Objective: The aim of the present study was to determine the relations of clinical symptoms with nigrostriatal neuron loss in untreated patients with Parkinson’s disease (PD).

Background: PD is an extrapyramidal neurological disorder, and the cardinal symptoms of PD are bradykinesia, rigidity, and tremor. The dopaminergic system is the most seriously affected, and initial successful therapeutic strategies are based on different forms of dopamine replacement therapy. The considerable proportion of dopaminergic neurons of substantia nigra have already degenerated at the time of diagnosis, but other areas of the nervous system are also affected by intraneuronal Lewy body function that contain aggregates of misfolded α-synuclein.

Method: Thirty-two untreated PD patients (14 men and 18 women with a mean age of 71.4 years) were included in this study. They underwent clinical assessments measured by Unified Parkinson’s Disease Rating Scale (UPDRS) and overactive bladder symptom score (OABSS) and evaluated striatal dopamine transporter (DAT) binding measured by 123I-FP-CIT SPECT. Patients were divided into high score group and low score group according to the UPDRS motor score, akinetic-rigid score, tremor score. Patients were also divided into symptomatic group and asymptomatic group due to existences of fall, freezing of gait (FOG), overactive bladder (OAB). Clinical symptoms and striatal DAT availability of PD were compared.

Results: The results showed that the striatal DAT availability was significantly lower in the high UPDRS motor score group, high akinetic-rigid score group, FOG group, OAB group than in the low UPDRS motor score group, low akinetic-rigid score group, Non-FOG group, Non-OAB group. However, results showed no significant differences between the high tremor score group or faller group, and low tremor score group or Non-faller group.

Conclusion: Severity of bradykinesia and axial symptoms and existence of FOG, OAB in untreated PD are related to a decrease in the striatal DAT availability. Severity of tremor and existence of fall are not related to a decrease in the striatal DAT availability. The mechanism of clinical symptoms of PD has not only dopaminergic pathways but also non-dopaminergic pathways. We should be conscious to relevance of degenerated dopaminergic or non-dopaminergic pathways in each symptoms.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/relations-of-clinical-symptoms-with-dopamine-transporter-imaging-in-untreated-parkinsons-disease/