Subtypes of Aphasia – Comprehensive Study Notes

Why Do We Describe Language?

• Clarifies which language abilities are impaired vs. relatively spared.

• Highlights strengths/limitations → guides differential Dx (aphasia vs. other neurogenic language disorders such as dementia, TBI, right-hemisphere disorder).

• Informs medical diagnosis by localising lesions (e.g., perisylvian vs. extrasylvian).

• Provides the foundation for intervention planning: what to treat, why it matters, treatment priorities, measurable goals.

What Are We Describing?

• Modalities:

  • Output/Expression → Speaking & Writing.

  • Input/Comprehension → Auditory comprehension & Reading.

Core Signs of Aphasia

• Disturbance in fluency (non-fluent vs. fluent).

• Paraphasias (semantic & phonemic).

• Impaired repetition.

• Impaired auditory comprehension.

• Word-finding difficulty (anomia).

• Disturbance in reading/writing.

Connectionist Theory & Neuro-anatomy

• Perisylvian region = language hub.

  • Anterior language zone (left frontal lobe) → planning/executing language output (speech, writing, gesture).

  • Posterior language zone (left temporal/parietal lobes) → comprehension & formulation of syntactically/semantically appropriate messages.

• Lesions in or around perisylvian cortex produce classic aphasia subtypes.

• Lesions outside (transcortical/watershed) spare repetition.

Fluency Continuum

• Non-Fluent (Anterior)

  • Rate <50\ \text{wpm}, phrase length $1\text{–}2$ words.

  • Impaired prosody, effortful, many pauses.

  • Excess substantive words; paucity of grammatical functors.

• Fluent (Posterior)

  • Rate $100\text{–}200\ \text{wpm}$, phrase length $5\text{–}8$ words.

  • Normal prosody, ease of production.

  • Normal/long utterances, but semantic content may be low.

Detailed Clinical Features

• Paraphasia

  • Semantic: meaning-related substitutions (e.g., chair→“table”).

  • Phonemic: sound-related substitutions (e.g., “dable” for table).

• Neologisms → novel nonsense words; phonologically possible (e.g., “fribis” for home).

• Echolalia → automatic repetition of another’s utterance.

• Perseveration → persistent/recurrent response despite stimulus change.

• Repetition deficit → hallmark of perisylvian damage.

• Anomia → pervasive word-retrieval failure; evidenced by circumlocution in spontaneous speech & poor confrontation naming.

• Circumlocution → indirect description to avoid the missing word.

• Agrammatism (hallmark of Broca’s) → reduced/omitted grammatical morphemes, reliance on content words.

Decision Tree for Classification (Helm-Estabrooks & Albert, 1991)

1. Assess Naming.

   • No naming problem → not aphasic.

   • Naming problem → proceed.

2. Assess Fluency.

   • Non-fluent → Global, Broca’s, TMA.

   • Fluent → Wernicke’s, TSA, Conduction, Anomic.

3. Assess Auditory Comprehension (AC).

   • Poor vs. Good helps split Global/Broca/TMA and Wernicke/TSA/Conduction/Anomic.

4. Assess Repetition (REP).

   • Poor vs. Good refines each branch (e.g., Broca = poor REP; TMA = good REP).

Non-Fluent Aphasias (Lesion Anterior to Central Sulcus)

Broca’s Aphasia

• Lesion: fronto-parietal operculum & insula (superior division of left MCA).

• Speech: non-fluent, effortful, agrammatic, apraxia common.

• Auditory comprehension: relatively spared; breaks down with length/complexity.

• Repetition: poor.

• Naming: impaired; circumlocutions.

• Reading > writing (input > output).

• Classic “Cookie-Theft” example: telegraphic utterances (“mother…dishes… water… floor…”).

Transcortical Motor Aphasia (TMA)

• Lesion: anterior/watershed area between ACA & MCA.

• Speech: markedly reduced initiation & complexity; may rely on stereotyped phrases/echolalia.

• Repetition: intact → key differential.

• Auditory comprehension & naming: relatively preserved.

• Reading aloud better than spontaneous speech; writing mirrors speech.

Global Aphasia

• Large perisylvian lesion; involves all language modalities.

• Speech: minimal, non-fluent, possibly mute.

• Auditory & reading comprehension: severely impaired.

• Repetition & naming: impossible.

• No meaningful writing.

• Prognosis: AC often improves more than expression over time.

Fluent Aphasias (Lesion Posterior to Central Sulcus)

Wernicke’s Aphasia

• Lesion: posterior superior temporal gyrus.

• Speech: fluent, effortless, paraphasic, jargon; monitoring deficit (anosognosia).

• AC & repetition: severely impaired; reading parallels AC.

• Writing parallels spoken output.

Transcortical Sensory Aphasia (TSA)

• Lesion: posterior watershed (PCA/MCA border).

• Speech: fluent, empty, circumlocutory; naming poor.

• AC: impaired (but less severe than Wernicke’s); patient often echoes questions.

• Repetition: intact.

• Reading comprehension worse than AC; writing worse/equal to speech.

Conduction Aphasia

• Lesion: arcuate fasciculus/supramarginal gyrus.

• Speech: fluent with phonemic paraphasias, frequent self-corrections.

• AC: good.

• Repetition: markedly impaired, esp. multisyllabic words & sentences.

• Naming: phonemic errors.

• Reading aloud & writing impaired; apraxia (oral/limb) common.

Anomic Aphasia

• Lesion: variable (often temporal–parietal).

• Speech: fluent but severe word-finding difficulty; heavy circumlocutions & non-specific fillers (“thingamajig”).

• AC, reading & repetition: intact.

• Naming: impaired; frequency effect (high-frequency words easier).

• Writing mirrors spoken word-finding issues.

Comparative Summary (all modalities)

• Global: Severe deficits across the board.

• Broca’s: AC relatively spared; non-fluent; repetition poor.

• Wernicke’s: Fluent; AC & repetition poor.

• Conduction: Fluent; AC spared; repetition disproportionately poor.

• Anomic: Isolated naming deficit.

• TMA: Non-fluent; repetition spared.

• TSA: Fluent; repetition spared; AC impaired.

Practical / Ethical / Clinical Notes

• Accurate subclassification affects:

  • Prognosis (e.g., Global vs. Anomic).

  • Therapy focus (e.g., syntax drills for Broca’s; self-monitoring for Wernicke’s).

  • Communication partner training strategies (e.g., simplification vs. supportive listening).

• Ethical obligation to communicate Dx & prognosis transparently and to tailor interventions to meaningful, person-centred goals (participation, quality of life).

• Real-world relevance: aphasia impacts return to work, social participation, mental health; clinicians must advocate for accessible environments & informed communities.

Key Numerical / Statistical References

• Fluency rates:

  • Non-fluent: <50\ \text{wpm}.

  • Fluent: $100\text{–}200\ \text{wpm}$.

• Phrase lengths:

  • Non-fluent: $1\text{–}2\ \text{words}$.

  • Fluent: $5\text{–}8\ \text{words}$.

Glossary (Essential Terms)

• Aphasia

• Anomia

• Paraphasia (Semantic, Phonemic, Neologistic)

• Agrammatism

• Echolalia

• Perseveration

• Fluent vs. Non-Fluent

• Auditory Comprehension (AC)

• Repetition (REP)

• Naming / Confrontation Naming

• Lesion, Perisylvian, Watershed

• Apraxia (Oral & Limb)

• Circumlocution

• Telegraphic Speech