Transcortical sensory aphasia
Encyclopedia
Transcortical sensory aphasia is caused by lesions in the inferior left temporal lobe
of the brain
located near Wernicke's area
, and is usually due to minor hemorrhage
or contusion
in the temporal lobe, or infarcts
of the left posterior cerebral artery
(PCA). This type of aphasia
is very similar to Wernicke's aphasia
in that patients exhibit poor comprehension and naming, have fluent spontaneous speech, and exhibit paraphasia
. However, transcortical sensory aphasia differs from Wernicke’s aphasia in that patients still have intact repetition and exhibit echolalia
, or the compulsive repetition of words. Transcortical sensory aphasia cannot be diagnosed through brain imaging techniques, and the results of functional magnetic resonance imaging
(fMRI) are difficult to interpret. Therefore, clinicians rely on assessment and observation to determine if a patient presents with the characteristics of TSA.
between asymptomatic subjects and affected patients can be observed via functional magnetic resonance imaging (fMRI). However, these results only reveal temporal differences in cognition between control and diagnosed subjects. The degree of progression during therapy can also be surveyed through cognition tests monitored by fMRI. Many patients’ progress is assessed over time via repeated testing and corresponding cerebral imaging by fMRI.
Sensory aphasias are typically diagnosed by non-invasive
evaluations. Neurologists or speech pathologists
will administer oral evaluations to determine the extent of a patient’s comprehension and speech capability. The following standardized testing techniques are most commonly used in the diagnosis of transcortical sensory aphasia.
deficiency is aphasia. If the diagnosis is then confirmed, testing will next address the type of aphasia and its severity. The Boston Diagnostic Aphasia Examination
specializes in determining the severity of a sensory aphasia through the observation of conversational behaviors. Several modalities of perception and response are observed in conjunction with the subject’s ability to process sensory information. The location of the brain lesion and type of the aphasia can then be inferred from the observed symptoms. The Minnesota Test for Differential Diagnosis is the most lengthy and thorough assessment. It pinpoints the subject’s strengths and weaknesses in the areas of audio, vision, reading comprehension, speech, and writing. From this differential diagnosis, a patient’s course of treatment can be determined. After treatment planning, the Porch Index of Communicative Ability is the best test of prognosis and the degree of recovery.
is determined by direct qualitative observation of the patient’s speech to determine the length of spoken phrases, and is usually characterized by a normal or rapid rate; normal phrase length, rhythm
, melody, and articulatory agility; and normal or paragrammatic speech. Transcortical sensory aphasia is a disorder in which there is a discrepancy between phonological processing
, which remains intact, and lexical-semantic processing
, which is impaired. This disconnect occurs since Wernike’s area is not damaged in patients with TSA, therefore repetition is spared while comprehension is affected. In addition to problems in comprehension, Transcortical sensory aphasia is further characterized based on deficits in naming and paraphasia.
. Wernicke also proposed the idea that these two centers, along with the commissure
linking the acoustic nerve with the center for motor images, were the first structures used when a child is beginning to acquire language abilities through imitation of what he hears.
Ludwig Lichtheim
, another German physician, was influenced by the work of Wernicke and Broca
and is responsible for developing the localizationalist concept of aphasia. He had a great interest in aphasia, especially those that he believed could not be explained by Wernicke’s model. He proposed that these types of aphasia were due to disturbances in the pathways that connect major speech centers instead of the speech centers themselves. According to Lichtheim, there were specific centers in the brain for auditory images and motor images, and these centers were connected by a commissure that passes through the insula, similar to Wernicke’s proposal. However, Lichtheim postulates the existence of a third center where concepts are elaborated because he believed that other parts of the brain had to be accessed when less automatic characteristics of language, such as comprehension, were involved. Pathways that link the auditory center to non-language areas where concepts are determined accomplish this. Lichtheim also presents the idea that the phonological information that is used in verbal output is controlled by not only the direct connections linking the center for auditory images and the center of motor images, but also by an indirect connection linking these two centers with the non-language concept center. According to his model, the commissural pathways that link the concept center with the sensory and motor speech centers include two separate commissures and a set of converging fiber tracts that come from various regions of the cerebral cortex to the sensory and motor centers.
Lichtheim suggested that a lesion interrupting the commissures between the auditory image center and the concept center would cause a sensory aphasia with fluent paraphasic speech and difficulty in understanding both spoken and written language, similar to Wernicke’s aphasia. However, unlike Wernicke’s aphasia, the lesion would not disrupt the capacity to repeat, read aloud, or write to dictation, although there is a loss of intelligence regarding what the patient comprehends. Lichtheim discusses a patient in an 1885 article who could repeat what was spoken to him and had fluent expression of language but had poor comprehension of what was spoken to him. Lichtheim first refers to this as inner-commissural word-deafness. In 1908, Wernicke recognizes aphasias in which repetition remains intact and refers to them as transcortial aphasias, using transcortical sensory aphasia to refer to Lichtheim’s “inner-commissural word-deafness.”
