Prevalence of the Hot Cross Bun Sign and Factors Associated With HCBS Positivity in Patients With Multiple System Atrophy

Objective In patients with multiple system atrophy (MSA), the hot cross bun sign (HCBS) has been associated with disease severity in MSA. This study is aimed at investigating the prevalence of HCBS and its potential risk factors in Chinese MSA patients. Materials and Methods A total of 175 MSA patients who met “possible” or “probable” diagnostic criteria were included in this cross‐sectional study. The Unified MSA Rating Scale (UMSARS), Nonmotor Symptoms Scale (NMSS), Hamilton Depression Rating Scale‐17 (HDRS‐17), Hamilton Anxiety Scale (HAMA), and Montreal Cognitive Assessment (MoCA, permission has been granted) were compared between MSA patients with and without HCBS (defined as pontine cruciform hyperintensity on T2‐weighted fluid‐attenuated inversion recovery T2‐FLAIR sequences). Binary logistic regression analysis was used to identify the independent risk factors for the presence of HCBS. Results HCBS was identified in 110 of 175 patients (62.86%). Univariate analysis revealed significant relationships between HCBS and female, cerebellar subtype, REM sleep behavior disorder (RBD), higher UMSARS‐IV score, and moderate‐to‐severe white matter hyperintensities (WMHs). The occurrence of HCBS in MSA was independently associated with the MSA‐C subtype (OR = 6.05, 95 % CI = 2.55–14.38), RBD (OR = 2.56, 95 % CI = 1.06–6.20), higher UMSARS‐IV scores (OR = 2.48, 95 % CI = 1.42–4.35), and moderate‐to‐severe WMH (OR = 4.10, 95 % CI = 1.14–14.75). Conclusions HCBS is a common neuroimaging observation in MSA patients. Our research shows that the MSA‐C subtype, RBD, greater disability severity (as assessed by UMSARS‐IV), and moderate‐to‐severe WMH are independent risk factors for HCBS. Higher UMSARS‐IV scores were substantially linked to the presence of HCBS, but there was no association between the severity grade of HCBS and the degree of disability. The prevalence of HCBS and its clinical correlates in a Chinese MSA cohort are demonstrated cross‐sectionally in this study, especially with regard to subtype, RBD, disability, and WMH burden.