Disturbance of vertical saccadesis a cardinal feature of progressive supranuclear palsy (PSP). We investigated whether the amplitude and peak velocity of saccades is affected by the orbital position fromwhich movements start in PSP patients and age-matched control subjects. Subjects made vertical saccades in response to ± 5 degree vertical target jumps with their heads in one of three positions: head “center,” head pitched forward ~15 degrees, and head pitched back ~ 15 degrees.All patients showed some effect of starting eye position, whether beginning in the upward or downward field of gaze, on saccade amplitude, peak velocity (PV), and net range of movement. Generally, reduction of amplitude and PV were commensurate and bidirectional in the affected hemifield of gaze. Such findings are unlikelyto be due to orbital factors and could be explained by varying degrees of involvement of rostral midbrain nucleiin the pathological process.

Objective

To determine whether low concentrations of a dopamine agonist worsen parkinsonism, which would suggest that activation of presynaptic dopamine autoreceptors causes a super-off state.

Design

Randomized, double-blind, placebo-controlled, crossover clinical trial.

Setting

Academic movement disorders center.

Patients

Patients with Parkinson disease and motor fluctuations.

Intervention

Fourteen patients with Parkinson disease and motor fluctuations were randomized to receive 1 of 6 possible sequences of placebo, low-dose (sub-threshold) apomorphine hydrochloride, and high-dose (threshold to suprathreshold) apomorphine hydrochloride infusions. Subthreshold doses of apomorphine hydrochloride (12.5 μg/kg/h every 2 hours and 25 μg/kg/h every 2 hours), threshold to suprathreshold doses of apomorphine hydrochloride (50 μg/kg/h every 2 hours and 100 μg/kg/h every 2 hours), and placebo were infused for 4 hours daily for 3 consecutive days.

Main Outcome Measures

Finger and foot tapping rates.

Results

There was no decline in finger or foot tapping rates during the low-dose apomorphine hydrochloride infusions relative to placebo. The high-dose infusions increased foot tapping (P<.001) and trended toward increasing finger tapping compared with placebo infusions.

Conclusions

Subthreshold concentrations of apomorphine did not worsen parkinsonism, suggesting that pre-synaptic dopamine autoreceptors are not important to the motor response in moderate to advanced Parkinson disease.

Glutamate antagonists decrease dyskinesia and augment the antiparkinsonian effects of levodopa in animal models of Parkinson’s disease (PD). In a randomized, double-blind, placebo-controlled clinical trial we investigated the acute effects of placebo and two doses of a NR2B subunit selective NMDA glutamate antagonist, CP-101,606, on the response to two-hour levodopa infusions in 12 PD subjects with motor fluctuations and dyskinesia. Both doses of CP-101,606 reduced the maximum severity of levodopa-induced dyskinesia approximately 30% but neither dose improved parkinsonism. CP-101,606 was associated with a dose-related dissociation and amnesia. These results support the hypothesis that glutamate antagonists may be useful antidyskinetic agents. However, future studies will have to determine if the benefits of dyskinesia suppression can be achieved without adverse cognitive effects.