Aphasia in Adults: Theoretical Models and Error Patterns

Aphasia in Adults: Theoretical Models, Error Patterns, and Co-Occurring Conditions

1. Learning Objectives

  • Apply models of language processing to analyze connected speech transcripts and identify error patterns.

  • Distinguish fluent from non-fluent verbal expression profiles in people with aphasia (PWA).

  • Hypothesize which stages of language processing may be impaired based on observed breakdowns in connected speech.

  • Demonstrate understanding of written language impairments associated with aphasia.

  • Define limb and oral apraxia, and acquired apraxia of speech.

  • Generate considerations to distinguish deficits in auditory comprehension from praxis difficulties.

2. Theoretical Models of Language Processing & Error Patterns in Aphasia

2.1 Overview

  • Provide a roadmap to better understand the following:

    • Rating Errors in Connected Speech

    • Alexia & Agraphia

    • Acquired Apraxia of Speech

3. What is Aphasia?

3.1 Definition of Aphasia

  • Roserbek, LaPointe, & Wertz (1967): "Aphasia is an impairment of the canal nervous system's ability to comprehend and produce language. The disrupted language may be influenced by physiological factors or impaired cognition but cannot be explained by dementia or motor dysfunction."

3.2 Language Modalities Impacted

  • Various modalities may be affected together and/or exhibit varying degrees of impairment:

    • Auditory comprehension

    • Reading

    • Oral expression

    • Writing

3.3 Types of Aphasia Syndromes

  • Global Aphasia: Severe impairment across all forms of language.

  • Broca's Aphasia: Non-fluent speech with relatively preserved comprehension.

  • Mixed Aphasia: Combination of fluent and non-fluent features.

  • Transcortical Motor Aphasia: Impaired speech production but preserved repetition.

  • Wernicke's Aphasia: Fluent but nonsensical speech with poor comprehension.

  • Transcortical Sensory Aphasia: Fluent speech and preserved repetition but poor comprehension.

  • Conduction Aphasia: Impaired repetition with relatively preserved comprehension and fluency.

  • Anomic Aphasia: Difficulty in word finding, fluent speech, and comprehension are intact.

  • Subcortical Aphasia: Damage to subcortical structures affecting language.

  • Other Syndromes: Various other types not specifically categorized above.

4. Word Finding Difficulties in PWA

4.1 Observation of Word Finding Difficulties

  • Clinicians assess language abilities to determine the presence of word finding difficulties.

  • Such difficulties may range from frequent and obvious to subtle and infrequent.

  • Various types of errors can be analyzed in clinical practice.

4.2 Theoretical Models of Language Processing
4.2.1 Psycholinguistic Approach to Aphasia (Macoira et al., 2016)

  • Involved in both spoken and written language processing, depicted by:

    • Phonological input analysis

    • Object perceptual analysis

    • Phonological output conversion

    • Articulatory programming

    • Graphemic analysis for written language.

4.2.2 2-Step Model of Word Production (Dell & O'Seaghdha, 1992)

  • The model details monitoring and control in language production, highlighting the complexity of the retrieval process.

5. Assumptions of Theoretical Models in PWA.

5.1 Breakdown of Word Retrieval Errors

  • Word retrieval errors stem from breakdowns in one or more stages of the processing model.

  • Types of word retrieval failures include:

    • Paraphasia: Unintended sound or word production, including:

    • Phonemic Paraphasia: Errors that retain phonetic similarity to the intended word.

    • Semantic Paraphasia: Errors involving words related in meaning.

    • Non-Semantic Paraphasia: Errors with entirely irrelevant words.

    • Combined Paraphasia: A mix of both types.

    • Neologism: Producing entirely made-up words with no meaning.

5.2 Analysis of Errors in Clinical Practice

  • By examining errors, clinicians infer which mechanisms may be impaired, aiding in the selection of appropriate therapies.

6. Other Error Types Indicative of Anomia

  • Hesitations: Pauses, fillers or delays in speech output.

  • False Starts: Aborted or partially produced words/phrases.

  • Circumlocution: Descriptive phrases to convey a word or concept.

