Two methods of measuring muscle tone applied in patients with decerebrate rigidity.

Two methods were used to measure muscle tone in patients with decerebrate rigidity. In the first method forces of square waveform were applied and the calculated compliance of the joint was used as an index of rigidity. Oscillatory transients were seen at the same frequency as the physiological tremor. The range of normal variation in compliance was large and the values measured in the patients flucuated markedly which limited the value of this index. In the second method, where forces of sinusoidal waveform were employed, the resonant frequency of the joint was measured and used as an index of rigidity. This index proved reliable and reproducible.