The use of a portable muscle tone measurement device to measure the effects of botulinum toxin type A on elbow flexor spasticity

Objective: To use a portable muscle tone assessment device to measure spasticity after a botulinum toxin type A (BTX-A) injection. Design: Before-after trial. Setting: Hospital. Participants: Ten chronic stroke patients with upper-limb spasticity. Intervention: BTX-A was injected in the biceps brachii. Main Outcome Measures: The biomechanic parameters, viscous component, and averaged viscosity derived from the acquired reactive resistance and angular displacements, as well as the reflex electromyographic threshold of biceps brachii, were used for spasticity evaluation. Results: A statistically significant decrease in averaged viscosity and a significant increase in reflex electromyographic threshold (P<.05) both indicated reduction in spasticity owing to BTX-A intervention. There was no clear reflex electromyographic activity detected at lower stretch frequencies. Conclusions: Our portable design allows for the convenient use of the device for quantifying spasticity in clinics. All quantitative measurements suggest that BTX-A decreases spasticity within 2 weeks of injection. Our portable muscle tone measurement device may be useful for the clinical assessment of elbow flexor spasticity.