Self-reported urinary impairment identifies 'fast progressors' in terms of neuronal loss in multiple system atrophy.

Introduction: MSA is an adult-onset, sporadic, progressive parkinsonian syndrome characterised by the presence of akinesia, cerebellar dysfunction, autonomic failure and pyramidal signs. Annualized-whole-brain atrophy rate (a-WBAR) is an informative way to quantify disease progression. In this longitudinal work we investigate the correlations of a-WBAR with clinical scales for motor impairment, autonomic disability and cognitive decline in MSA and explore how atrophy progresses within the brain.

Method: Fourty-one MSA patients were studied using Structural Imaging Evaluation with Normalization of Atrophy (SIENA). SIENA is an MRI-based algorithm that quantifies brain tissue volume. Clinical parameters were explored using the 18-item Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale, the Hoehn and Yahr Scale, the Frontal Assessment Battery and the Natural History and Neuroprotection in Parkinson Plus Syndromes scale (sub-items for orthostatic and urinary functions).

Results: The mean (±SD) age was 60.4 years ± 7.7 and a-WBAR was 1.65% ± 0.9. Demographics and clinical ratings at the time of the first scan were non-significantly associated with a-WBAR. The only exception was the baseline urinary score with a weak but significant association (R2 = 0.15, p = 0.04). Progression of grey matter atrophy was detected in the left superior temporal gyrus, right middle frontal gyrus, right frontopolar region and midbrain.

Conclusion: Urinary impairment at baseline may help to identify 'fast progressors' in terms of neuronal loss, particularly in the frontal and temporal lobes. Thus, urinary impairment should be recognized as a key target for disease modifying therapeutic interventions in MSA.