Aphasia (Wernicke’s and Broca’s): Pathogenesis and clinical findings
Authors: Davis Maclean Reviewers: Heather Yong Tony Gu Yan Yu* Scott Jarvis* *MD at time of publication
Ischemic stroke (common)
Local Invasion (e.g. by a tumour, Head infection, or hemorrhage) Trauma
Intracerebral Hemorrhage
Dementia (e.g. Fronto- temporal Dementia)
Episodic occurrences (e.g., migraine, epilepsy)
Damage to language-dominant cerebral hemisphere (the left hemisphere, for the majority of humans):
Damage affecting Broca’s Area in the Inferior frontal gyrus (area 44 & 45)
Damage affecting Wernicke’s Area in the posterior part of the superior temporal gyrus (area 22)
Localization: Inferior frontal gyrus, superior sylvian fissure
Blood supply: superior division M2 branch middle cerebral artery
Localization: Posterior perisylvian region, temporal lobe
Blood supply: inferior division M2 middle cerebral artery
Sensory speech
areas still intact (posterior superior temporal lobe)
Intact comprehension (intact hearing & reading)
Impaired function of Broca’s Area
↓ output or generation of speech/ text
If function of nearby motor areas is also impaired
Contralateral hemiparesis (face, arm > leg)
If function of other nearby areas is also impaired
Impaired naming and repetition
Motor speech areas still intact (inferior frontal lobe)
Fluent (but non-sensical) speech output
Impaired function of Wernicke’s Area
Impaired compre- hension (i.e. cannot understand speech or text)
Loss of sensory speech input to motor areas
Errors in word usage, tense, structure
If function of nearby sensory areas is impaired
Contralateral sensory deficits
Broca’s Aphasia
Wernicke’s Aphasia
(Expressive language impairment: non-Fluent)
Notes/Definitions:
(Receptive language impairment/Fluent: the person can talk but their speech is nonsensical)
• Dysarthria ≠ Aphasia (Dysarthria: disruption to neurons controlling the muscles that produce sounds, resulting in slurred/disjointed speech. Aphasia: acquired deficit in language comprehension or generation/output usually due to disruption of neurons in the cerebral cortex.)
• “Global” aphasia affects both receptive and expressive language.
Legend:
Pathophysiology
Mechanism
Sign/Symptom/Lab Finding
Complications
Published January 1, 2020 on www.thecalgaryguide.com