Development and preliminary validation of a multimodal instrument for spasticity quantification using a composite...

Area of Science:

• Biomedical Engineering
• Rehabilitation Medicine
• Neurology

Background:

• Spasticity is a common neuromuscular impairment following conditions like cerebral palsy and stroke.
• Current spasticity assessment relies heavily on subjective clinical scales, limiting objective quantification.
• There is a need for reliable, objective methods to measure spasticity severity and guide treatment.

Purpose of the Study:

• To develop and preliminarily validate a multimodal wearable instrument for objective spasticity quantification.
• To create a Composite Index integrating multiple sensor data for spasticity stratification.
• To assess the feasibility of the system in individuals with upper-limb spasticity.

Main Methods:

• A wearable system integrating surface electromyography (sEMG), inertial measurement units (IMUs), and force sensors was designed.
• Data on muscle activation, joint kinematics, and resistance force were collected during passive mobilizations.
• Principal component analysis and min-max normalization were used to derive a Composite Index from six area under the curve (AUC)-based indicators.

Main Results:

• The Composite Index successfully differentiated between spasticity severity levels (p=0.0327).
• Three latent components explained 83.86% of the observed variance in spasticity indicators.
• Surface electromyography activity during slow stretch (AUC sEMG R2) was the most significant contributor to the index.

Conclusions:

• The developed multimodal instrument shows preliminary feasibility for objective spasticity quantification.
• The system offers a non-invasive, portable approach for assessing spasticity in cerebral palsy and stroke patients.
• Further validation in larger cohorts is warranted to confirm its clinical utility.