6. Types and localisation of aphasia Flashcards
Cause of aphasia
Lesions of cortical speech centers and their conncetions
Cortical speech center
- Wernicke’s speech center
- Broca’s motor speech center
Where is Wernicke’s speech center?
Left hemisphere, Br22
adjacent to prim. auditory cortex in post. 2/3 of the sup. temporal gyrus
Where is Broca’s motor speech center?
Left hemisphere, Br44 Br45. In middle and inferior frontal gyrus.
Basic types of aphasia
- Motor (Broca’s, expressive, non-fluent, anterior type)
- Sensory (Wernicke’s, receptive, fluent, posterior type)
Main causes of aphasia (3 types)
- lesions of the cortical speech centers
- dissociation syndromes
- subcortical aphasia
Types of lesions of cortical speech centers
- Global aphasia
- Motor (Broca’s) aphasia
- Sensory (Wernicke’s) aphasia
Types of dissociations syndromes
- Conduction aphasia
- Alexia (reading) without agraphia (writing)
- Auditory agnosia (process words)
- Transcortical motor aphasia
- Amnestic aphasia
Define subcortical aphasia
Damage to subcortical areas of the dominant hemisphere (mainly in cerebrovascular disorders) leading to aphasia. Lesions to basal ganglia, internal capsule and corona radiata
Define global aphasia
Lesion of entire distribution of middle cerebral artery, including Broca’s and Wernicke’s. Involves all aspects of language and severely impairs spoken communication. Patient unable to speak and understand language.
Characteristic feature of global aphasia
Patient unable to speak and understand language. Language automatism (repetition or gibberish).
Associated disease of global aphasia
Hemiparesis
Define motor (Broca’s) aphasia
Disorder of coordination of the muscles of speech and verbal elements of language.
Etiology of motor (Broca’s) aphasia
Infarction of a branch of the middle cerebral artery
Characteristics of motor (Broca’s) aphasia
Severe impairment of spontanous speech, while comprehension is not affected. The patient can only speak with great effort (pt. knows what he wants to say, but unable to do so)
Subtypes of motor (Broca’s) aphasia
- Paraphasia: substitues one word for another
- Agrammatism: grammatical errors in speech
- Telegraphic type: gives response with one word
- Agraphia: writing is affected
- Patient is aware of disorder and will be quiet
Define sensory (Wernicke’s) aphasia
Infarction of posterior temporal artery (branch of middle cerebral artery). Severe impairment of comprehension, while spontanous speech remains fluent with a normal rhythm.
Characteristics of sensory (Wernicke’s) aphasia
- Use of inappropriate words
- Repetition of certain words
- Paraphasia
- Agrammatism
- Neologism
- Patient unaware of disorder
Define dissociation syndromes
Disruption of pathways between language areas
Conduction aphasia
Lesion of arcuate fasciculus. Characterized by normal speech, but impaired repition. Patient is aware and frustrated.
Alexia without agraphia
Lesion in left occipital lobe usually due to infarct of posterior cerebral artery. Visual information cannot reach the language areas. Patient is unable to read, but can write
Auditory agnosia
Bilateral lesion of superior temporal gyri. Patient unable to understand spoken words, thus unable to repeat them.
Transcortiocal motor aphasia
Lesion in frontal lobe bordering on Broca’s area. Disrupts connection between broca, premotor and supplementory motor areas. Heard words can be repeated, but other linguistic functions are impaired.
Amnestic aphasia
Diffuse lesion of temporoparietal cortex, or in metabolic encephalopathies. Difficult in finding words.
Examination of aphasia
- fluent or not
- comprehensive or not
- repeats or not
- check reading, writing and object naming
