Abstract
Background: Classifying PD into tremor dominant (TD) and postural instability gait difficulty (PIGD) subtypes may have several limitations, such as its diagnostic inconsistency and inability to reflect disease stage. In this study, we investigated the patterns of progression and dopaminergic denervation, by prospective evaluation at regular time intervals.Methods: 325 PD dopamine replacement drug-naïve patients (age 61.2 ± 9.7, M:F = 215:110) were enrolled. Patients were grouped into TD, indeterminant, and PIGD subtypes. Clinical parameters and I-123 FP-CIT SPECT images of each groups were analyzed and compared at baseline, 1, 2, and 4 years of follow up periods.Results: Baseline I-123 FP-CIT uptakes of the striatum were significantly higher in the TD group compared with the indeterminant group and PIGD group (p < 0.01). H & Y stage and MDS-UPDRS part III scores of the indeterminant group were significantly worse at baseline, compared with the TD and PIGD groups (p < 0.001 and p < 0.01, respectively), and MDS-UPDRS part II scores of the indeterminant group were significantly worse than the PIGD group (p < 0.001). There were no other significant differences of age, gender, weight, duration of PD, SCOPA-AUT, MOCA, usage of dopamine agonists, and levodopa equivalent daily doses at baseline. After 4 years of follow up, there were no differences of I-123 FP-CIT uptakes or clinical parameters, except for the MDS-UPDRS part II between the TD and indeterminant group (p < 0.05). The motor-subtypes were reevaluated at the 4 years period, and the proportion of patients grouped to the PIGD subtype increased. In the reevaluated PIGD group, MDS-UPDRS part II score (p < 0.001), SCOPA-AUT (p < 0.001), the proportion of patients who developed levodopa induced dyskinesia were higher than the reevaluated TD group, and the striatal I-123 FP-CIT uptakes were significantly lower (p < 0.01).Conclusion: There are no significant differences of symptoms and dopaminergic innervation between the TD and PIGD group after a certain period of follow up. Significant portion of patients switched from the TD subtype to the PIGD subtype during disease progression, and had a worse clinical prognosis.
Highlights
Parkinson’s disease (PD) is a neurodegenerative disorder that is mainly known for the deterioration of one’s motor functions
There are some controversies on this topic, while some report the tremor dominant (TD) subtype to have a better prognosis and mild disease progression rate compared with the postural instability gait difficulty (PIGD) subtype, while others claim no differences of long term outcomes (6– 15)
H & Y stage and MDS-UPDRS part III scores of the indeterminant group were significantly worse at baseline, compared with the TD and PIGD groups (P < 0.001 and P < 0.01, respectively), and MDS-UPDRS part II scores of the indeterminant group were significantly worse than the PIGD group (P < 0.001)
Summary
Parkinson’s disease (PD) is a neurodegenerative disorder that is mainly known for the deterioration of one’s motor functions It is accompanied by a broad spectrum of non-motor symptoms such as cognitive decline, mood disorder, sleep disorder, and autonomic dysfunction (1), and each PD patient presents with heterogenous symptoms and progression rates (2). Several studies have depicted different patterns of striatal dopaminergic denervation between the two subtypes (16, 17), and some studies investigated the patterns of dopamine denervation in different motor subtypes of PD, via [I-123] N-ω-fluoropropyl- 2β-carbomethoxy- 3β(4-iodophenyl) nortropane (I-123 FP-CIT) SPECT imaging. They have have failed to show a consistent description. We investigated the patterns of progression and dopaminergic denervation, by prospective evaluation at regular time intervals
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