Parkinsonian Tremor

Parkinsonian tremor is an involuntary, rhythmic shaking that occurs primarily at rest and is associated with Parkinson's disease. It is caused by the reciprocal activation of antagonistic muscle groups and typically has a frequency of 4-6 Hz with a harmonic frequency distribution, meaning the frequencies occur at integer multiples of the peak frequency and decrease in amplitude with each successive harmonic. In the context of accessibility, Parkinsonian tremor significantly affects a person's ability to use standard computer pointing devices, with the tremor characteristically attenuating during goal-directed movement but present when the hand is at rest.