Primary Progressive Aphasia and Apraxia of Speech

A 59-year-old man presents with progressive difficulty talking over several years. Although he knows what he wants to say, he has difficulty saying it and he is frequently frustrated. His family has gotten into the habit of suggesting words and phrases for him. His speech is slow, halting, non-fluent with grammatical errors. When asked to perform simple commands (“point to the ceiling,” “point to the way you would go to get out of this room”) his comprehension seems intact, but when tested with syntactically complex sentences (“The lion was eaten by the tiger, which one is dead?” and “Pick up the cup after writing with the pen”), he makes errors.

Quick Start

Definition and etiology	• Primary Progressive Aphasia (PPA) is a clinical syndrome characterized by progressive language dysfunction. There are three variants: • Logopenic variant is most often associated with Alzheimer’s disease pathology. • Semantic variant (also called semantic dementia or temporal variant frontotemporal dementia) is most often associated with TDP-43 pathology. • Non-fluent/agrammatic variant (also called progressive non-fluent aphasia) is most often associated with tau pathology. • Primary Progressive Apraxia of Speech (PPAOS) is an impairment in the production of speech sounds in the absence of language impairment (also called progressive apraxia of speech; PAOS). It is most often associated with tau pathology.
Prevalence and Genetic risk	• Impairments of speech and language are common in neurodegenerative diseases. • The number of patients who meet criteria for primary progressive aphasia or primary progressive apraxia of speech is relatively small. • Genetic risk will depend upon underlying etiology; most individuals with primary progressive aphasia or apraxia of speech have no family history.
Cognitive and behavioral symptoms	• In the logopenic variant of primary progressive aphasia there is hesitant speech, difficulty naming and finding words, and phonologic and/or repetition errors, with no loss of comprehension and preserved grammar. • In the semantic variant of primary progressive aphasia there is a loss of memory for words, starting with anomia, continuing with impaired comprehension of words, and ultimately leading to impaired comprehension of objects as well. Speech is fluent with normal rate and minimal syntactic errors. • In the non-fluent/agrammatic variant of primary progressive aphasia there is a reduction in the ability to produce speech characterized by slow, effortful, apraxic speech, grammatical errors, short sentences, reduced phrase length, omission of articles (a, an, the), and difficulty pronouncing words, somewhat similar to that of a patient with Broca’s aphasia. • Characteristics of primary progressive apraxia of speech include slow rate, articulatory distortions, distorted sound substitutions, and segmentation of syllables.
Diagnostic criteria	• Primary progressive aphasia core criteria • Inclusion: 1. Most prominent clinical feature is difficulty with language; 2. These deficits are the principle cause of impaired function; 3. Aphasia is the most prominent deficit at onset and for the initial phases of the disease. (For exclusion criteria see Box 7-1 .) • For specific criteria for the logopenic, semantic, and non-fluent/agrammatic variants, see Boxes 7-2 to 7-4 . • For features of primary progressive apraxia of speech, see Box 7-5 .
Treatment	• Treatment is supportive. Speech therapy is helpful in some patients.
Top differential diagnoses	• Alzheimer’s disease, frontotemporal dementia, vascular dementia, progressive supranuclear palsy, corticobasal degeneration.

Communication problems are common in neurodegenerative diseases. Patients with Alzheimer’s disease, for example, almost always manifest word-finding difficulties and impaired comprehension of language at some point in the disease course. Patients with corticobasal degeneration and progressive supranuclear palsy often show apraxia of speech. Some patients with progressive speech disorders, however, do not meet criteria for any neurodegenerative disorder—at least at the time of presentation. For this reason the classification of patients into the different syndromes of primary progressive aphasia (PPA) and primary progressive apraxia of speech (PPAOS) is useful.

Prevalence, Definition, and Pathology

Primary progressive aphasia and primary progressive apraxia of speech are not diseases. They are clinical syndromes that patients may manifest, with varying underlying neurodegenerative disease etiologies ( Table 7-1 ).

