Controllable mechanical tremor reduction. Assessment of two orthoses

This paper presents the results of clinical trials performed using two upper-limb orthotic devices for tremor suppression, developed under the Fifth Framework Project DRIFTS (Contract QLK6-CT-2002-00536). The orthoses were tested on six subjects presenting various aetiological forms of tremor. Two different strategies of tremor reduction were investigated: viscous friction and notch filtering. The results obtained from the trials suggest that ambulatory and controllable mechanical suppression of tremor by orthotic means is a feasible intervention. The degree of tremor reduction is dependent upon the power associated with tremor. Expected reduction of tremor can be as high as 98% in severe cases. There are hints that for many persons suffering with tremor active mechanical suppression of tremor can produce a reinforcing feedback: when participants perceived and initial reduction of tremor due to the orthosis, they exhibited a further spontaneous reduction of the tremor. There are also indications in some participants that tremor can migrate from a controlled joint to other free joints.