Comparison of magnetic resonance imaging in subtypes of multiple system atrophy

Some abnormal findings in routine MRI have been proposed as helpful discriminators for distinguishing multiple system atrophy (MSA) from Parkinson's disease (PD). However, what the most distinguishing MRI findings for MSA-p (parkinsonism dominant) or MSA-c (cerebellar dominant) are separately has not been systematically analyzed. To determine what the most helpful discriminators for MSA-p or MSA-c are and whether those findings are correlated with the presence of parkinsonism or cerebellar dysfunction, we compared 10 previously reported MRI findings in 36 patients with probable MSA-p, 27 patients with probable MSA-c and 30 patients with PD separately. In our results, hyperintense rim and putaminal atrophy among supratentorial parameters and the parameters of infratentorial atrophy were significantly prominent in MSA-p comparing to PD. Hyperintense rim showed the highest specificity in MSA-p patients (90.0%) with relatively suboptimal sensitivity (72.2%). In MSA-c, all infratentorial parameters had strong discriminating power comparing to PD. Signal increase in the middle cerebellar peduncle showed the highest specificity (100%) and had fair sensitivity (85.2%) in MSA-c. Compared between MSA-p and MSA-c, supratentorial parameters were not valid to differentiate MSA-c from MSA-p except for putaminal atrophy. On the contrary, infratentorial parameters were good for distinguishing MSA-c from MSA-p except dilatation of the fourth ventricle. Parkinsonism was not correlated with a hyperintense rim, but cerebellar symptoms were correlated with signal increase in the middle cerebellar peduncle. Our findings suggest the characteristic MRI can be helpful for differentiating MSA-p and MSA-c from PD, respectively, although they do not reflect the presence or lateralization of parkinsonism.