Background and Purpose
Frontotemporal lobar degeneration (FTLD) can be subdivided into those in which the abnormal protein is tau (FTLD-TAU), the TAR DNA binding protein 43 (FTLD-TDP) and the fused in sarcoma protein (FTLD-FUS). We have observed severe caudate atrophy at autopsy in FTLD-FUS, and hence we aimed to determine whether caudate atrophy on MRI is a feature that can distinguish FTLD-FUS from FTLD-TDP and FTLD-TAU.
From a cohort of 207 cases of FTLD we identified all cases of FTLD-FUS that had a volumetric antemortem head MRI (n=3). Caudate and frontal lobe volumes were measured in all three cases using atlas based parcellation and SPM5, and were compared to 10 randomly selected cases of FTLD-TDP and 10 randomly selected cases of FTLD-TAU. Total grey matter volumes were also calculated for all cases.
The FTLD-FUS cases had significantly smaller caudate volumes (p=0.02) yet similar frontal lobe grey matter volumes (p=0.12) compared to FTLD-TDP and FTLD-TAU. Caudate volumes when corrected for total grey matter volume (p=0.01) or frontal lobe grey matter volume (p=0.01) were significantly smaller in FTLD-FUS than FTLD-TDP and FTLD-TAU, and showed no overlap with the other two groups.
Caudate atrophy on MRI appears to be significantly greater in FTLD-FUS compared with FTLD-TDP and FTLD-TAU suggesting that severe caudate atrophy may be a useful clinical feature to predict FTLD-FUS pathology.