DBS for Visuomotor Function in Parkinson's Disease (NCT05400499)

Deep Brain Stimulation for Visuomotor Function in Parkinson's Disease

Overview

This observational clinical trial investigates how deep brain stimulation (DBS) of the subthalamic nucleus (STN) affects visuomotor function in patients with Parkinson's disease. Specifically, the study focuses on vergence — the coordinated movement of both eyes to maintain binocular alignment when focusing on objects at different distances. Vergence deficits are a common but understudied non-motor symptom in PD that affects reading, depth perception, and daily activities.

Deep Brain Stimulation for Visuomotor Function in Parkinson's Disease

Overview

This observational clinical trial investigates how deep brain stimulation (DBS) of the subthalamic nucleus (STN) affects visuomotor function in patients with Parkinson's disease. Specifically, the study focuses on vergence — the coordinated movement of both eyes to maintain binocular alignment when focusing on objects at different distances. Vergence deficits are a common but understudied non-motor symptom in PD that affects reading, depth perception, and daily activities.

The study aims to characterize how STN DBS influences vergence metrics and identify optimal stimulation locations and parameters that can preserve motor symptom control while improving binocular coordination.

Trial Details

| Parameter | Value |
|-----------|-------|
| NCT Number | NCT05400499 |
| Status | Recruiting |
| Phase | Not Applicable (Observational) |
| Sponsor | VA Office of Research and Development |
| Study Type | Observational (Cohort) |
| Enrollment | 40 participants (estimated) |
| Start Date | October 4, 2022 |
| Primary Completion | June 30, 2026 |
| Completion Date | July 1, 2026 |
| Location | Louis Stokes VA Medical Center, Cleveland, OH |

Scientific Rationale

Why Study Vergence in PD?

Parkinson's disease affects not only motor function but also oculomotor control. Patients with PD commonly experience:

These deficits impact:

• Reading ability and speed
• Depth perception (affecting driving, walking on stairs)
• Fine visual tasks
• Quality of life

Subthalamic Nucleus and Oculomotor Control

The [subthalamic nucleus](/cell-types/subthalamic-nucleus-neurons) (STN) is a key component of the basal ganglia-thalamocortical circuit and a primary target for DBS in Parkinson's disease. While STN DBS is highly effective for motor symptoms (rigidity, bradykinesia, tremor), its effects on oculomotor function are less understood.

The STN has connections to:

• Premotor cortex — movement planning including eye movements
• Superior colliculus — orienting responses and eye movements
• Brainstem nuclei — controlling eye muscle activation
• Thalamus — sensory integration for motor commands

Patient-Specific Modeling Approach

A key innovation of this study is integrating patient-specific DBS models with high-resolution eye-tracking:

This approach allows researchers to correlate specific stimulation locations with vergence outcomes, potentially enabling optimized targeting for both motor and oculomotor symptoms.

Study Design

Participant Population

The study enrolls veterans with Parkinson's disease who have undergone bilateral STN DBS implantation:

Inclusion Criteria

• Parkinson's disease with bilateral STN DBS
• Pre-operative MR images available
• Post-operative MRI or CT scans available
• Hoehn and Yahr stage 2-4 when off medication
• Stable antiparkinsonian medication regimen
• Stable DBS parameter settings

Exclusion Criteria

• Previous surgical therapy for Parkinson's disease (other than DBS)
• [Dementia](/diseases/dementia)
• Clinically significant untreated depression or anxiety
• Clinical features suggestive of atypical parkinsonism

Outcome Measures

Primary Outcome: Eye Alignment (Vergence)

The primary outcome measure is dynamic eye alignment measured using non-invasive high-resolution video oculography:

| Metric | Description |
|--------|-------------|
| Vergence ratio | Ratio of actual versus desired vergence movements |
| Vergence latency | Delay from target change to vergence onset |
| Peak vergence velocity | Maximum speed of vergence eye movements |
| Binocular congruency | Agreement between left and right eye positions |

Assessment Protocol

Participants perform vergence tasks while their eye movements are recorded:

• Duration: 1 hour testing session
• Paradigms: Step and ramp stimuli at various distances
• Measurement: High-resolution video oculography

Clinical Significance

Non-Motor Symptoms in PD

Non-motor symptoms are increasingly recognized as major contributors to disability in Parkinson's disease:

• Visual dysfunction affects up to 78% of PD patients
• Reading difficulty is a common complaint
• Reduced quality of life from oculomotor deficits

Optimizing DBS Parameters

By correlating stimulation location with vergence outcomes, this research may enable:

Veterans Health Priority

As a VA-funded study, this research directly addresses the health needs of veterans with Parkinson's disease, a population with significant service-related exposures and age-related neurodegenerative disease risk.

Research Team

| Role | Name | Contact |
|------|------|---------|
| Principal Investigator | Aasef G. Shaikh, MD PhD | (216) 791-3800 ext 60000 |
| Study Coordinator | Monica O'Loughlin | (216) 791-3800 |
| Study Coordinator | Cheryl Dudek | 216-679-3800 |

Institution: Louis Stokes VA Medical Center, Cleveland, OH 44106-1702

Related Pages

• [Parkinson's Disease](/diseases/parkinsons-disease)
• [Deep Brain Stimulation](/therapeutics/deep-brain-stimulation)
• [Subthalamic Nucleus](/cell-types/subthalamic-nucleus-neurons)
• [Oculomotor Nucleus](/cell-types/oculomotor-nucleus-neurons)
• [Basal Ganglia](/brain-regions/basal-ganglia)
• [Clinical Trials in Parkinson's Disease](/clinical-trials/parkinsons-disease)
• [VA Parkinson's Disease Research](/institutions/va-parkinsons-disease-research)

External Links

• [ClinicalTrials.gov: NCT05400499](https://clinicaltrials.gov/study/NCT05400499)
• [Louis Stokes VA Medical Center](https://www.cleveland.va.gov/)
• [VA Office of Research and Development](https://www.research.va.gov/)

References