Quantitative assessment of parkinsonian and essential tremor: clinical application of triaxial accelerometry.

Triaxial accelerometry was used to study various motion characteristics in 10 patients with Parkinson disease and 11 patients with essential tremor. The smoothness of motion factor (SPMEF) and the acceleration waveform factor (TIPAR) were frequently and consistently abnormal. When both factors were analyzed together and compared with a control population, 100% of the left arm and 88% of the right arm values were abnormal in the Parkinson disease group, and 82% of the left arm and 91% of the right arm values were abnormal in the essential tremor patients. Repeat evaluation revealed consistent intrapatient results. Therefore, this technique may provide an objective assessment of movement disorders.