Primary lateral sclerosis as progressive supranuclear palsy: Diagnosis by diffusion tensor imaging

Background:: Evaluating the integrity of white matter tracts with diffusion tensor imaging may differentiate primary lateral sclerosis from progressive supranuclear palsy. Methods:: Thirty-three prospectively recruited subjects had standardized evaluations and diffusion tensor imaging: 3 with primary lateral sclerosis who presented with features suggestive of progressive supranuclear palsy, 10 with probable or definite progressive supranuclear palsy, and 20 matched controls. We compared fractional anisotropy of the corticospinal tract, superior cerebellar peduncles, and body of the corpus callosum between groups. Results:: Both the primary lateral sclerosis and progressive supranuclear palsy subjects showed reduced fractional anisotropy in superior cerebellar peduncle and body of the corpus callosum compared with controls, but only primary lateral sclerosis subjects showed reductions in the corticospinal tracts. A ratio of corticospinal tract/superior cerebellar peduncle best distinguished the disorders (P <02). Conclusions:: The corticospinal tract/superior cerebellar peduncle ratio is a marker to differentiate primary lateral sclerosis from progressive supranuclear palsy.