With the aim of assessing dopaminergic responsiveness in essential blepharospasm, we investigated the effects of oral levodopa and subcutaneous apomorphine on blink reflex recovery cycle in 7 blepharospasm patients. We found that in blepharospasm the excitability of the blink reflex recovery cycle was increased compared with control subjects. The oral administration of levodo-pa/carbidopa (500/50 mg) did not significantly modify the blink reflex recovery cycle. The 50 µg/kg dose of apomorphine decreased the amplitude of conditioned responses at 300 and 500 ms, whereas the 10 µg/kg dose was ineffective. We conclude that the excitability of the blink reflex recovery cycle in blepharospasm is partly under dopaminergic control. The partial normalization of the blink reflex recovery cycle excitability observed with 50 µg/kg apomorphine is consistent with the reported clinical efficacy of the drug in this condition.

Keywords:
Essential blepharospasm, Blink reflex recovery cycle, Dopaminergic responsiveness, Levodopa, Apomorphine
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© 1997 S. Karger AG, Basel
1997
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