Dynamic measurement of rigidity, strength, and tremor in Parkinson patients before and after destruction of mesial globus pallidus

Abstract

An apparatus has been constructed to record rotational torque versus arm position as the forearm is alternately flexed and extended through a 100[degree] arc. Force and displacement plots are made during both active and passive motion. Torques are recorded on a logarithmic scale ranging from [plus or minus] 0.02 to 90 foot-pounds. Thus, gross tremor and cogwheeling can be detected as a modulation of the force plot. The energy required to move the forearm through a 100[degree] arc is automatically calculated and recorded at rotational speeds ranging from 1.25 to 40[degree] per second. Preliminary tests show energy loss per cycle of passive motion is fairly proportional to muscle rigidity; rigidity is a function of the state of consciousness; simple activating procedures can be used to "precipitate" rigidity in Parkinson patients; significant changes are produced by medication and brain surgery in Parkinson''s disease.