Abstract
The pathophysiological assessment of joint properties and voluntary motion in neurological patients remains a challenge. This is typically the case in cerebellar patients, who exhibit dysmetric movements due to the dysfunction of cerebellar circuitry. Several tools have been developed, but so far most of these tools have remained confined to laboratories, with a lack of standardization. We report on a new device which combines the use of electromyographic (EMG) sensors with haptic technology for the dynamic investigation of wrist properties. The instrument is composed of a drivetrain, a haptic controller and a signal acquisition unit. Angular accuracy is 0.00611 rad, nominal torque is 6 N·m, maximal rotation velocity is 34.907 rad/sec, with a range of motion of −1.0472 to +1.0472 rad. The inertia of the motor and handgrip is 0.004 kg·m2. This is the first standardized myohaptic instrument allowing the dynamic characterization of wrist properties, including under the condition of artificial damping. We show that cerebellar patients are unable to adapt EMG activities when faced with an increase in damping while performing fast reversal movements. The instrument allows the extraction of an electrophysiological signature of a cerebellar deficit.
Highlights
Fast single-joint monodirectional movements are associated with a triphasic pattern of electromyographic (EMG) activity: a first burst in the agonist muscle is followed by a second burst in the antagonist muscle, followed by a second burst in the agonist muscle [1,2]
As compared to previous works [6,7,8,9,10,11,12], the present paper extends the application of the wristalyzer to a group of cerebellar patients and shows for the first time (1) how kinematic and electromyographic data correlate with clinical observations, and (2) the assessment of stretch reflexes in cerebellar disorders
We found a linear correlation between the AS20 Ataxia score and the hypermetria associated with the execution of fast pointing movements (FPM) during the basal mechanical state (Figure 2; p < 0.001, p = 0.014 and p = 0.002, respectively for an aimed target of 0.2, 0.3 and 0.4 rad)
Summary
Fast single-joint monodirectional movements are associated with a triphasic pattern of electromyographic (EMG) activity: a first burst in the agonist muscle (providing the launching torque) is followed by a second burst in the antagonist muscle (providing the braking torque), followed by a second burst in the agonist muscle (to bring the limb accurately to the target) [1,2]. During a fast voluntary movement, muscle damping is typically asymmetrical, predominant in the direction of muscle shortening [4]. The structures in the central nervous system (CNS) regulating the damping compensation signal have not been identified so far. It is widely accepted that the cerebellum regulates the planning and the execution of voluntary movements [5], the contribution of the cerebellar pathways in the damping compensation signal has remained elusive
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