•

Primary progressive aphasia is divided into three variants:
- •
  
  Logopenic variant (often abbreviated to lvPPA).
- •
  
  Semantic variant (also called semantic dementia or temporal variant frontotemporal dementia; often abbreviated to svPPA or SD or tv-FTD).
- •
  
  Non-fluent/agrammatic variant (also called progressive non-fluent aphasia; often abbreviated to naPPA or agPPA or PNFA).
•

Primary progressive apraxia of speech is an impairment in the production of speech sounds in the absence of language impairment (also called progressive apraxia of speech; often abbreviated to PPAOS or PAOS).

TABLE 7-1

Pathological and Anatomical Correlates of Primary Progressive Aphasia and Primary Progressive Apraxia of Speech

Feature	Logopenic Variant Primary Progressive Aphasia	Semantic Variant Primary Progressive Aphasia	Non-fluent/Agrammatic Variant Primary Progressive Aphasia	Primary Progressive Apraxia of Speech
Underlying etiology and pathology	Alzheimer’s disease (50%) Frontotemporal lobar degeneration (TDP-43 38%, tau 12%)	Frontotemporal lobar degeneration (TDP-43 69%, tau 6%) Alzheimer’s disease (25%)	Frontotemporal lobar degeneration (tau 52%, TDP-43 19%, other 4%) Alzheimer’s disease (25%)	Progressive supranuclear palsy syndrome (38%) or other tauopathy (62%)
Cortical atrophy or hypometabolism	Left temporoparietal	Anterior temporal, often left greater than right	Left posterior frontoinsular	Superior premotor, supplementary motor

References: ; ; ; ; .

Although impairments of language are common in neurodegenerative diseases, the number of patients who meet criteria for primary progressive aphasia or apraxia of speech is quite small. Risk factors, pathology, pathophysiology, prognosis, and age of presentation all depend upon underlying etiology: for example, those patients with underlying frontotemporal lobar degeneration or progressive supranuclear palsy often present in their 50s and 60s, whereas patients with underlying Alzheimer’s disease pathology typically present in their 70s and 80s. Please see Chapter 4 , Chapter 8 , Chapter 9 , Chapter 10 for more information on some of the specific etiologies.

Criteria

Criteria for primary progressive aphasia consists of core criteria ( Box 7-1 ) plus additional criteria for each variant ( Boxes 7-2–7-4 ). Note that patients who meet the core criteria but have a combination of both agrammatism and semantic impairments at early stages of disease can be described as having “mixed primary progressive aphasia” ( ). Primary progressive apraxia of speech is diagnosed by a list of common features ( Box 7-5 ) in the absence of aphasia (i.e., language itself is normal).

Box 7-1

Primary Progressive Aphasia Core Criteria

Inclusion: Criteria 1–3 must be answered positively.

1.

Most prominent clinical feature is difficulty with language
2.

These deficits are the principle cause of impaired daily living activities
3.

Aphasia should be the most prominent deficit at symptom onset and for the initial phases of the disease

Exclusion: Criteria 1–4 must be answered negatively.

1.

Pattern of deficits is better accounted for by other nondegenerative nervous system or medical disorders
2.

Cognitive disturbance is better accounted for by a psychiatric diagnosis
3.

Prominent initial episodic memory and visuoperceptual impairments are present
4.

Prominent, initial behavioral disturbance is present

Adapted from .

Box 7-2

Logopenic Variant Primary Progressive Aphasia Criteria

I

Clinical Diagnosis of Logopenic Variant Primary Progressive Aphasia

Both of the following core features must be present:

1.

Impaired single-word retrieval in spontaneous speech and naming
2.

Absence of definite grammar and comprehension impairment

At least three of the following other features must be present:

1.

Speech (phonologic) errors in spontaneous speech and naming
2.

Impaired repetition of sentences and phrases
3.

Spared single-word comprehension and object knowledge
4.

Spared motor speech

II

Imaging-Supported Logopenic Variant Diagnosis

In addition to fulfilling clinical criteria, imaging must show one of the following results:

1.

Predominant left posterior perisylvian or parietal atrophy
2.

Predominant left posterior perisylvian or parietal hypoperfusion or hypometabolism on SPECT or PET

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