The lesion is often found in the posterior inferior frontal gyru in the left hemisphere, which is a site often known as Broca’s Area. Broca’s aphasia is characterized by nonfluent speech that is agrammatic as well as telegraphic. For example, a person with Broca’s aphasia may say “boy….fall down!” rather than “the boy is going to fall down” where content words are still present but smaller grammatical structures are omitted. Individuals with Broca’s aphasia often have relatively intact receptive language. Phonemic paraphasias, which is when some part of the intended word is switched or altered (e.g., “crow” for “cow”), are commonly seen in this type of aphasia.
The underyling lesion for this aphasia is often found in the left temporal lobe often including Wernicke’s area. This aphasia is characterized by fluent, non-grammatical speech and poor auditory comprehension. Individuals with Wernicke’s aphasia often have a lack of awareness of their errors, which can lead to frustration.
Transcortical sensory aphasia
This type of aphasia is caused by involvement of the angular gyrus and the posterior sector of the middle temporal gyrus. Wernicke’s area and the primary auditory cortices are both spared. This aphasia is similar to Wernicke’s with fluent paraphasic speech but is different in that repetition is relatively intact.
This lesion is limited to the supramarginal gyrus in the left hemisphere. Characteristics of conduction aphasia include fluent speech with a significant impairment in repetition. This impairment in repetition is disproportionate to the accuracy of their spontaneous speech. When these individuals attempt to repeat language that is spoken to them, they will often produce successive approximations, meaning they will produce phonemic paraphasias that are similar to the target word. Often, the individual is able to spell out or write out the word that they cannot retrieve.
When extensive damage is done to the frontal, parietal and temporal regions of the left hemisphere, global aphasia often ensues. Global aphasia consists of severe receptive and expressive language deficits, sometimes to the point where the individual can understand almost no language and cannot produce almost any language. Occasionally the individually is able to produce one or two route utterances, however, sometimes those utterances are non-words (e.g., “tadada”). Some individuals may present with global aphasia immediately after a stroke has occurred, but over time morph into what appears to be more like Broca’s aphasia.
Transcortical motor aphasia
Nonfluent speech with preserved repetition characterize this type of aphasia. The location of the underlying lesions are not always predictable, but often times they are more anterior than those found in Broca’s aphasia. This similar location of the lesion lends itself to a presentation similar to Broca’s aphasia. However, the differentiating feature is that repetition is spared.
Lesions underlying this aphasia are often found in the left temporal pole, although specific locations can vary. The main characteristic consists of a deficit in naming, especially naming specific individuals, animals and tools while retaining recognition. No other language deficit is typically present.
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Williams & Wilkins.
The Dementia That Acts Like Aphasia
PPA is similar to an Aphasia caused by stroke however; deficits appear to be much less severe.This phenomenon is due to the fact that residual neurons which would not remain in strokepatients continue to function on some level despite atrophy associated with PPA (Sonty et al.,2003 as cited by Rogalski et al., 2011). Atrophy found in PPA affects the frontal temporal lobesin both symmetrical and asymmetrical patterns as well as the hippocampus (Knibb, Woollams,Hodges & Patterson, 2009).