Electromyographic assessment of spasticity.

We define the concept of muscle tone and describe the signs and symptoms of its alteration in spasticity. In assessing muscle tone it is important to consider all the inputs and outputs affecting it, using biomechanical-EMG techniques for measuring active tone. We list the various features of the myotatic and defence reflexes that are altered in spastics and analyze the altered parameters in relation to the tonic reflexes. The degree of displacement, the position from which it is initiated and the velocity of displacement constitute a specific, sensitive and reliable criterion. We report the results of a personal study of these reflexes and of the shortening reflexes.