Specific Imaging Findings

MRI is the imaging method of choice. In MSA-p the putamina may show a T2 hyperintense lateral rim, central low T2 signal and atrophy. On T1WI, the posterior putamen may be slightly bright, which is suggestive of MSA but not pathognomonic. Central T2 hypointensity is accentuated on T2*WI, such as SWI. In MSA-c, FLAIR images may show bilateral symmetric hyperintensity in the middle cerebellar peduncles. This finding, however, may also be found in normal aging individuals. The entire brain shows atrophy, but it tends to be more prominent in the brainstem, cerebellum, and spinal cord. In patients with MSA-c increased T2 signal of the transverse white matter fibers in the lower pons may produce the “hot cross bun” sign. MRI features such as the “hot cross bun” sign have very high specificity and positive predictive value (up to 100%) but low sensitivity (in the range of 60%). Differentiation of MSA from Parkinson disease (PD) and progressive supranuclear palsy (PSP) is challenging and not always possible on standard MR imaging. Putaminal T2 hyperintense lateral rim is a frequent normal finding on 3.0 T scanners.

Pertinent Clinical Information

The most common presentation (> 60% of cases) of MSA is Parkinson-like symptoms. Balance abnormalities are seen in about 20% of patients at presentation and urinary incontinence or retention in about 10%. In males, erectile dysfunction may be an early sign. Due to the lack of balance, falls are quite common early in the disease. MSA progresses rapidly with no periods of remission and patients generally live less than 10 years after the diagnosis is first made. Respiratory problems become prominent as the disease progresses. Vocal cord paralysis may lead to death. No curative treatment exists and management is geared towards control of hypotension and Parkinson-related symptoms.