Tremor is an approximately rhythmic, roughly sinusoidal involuntary movement. Despite nearly a century of modern clinical and laboratory investigations, no tremor is understood completely. Human tremors derive from different etiologies and thus, not suprisingly, the physiologies are diverse. Tremors may derive from mechanical oscillations, mechanical reflex oscillations, normal central oscillators, and pathologic central oscillators. However the definitive identification of oscillators for any tremor have not yet been established. Measuring tremor clinically is difficult because tremors behave in different and often complex ways. There are several different techniques for measuring tremor. One of most popular and sensitive methods use accelerometries. An excellent method consists of accelerometry and EMG combined with spectral analysis and weighting of the body part, which allows separation of tremors coming from mechanical reflex and central oscillators. Now times, increased power and speed of microprocessors enable clinical laboratories to quantify tremor and other aspects of motor disability with accuracy and precision not possible a decade ago.
