Striatal dopaminergic function in restless legs syndrome -: 18F-dopa and 11C-raclopride PET studies

Objective: To use PET to study striatal dopaminergic function in restless legs syndrome (RLS). Background: RLS is a common disorder experienced by as much as 5% of the population. It has been suggested that this condition is associated with a disturbance of dopaminergic transmission. Methods: The authors measured nigrostriatal terminal dopamine storage with F-18-dopa and striatal D-2 receptor binding with C-11-raclopride PET in 13 RLS patients, five of whom were receiving treatment with L-dopa at the time of scanning. RLS results were compared with those of age-matched control subjects. Results: Mean caudate and putamen F-18-dopa uptake were mildly reduced in the RLS patients compared with control subjects, and this reached significance (p = 0.04) in the putamen. Mean D-2 binding was reduced in the caudate (p = 0.01) and the putamen (p = 0.008) in RLS patients compared with control subjects. Six of the 13 RLS patients had caudate and putamen D-2 binding reduced below the control range. Three other RLS patients showed only reduced putamen D-2 binding. There were no significant differences in striatal F-18-dopa uptake or D-2 binding between L-dopa-naive and L-dopa-treated RLS patients. Conclusions: These PET findings support the hypothesis of central dopaminergic dysfunction in RLS.