Objective: In this study, we have compared the clinical features of atypical parkinsonism with high vascular load to find the difference between isolated vascular pathology and combined dual pathology (vascular and degenerative) groups. We have used the loss of swallow tail in SN as a surrogate marker for degenerative parkinsonism.

Background: Over the years, vascular parkinsonism(VP) has been established, rejected, and again accepted in the list of differential diagnoses of PD. VP usually presents with red flag signs along with PD. Exclusion of vascular etiology is a mandatory diagnostic criterion in diagnosing degenerative atypical parkinsonism. But it is difficult to determine whether vascular lesions in MRI are causing parkinsonism, or contribute to the degenerative pathology, or are just coincidental because both cerebrovascular disease and degenerative parkinsonism increase with age. Loss of swallow tail in SN in nigrosomal imaging can differentiate between IPD and healthy controls, but unable to distinguish between IPD and Parkinson plus syndromes.

Method: We assessed 75 atypical Parkinson patients for evidence of vascular disease using a vascular rating scale. MRI was performed to assess vascular load and swallow tail presence in SN. Patients were categorized into two groups based on the presence or absence of swallow tail on MRI scans. MRI scans of patients with high vascular load and preserved swallow tail were assigned to isolated vascular pathology groups. Those with high vascular load and loss of swallow tail are categorized together as dual pathology groups.

Results: PSP and CBS phenotypes were more prevalent in patients with atypical parkinsonism and high vascular load than MSA and DLB. PSP phenotype patients with high vascular score and preserved swallow tail had a higher rate of pyramidal and pseudobulbar signs, lower body involvement, and asymmetry than patients with loss of swallow tail on MRI. CBS phenotype patients with high vascular score who has preserved swallow tail showed a high degree of bulbar and pseudobulbar involvement. In contrast, patients with loss of swallow tail demonstrated a high prevalence of limb apraxia, limb dystonia, and oculomotor abnormalities.

Conclusion: Atypical parkinsonism syndromes like PSP and CBD are more likely to be associated with increased vascular load in neuroimaging.

References: 1. Can loss of the swallow tail sign help distinguish between Parkinson Disease and the Parkinson-Plus syndromes? April 2017Clinical Imaging 44 DOI:10.1016/j.clinimag.2017.04.005
2. Vascular Parkinsonism: A Clinical Review. Benamer H.T.S. Grosset D.G. Eur Neurol 2009;61:11–15 https://doi.org/10.1159/000165343

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MDS Abstracts - https://www.mdsabstracts.org/abstract/vascular-causes-of-atypical-parkinsonism-versus-vascular-contribution-towards-atypical-parkinsonism/