Transcortical motor aphasia
Encyclopedia
Transcortical Motor Aphasia (TMA), also known as adynamic aphasia and extrasylvian motor aphasia, results from an injury to the anterior superior frontal lobe
. The injury is typically caused by a cerebrovascular accident (CVA), commonly referred to as a stroke
. The area of insult is sometimes referred to as a watershed region, a region surrounding Broca's area
. The insult typically involves the left hemisphere as most people (regardless of handedness) are left hemisphere dominant for language (nearly 100% of right-handers, about 85% of left-handers).
is usually not affected. People with TMA experience non-fluent (halting and effortful
) speech due to frontal lobe damage and their utterances are typically only one or two words long. People with TMA retain the ability to repeat words, phrases or sentences. Repetition is preserved since the arcuate fasciculus (the neural pathway that connects Wernicke’s and Broca’s areas via the parietal lobe) is intact. Preserved repetition is a defining quality of all transcortical aphasias. People who suffer from transcortical motor aphasia, however, may experience delays in initiation when they try to repeat words due to damage in the frontal lobe.
People who suffer from TMA also have severely impaired writing ability. As writing is a secondary modality (learned through formal instruction in grade school) it is often more severely affected than a primary modality like speaking.
Frontal lobe
The frontal lobe is an area in the brain of humans and other mammals, located at the front of each cerebral hemisphere and positioned anterior to the parietal lobe and superior and anterior to the temporal lobes...
. The injury is typically caused by a cerebrovascular accident (CVA), commonly referred to as a stroke
Stroke
A stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...
. The area of insult is sometimes referred to as a watershed region, a region surrounding Broca's area
Broca's area
Broca's area is a region of the hominid brain with functions linked to speech production.The production of language has been linked to the Broca’s area since Pierre Paul Broca reported impairments in two patients. They had lost the ability to speak after injury to the posterior inferior frontal...
. The insult typically involves the left hemisphere as most people (regardless of handedness) are left hemisphere dominant for language (nearly 100% of right-handers, about 85% of left-handers).
Characteristics
TMA is a less common impairment than Broca's aphasia. People with TMA generally have good comprehension since Wernicke's areaWernicke's area
Wernicke's area is one of the two parts of the cerebral cortex linked since the late nineteenth century to speech . It is involved in the understanding of written and spoken language...
is usually not affected. People with TMA experience non-fluent (halting and effortful
Effortfulness
In psychology effortfulness is the subjective experience of exertion in connection with an activity, but especially the mental aspects of an activity. In many applications, effortfulness is simply reported by a patient, client, or experimental subject. There has been some work establishing an...
) speech due to frontal lobe damage and their utterances are typically only one or two words long. People with TMA retain the ability to repeat words, phrases or sentences. Repetition is preserved since the arcuate fasciculus (the neural pathway that connects Wernicke’s and Broca’s areas via the parietal lobe) is intact. Preserved repetition is a defining quality of all transcortical aphasias. People who suffer from transcortical motor aphasia, however, may experience delays in initiation when they try to repeat words due to damage in the frontal lobe.
People who suffer from TMA also have severely impaired writing ability. As writing is a secondary modality (learned through formal instruction in grade school) it is often more severely affected than a primary modality like speaking.