Aktuelle Neurologie 2005; 32 - M22
DOI: 10.1055/s-2005-919186

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

R Wenzelburger 1, J Raethjen 1, S Pohle 1, R Govindan 1, A Morsnowski 1, G Deuschl 1
  • 1Kiel

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 normal volunteers served as a control group.

While holding the object there were force oscillations in the 3.5–6.5Hz band indicating (re-emerging) classical Parkinsonian tremor in 65% of the patients. This was reduced to 15–20% under medication with levodopa. Oscillations in the 6–15Hz band were found in 30% of the patients (in 50% with weight), remaining unchanged under levodopa, and in 10% of the normal controls (in 20% with weight). During lift initiation 6–15Hz oscillations were found in all patients and in the majority of controls. The 6–15Hz band power was positively correlated with the movement transition times in the severely akinetic patients and was significantly higher than in controls. It remained unchanged under levodopa.

The present data confirm that Parkinsonian action tremor activated during complex voluntary movements is distinct from classical resting tremor. It shows no clear levodopa response but affects dextrous movement coordination when associated with clinically severe overall akinesia.