Quantification of tremor with a digitizing tablet.

Handwriting and drawing are commonly employed in the clinical assessment of tremor. These tasks have been quantified heretofore by subjective rating schemes, which are incapable of providing precise measures of the amplitude and frequency of tremor. A commercially-available digitizing tablet and personal computer can be interfaced so as to reliably record any pathologic tremor that is induced by writing or drawing. Numerical differentiation and spectral analysis can be used to conveniently quantify the amplitude and frequency of tremor. However, digitizing tablets lack sufficient sensitivity to measure physiologic tremor.