Parkinson's disease and levodopa-induced dyskinesias: a quantitative analysis through 99mTc-TRODAT-1 SPECT imaging of the brain.

Objective: To compare the dopamine transporter (DAT) density with other risk factors for L-DOPA-induced dyskinesia (LID) in patients with Parkinson's disease (PD), with and without LID.

Materials and methods: We evaluated 67 subjects: 44 patients with idiopathic PD of varying degrees of severity (PD group), and 23 healthy age-matched volunteers (control group). Among the 44 patients in the PD group, 29 were male and the following means were recorded at baseline: age, 59 ± 7 years; disease duration, 10 ± 6 years; Hoehn and Yahr (H&Y) stage, 2.16 ± 0.65; and Unified Parkinson's Disease Rating Scale part III (UPDRS III) score, 29.74 ± 17.79. All subjects underwent ^99mTc-TRODAT-1 SPECT. We also calculated specific uptake ratios or binding potentials in the striatum.

Results: The DAT density in the ipsilateral and contralateral striata was lower in the PD group. The variables disease duration, L-DOPA dosage, doses per day, L-DOPA effect duration time, H&Y stage, and UPDRS III score explained the occurrence of LID. The DAT density in the ipsilateral striatum, contralateral striatum, and caudate nucleus was lower in the patients with LID than in those without.

Conclusion: Our findings suggest that presynaptic dopaminergic denervation is associated with LID in individuals with PD.