Methods Six patients with probable MSA (mean age (years±SD) was 61±10.4) and 7 with PSP (64.7±5.9 years) according to NNIPPS criteria were prospectively recruited for MRI scanning at King's College Hospital. Illness duration at baseline was 5.6±2 (MSA) and 3.72±2.6 (PSP), and at follow-up 8.29±1.7 and 6.58±2.7, respectively; assessment intervals were 2.6±0.2 (MSA) and 2.8±0.3. SIENA was used to estimate local and global brain volume change between MRI at each timepoint, by co-registering and segmenting the images and calculating displacement of the brain/nonbrain boundary.

Results Annual global brain atrophy was 1.27±0.6% (MSA) and 1.5±0.7% (PSP). In PSP, localised grey matter atrophy was detected in left superior temporal gyrus, right parahippocampal gyrus, left nucleus dentate, left cerebellar tonsil and right semilunar cerebellum. In MSA, left superior, middle frontal gyrus and right frontopolar regions were affected.

Discussion Progressive atrophy was found in frontal and temporal cortices in both disorders; the absence of change in striatum and pallidum may reflect already severely damage at baseline.