A new method for selective measurement of joint movement in hand tremor in Parkinson's disease patients.

Parkinson's disease (PD) is a progressive degenerative disorder of the central nervous system with tremor being one of its four main clinical features. Currently used methods can directly evaluate tremor amplitude and frequency but not joint movement in the affected limb. Measurement of joint movement facilitates the location of muscle groups that participate in PD tremor and this is important for treatment with local botulinum toxin injections. We developed and tested a method that measured tremor amplitude and frequency in a specific joint of the hand in PD patients. The tremor analysis method was based on force transducers adapted to record rest tremor of the wrist and metacarpophalangeal joints in two degrees of freedom for each joint. Direct measurements of joint movement in the hand can evaluate tremor amplitude and frequency and also locate the muscle groups that are most active in tremor movement, thus enabling their local treatment.