Analysis and Suppression of Tremor During Grasp Using Ultrasound Imaging and Electrical Stimulation (Tremor)

Individuals experiencing tremors face difficulty performing activities of daily living caused by involuntary oscillation of the muscles in the hands and arms. Current solutions to help suppress tremors include medication, surgery, assistive devices and lifestyle change. However, each of these has a drawback of its own including cost and unwanted side effects. Aside from the solutions listed, it has been shown that functional electrical stimulation (FES) is a possible solution to help suppress tremor. Additionally, FES can be combined with different technologies including accelerometers, gyroscopes and motion capture to develop a closed loop system for tremor suppression. However, this has drawbacks including signal interference and the need for multiple sensor to fully classify the tremor. Ultrasound imaging solves some of these issues because it can provide a direct visualization of hand muscles that contribute to tremor. This study will focus on detecting characterizing and differentiating tremors from voluntary hand motion using ultrasound imaging. The results obtained from this study will help design FES-based tremor-suppression techniques in the future. This study will target both subjects with different tremor disorders and able bodied subjects.

Study Overview

• Status: Completed
• Conditions: Parkinson Disease; Essential Tremor
• Intervention / Treatment: Device: Ultrasound Imaging; Device: Electromyography; Device: Inertial Measurement Units (IMU); Device: Functional Electrical Stimulation (FES)

• Study Type: Interventional
• Enrollment (Actual): 12
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • North Carolina
    • Raleigh, North Carolina, United States, 27606
      • Engineering Building III

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 90 years (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria (Tremor Group):

1. At least 40 years of age, and no more than 90 years of age.
2. Meet UK Parkinson's disease brain bank diagnostic criteria
3. Have clinical evidence of rest tremor of one or both upper extremities defined as involuntary, rhythmic oscillations about any joint within the upper extremities
4. Tremor amplitude must be at minimum 1 cm as determined by expert opinion by a movement disorders specialist.
5. Due to the nature of measurements occurring during a grasp maneuver, the tremor must be deemed to become re-emergent with a fixed posture. This shall be defined by development of postural tremor that does not begin immediately upon grasping the vertical object, but instead with a delay in development of oscillatory movement of at least half a second as timed by a stopwatch, and that may grow in amplitude over seconds to maximum amplitude without changing the force of the grasp at first. Note that within-individual intermittency and variability of tremor can be influenced by anxiety, stress, cold temperature, and fatigue. In an effort to reduce this variability, we will have subjects perform tasks in a comfortable area, providing up to 20 minutes to allow them to relax in a temperature-neutral location, and reduce anxiety

Exclusion Criteria (Tremor Group):

1. Muscle weakness as determined by Medical Research Council grade less than 5/5 on direct testing in the upper limb afflicted with rest tremor
2. Infection at the upper limb at time of assessment
3. Pre-existing, concomitant neuromuscular or cerebellar disorders
4. Use of medications that can alter the function of the neuromuscular junction.
5. Those with concomitant essential tremor as determined by history or confirmed by movement disorders specialist prior to assessments.

Inclusion Criteria (Able Body):

Subjects will fall under the able body category if they exhibit no movement disorders and can perform grasping motion with no inhibition.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Non-Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Tremor Group; Individuals with either parkinson's disease or essential tremor will be recruited in this group	Device: Ultrasound Imaging; We will collect ultrasound images during the grasping motion for both groups; Device: Electromyography; We will collect electromyography (EMG) signals of both the flexor and extensor muscles of the wrist during the grasping motion for both groups; Device: Inertial Measurement Units (IMU); We will use data from the ultrasound images and EMG to develop a tremor model. The model will be validated in comparison to joint angle measurements from an Inertial Measurement Unit (IMU) collected during the grasping motion; Device: Functional Electrical Stimulation (FES); We will use the develop closed-loop control methods for tremor suppression using information from the ultrasound-image based tremor models. FES will be used to provide stimulation that will help with tremor suppression
Experimental: Able Body Group; Individuals with no disorders will be recruited in this group	Device: Ultrasound Imaging; We will collect ultrasound images during the grasping motion for both groups; Device: Electromyography; We will collect electromyography (EMG) signals of both the flexor and extensor muscles of the wrist during the grasping motion for both groups; Device: Inertial Measurement Units (IMU); We will use data from the ultrasound images and EMG to develop a tremor model. The model will be validated in comparison to joint angle measurements from an Inertial Measurement Unit (IMU) collected during the grasping motion; Device: Functional Electrical Stimulation (FES); We will use the develop closed-loop control methods for tremor suppression using information from the ultrasound-image based tremor models. FES will be used to provide stimulation that will help with tremor suppression

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Tremor Model Accuracy	The investigators will use ultrasound features collected on participants to develop novel models for tremor that can accurately predict the joint position. The joint position measured by the IMU will used as a benchmark and the root mean squared error (RMSE [Deg.]) between the model's predicted joint angle and the true angle will be used as a metric. A higher RMSE (in the scale of 0-100%) implies lower model accuracy.	Through Completion of Study, an average of 3 years
Ultrasound Imaging Based Frequency Detection	The investigators will benchmark the performance of the ultrasound features (fascicle length [mm], muscle thickness [mm]) in detecting the actual tremor frequency (Hz) measured by an inertial measurement unit (IMU) sensor and electromyography (EMG). Here error between the tremor frequency measured with IMU and the ultrasound feature-derived tremor frequency is reported. A lower mean error (0-100%) implies higher concurrence with the IMU-derived or EMG-derived tremor frequency.	Through Completion of Study, an average of 3 years
Tremor Suppression (Percentage)	The investigators will use the developed tremor models to develop closed loop control methods using FES which enable tremor suppression. The goal of the controller will be to maintain a desired wrist angle position while performing a grasping motion. A tremor suppression ratio metric, formulated as 1-(W_t/W_b), where W_t is the angular velocity of the wrist around the vertical during periods in which stimulation was turned on and W_b is the angular velocity during baseline periods without any stimulation, is used as an evaluation metric. A higher tremor suppression ratio (0-100%) means higher effectiveness in suppressing the tremor.	Through Completion of Study, an average of 3 years

Collaborators and Investigators

• Sponsor: North Carolina State University
• Collaborators: University of North Carolina, Chapel Hill

Study record dates

Study Major Dates

• Study Start (Actual): April 11, 2021
• Primary Completion (Actual): July 31, 2025
• Study Completion (Actual): July 31, 2025

Study Registration Dates

• First Submitted: March 16, 2022
• First Submitted That Met QC Criteria: March 25, 2022
• First Posted (Actual): April 4, 2022

Study Record Updates

• Last Update Posted (Estimated): October 27, 2025
• Last Update Submitted That Met QC Criteria: October 9, 2025
• Last Verified: October 1, 2025

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Synucleinopathies; Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Neurodegenerative Diseases; Movement Disorders; Parkinsonian Disorders; Basal Ganglia Diseases; Parkinson Disease; Essential Tremor; Diagnostic Techniques and Procedures; Diagnosis; Diagnostic Imaging; Electrodiagnosis; Myography; Ultrasonography; Electromyography
• Other Study ID Numbers: 19247; 5R21EB032059 (U.S. NIH Grant/Contract)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: IPD will not be shared outside of this research group. However, selected data may be published in academic journals, conference papers, or other publications. This data will be de-identified, and will not include the full set of data

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No