Abstract
Frontotemporal Lobar Degeneration (FTDL) is a neurodegenerative disorder which is predominantly characterized by changes in behaviour and loss of cognitive abilities. Three major clinical syndromes have been identified, Frontotemporal dementia (FTD), in which changes in social behaviour predominate, Semantic Dementia (SD) which is characterized by a loss of semantic knowledge, and Primary Progressive Aphasia (PPA), a disorder of phonological and syntactic aspects of language. All subtypes of FTLD have insiduous onset and stepwise progression. The present review lists the clinical symptoms and main findings of the three FTLD-subtypes, and discusses the difficulties of their diagnosis and differential diagnosis. The diagnosis of FTLD is based on the clinical consensus criteria of the Lund and Manchester groups, neuroradiological and neuropsychological investigations.