Comprehensive Notes on Aphasia

Aphasia: Core Concepts

  • Aphasia affects listening, speaking, reading, writing, and gesturing (including sign language).
  • The common denominator is the central linguistic processing of verbal symbols.
  • Key aspects include:
    • Fluency: The ease and flow of speech.
    • Prosody: Intonation and emotional expression in speech.
    • Familiar, personally relevant stimuli are important in assessment and therapy.

Verbal Functions and Language Skills

  • Aphasia: Specifically a language impairment.
  • Apraxia and Dysarthria: Involve motor performance and planning aspects of speech.
  • Dyslexia/Alexia: Affect reading abilities.
  • Agraphia: Affects writing abilities.
  • Dysphasia: Refers to developmental language impairment.
  • It's crucial to differentiate types of aphasia and distinguish aphasia from:
    • Motor impairment.
    • Memory impairment.
    • Mood impairment.
    • Social withdrawal.

Language Errors: Paraphasias

  • Paraphasia: Unintended syllables, words, or phrases.
    • Semantic Paraphasia: Substitution of a word with an incorrect word from the same category (e.g., "fork" for "spoon").
    • Phonemic Paraphasia: Substitution of a sound, creating an incorrect word (e.g., "shoon" for "spoon").
  • Neologisms: Use of nonexistent word forms.
  • Jargon Speech: A pattern of paraphasic errors and neologisms that severely contaminate speech, making it incomprehensible.
  • "Word Salad": Normal speech morphology and sentence structure but with incoherent content.
  • Telegraphic Speech: Production of primarily nouns and verbs, omitting grammatical words and morphemes.

Errors in Language

  • Syntax: Grammatical construction of phrases and sentences.
  • Pragmatics: Proper use of speech and language in a conversational setting, including pausing, turn-taking, and responding to questions.
  • Morphology: Use of appropriate word endings and connector words for tenses, possessives, and singular versus plural forms.

Aphasia Assessment

  • Key questions to determine the type of aphasia:
    • Is speech fluent?
    • Does the patient comprehend spoken messages?
    • Can the person repeat words or phrases?
  • Types of Aphasia (Categorized in a flowchart):
    • Global Aphasia: Non-fluent speech, impaired comprehension and repetition.
    • Mixed Transcortical Aphasia
    • Broca's Aphasia: Non-fluent speech, impaired repetition, relatively intact comprehension.
    • Transcortical Motor Aphasia: Good comprehension and intact repetition, but poor spontaneous production.
    • Wernicke's Aphasia: Fluent speech with paraphasic errors, impaired comprehension and repetition.
    • Transcortical Sensory Aphasia: Fluent speech with paraphasias, impaired comprehension, but intact repetition.
    • Conduction Aphasia: Relatively fluent speech, good comprehension, impaired repetition.
    • Anomic Aphasia: Fluent speech, good comprehension and repetition, difficulty with naming.
    • Relevant brain areas include the primary motor cortex, primary somatosensory cortex, Broca's area, Wernicke's area, primary auditory cortex, and primary visual cortex.

Key Figures

  • Andrade et al., 2015
  • Geschwind
  • Broca
  • Wernicke

Broca's Aphasia

  • Bedside Features:
    • Spontaneous Speech: Nonfluent, mute, or telegraphic; often dysarthric.
    • Naming: Impaired.
    • Comprehension: Relatively intact, with mild difficulty understanding complex grammatical phrases.
    • Repetition: Impaired.
    • Reading: Often impaired ("third alexia").
    • Writing: Impaired (dysmorphic, dysgrammatical).
    • Associated Signs: Right hemiparesis, right hemisensory loss, possible apraxia of left limbs.

Wernicke's Aphasia

  • Bedside Features:
    • Spontaneous Speech: Fluent, with paraphasic errors; usually not dysarthric; sometimes logorrheic.
    • Naming: Impaired, often with bizarre paraphasic misnaming.
    • Comprehension: Impaired.
    • Repetition: Impaired.
    • Reading: Impaired for comprehension and aloud reading.
    • Writing: Well-formed, but paragraphic.
    • Associated Signs: Right hemianopia; motor and sensory signs usually absent.

