Introduction to Aphasia Notes

Learning Outcomes

  • Define the signs/symptoms of acquired language disorders (aphasia).
  • Discuss aphasia classification criteria.
  • List causes of aphasias and other acquired language deficits.

Aphasia

  • Acquired deficit in language abilities resulting from damage to the brain.
    • Deficit in production, comprehension, or both.
    • Dissociation syndrome - some aspects of language may be affected differently than others.
    • In all modalities of language.
  • Not a result of motor, intellectual, or psychological impairment.

Causes of Aphasia

  • Neurogenic – affects the nervous system.
  • Most common: stroke
  • Also:
    • Traumatic brain injury (TBI).
    • Brain tumors.
    • Surgical damage to brain tissue.
    • Brain infections.
    • Metabolic problems.
    • Neurodegenerative diseases.

Expressive Deficit

  • Difficulty in formulation/production of language.

Receptive Deficit

  • Difficulty deriving meaning from language.

Anomia

  • Deficit in word-finding ability.
  • Person knows the meaning they want to convey but cannot find the word.
  • Can often describe the concept in detail.

Verbal Comprehension Deficits

  • Deficit in any modality of language interpretation
  • Even of one's own speech.

Paraphasia

  • Errors in expressive language unrelated to motor deficits.
  • Syllables, words, phrases produced unintentionally.

Types of Paraphasias

  • Phonemic:
    • Word is correct, but there are phonemic errors.
    • Substitutions, omissions, or transpositions.
    • Example: “taples” for “staple”.
  • Neologism:
    • A word entirely different from intended.
    • Mostly unintelligible.
    • Example: “dowfler” for “flower”.
  • Semantic:
    • Whole word is substituted for another word of similar meaning.
    • Example: “airplane” for “helicopter”.
  • Unrelated Verbal:
    • Whole word is substituted for another word of unrelated meaning.
    • Example: “lunch” for “bicycle”.

Perseveration

  • To do something repeatedly, redundantly, and often inappropriately.
  • Perseverative Paraphasia:
    • Word produced earlier is repeatedly and inadvertently produced by an individual in place of another word.

Agrammatism

  • Lack of grammar.
  • Telegraphic Speech:
    • When function words (articles, prepositions, conjunctions, etc.) are missing, language may still be able to convey meaning but sound halted

Alexia & Agraphia

  • Alexia:
    • Acquired reading impairment.
  • Agraphia:
    • Acquired impairment in ability to form words using letters.

Self-Repair

  • Speaker restates or revises a word/phrase.
  • Persons with aphasia may be less successful at correctly self-repairing.

Preserved/ Automatic Language

  • Rote/overlearned language may be preserved
  • e.g., days of the week, months of the year, counting, curse words, favorite recited passage or poem, singing.

Quality of Life (QOL)

  • Goal: investigation of factors associated with QOL in individuals with aphasia
  • Participants: 32 individuals with aphasia following stroke with “usable auditory comprehension”
  • QOL associated with:
    • Increased severity of aphasia
    • Increased communication activity limitation
    • Increased severity of stroke
    • Increased limitations on activities of daily living
    • Increased fatigue symptoms
    • Increased depression symptoms

Dichotomous Classifications

  • Non-Fluent:
    • Speech is effortful, halting, agrammatic, with short phrases
    • Usually aware of their deficits
  • Fluent:
    • Speech is smooth with appropriate prosody but little meaning.

Aphasia Decision Tree

  • Variants of aphasia can be determined based on assessment of a patient's fluency, comprehension, and repeating abilities.
  • Each form of aphasia is correlated with damage to a specific region of the perisylvian language zone.

Broca’s Aphasia

  • Damage to inferior posterior frontal lobe of language-dominant hemisphere (Broca’s area)
  • Nonfluent
    • Halting, effortful, agrammatic, telegraphic
    • Mostly content words, few function words
    • Pausing to overcome anomia
    • Repeated attempts to self-correct
    • Short phrases
  • Misarticulations are common
  • Functionally intact comprehension
    • Can understand normal conversational speech, but may break down with detail-heavy or complex language
  • Difficulty repeating
    • Due to difficulty with expressive language
  • Written language mirrors spoken language abilities
  • Often associated with contralesional hemiparesis/hemiparalysis
  • Often aware of their deficits
    • Self-monitoring is preserved
    • And will use whatever forms of expression they have left, e.g., gestures
    • “… individuals with Broca’s aphasia are very poor speakers but very good communicators”

Wernicke’s Aphasia

  • Damage to posterior ⅓ of superior gyrus of temporal lobe in language-dominant hemisphere (Wernicke’s area)
  • Significant receptive deficits
    • Unable to understand simple requests/statements
    • Difficulty with conversational norms, e.g., turn-taking
  • Fluent
    • Tangential to conversation topic
    • Comprised of neologism and paraphasias
    • Empty speech: devoid of meaning
    • Logorrhea: near nonstop output of speech
  • Impaired repetition
  • Unable to recognize deficits
    • Anosognosia

