Objective: We investigated whether smaller substantia nigra is associated with worse parkinsonism on the corresponding contralateral side.

Background: Degeneration of dopaminergic cells and morphologic changes in substantia nigra (SN) is well documented in Parkinson’s disease (PD). Although magnetic resonance imaging-based volumetric measurement of SN has been shown to be a sensitive method in PD, there are studies that claim the opposite. Yet there are studies indicating that width of SN pars compacta is reduced, and it is correlated to motor performance in PD, the value of volumetric analysis of substantia nigra as an indicator of PD is still uncertain.

Methods: The clinical features of 60 patients with PD were retrospectively reviewed from hospital records between 2009-2015. Clinical asymmetry was assessed for each patient by comparing UPDRS motor part III (motor examination) scores on both sides. Brain magnetic resonance images of these patients were re-assessed by an experienced neuroradiologist who was blinded to patient data. Magnetic resonance imaging was performed using a 1.5 Tesla Magnetom Avanto system (Siemens, Germany). Whole brain SWI (susceptibility weighted imaging) was conducted. The purpose was to image the substantia nigra for subsequent off-line planimetric, volumetric, and densitometric analyses. The main criteria for to determine the substansia nigra is the hipointensity caused by the increased iron deposition.

Results: Sixty patients, mean age (37 (61,6%) male, 23 (38,3) female, mean age 68,1 (±11,6SD)) were enrolled to the study. Mean disease duration was 5.4 (±7,1± SD). A Kappa analysis was run to determine if there is an agreement between the clinical asymmetry and MRI results [table 1]. There was a ‘poor’ agreement between the SN volume asymmetry in MRI and clinical asymmetry. Weighted Kappa= 0.075±.86 (95%CI: 0.000 – 0.244).

Conclusions: Although for accurate differential diagnosis and disease monitoring, detecting SN changes in magnetic resonance imaging (MRI) may be a good non-invasive method, the results of the studies are controversial. Especially volume changes of putamen and SN was shown to be potential indicators for diagnosis. However our study indicates that the volumetric analysis of SN does not have a role in the diagnosis of PD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/may-substantia-nigra-volume-asymmetry-be-an-indicator-of-motor-asymmetry-in-parkinsons-disease-a-retrospective-analysis/