Parkinsonian action tremor in a grip-lift task: interference with object manipulation and lacking levodopa response

It has been postulated that Parkinsonian action tremor is distinct from classical resting tremor and that it may contribute to a loss of manual dexterity in Parkinson's disease. We analysed grip-lift coordination in 20 patients with Parkinson's disease. An object with and without an additional 500g weight was grasped, lifted and held for a short time with opposed thumb and index finger on the more affected side. Force sensors recorded the force exerted by both fingers. Spectral analysis of the force traces was performed. Transition times between grasping and lifting the object were measured. 18 age-matched norma…