The influence of various stimuli upon Parkinsonian tremor and rigidity

Abstract

The influence of different stimuli upon tremor and rigidity in 64 Parkinsonian patients was electro-myographically investigated. The following results were obtained: Tremor and rigidity behaved differently under the influence of diverse peripheral stimuli. The alteration of proprioceptive input had an inhibitory influence upon tremor at rest but not upon rigidity. Active contralateral movements exaggerated rigidity but had random and vague inhibitory influences upon tremor. Mental stress produced a strong exaggeration of tremor and to a lesser degree of rigidity. Visual and acoustic stimulation did not influence either rigidity or tremor. On the basis of results obtained it appears that rigidity is less dependent upon proprioceptive feedback than is tremor. In the latter pathologically altered proprioceptive feedback seems to play a more important role.