  • Perseveration: Repetitions of previous responses or words.

  • Stereotypy: Involuntary, repetitive saying of the same expressions.

  • Echolalia: Automatic repetition of phrases spoken by another person.

  • Logorrhea: Excessive and uncontrolled speech.

  • Conduit d’approche: Successive approximations toward a target word.

  • Conduit d'écart: Responses that move further away from the target.

7. Rating Errors in Connected Speech

7.1 Transcription as An Evaluative Tool

  • Conduct transcription for various conversational tasks:

    • Storytelling

    • Supported interviews

    • Picture description

  • Analyze fluency and identify patterns in error types and strengths.

7.2 Characteristics of Connected Speech

  • Requirements for connected speech analysis include:

    • Lexical retrieval

    • Grammatical structure

    • Prosody

    • Discourse organization

    • Fluency

    • Motor planning

7.3 Common Lexical Retrieval Errors in Connected Speech

  • Examples of errors observed during connected speech tasks include:

    • Paraphasias, hesitations, false starts, circumlocution.

  • Jargon: Production of incoherent word salad, with a mix of coherent words.

  • Empty Speech: Grammatically correct yet vague messages lacking specifics or content.

7.4 Grammatical Form Errors

  • Agrammatism: Difficulty adhering to basic grammar and syntax, often resulting in telegraphic speech.

  • Paragrammatism: Well-constructed sentences but with grammatical errors or incorrect substitutions.

7.5 Prosody in Discourse

  • Prosody: The rhythm, pitch, and stress of speech, which may be monotone or exhibit unusual interruption due to prosody-related impairments.

7.6 Discourse Organization

  • Attention to:

    • Micro Level: Grammar and sentence complexity.

    • Macro Level: Coherence and pragmatic communication skills.

7.7 Phrase Length and Fluency in Aphasia

  • Phrase length categorization:

    • Non-fluent: 4 words or fewer.

    • Borderline Fluent: 5-6 words.

    • Fluent: 7 or more words.

8. Alexia and Agraphia

8.1 Cognitive Processing of Single Words

  • Mapping cognitive processes involved in reading and writing, highlighting the connection between visual input and phonology.

8.2 Co-Occurring Diagnoses for PWA

  • Alexia as an acquired reading disorder.

  • Agraphia as an acquired writing disorder.

8.3 Pure Alexia (without Agraphia)

  • Defined first by Dejerine (1892): Complete inability to read aloud while preserving writing abilities.

8.4 Alexia with Letter-by-Letter (LBL) Reading

  • Common in Wernicke’s aphasia; reliance on individual letter reading due to impaired holistic word recognition.

8.5 Deep vs. Surface Dyslexia

  • Deep Dyslexia: Inability to employ grapheme-to-phoneme conversion;

    • Features semantic paralexias and inability to read aloud functional or nonsense words.

  • Surface Dyslexia: Ability limited to pronouncing regular words without grasping overall meaning.

9. Apraxia

9.1 Definitions

  • Apraxia: The loss of ability to execute learned movements without weakness or coordination issues, and not due to comprehension deficits.

9.2 Types of Apraxia

  • Limb Apraxia: Affecting upper/lower limb movements.

  • Oral Apraxia: Affecting facial and respiratory motor coordination.

  • Apraxia of Speech: Impacts the motor planning and programming necessary for speech production.

9.3 Assessment of Apraxia

  • Assessments consider verbal commands, imitation, and actual object manipulation among various body regions.

9.4 Clinical Characteristics of Apraxia of Speech (AOS)

  • Symptoms:

    • Impaired production of articulation and prosody.

    • Results from disruption in neural programming for motor skills rather than motor weakness or hearing loss.

9.5 Differentiation of AOS from Other Language Errors

  • Clinical characteristics unique to AOS include:

    • Slowed rate of speech, sound errors, groping, and increased errors with complexity.

  • Distinguishes from phonemic paraphasia which involves typical speech rates and prosody.

This study guide covers the comprehensive concepts and detailed structures necessary for understanding aphasia in adults. Additional exploration into elective courses or topics such as acquired reading and writing disorders may also be beneficial for more in-depth knowledge.