The challenge

Spasticity is a muscle disorder that occurs in commonly in stroke patients. In spasticity, the affected muscle becomes abnormally stiff and results in abnormalities of joint movements.  Prolonged and severe spasticity can cause pain and contractures of joints with resultant impairment on function. For example, spasticity of the upper limb can impair upper limb use and that of the lower limb can affect gait. Spasticity is a common complication in stroke patients with a prevalence of 30-80%. In a study of chronic stroke patients attending a rehabilitation clinic locally, many patients had symptomatic upper limb spasticity.

 In clinical practice, spasticity is evaluated by moving the affected joint through its range of motion, and then grading the degree of resistance felt as the joint is moved. Clinical scales used include the Modified Ashworth Scale and the Tardieu Scale. Although these scales are easy to use, they are subjective, has low inter-rater reliability and are not sensitive to mild changes in spasticity. Limited methods of quantitative measurements of spasticity exist, but these methods involve the use of bulky and complex systems, and are not practical for routine clinical use.

Thus there is a need for a technological solution that can measure spasticity reliably and with ease.

The proposed solution

This project aims at developing a wearable and portable solution for precise spasticity diagnosis. The combination of an actuator and a sensor lays the foundation of the wearable device. When integrated in a wearable cuff, the assembly can be applied on a certain muscle or muscle group with the sensor close to the muscle and the actuator on the outer layer. The actuator could be inflated controllably and then cause a bending motion in the sensor to register a voltage output. The amplitude and waveform of such a voltage output could be used to correlate, calibrate, and determine the severity of spasticity.

To assist the functioning of the wearable device, a testing system comprising an actuator module and a voltage readout circuit was developed with a microcontroller in a portable system. It can further communicate with a computer to enable real-time data display and digital analyses for the ease of routine clinical applications.