Spastic muscle stiffness evaluated using ultrasound elastography and evoked electromyogram in patients following severe traumatic brain injury: an observational study

Objective To determine the relationship between muscle stiffness assessed using ultrasound shear wave elastography, spinal motor neuron excitability assessed using the F wave, and clinical findings of spasticity in patients with spastic muscle overactivity following severe traumatic brain injury. Methods This study enrolled 17 inpatients with severe traumatic brain injury and 20 healthy volunteers. Biceps brachii muscle stiffness was then evaluated using ultrasound shear wave speed. Spinal motor neuron excitability was evaluated using the F/M ratio recorded from abductor pollicis brevis muscle. Clinical parameters, such as the modified Ashworth scale and modified Tardieu scale, were assessed in the patient with traumatic brain injury. Results The patients with traumatic brain injury group had a significantly higher shear wave speed and F/M ratio compared with the healthy group. A higher shear wave speed was correlated with higher clinical spastic severity in patients with traumatic brain injury. The F/M ratio was not significantly correlated with clinical spastic severity. Conclusion Ultrasound shear wave elastography might be helpful for assessing muscle stiffness in patients with spastic muscle overactivity following severe traumatic brain injury. Further studies comprising larger cohorts are warranted.