PEDUNCULAR RUBRAL TREMOR AND DOPAMINERGIC DENERVATION - A PET STUDY

Lesions causing so-called rubral tremors frequently involve the substa ntia nigra or the nigrostriatal fibers, suggesting dopaminergic denerv ation as possibly contributory. We examined this hypothesis using PET and [F-18]-fluorodopa in six patients with a contralateral tremor foll owing a peduncular lesion. The denervation revealed by PET was even mo re marked than in severe parkinsonian patients. All patients show ed p artial to complete improvement with levodopa therapy. PET evaluation o f D-2-receptors with [Br-76]bromolisuride showed no asymmetry of the D -2 binding despite the important asymmetry of F-18-fluorodopa uptake. Our results indicate an important involvement of the nigral dopaminerg ic system in peduncular tremors that appears to be independent of post synaptic dopamine receptors.