Global Aphasia

  • Bedside Features:
    • Spontaneous Speech: Mute or nonfluent.
    • Naming: Impaired.
    • Comprehension: Impaired.
    • Repetition: Impaired.
    • Reading: Impaired.
    • Writing: Impaired.
    • Associated Signs: Right hemiparesis, right hemisensory loss, right hemianopia.

Transcortical Aphasias

  • Involve isolation of frontal (transcortical motor aphasia) or temporal (transcortical sensory aphasia) cortices from the rest of the brain.
  • Symptoms can mimic Broca or Wernicke subtypes; differentiation requires behavioral examination, as neuroimaging may not suffice.
  • Sensory: Fluent, paraphasic, dysnomic.
  • Motor: Good comprehension, intact repetition; poor spontaneous production; often subsequent to ischemic stroke in arterial watershed areas.

Acquisition of Aphasia

  • Aphasia is typically acquired through:
    • Traumatic brain injury.
    • Lesions.
    • Dementia (progressive).
    • Vascular lesions.
    • Tumors.
    • Infections of the CNS (abscesses, TB, Syphilis, Herpes, AIDS).
    • Epilepsy.
  • Aphasia can be part of the overall behavioral picture in several pathologies.
  • Considerations include:
    • Contribution to the disorder and disability.
    • Improving quality of life.
    • Aphasia can provide important diagnostic and prognostic information.

Implicated Brain Regions

  • Dominant (usually Left) superior temporal gyrus.
  • Broca’s and Wernicke’s areas.
  • Networks: including right frontal (planning), thalamus (relay), hippocampus (memory), occipitotemporal (vision, reading).

Comorbidity

  • Aphasia is commonly comorbid with motor and/or sensory impairments on the right side of the body.

Anatomical Considerations

  • Broca's area infarction involves the cortical area, subcortical white matter, and the insula, which can lead to Broca's aphasia; recovery is possible.
  • Wernicke's aphasia results from damage evident in brain imaging.

Middle Cerebral Artery (MCA)

  • Supplies blood to areas important for language.
    • Rolandic branches
    • Prerolandic branches
    • Orbitofrontal branches
    • Orbital branches of anterior cerebral artery
    • Anterior temporal branches
    • Anterior and posterior parietal branches
    • Angular branches
    • Posterior temporal branches
    • Middle temporal branches

Atypical Presentations

  • COVID-19 can present with agraphia and conduction aphasia in patients with left-hemisphere ischemic stroke.

Considering Confounds

  • Important factors to consider in assessment:
    • Language.
    • Age.
    • Dementia.
    • Sex.
    • Education.
    • Culture.
    • Geographic region.
    • Socioeconomic status.
  • Distinguish between language production and other cognitive deficits such as lexical retrieval, semantic retrieval, and emotional withdrawal.

Right Hemisphere Deficits

  • The Montreal Protocol for the evaluation of communication (Protocol MEC; Joanette et al. 2004) is relevant.
  • 80% of patients with right hemisphere deficits have communication disorders (Cote et al., 2007).
  • Impact on social communication, emotion, and abstract meaning.
  • Deficits in awareness, conversation, understanding metaphors, fluency, indirect speech, prosody, and narrative.

Types of Tests

  • Include open-ended, multiple-choice, practical, role-play, and gestural tasks.
  • Assess ability to:
    • Name simple objects.
    • Recognize simple spoken words.
    • Perform simple commands.
    • Repeat words or phrases (e.g., tongue twisters like “no ifs, ands or buts”).
    • Recognize simple printed symbols (letters, words, numbers).
    • Read aloud and follow written instructions (comprehension).
    • Provide verbal and gestural answers to simple questions.
    • Write simple letters, words, and numbers.

Assessment Domains

  • Auditory Comprehension.
  • Expressive Language:
    • Naming.
    • Vocabulary.
    • Discourse.
  • Reading and Writing (Academic skills).

