Atypical association of semantic dementia, corticobasal syndrome, and 4R tauopathy

Abstract

A 57-year-old male with no family history was diagnosed with semantic dementia. He also showed some unusual cognitive features such as episodic memory and executive dysfunctions, spatial disorientation, and dyscalculia. Rapidly progressive cognitive and physical decline occurred. About 1.5 years later, he developed clinical features of a corticobasal syndrome. He died at the age of 60. Brain autopsy revealed numerous 4R-tau-positive lesions in the frontal, parietal and temporal lobes, basal ganglia, and brainstem. Neuronal loss was severe in the temporal cortex. Such association of semantic dementia with tauopathy and corticobasal syndrome is highly unusual. These findings are discussed in the light of current knowledge about frontotemporal lobar degeneration.

The clinical spectrum of sporadic and familial forms of frontotemporal dementia

“…Overlap of svPPA with PSPS or CBS is rare, and if present, is usually associated with atypical FTLD‐tau pathology (Clerc et al . ), although parkinsonism can appear late on in disease (Hodges and Patterson ; Kremen et al . ).…”

“…As disease progresses, parkinsonism can worsen and lead to a frank parkinsonian syndrome, most commonly with features of CBS (Graham et al 2003;Josephs et al 2006;Josephs and Duffy 2008) and less commonly PSPS (Josephs et al 2005(Josephs et al , 2006. Overlap of svPPA with PSPS or CBS is rare, and if present, is usually associated with atypical FTLDtau pathology (Clerc et al 2013), although parkinsonism can appear late on in disease (Hodges and Patterson 2007;Kremen et al 2011). Patients with lvPPA typically do not develop florid parkinsonism (unless there is underlying CBD (corticobasal degeneration) pathology).…”