Transcortical Motor Aphasia

  • Damage to supplementary motor cortex and regions just anterior to Broca’s area in the language-dominant hemisphere
  • Non-fluent speech patterns
  • Articulation may be preserved
    • Unless the areas of the primary motor cortex that control the face
  • Relatively intact comprehension
  • Intact repetition

Transcortical Sensory Aphasia

  • Damage posteriorly to Wernicke’s area, near the temporo-occipital-parietal junction of the language-dominant hemisphere
  • Poor auditory comprehension
  • Fluent speech
    • With semantic paraphasias
  • Relatively intact repetition

Conduction Aphasia

  • Damage to arcuate fasciculus at the supramarginal gyrus in the language-dominant hemisphere, sparing Broca’s and Wernicke’s areas
  • Mostly fluent speech
    • Phonemic paraphasias
    • Anomia
  • Relatively intact auditory comprehension
  • Significant deficits in repetition
    • Particularly with multisyllabic words and phrases
  • Often aware of paraphasias
    • Made disfluent by attempts at self-repair
    • Conduit d’approche: zeroing-in to produce the correct target after several attempts

Anomic Aphasia

  • Damage to anywhere within the language areas of the language-dominant hemisphere
  • Fluent speech
  • Intact receptive language
  • Relatively preserved repetition
  • Significant deficit in naming

Global Aphasia

  • Damage to most of the language areas of the language-dominant hemisphere
  • Little to no receptive language ability
  • Little to no expressive language ability
    • Including preserved/automatic language
  • Inability to repeat
  • Often occur with severe motor and/or cognitive deficits

Subcortical: Thalamic Aphasia

  • Damage to the language-dominant side of the thalamus
  • Almost fluent speech
  • Significant anomia
    • Worse in spontaneous speech, but improved in confrontational naming
  • Impaired receptive language
  • Perseverative semantic paraphasias
  • Normal articulation
  • Hypophonic (soft) voice
  • Intact repetition
  • Intact grammar

Subcortical: Striatocapsular Aphasia

  • Damage to the striatum (portion of the basal ganglia), with likely resulting loss of blood flow to the language cortices
  • Loss of fluency
  • Rare phonemic paraphasias
  • Preserved repetition
  • Mild anomia

Primary Progressive Aphasia (PPA)

  • Subtype of frontotemporal dementia
  • Frontal and temporal lobes of the brain atrophy while the parietal and occipital lobes remain intact
  • In PPA, language deficits appear before cognitive deficits
  • Neurodegenerative
  • Insidious (gradual) onset
  • Symptoms get progressively worse

Semantic variant (svPPA)

  • Impaired naming
  • Impaired single-word comprehension
  • Loss of conceptual knowledge
    • Not limited by modality
    • May have difficulties reading/writing
  • Repetition is relatively intact

Logopenic variant (lvPPA)

  • Anomia
  • Impaired repetition of phrases and sentences
  • May have paraphasias
  • Motor speech, single word comprehension, and object knowledge generally spared
  • Grammar is typically spared

Nonfluent variant (nfvPPA)

  • Impaired grammar and/or motor speech
  • Impaired syntactic comprehension
    • Especially for complex sentence structures
  • Comprehension and semantic knowledge typically spared

Crossed Aphasia

  • Aphasia due to damage to the right hemisphere
  • Rare (<3% of people with aphasia)
  • Lesion sites mirror those with classical aphasia
  • Writing ability is generally preserved in Broca’s aphasia
  • May have symptoms associated with right hemisphere lesions
    • E.g., visuospatial deficits or neglect

Transient Aphasia

  • Temporary difficulty with language
  • Caused by:
    • Migraine aura
    • Epileptic seizure
    • Other neural disruption

Callosal Disconnection Syndrome

  • Corpus callosum is damaged or surgically ‘disconnected’ (commissurotomy: as a treatment for seizures)
  • If anterior corpus callosum is damaged, people with left language- dominant hemisphere have difficulty responding to verbal commands involving the left hand or describing objects in the left hand (when out of sight)
  • If posterior corpus callosum is damaged, words/pictures presented to the left field of vision cannot be named

Limitations of Aphasia Classification

  • Language functions include networks of many connected regions
  • A minority of people with aphasia can be classified based on site of lesion alone
  • The classification depends strongly on which assessments are used
  • Symptom constellations can evolve over time
  • There are people whose symptoms do not match with classification boundaries

Summary

  • Acquired language deficits (aphasia) can occur after damage to the language-dominant hemisphere in cortical or subcortical areas
  • Aphasia is classified by location of injury and specific expressive, receptive, and repetition deficits
  • Aphasia classification is not perfect, but it gives us a common set of terms to describe performance
  • Aphasia is caused by damage to language networks in the brain