14 February 2012
Chen R
Despite many recent advances in the treatment of Parkinson disease (PD),
levodopa is still the most effective medication for PD. While there are
many "nondopaminergic" features of PD that do not improve with
levodopa, PD motor symptoms generally improve with dopaminergic
medications.
However, not all the motor manifestations of PD are
improved to the same extent and some may not respond at all to levodopa.
Tremor is often less responsive to levodopa than bradykinesia.
Different aspects of bradykinesia may even respond differently. For
example, recent studies showed that with self-paced finger and hand
movement tasks similar to those used in the Unified Parkinson's Disease
Rating Scale, levodopa improved the speed of movement but had little
effect on the amplitude of movement and on movement fatigue, although
impairment of movement amplitude was more prevalent than impairment of
speed in PD.
In contrast, when finger tapping was paced to an
external rhythm, patients with PD had a dramatic reduction in the
amplitude of movement when the tapping rate was higher than 2 Hz and
this reduction in amplitude did not improve with levodopa.
