Daily fluctuations in movement capacity and dyskinesias are well recognized as the two major complications emerging after chronic levodopa treatment. Progressive loss of efficacy leading to severe disability and immobility is a very rare finding, most often reflecting pathological involvement beyond the limits of typical idiopathic Parkinson's disease.
Motor fluctuations may be classified in three major clinical patterns (1,2): (a) "End of dose" deterioration or "wearing off" phenomenon, in which changes in mobility are predictable and precisely related to the timing of levodopa administration. Patients with this type of motor oscillation have as many cycles as levodopa tablets they take. (b) "End of dose" with levodopa-resistant "off' periods. This category may be understood as a complication of simple "end of dose" deterioration. Off periods, which are not easily overcome by increasing or altering the timing of levodopa doses, usually occur in late afternoon or evening. (c) Complicated "end of dose" or "on-off'' phenomenon, in which individual levodopa doses may fail to improve motor function, giving rise to what seems to be unpredictable changes in mobility throughout the day. In fact such degree of variability is often reduced, albeit not abolished, when patients are rigorously tied to a given levodopa schedule after close monitoring of their motor activity during several consecutive days (on-off charts). (d) Night immobility: most patients with daily fluctuations sooner or later show this important, although often neglected, source of disability. Night parkinsonism probably has the same pathophysiolog ical basis as fluctuations during the day, but in a significant proportion of patients the degree of functional and psychological distress may outweigh other complications.
Levodopa-related dy skinesias may also be divided according to their presentation pattern in three categories: (a) "benefit of dose" dyskinesias occurring eithei during the whole on period ("square wave") or just coinciding with the time ol maximal mobility ("peak of dose"); (b) diphasic dyskinesias appearing at thc