2025 年 42 巻 5 号 p. 787-792
Multiple system atrophy (MSA) is one of the representative neurodegenerative diseases and is an intractable disease. MSA has a wide variety of phenotypes, characterized by a combination of various degrees of parkinsonism, cerebellar ataxia, and autonomic disturbance. Many cases are difficult to diagnose, and especially early diagnosis is extremely difficult. So far, MSA has been diagnosed based on the second consensus statement in 2008, but there were some problems, such as low sensitivity in early diagnosis. So, the Movement Disorder Society created new diagnostic criteria in 2022, and MSA is currently diagnosed based on these diagnostic criteria. Based on these diagnostic criteria, the diagnosis of MSA improved sensitivity and specificity compared to the second consensus statement. However, further improvement is needed, especially in terms of sensitivity, and further revisions are required in the future. Therefore, we are developing new imaging biomarkers that will contribute to early diagnosis and elucidation of pathophysiology. Individual Voxel–based Morphometry Adjusting Covariates (iVAC) is a new brain volumetry that distinguish between Parkinson disease (PD) and MSA with a sensitivity of 98.1%, specificity of 96.2%, positive predictive value of 96.3%, and negative predictive value of 98.1%. We noticed that 123I–FP–CIT Single Photon Emission Computed Tomography (SPECT) bound to the serotonin transporter (SERT), and developed serotonin transporter SPECT. We found that in MSA–P, there was consistently increased accumulation in the pons from the early stages and that this accumulation decreased as the disease progressed. We assessed the longitudinal MRI of MSA and pontine volume decreased ranging from 3.6% to 16.8% per year (mean 9.1%), exhibiting a nonlinear decline. The predictive model suggested that pontine atrophy may begin before the onset of MSA–C symptoms, potentially contributing to earlier diagnosis.
