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Completed

NCT Number: NCT05308368

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

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.

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Key information

Conditions

Parkinson Disease Basal Ganglia Diseases Brain Diseases Central Nervous System Diseases Essential Tremor Movement Disorders Nervous System Diseases Neurodegenerative Diseases Parkinsonian Disorders Synucleinopathies

Age range

18 year–90 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Engineering Building III

Raleigh, North Carolina, 27606, United States

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

(Tremor Group):

  • At least 40 years of age, and no more than 90 years of age.
  • Meet UK Parkinson's disease brain bank diagnostic criteria
  • Have clinical evidence of rest tremor of one or both upper extremities defined as involuntary, rhythmic oscillations about any joint within the upper extremities
  • Tremor amplitude must be at minimum 1 cm as determined by expert opinion by a movement disorders specialist.
  • 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):

  • Muscle weakness as determined by Medical Research Council grade less than 5/5 on direct testing in the upper limb afflicted with rest tremor
  • Infection at the upper limb at time of assessment
  • Pre-existing, concomitant neuromuscular or cerebellar disorders
  • Use of medications that can alter the function of the neuromuscular junction.
  • 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.

Treatment and study plan

Ultrasound Imaging

Device

We will collect ultrasound images during the grasping motion for both groups

Electromyography

Device

We will collect electromyography (EMG) signals of both the flexor and extensor muscles of the wrist during the grasping motion for both groups

Inertial Measurement Units (IMU)

Device

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

Functional Electrical Stimulation (FES)

Device

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

Primary outcomes

  1. Tremor Model Accuracy

    Time frame: Through Completion of Study, an average of 3 years

    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.

  2. Ultrasound Imaging Based Frequency Detection

    Time frame: Through Completion of Study, an average of 3 years

    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.

  3. Tremor Suppression (Percentage)

    Time frame: Through Completion of Study, an average of 3 years

    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.

Sponsors and collaborators

Lead sponsor

North Carolina State University

Other

Collaborators

  • University of North Carolina, Chapel Hill

Registry information

Acronym: Tremor

Important dates

Study start
2021
Primary completion
2025
Study completion
2025
First posted
Apr 4, 2022
Registry last updated
Oct 27, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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