[Multiple system atrophy--update]

Multiple system atrophy (MSA) is an adult-onset neurodegenerative disorder, showing various combination of progressive autonomic failure, cerebellar ataxia, and levodopa poorly responsive parkinsonism. MSA accounts for more than 40% of spinocerebellar ataxias in Japan. Pathologically, myelinopathy, neuronal loss and gliosis are the cardinal features in the brain of MSA. In addition, excessive accumulation of alpha-synuclein, mostly in oligodendroglia and partly in neuron, characterizes the cellular pathology of the disorder. However, mechanism causing the disorder is not known. Clinical diagnosis of MSA is based on Quinn's criteria or, more recently, on Consensus Criteria. In Japan, criteria of the Research Committee of Ataxic Diseases, the Ministry of Health and Welfare of Japan, was popular, and it contributed to the research base on MSA. Besides the major manifestations incorporated into those criteria, various dystonic manifestation, rhythmic myoclonus, emotional incontinence, sleep disturbance, sleep-related movement disturbances, and signs of vasomotor dysfunction, provide aids in the differential diagnosis of MSA. In neuroimaging studies, not only MRI but dopamine transporter and D2 receptor imaging by SPECT also contribute to the diagnosis of MSA. These laboratory diagnostic procedures can contribute to improve reliability of the diagnosis, and needs to be taken into account when preventive measures become available.