Obiective measurement of muscle tone in the hand

Abstract

With a device to measure the resistance offered by the middle finger to being driven externally by a D.C. servo motor running at a constant speed, the rheologic properties inherent in muscle (elasticity, viscosity, plasticity) are studied as a basis of muscle tone, independently of neurally mediated “tonus” or “postural contraction.” Provision is made for electromyographic monitoring with intramuscular electrodes and the strain gage output is recorded by an oscillograph and an oscilloscope. The resulting record appears as a Lissaious pattern on the oscilloscope with the torque (Kg.‐cm.) recorded on the vertical axis, and displacement (degrees) on the horizontal axis. By this device the stiffness of the finger is recorded in terms of torque resisting sinusoidal position change. Such data may be used to study effects of peripheral anesthesia and tension after voluntary contraction. It may also be offered as a useful tool for evaluating the effects of drugs on spasticity and rigidity.