Aphasia: Types and Classification

Key Examination Parameters

1. Fluency - spontaneous speech (rate, grammar, word choice)
2. Comprehension - understanding commands and questions
3. Repetition - ability to repeat phrases
4. Naming - confrontation naming
5. Reading and Writing

The Main Aphasic Syndromes

1. Broca Aphasia (Non-fluent, Expressive, Motor)

• Speech: Nonfluent, effortful, telegraphic/agrammatical (omits small grammatical words). Patient may be mute acutely. Example: "wife come hospital."
• Comprehension: Relatively preserved (but mildly impaired for complex syntax)
• Repetition: Impaired
• Naming: Impaired; tip-of-tongue phenomenon common
• Writing: Always impaired, dysmorphic, dysgrammatical
• Associated signs: Right hemiparesis, hemisensory loss, ± limb apraxia
• Lesion: Left inferior frontal gyrus (Brodmann areas 44 & 45 + adjacent subcortical white matter)

2. Wernicke Aphasia (Fluent, Receptive, Sensory)

• Speech: Fluent or even excessive (logorrhea), effortless but empty of meaning. Contains verbal paraphasias, neologisms, and jargon. A foreign listener may notice nothing odd.
• Comprehension: Impaired - sometimes even simple commands fail
• Repetition: Impaired
• Naming: Impaired, often with bizarre paraphasic substitutions
• Writing: Fluent but paragraphic (spelling errors, paraphasias in writing)
• Associated signs: ± Right homonymous hemianopia; no hemiparesis (key distinguishing feature from Broca)
• Lesion: Posterior superior temporal gyrus (Wernicke area, Brodmann area 22)

3. Global Aphasia

• Speech: Mute or severely non-fluent
• Comprehension: Severely impaired
• Repetition: Impaired
• All language modalities are affected - essentially Broca + Wernicke combined
• Associated signs: Dense right hemiplegia, hemisensory loss, hemianopia
• Lesion: Large left perisylvian lesion covering both frontal and temporal regions - most of the left MCA territory

4. Conduction Aphasia

• Speech: Fluent, but with frequent literal (phonemic) paraphasic errors and self-correction attempts
• Comprehension: Relatively preserved
• Repetition: Severely impaired out of proportion to other deficits - the hallmark. Patient who can converse may be unable to repeat a single word.
• Naming: Moderately impaired
• Associated signs: ± Hemisensory loss, ± hemianopia; hemiparesis usually absent
• Lesion: Arcuate fasciculus (disconnects Broca and Wernicke areas) or supramarginal gyrus / insula

5. Transcortical Motor Aphasia

• Speech: Nonfluent, reduced output
• Comprehension: Relatively good
• Repetition: Preserved (key differentiator from Broca aphasia)
• Tendency to echolalia (automatically repeats examiner's words)
• Lesion: Anterior or superior to Broca area (supplementary motor area or its connections), sparing perisylvian cortex

6. Transcortical Sensory Aphasia

• Speech: Fluent, paraphasic
• Comprehension: Impaired (like Wernicke)
• Repetition: Preserved (key differentiator from Wernicke aphasia) - may repeat in an echolalic manner
• Lesion: Posterior to Wernicke area (watershed zone of temporal-parietal cortex)

7. Anomic Aphasia (Nominal / Amnesic Aphasia)

• Speech: Fluent; only deficit is word-finding difficulty (anomia) with circumlocutions
• Comprehension: Normal
• Repetition: Normal
• Isolated loss of naming ability; other language functions relatively spared
• Often the residual syndrome after partial recovery from other aphasia types
• Lesion: Various locations; typically angular gyrus, inferior temporal lobe, or diffuse

8. Pure Word Deafness (Auditory Verbal Agnosia)

• Isolated inability to comprehend spoken language; speech, reading, and writing are intact or near normal
• Patient hears sounds but cannot decode spoken words
• Lesion: Bilateral (or left-sided) middle superior temporal gyrus - disconnection of Wernicke area from bilateral primary auditory cortex

9. Pure Word Blindness (Alexia without Agraphia)

• Unable to read despite normal speech, comprehension, repetition, and writing
• Can write but cannot read their own writing
• Lesion: Left calcarine cortex + splenium of corpus callosum (disconnects right visual cortex from left language areas)

10. Aphemia (Pure Word Mutism)

• Transient muteness with preserved writing
• Some argue it is not a true aphasia since language (writing) is intact
• Lesion: Isolated small lesion in or near Broca area

Summary Table

Quick Clinical Memory Aid

• Preserved repetition = transcortical aphasia (motor or sensory type) - the perisylvian arc is intact
• Non-fluent + good comprehension = Broca (anterior lesion)
• Fluent + poor comprehension = Wernicke (posterior lesion)
• Fluent + good comprehension + poor repetition = Conduction
• Everything impaired = Global

Sources: Bradley and Daroff's Neurology in Clinical Practice, Ch. 13; Adams and Victor's Principles of Neurology, 12th Ed., Ch. 22; Neuroscience: Exploring the Brain, 5th Ed., Ch. 20