Ambulatory objective assessment of tremor in Parkinson's disease.

Continuous ambulatory multichannel accelerometry (CAMCA) has recently been validated for the assessment of hypo-and bradykinesia and body position in patients with Parkinson's disease (PD). This study aims to validate CAMCA for the assessment of resting tremor in patients with PD. First, in seven patients with PD with varying degrees of tremor severity, a tremor detection algorithm was developed. Second, 59 patients with PD and 43 age-matched controls were assessed with CAMCA during 24 hours. Duration and intensity of resting tremor, and measures reflecting hypo-and bradykinesia and body position were calculated for the diurnal period. In part 1 of the study, the tremor detection algorithm had a high sensitivity (0.82) and specificity (0.93). Ambulatory monitoring revealed that categories with higher clinical tremor severity had increased objective values for duration and intensity of tremor. Duration and intensity of tremor were correlated with the clinical score for resting tremor (Spearman's rank correlation: 0.66-0.77). Measures for hypo-and bradykinesia differed between patients and controls, but not between groups of patients defined by tremor severity. This study has validated continuous ambulatory multichannel accelerometry for the assessment of tremor in PD, while simultaneously measuring hypo-and bradykinesia and body position.