Chapter

The frontotemporal dementias: an overview

Alexandre Henri-Bhargava and Morris Freedman

in Amyotrophic Lateral Sclerosis and the Frontotemporal Dementias

Published on behalf of Oxford University Press

Published in print October 2012 | ISBN: 9780199590674
Published online November 2012 | e-ISBN: 9780191753466 | DOI: http://dx.doi.org/10.1093/med/9780199590674.003.0004
The frontotemporal dementias: an overview

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FTLD describes a group of pathologically heterogeneous, yet related neurodegenerative diseases with focal onset primarily in the frontal and/or temporal lobes. There are three well-defined clinical syndromes associated with FTLD: bvFTD, SD, and PNFA. All have insidious onset and gradual progression. The core features of bvFTD include derangements of social and emotional functioning, lack of insight and impaired psychomotor activity. The characteristic feature of SD is progressive loss of semantic knowledge, in the verbal (recognition of word meaning) and visual (recognition of faces, recognition of object meaning) domains. Behavioural abnormalities are also often pronounced in SD. The specific symptoms of SD may depend upon whether the left or right temporal lobe is more affected at initial presentation, and to highlight this some prefer to use the terms left and right temporal variant FTD instead of SD. The hallmark of PNFA is progressively worsening non-fluent, agrammatical speech.

Another syndrome potentially associated with FTLD is logopenic progressive aphasia, although the underlying pathology of this syndrome is often AD. FTLD syndromes may overlap with PSP, CBS, or both. There is also an ALS overlap syndrome that includes ALSbi, ALSci, and ALS/FTD. Features specific to the ALS overlap syndrome include more frequent and earlier occurring executive dysfunction, as well as a greater prevalence of early psychotic symptoms, particular delusions.

Concepts regarding FTLD syndromes are undergoing rapid revision, as experience with these diseases has increased exponentially since the mid-1990s. Diagnosis remains heavily dependent upon accurate clinical description, based upon a careful case history, with assistance from physical exam and neuroimaging results, as well as neuropsychological and speech-language pathology assessments. These syndromes are becoming increasingly recognized, and refinements in clinical diagnostic criteria are currently underway.

Chapter.  10531 words. 

Subjects: Neurology

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