Test Batteries

  • Psycholinguistic Assessments of Language Processing (PALPA; Kay et al., 1992):
    • Developed in the UK, focuses on reading and spelling (word frequency, length, regularity).
    • Lacks conversation assessment or general screening test.
  • Multilingual Aphasia Examination (MAE; Benton et al., 1994):
    • Assesses receptive and expressive language, and immediate memory.
    • Sensitive to age and education.
  • Boston Diagnostic Aphasia Examination (BDAE-3; Goodglass et al., 2000):
    • Includes 12 domains and 34 subtests (1-4 hours).
    • Provides objective and qualitative measures.
  • Western Aphasia Battery-revised (WAB-R; Kertesz et al., 2007):
    • Yields an aphasia quotient, language (reading, writing) quotient, and cortical (apraxia) quotient.
    • Not sensitive to right-hemisphere deficits.
    • Differentiates subtypes of dementia.

Test Batteries (Continued)

  • Communication Abilities in Daily Living (CADL-2; Holland et al., 1999):
    • Uses simulated situations (e.g., doctor's office) with role-play.
  • Neuropsychological Assessment Battery; Language Module (NAB; Stern and White, 2003):
    • Includes picture description, auditory comprehension, naming, reading, writing, and practical tasks (paying a bill).
  • Comprehensive Aphasia Test (CAT; Swinburn et al., 2004):
    • Cognitive screen: semantic memory, recognition, arithmetic, word fluency, line bisection, gesture.
    • Language battery: spoken and written language (imageability, frequency, length), expressive language.
    • Disability questionnaire: effect of language impairments on quality of life and emotional wellbeing.

Screening Tests

  • Do not require expert/technical knowledge.
  • Indicate impairment but are insufficient for diagnosis.
  • Examples:
    • The Aphasia Screening Test (Halstead and Wepman, 1959).
    • The Western Aphasia Battery-R has a short bedside version (15 mins).

Auditory Comprehension Tests

  • Putney Auditory Comprehension Screening Test (PACST; Lintern et al., 2002):
    • Uses Yes/No questions (e.g., “Can babies look after themselves?”).
    • Useful for patients with severe disability (using buzzers for yes/no responses).

Naming Tests

  • Boston Naming Test.
  • Dysnomia: Inability to “pull out” the correct word.
  • Picture stimuli are used.
  • Types of errors:
    • Semantic paraphasic errors (e.g., brush vs. comb):
      • Associated with the left posterior superior temporal and inferior parietal regions.
    • Phonological paraphasic errors (e.g., woof vs. wife):
      • Associated with the insula, external capsule, and putamen.
  • Stimuli range from simple/common (e.g., hand) to complex/rarer (e.g., wrist).
  • Evidence suggests distinct verb & noun representation.
    • Links: https://doi.org/10.1016/s1053-8119(03)00217-9 and https://doi.org/10.1016/0093-934x(90)90002-x
  • Relevance to autistic language impairment.

Naming Tests (Specific)

  • Boston Naming Test (BNT; Goodglass and Kaplan, 2000):
    • Semantic and phonetic cues are provided if the patient is unable to name the object.
    • Patients with Alzheimer’s and temporal lobe epilepsy show similar gains with phonemic cueing.
    • Greater increase with cueing suggests impaired retrieval rather than encoding or storage.
    • No appreciable decline until late 70s (at group level), but greater variability from the 60s.
    • Affected by education (reading); sex findings are mixed.
    • Implicated brain regions: Left temporo-parietal, left-hippocampal, thalamus, right-frontal.
    • Dementia: Naming superordinate categories (e.g., boat vs. canoe) is sensitive to the presence and decline of dementia.
    • Good agreement between the full version and short versions: 15 items (90%), 30 items (93%).
    • Critical reviews are available in Harry and Crowe (2014) and Beattley et al. (2017).
  • Visual Naming Test (Benton et al., 1994):
    • Less sensitive than BNT to naming difficulties in temporal lobe epilepsy.
  • Graded Naming Test (GNT; McKenna and Warrington, 1980):
    • Uses 30 line drawings of increasing difficulty.
    • Affected by education and culture (Canadians < British).
    • Good test-retest reliabilities.
    • Available in a CANTAB version.
    • Dementia: Mild Az < matched controls; predictive of conversion from MCI to dementia.

