Objective: To investigate grey matter volume in typical and variant Parkinson-plus syndromes, to correlate these with disease severity, and to assess regional atrophy within disease subtypes.

Background: Classical presentation of Parkinsonian syndromes of Progressive supranuclear palsy (PSP), Corticobasal Syndrome (CBS), and Multiple System Atrophy (MSA) have specific clinicopathological and radiological features. However, variant presentation and atypical Parkinson-plus disorders are less well characterised.

Method: We evaluated cortical and subcortical volumes from baseline MRI images in 7 participant groups recruited into the PROSPECT-M-UK study: healthy controls (n=35), PSP ‘Richardson’ subtype (PSP-RS, n=25), PSP ‘subcortical’ subtype (n=11), PSP ‘cortical’ subtype (n=8), CBS (n=15), MSA (n=17), and 14 patients with related but indeterminate diagnosis (Atypical Parkinsonian Syndrome – APS). We performed ANCOVA comparing volumes across cortical and subcortical structures between groups (corrected for age, gender and total intracranial volume). Post-hoc analyses compared each disease group with controls. In a subgroup of patients we report how regional atrophy correlated with disease severity (PSP Rating Scale), or was asymmetrical (laterality index).

Results: Key volumetric differences were as follows: (1) midbrain-pons ratio in PSP-RS and MSA (p<0.001), (2) parietal and temporal lobes in PSP-cortical and CBS (p<0.001), (3) frontal lobes in PSP-RS, and PSP-cortical. In CBS the pattern of cortical atrophy was asymmetrical (P<0.05). Cerebellar volume was lower in MSA compared to controls (p<0.001). Using a general linear model, disease severity in PSP-RS correlated with atrophy in the temporal, frontal and parietal regions (p<0.05); in PSP-subcortical in frontal lobe and midbrain regions (P<0.05), and trends in CBS in frontal and pontine regions (P=0.06).

Conclusion: We confirm cortical and subcortical volume loss in Parkinson-plus syndromes. Atrophy in select regions related to disease severity, although further work is required to determine longitudinal change. The PROSPECT-M-UK study data confirms atrophy patterns found in prior studies of typical PSP (PSP-RS), CBS and MSA, but also now indicates the distinct patterns of atrophy in variant phenotypes as reported by the new diagnostic criteria[1], which have excellent neuropathological correlation[2].

References: 1. Hoglinger, G. U. et al. Clinical Diagnosis of Progressive Supranuclear Palsy: The Movement Disorder Society Criteria HHS Public Access Author manuscript. Mov Disord 32, 853–864 (2017). 2. Gazzina, S. et al. Neuropathological validation of the MDS-PSP criteria with PSP and other frontotemporal lobar degeneration. bioRxiv 520510 (2019). doi:10.1101/520510

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MDS Abstracts - https://www.mdsabstracts.org/abstract/cortical-and-subcortical-atrophy-in-typical-and-variant-parkinson-plus-syndromes-prospect-m-uk-study/