[A biomechanical analysis of cyclical hand motor function: a pilot study in different Parkinsonian syndromes]

Clinical assessment of hand bradykinesia in Parkinson's disease (PD) focuses mainly on the frequency, amplitude and rhythm of movements, thereby subjectively evaluating the correct performance of hand movements. The aim of the study was to quantify hand bradykinesia with kinematic data in different Parkinsonian syndromes.

This retrospective study compared patients with idiopathic PD (IPD, n = 18), atypical Parkinson's syndrome (APS, n = 17), secondary Parkinson's syndrome (SPS, n = 18) and healthy controls (C, n = 18). All patients were receiving the best medical treatment. Hand movements were recorded using an ultrasound-system (Zebris®, Isny, Germany). Subjects were asked to perform pronation/supination of the forearm (diadochokinesis), flexion/extension of the hand (hand tapping) and tapping of the index finger. Mean amplitude, mean frequency and mean variability of movements were determined.

APS patients had significant complex hand movement disability with reduced amplitude and frequency in combination with increased motion variability in all movement tasks. The key disturbance in the IPD group concerned the rhythm in hand tapping and index finger tapping in combination with moderately reduced velocity and range of motion in all conditions. The cyclical hand movement characteristics in SPS patients showed movement slowness with normal amplitude and variability in all motor conditions.

Our results suggest that computerized quantitative analysis of cyclical hand movements can characterize and identify different representations of hand bradykinesia in different Parkinsonian disorders and hence may help clinicians to accurately assess therapeutic targets and outcome of interventions.