Naming Tests (Subcategories)

  • Sometimes deficits are isolated to specific subcategories (e.g., living things, foods).
  • Tests for proper names:
    • Iowa Famous Faces Test (Tranel, 2006).
    • Landmark Recognition and Naming Test (Tranel et al., 2005).
  • Distinct neuroanatomical pathways exist for objects.
  • Proper Names: Bilateral (left more consistently) anterior temporal, medial temporal.
  • Verbs:
    • The (Object and) Action Naming Test (Oblar and Albert, 1979).
    • Some evidence suggests verbs rely more on frontal (vs. temporal) function.

Vocabulary

  • General verbal IQ in the general population (Wechsler 1944, 1997 etc.).
    • WIS-A and WAIS: “What does mean?”
    • 0, 1, 2 point answers; often responses don’t match examples, leading to poor interrater reliability.
  • Multiple-choice versions, spot the real word, and nonverbal (pictures) are available.
  • Confound = Impulsivity.
  • Confounds: education, age, urban/rural environment, culture, socialization.
  • Associated with the left hemisphere.

Discourse

  • Story Telling (e.g., Cookie Thief picture).
  • Amount of production: affected by education and age*sex effects.
  • Number of concepts used accurately and completely: affected by education.
  • Differentiates types of language impairment of different aphasic groups.
    • Alzheimer's patients have difficulty describing the central meaning, focus on less important details, and use fewer objects, persons, actions, and features.
    • Endophenotypic marker for Alz (i.e., seen in asymptomatic gene carriers).
  • Syntactic structure is important.
    • Dominant perisylvian association cortex, including Broca’s area.
    • Telegraphic speech: Impaired use of function words (articles, prepositions).
  • Open-ended Conversation and description.
  • Emotional content: enhances discourse in left hemisphere patients, impairs it in right hemisphere patients.

Verbal Comprehension

  • Assess using single words, commands, statements, and paragraphs.
  • Avoid confound by verbal expression: use gesture or “yes”/”no” responses.
  • Characteristic of Wernicke’s aphasia: Dominant posterior STG.
  • Right hemisphere damage:
    • Difficulty drawing coherence inferences.
    • Don’t show inference-related priming.
  • Lengthy/complex material:
    • Performance confounded by working memory deficits.
  • Token Test (Vignolo and colleagues):
    • Assesses understanding of shape, color, and size.
    • Affected by age and education; no practice effects.
    • Sensitive to progression in dementia.
    • Short forms are available.

Verbal Academic Skills: Reading

  • Involves the inferior occipital-temporal, inferior longitudinal fasciculus, and perisylvian fissure.
  • Alexia: impaired reading ability.
  • Tests:
    • Gate-MacGinitie Reading Tests (GMRT-4; MacGinitie et al., 2002):
      • Multiple-choice format.
      • Includes vocabulary and comprehension (conceptual and organizational ability) subtests.
    • Reading Subtest of the Kaufman Functional Academic Skills Test (K-FAST; Kaufman and Kaufman, 1994).
    • National Adult Reading Test (NART; Nelson and O’Connell, 1978; Nelson and Wilson, 1991):
      • Uses 50 phonetically irregular words.
      • Accounts for accents; Spanish version presents words without accents.
      • Correlates with premorbid IQ, education, and social class.
      • Decline with progressive dementia is mild compared to other cognitive tests.
    • Wechsler Test of Adult Reading (WTAR, Psychological Corporation, 2001):
      • Underestimates IQ in TBI; more accurate for dementia.
    • Word Reading subtest of Wide Range Achievement Test 4 (WRAT4; Wilkinson and Robinson, 2006):
      • Developed to assess educational achievement.