Aphasia Flashcards
What is Aphasia?
Aphasia is a disorder that affects how you communicate.
It can impact language and speech. It is usually caused by damage to the left side of the brain (e.g., usually caused by stroke or head injury)
What is Brain localisation?
different parts of the brain dedicated to more specific functions
damage to specific regions leads to specific patterns of impairment
Language is typically left lateralised
Language is typically left lateralised
- Many language networks are in the left hemisphere
- Even in the majority of left-handed people
Left vs. Right Hemisphere
Left brain- reading, writing, calculations, analytical thinking, language, numbers (logical side of the brain)
Right brain- visual, expression, emotional intelligence, imagination (creative side of the brain)
The Wada Test (1959)
Putting half the brain to sleep
Can help a physician evaluate how important each side of the brain is with respect to language and memory functions
It is used for the lateralisation of memory and language function
CASE STUDY: Broca’s Patient “Tan” (1861)
Broca provided the first case study of brain injury
-The patient could only repeat the word “tan” over and over
-Indicated that the patient had damage n the frontal area (Broca’s area)
-His speech was limited to “tan-tan”
-Lost the ability to speak
-No physical signs of trauma. Intelligence unaffected
-Responsive to environment (grasping objects, reacting)
Later: right sided paralysis, decline in mental abilities
- 1861: autopsy revealed left sided damage.
- Over time carried out further autopsies on several other individuals with similar patterns of behaviour—concluding that the left frontal lobe (third frontal gyrus; Broca’s area) is critical for producing language.
Broca’s Theory
The lower part of the brain of the frontal lobe of the brain was responsible for what we now call speech production
Carl Wernicke (1874)
Wernicke discovered speech perception is localised in the left temporal lobe (Wernicke’s area).
Dissociations between language functions (one impaired whilst other is spared)
These early cases (Broca’s and Wernicke’s) demonstrate both lateralisation and localisation of language functions
Broca’s Aphasia (non-fluent aphasia)
Deficits in speech production (word finding difficulty)
Agrammatism (impaired syntax) in spoken language
Speech is laborious, but comprehension generally ok (difficulty with complex sentences)
Motor function often impaired (due to location of lesion)
Wernicke’s Aphasia (fluent aphasia)
Deficits in speech comprehension (understanding language)
Speech is fluent/effortless but lacks meaningful content
Often unaware of their errors, even in mild cases
Fluent vs non-fluent aphasia
Non-fluent
Broca’s aphasia leaves you with limited language. You might only be able to say single words or very short sentences, but others usually understand what you mean.
Fluent
Wernicke’s aphasia causes you to speak in a jumbled “word salad” that others can’t understand.
Conduction Aphasia
- Rare
- Some naming deficits (mostly fluent), comprehension is ok
- However, repetition is impaired
- (Especially non-words, counting)
- Aware of errors and they try to correct them
Transcortical Motor Aphasia
- Non-fluent (initially can be mute), like Broca’s Aphasia
- Reduced output, but comprehension is good
- However, repetition is better than language production
- Connections between Broca’s area and the supplementary motor area; medial frontal lobe (areas for planning and generating language)
Transcortical Sensory Aphasia
- Impaired comprehension (like fluent aphasia)
- Repetition is relatively intact
- Lesions vary but typically at temporo-parieto-occipital junction area (Wernicke’s)
Global Aphasia
- Combination of non-fluent and fluent aphasias
- Impairments across all aspects of language
- Speech production, comprehension, and repetition impaired
- Lesions vary but are typically more extensive (often extend deeper too leading to more severe right sided sensory and motor impairments)
Language recovery
Impairments are worst just after stroke/brain injury.
-Spontaneous recovery occurs- plasticity, right hemisphere involvement (Usually within first 6 months- acute stage
-Speech and language therapy to target specific language functions- as outlined by assessment – (Chronic stage: strategies / management of speech and language difficulties.)
What abilities do language assessments usually test?
Speech production
- Fluency (fluent vs. non-fluent)
- Spontaneous speech
- Picture description
- Repetition (words and non-words)
Naming
- Objects
- Actions
- Body parts
Comprehension
- Auditory and written
- Single words
- Sentences (increasing complexity, paragraphs)
- Commands
Reading and Writing
- Reading real words, nonwords, and sentences
- Spelling and sentence/story writing (writing often poor due to LH damage and handedness)
Right hemisphere and aphasia
We know that generally language is left lateralised.
However, there are a handful that are attributed to the right: some word processing (high frequency short words, ambiguous words), some aspects of comprehension, pragmatic skills and identifying and expression emotional prosody.
CASE STUDY: Right Hemisphere and Aphasia
Patient was enrolled in a RCT for transcranial magnetic stimulation for chronic non-fluent aphasia
Induces an electric field at cortex:
-Causes action potential
-Virtual lesion approach
-Silent period
-Interference of a process
The case study shows effects of right hemisphere involvement in aphasia:
- Inhibitory TMS in right hemisphere showed improvement
- Stroke to right hemisphere led to worsening of language
- Clinical evidence that a lesion to the left hemisphere can induce re-organisation in the right hemisphere
