Failure of L-dopa to relieve activated rigidity in Parkinson's disease.

Rigidity in Parkinson patients can be easily quantitated by determining net work required to passively flex and extend the forearm through an arc of 100 degrees. Rigidity thus measured can be subdivided into two very distinct types, resting and activated. Resting rigidity, measured while the patient is relaxed, responds to all effective therapeutic agents and correlates closely to degree of clinical improvement. Activated rigidity, measured during voluntary activity, is not relieved by any presently available medical treatment. It remains unchanged at pre-therapy levels even in patients who may temporarily appear to have dramatic improvement in clinical symptomatology. Longitudinal measurements made in hundreds of parkinson patients over intervals ranging from 5 to 15 years show continuing high levels of activated rigidity through the entire period of study. In marked contrast to our wide experience with parkinson patients is a single, well documented case of Wilson's disease who appears to have recovered completely both by clinical examination and by all of our machine measurements. This patient had high levels of extrapyramidal deficit, repeatedly measured over a period of four months when penicillamine therapy was being investigated. He then suddenly reverted to normal and returned to full time employment. High values of resting rigidity activated rigidity, akinesia and resting tremor all reverted to normal and have remained normal for the past 6 years. The implication of this study is that L-dopa and related treatments only mask the symptomatology of Parkinson's disease and are not retarding the underlying pathological process. Penicillamine, on the other hand, probably does relieve the destructive process in Wilson's disease and may in early cases, permanently relieve the extrapyramidal dysfunction.