What are the signs and symptoms of primary progressive aphasia (PPA) in frontotemporal dementia (FTD)?

Updated: Jun 14, 2018
  • Author: Howard S Kirshner, MD; Chief Editor: Jasvinder Chawla, MD, MBA  more...
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Answer

For the subgroup of patients with frontotemporal lobe dementia (FTD) who have primary progressive aphasia (PPA), the presenting symptoms involve a deterioration of language function. [3, 4, 51] At first, other aspects of cognitive function and behavior may seem entirely normal. Pick first described the presentation of focal language deterioration as a sign of a dementing illness. [1] Sporadic cases were presented into the 20th century, until Mesulam named the syndrome of PPA. [2] Other authors, such as Kirshner et al [5] and Green et al, [39] described focal, aphasic presentations in patients who later showed signs of more general dementia.

Patients with PPA who do not depend on their verbal skills for their livelihood may continue to function at work. They do not act forgetful, they remember their way to familiar destinations, and they generally comport themselves normally, although some show the behavioral changes described under FTD. Artistic expressions may even increase or be taken on as new hobbies in these patients, [52, 53] although, according to Miller and Hou, [53] their productions are often compulsive in style.

The most common presenting symptom is word-finding difficulty. However, decreased fluency or hesitancy in producing speech, difficulty with language comprehension, and motor speech difficulties (eg, dysarthria) are also common. The descriptions of language syndromes in PPA have become more complex.

The mode of presentation in PPA suggests a focal lesion of the left hemisphere language cortex, but a focal lesion, other than evidence of focal atrophy, is usually not found. Magnetic resonance imaging (MRI), especially when combined with voxel-based morphometry, has become much more accurate in mapping localized areas of cortical atrophy. Rohrer and colleagues suggested that MAPT mutations are more often associated with symmetrical atrophy, whereas the progranulin mutations show more asymmetric atrophy. [54] There are also patterns of regional atrophy in the different FTD variants, which we will return to later. The course is progressive, with slowly worsening language function.

Initially, PPA was divided into 2 subtypes: (1) a progressive nonfluent aphasia, and (2) fluent aphasia with anomia. More recently, 3 subtypes have been described: (1) progressive nonfluent aphasia; (2) semantic dementia, and (3) logopenic progressive aphasia, also called the logopenic/phonologic variant. [10, 11]


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