Tremor suppression orthoses for parkinson's patients: a frequency range perspective

Area of Science:

• Biomedical Engineering
• Neuroscience
• Movement Disorders

Background:

• Parkinsonian tremor (PD) primarily manifests as rest tremors, but action tremors can significantly impair daily activities.
• Orthotic design for tremor suppression requires understanding tremor frequency bands and affected joints.
• Elbow tremors are less common but can be disabling in severe PD cases.

Purpose of the Study:

• To investigate tremor characteristics, including frequency and amplitude, in healthy subjects and PD patients with varying tremor severity.
• To analyze tremor patterns at the elbow joint, particularly in a PD patient with severe, widespread tremors.
• To evaluate the coexistence of classical Parkinsonian tremor and physiological tremor in PD patients and inform orthotic design.

Main Methods:

• Recruited nine subjects: six healthy, two with typical PD tremors, and one with severe PD tremors affecting fingers, wrist, and elbow.
• Measured tremor amplitude and frequency distribution at the elbow across different torque levels.
• Analyzed tremors in two frequency bands (4-6 Hz and 8-12 Hz) in the highly afflicted patient before and after medication.

Main Results:

• Typically afflicted PD patients showed comparable tremor amplitudes to healthy subjects but different frequency distributions at high elbow torque.
• The highly afflicted PD patient exhibited different tremor amplitude and frequency distribution at all elbow torque levels.
• Power spectrum and amplitude comparisons indicated that some PD patients exhibit coexisting classical and physiological tremors, necessitating broad-spectrum orthotic intervention.

Conclusions:

• PD tremor characteristics vary significantly, with some patients experiencing disabling action tremors affecting proximal joints like the elbow.
• The presence of both classical (4-6 Hz) and physiological (8-12 Hz) tremor bands in some PD patients requires orthotic solutions that address both frequencies.
• Effective tremor suppression orthoses for PD may need to target multiple frequency bands and more proximal joints, adapting to individual patient needs and affliction levels.