Local Field Potentials in Dystonia

Dystonia is a disabling movement disorder characterized by sustained or intermittent muscle contractions that cause abnormal postures and movements. Deep brain stimulation (DBS) of the globus pallidus interna (GPi) is an established treatment for patients who do not respond adequately to first-line therapies such as botulinum toxin. However, clinical response to DBS in dystonia is highly variable, and optimization of stimulation settings often requires months of trial and error. This delay can prolong disability and increase healthcare burden.

Local field potentials (LFPs) are neural signals recorded from implanted DBS electrodes. In Parkinson's disease, LFP analysis has been used to guide programming and develop adaptive stimulation strategies. In dystonia, early studies suggest that low-frequency LFP peaks (typically in the alpha-theta range) may correlate with disease severity and optimal stimulation sites, but these findings have been limited to short-term recordings using externalized leads. The Medtronic Percept™ DBS system now allows chronic sensing of LFPs during routine clinical care, creating an opportunity to validate these observations and assess their clinical utility.

This single-site, prospective study will evaluate whether LFP profiles recorded from the GPi can guide DBS programming in patients with primary dystonia. The study includes an internal pilot phase followed by two main cohorts. Cohort 2 will undergo traditional programming based on clinical assessment and imaging, with LFP recordings collected at each visit. Cohort 3 will use an LFP-guided approach, selecting contacts and stimulation parameters based on the site and characteristics of LFP peaks. Participants will be followed for up to 12 months, with blinded video assessments and standardized rating scales to compare outcomes between programming strategies. Neurophysiological measures such as surface electromyography (EMG), electroencephalography (EEG), and reaction time tasks will also be collected to explore mechanistic links between stimulation and motor control.

The study aims to determine whether LFP analysis can shorten the time to optimal DBS settings and improve clinical outcomes compared to traditional methods. If successful, this approach could inform future development of adaptive DBS systems for dystonia, reducing variability in care and improving patient quality of life.

Inclusion criteria

• Age 18 years or older at screening.
• Clear clinical diagnosis of primary dystonia (idiopathic or genetic forms).
• Candidate for GPi DBS surgery for dystonia treatment.
• Able to provide informed consent.

Exclusion criteria

• Significant neurological or psychiatric disorder (including dementia) that would interfere with outcome evaluation.
• Participation in a therapeutic research trial within the last year.
• Diagnosis of functional (psychogenic) dystonia.