Assessment of rest tremor in Parkinson's disease

Rest tremor is the most frequent sign of Parkinson's disease (PD) after bradykinesia, occurring with various severity in about 75% of patients. An objective assessment of rest tremor is difficult. The aim of the study was to analyze rest tremor in PD with the three-dimensional gauging system CMS 10; more specifically, the impact of levodopa treatment on rest tremor, the influence of clinical factors, and the correlation between rest tremor and clinical scales were assessed.

Ninety-five patients with PD (mean age 67.6 years) and 30 healthy people in a control group (mean age 59.3 years) were examined. Clinical scales (UPDRS, Hoehn and Yahr, Schwab and England, as well as Webster scale) were used to assess severity of PD. The assessment of rest tremor was performed within the more and less affected upper limb with the three-dimensional gauging system CMS 10 (Zebris GmbH) before and 1-2 hours after levodopa intake. Frequency (Hz), amplitude (deg), velocity (deg/ms) and acceleration (deg/s2) of the tremor were evaluated. Results were compared with averaged results for left and right upper limb in the control group.

The method used in this study objectively showed asymmetry in rest tremor. After levodopa intake, all evaluated parameters of rest tremor were decreased (mainly the amplitude and frequency, and to a lesser degree, velocity and acceleration). The motor part of UPDRS showed the best correlation with rest tremor.

The three-dimensional measuring system CMS 10 is useful in the objective assessment of rest tremor in PD. Rest tremor in PD is under the influence of PD form, the intake of levodopa dose, the amount of levodopa, gender and level of education.