on the Columbia Suicide Severity Rating Scale, C-SSRS.
11. Refractory Epilepsy.