• Information
  1. Definitions
  2. Broca's Aphasia
  3. Wernicke's Aphasia
  4. Conduction Aphasia
  5. Global Aphasia

A. Definitions [1]
[Figure] "Schematic of Brain Centers"

1. Aphasia is a disturbance of COMPREHENSION and FORMULATION of language
2. Caused by dysfunction of specific brain regions
   1. Speech centers are found in the left cerebral hemispheres in >95% of people
   2. Speech centers are on the right side in ~10% of left handed people
   3. Very unusual to have right sided lesions causing aphasia - then called "crossed aphasia"
   4. Some left handed persons have bilateral speech centers with left dominance
3. Aphasia is not a disorder of basic thought processes
   1. Dementia - progressive decline in thought processes
   2. Schizophrenia - disordered thought processes
4. Dysarthria - uncoordinated speech with abnormal phonemes (disarticulation)
5. Alexia - word or text blindness, "visual aphasia", cannot grasp meaning of written words
6. Agraphia -inability to write
7. Apraxia - disorder of voluntary movement; inability to execute purposeful movements
8. Agnosia - lack of sensory-perceptual ability to recognize objects
9. Different patterns of aphasia correspond to specific brain regions

B. Broca's Aphasia (Expressive)

1. Damage to Broca's Area (Inferior L Frontal Gyrus in R Handed Persons)
   1. Damage to white matter commonly found
   2. Damage to Basal Ganglia frequent also
2. Unable to repeat sentences correctly
3. Loss of fluency in speech
   1. Speech effortful and always slow
   2. Pauses between words
   3. Labored and flat
   4. Words are usually recognizable
4. Hallmark is inability to organize normal grammatically correct sentences
5. "Broca's Area Aphasia" develops from lesions which affect only Broca's area

C. Wernicke's Aphasia (Fluent)

1. Usually due to damage to L Parietal area
2. Cannot repeat sentences correctly; abnormal phonemes
3. Motor deficits are very uncommon
4. Speech is FLUENT
   1. Content is usually unintelligible
   2. Frequent errors in phoneme and word choices
   3. Difficulty comprehending phrases
   4. No difficulty producing individual sounds
   5. Examples: "Trable" (Table), "Pymarid" (Pyramid)
5. May become extremely anxious, agitated, or paranoid due to inability to comprehend
6. Wernicke's Area
   1. Previously thought to be auditory comprehension area
   2. Area is actually a processor of speech sounds which allow them to be mapped as words
   3. Allows subsequent evoking of conceptual meanings
   4. Also appears important in implementing speech sounds

D. Conduction Aphasia

1. Patients can comprehend essential sentences and produce intelligent speech
2. Cannot repeat sentences verbatim or assemble phonemes effectively
3. Ability to produce words on confrontation is impaired
4. R-sided facial weakness may occur
5. Damage
   [Figure] "Schematic of Brain Centers"
   1. Area 40: L supramarginal gyrus
   2. Areas 41-2: L primary auditory cortex

E. Global Aphasia

1. Nearly complete loss of ability to comprehend language or formulate speech
2. Combines features of Broca's and Wernicke's Aphasias
   1. Deliberate speech is reduced to few words and sentences
   2. Automatic speech is preserved, for example: "mama", expletives such as "hell"
   3. Repetitious, learned tasks such as counting or reciting days of week occasionally intact
3. Usually accompanied by weakness of R side of face and R hemiplegia
4. Classic Global Aphasia
   1. Hemiplegia (R sided)
   2. Damage in Broca's area
   3. Damage to entire basal ganglia region
   4. Damage to insula and auditory cortices (as in conduction aphasia)
   5. Damage to Wernicke's Area
5. Little or no improvement expected

References

1. Damasio AR. NEJM. 1992.326(8):531