Broca's Aphasia: Expressive Language Deficit with Preserved Comprehension
A patient who can understand but cannot speak has Broca's aphasia (also called expressive or non-fluent aphasia), caused by damage to Broca's area in the left frontal lobe, specifically involving the inferior frontal gyrus and surrounding white matter structures. 1, 2
Brain Area Involved
The critical anatomical structures damaged include:
- Broca's area in the left inferior frontal gyrus (frontal operculum), specifically the pars opercularis 2, 3
- White matter above the insula and the anterior arcuate fasciculus, which are critical predictors of persistent speech production impairment 2
- The dorsal language pathways, including the arcuate fasciculus and superior longitudinal fasciculus, connecting frontal, temporal, and parietal regions 4, 5
The evidence from the International Journal of Stroke demonstrates that structural damage to the arcuate fasciculus and Broca's area is specifically associated with impaired repetition and speech production deficits 4. Imaging studies confirm that lesions involving the left frontal and opercular regions produce the characteristic features of this syndrome 3.
Type of Aphasia: Broca's Aphasia (Expressive Aphasia)
This condition is called Broca's aphasia or expressive aphasia, characterized by the following features 1:
Key Clinical Characteristics:
- Non-fluent speech production with hesitations and pauses during speech attempts 2, 5
- Relatively preserved comprehension (though not completely intact—this is a common pitfall) 1, 5
- Telegraphic or agrammatic speech with simplified grammatical structure 6, 7
- Impaired repetition due to arcuate fasciculus involvement 4
- Apraxia of speech commonly co-occurs, with motor planning difficulties 1, 5
Important Clinical Pitfall:
Comprehension is NOT completely normal in Broca's aphasia—it appears relatively preserved only when compared to the severely impaired expression 5. A comprehensive assessment should evaluate all language domains including speaking, comprehension, reading, writing, and gesturing 5. The patient may struggle with complex grammatical structures even in comprehension 6.
Differential Considerations
Distinguish Broca's aphasia from:
- Wernicke's aphasia: Fluent but meaningless speech ("word salad") with severely impaired comprehension—the opposite pattern 2
- Global aphasia: Both severe expressive AND receptive deficits with near-total language loss 2
- Transcortical motor aphasia: Non-fluent speech but with preserved repetition ability, associated with medial frontal lesions 7
- Pure apraxia of speech: Motor planning disorder without the linguistic deficits (agrammatism) seen in Broca's aphasia 1
Treatment Approach
Speech and language therapy is the primary treatment, with intensive therapy probably indicated 1:
- Communication partner training to optimize functional communication 1
- Computerized treatment as a supplement to traditional therapy 1
- Group therapy shows equivalent outcomes to individual therapy 1
- Pharmacotherapy may be considered case-by-case in conjunction with speech therapy, though no specific regimen is routinely recommended 1
The prognosis depends on lesion extent, with recovery of naming predicted by reperfusion of Broca's area and surrounding structures 4.