A palm-worn device to quantify rigidity in Parkinson's disease.

Area of Science:

• Biomedical Engineering
• Neuroscience
• Medical Devices

Background:

• Parkinsonian rigidity, a key motor symptom, is clinically assessed via subjective ordinal scales like the MDS-UPDRS.
• Objective, instrumented measurement of rigidity could offer greater mechanistic understanding and precision.

Purpose of the Study:

• To introduce and validate a novel palm-worn instrument for objective, continuous quantification of Parkinsonian rigidity.
• To assess the instrument's congruence with the MDS-UPDRS, its sensitivity to deep brain stimulation (DBS) and contralateral limb movement, and its performance compared to healthy individuals.

Main Methods:

• A palm-worn device was developed using a miniature motor to flex the third digit and transducers to measure forces.
• Eight participants with Parkinson's disease were evaluated on and off DBS, with and without contralateral limb activation.
• Wash-in/out effects of DBS were tracked, alongside comparisons with two blinded clinical raters and 16 healthy volunteers.

Main Results:

• The instrument demonstrated moderate agreement with the MDS-UPDRS ratings.
• Significant differences in rigidity were observed based on therapeutic state (DBS on/off), activation conditions, and disease versus healthy cohorts.
• Rigidity increased after DBS cessation and improved upon DBS resumption, with gradual changes tracked over time.

Conclusions:

• The developed instrument provides an objective, continuous measure of Parkinsonian rigidity.
• The device shows sensitivity to therapeutic interventions like DBS and contralateral movement, offering potential advantages over existing methods.
• This technology could be valuable for continuous monitoring in clinical settings or where expert raters are unavailable.