Study objectives: To investigate the effects of apomorphine on the frequency of periodic limb movements during sleep (PLMS) and on sleep architecture.
Design: Nine patients presenting PLMS (including eight patients with restless legs syndrome) underwent three consecutive night sleep recordings. They received a single dose of 0.5 mg subcutaneous apomorphine at bedtime the third night.
Results: When computing PLMS during four 2-h periods of sleep, a significant period by apomorphine-effect was demonstrated, with a marked reduction of PLMS during the first 4 h post-injection (P < 0.01). No significant differences were found in sleep macroarchitecture between the three recorded nights, excepted a slight reduction in sleep latency during the third night (P < 0.05). Despite the decreased number of PLMS after apomorphine injection, there were significant changes neither in the total number of arousals nor in the index of arousals per hour of sleep.
Conclusion: Our results add further support to the dopaminergic hypothesis in the generation of PLMS. The persistence of arousals suggests that they are not simply the consequence of PLMS but a primary phenomenon, not related with the dopaminergic system.