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The purpose of this study was the evaluation of pupil light reflex (PLR) in patients with Parkinson's disease (PD) by using a modern pupillometry system and the investigation of its potential relationship with dopamine transporter imaging (DaTSCAN), which is an objective method for the evaluation of presynaptic dopaminergic system. PLR was evaluated using pupillometry in 35 patients with PD without clinical evidence of autonomic dysfunction and 44 healthy matched controls. PLR was elicited using a fully automated pupillometry system and six parameters were measured. Dopamine transporter imaging was performed using radioactive ioflupane 123I-FP-CIT [[123I-N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl)-nortropane]]. A significant increase in latency and a significant decrease in amplitude, maximum constriction velocity, as well as maximum acceleration were observed in PD patients. There was no significant difference in initial radius and minimum radius values. Investigating the relationship between pupillometry parameters and 123I-FP-CIT binding values, we correlated values from the semiquantitative analysis of radioligand uptake with pupillometry parameters, but we found no significant correlation. This study demonstrates PLR impairment in patients with PD without overt autonomic dysfunction. This impairment does not seem to correspond to the reduction of radioligand binding in the striatum as the result of presynaptic dopaminergic dysfunction, suggesting a different deterioration rate of these systems. [ABSTRACT FROM AUTHOR]

Parkinson 's disease (PD) is characterized by progressive loss of dopaminergic neurons in the nigrostriatal pathway, but this seems to constitute only part of the whole pathological process of the disease. Accumulating data have documented the concomitant degeneration of other dopaminergic pathways and of the serotonergic, cholinergic and noradrenergic neurotransmitter systems. In addition, pathologic process is not only restricted in the brain, since the spinal cord and the peripheral autonomic nervous system are also affected. The pathogenesis of PD remains unclear. The use of positron emission tomography and single photon emission tomography may contribute to the understanding of these aspects of the disease. This review will discuss the role of PET and SPET in imaging the extrastriatal dopaminergic system and other neurotransmitter systems as well as the imaging of microglial activation and cardiac sympathetic denervation in PD. In conclusion, several PET and SPET ligands can detect changes in extrastriatal dopaminergic system as well as in the serotonergic, cholinergic and noradrenergic systems in PD and also explore its possible correlation with motor and non motor symptoms. The use of PET scintigraphy allows the detection of microglial activation in PD, while (123)I-MIBG scintigraphy depicts cardiac sympathetic denervation in PD and is a useful imaging tool for differentiating PD from other types of parkinsonism.

The purpose of this study was the evaluation of pupil light reflex (PLR) in patients with Parkinson's disease (PD) by using a modern pupillometry system and the investigation of its potential relationship with dopamine transporter imaging (DaTSCAN), which is an objective method for the evaluation of presynaptic dopaminergic system. PLR was evaluated using pupillometry in 35 patients with PD without clinical evidence of autonomic dysfunction and 44 healthy matched controls. PLR was elicited using a fully automated pupillometry system and six parameters were measured. Dopamine transporter imaging was performed using radioactive ioflupane (123)I-FP-CIT [(123)I-N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl)-nortropane]. A significant increase in latency and a significant decrease in amplitude, maximum constriction velocity, as well as maximum acceleration were observed in PD patients. There was no significant difference in initial radius and minimum radius values. Investigating the relationship between pupillometry parameters and (123)I-FP-CIT binding values, we correlated values from the semiquantitative analysis of radioligand uptake with pupillometry parameters, but we found no significant correlation. This study demonstrates PLR impairment in patients with PD without overt autonomic dysfunction. This impairment does not seem to correspond to the reduction of radioligand binding in the striatum as the result of presynaptic dopaminergic dysfunction, suggesting a different deterioration rate of these systems.