One such method involves focusing on the relationship between learning and how if an individual learns something at the same time as something else, these two ‘events’ can be wired together in the brain. As a result, if a therapist can find and improve correlations or coincidences that have been either damaged or deleted by severe cases of aphasia such as transcortical sensory aphasia, can be important in brain function and recovery. This can be achieved with intensive therapy hours in order to maximize time where correlation is emphasized.
Through careful analysis of neuroimaging studies, a correlation has been developed with motor function and the understanding of action verbs. For example, leg and motor areas were seen to be activated words such as "kick", leading scientists to understand the connection between motor and language processes in the brain. This is yet another example of using relationships that are related in the brain for the purpose of rehabilitating speech and comprehension.
Of huge importance in aphasia therapy is the need to start practicing as soon as possible. Better recovery occurs when a patient has attempted to improve their comprehension and speaking early on. There is a relationship between the length of time spent not practicing and level of recovery. The patient should be pushed to their verbal communication limits in order to get the patient to get comfortable with making full use of residual language skills that remain.
One effective therapy technique is using what are known as language games in order to encourage verbal communication. One famous example is known as "Builder's Game", where a builder and a helper must communicate in order to effectively work on a project. The helper must hand the builder the tools he or she may need, which requires effective oral communication. Furthermore, when the helper hands the block to the builder, the game incorporates action with language, a key therapy technique.
Temporal lobe
The temporal lobe is a region of the cerebral cortex that is located beneath the Sylvian fissure on both cerebral hemispheres of the mammalian brain....
of the brain
Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
located near Wernicke's area
Wernicke'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...
, and is usually due to minor hemorrhage
Bleeding
Bleeding, technically known as hemorrhaging or haemorrhaging is the loss of blood or blood escape from the circulatory system...
or contusion
Bruise
A bruise, also called a contusion, is a type of relatively minor hematoma of tissue in which capillaries and sometimes venules are damaged by trauma, allowing blood to seep into the surrounding interstitial tissues. Bruises can involve capillaries at the level of skin, subcutaneous tissue, muscle,...
in the temporal lobe, or infarcts
Infarction
In medicine, infarction refers to tissue death that is caused by a local lack of oxygen due to obstruction of the tissue's blood supply. The resulting lesion is referred to as an infarct.-Causes:...
of the left posterior cerebral artery
Posterior cerebral artery
-External links: - Posterior Cerebral Artery Stroke* at strokecenter.org* at State University of New York Upstate Medical University* at psyweb.com* at neuropat.dote.hu...
(PCA). This type of aphasia
Aphasia
Aphasia is an impairment of language ability. This class of language disorder ranges from having difficulty remembering words to being completely unable to speak, read, or write....
is very similar to Wernicke's aphasia
Receptive aphasia
Receptive aphasia, also known as Wernicke’s aphasia, fluent aphasia, or sensory aphasia, is a type of aphasia traditionally associated with neurological damage to Wernicke’s area in the brain,...
in that patients exhibit poor comprehension and naming, have fluent spontaneous speech, and exhibit paraphasia
Paraphasia
Paraphasia is a feature of aphasia in which one loses the ability of speaking correctly, substitutes one word for another, and changes words and sentences in an inappropriate way. It often develops after a stroke or brain injury. The patient's speech is fluent but is error-prone, e.g...
. However, transcortical sensory aphasia differs from Wernicke’s aphasia in that patients still have intact repetition and exhibit echolalia
Echolalia
Echolalia is the automatic repetition of vocalizations made by another person. It is closely related to echopraxia, the automatic repetition of movements made by another person....
, or the compulsive repetition of words. Transcortical sensory aphasia cannot be diagnosed through brain imaging techniques, and the results of functional magnetic resonance imaging
Functional magnetic resonance imaging
Functional magnetic resonance imaging or functional MRI is a type of specialized MRI scan used to measure the hemodynamic response related to neural activity in the brain or spinal cord of humans or other animals. It is one of the most recently developed forms of neuroimaging...
(fMRI) are difficult to interpret. Therefore, clinicians rely on assessment and observation to determine if a patient presents with the characteristics of TSA.
Imaging
Sensory aphasia cannot be diagnosed through the use of imaging techniques. Differences in cognitionCognition
In science, cognition refers to mental processes. These processes include attention, remembering, producing and understanding language, solving problems, and making decisions. Cognition is studied in various disciplines such as psychology, philosophy, linguistics, and computer science...
between asymptomatic subjects and affected patients can be observed via functional magnetic resonance imaging (fMRI). However, these results only reveal temporal differences in cognition between control and diagnosed subjects. The degree of progression during therapy can also be surveyed through cognition tests monitored by fMRI. Many patients’ progress is assessed over time via repeated testing and corresponding cerebral imaging by fMRI.
Sensory aphasias are typically diagnosed by non-invasive
Invasiveness of surgical procedures
There are three main categories which describe the invasiveness of surgical procedures. These are: non-invasive procedures, minimally invasive procedures, and invasive procedures ....
evaluations. Neurologists or speech pathologists
Speech and language pathology
Speech-Language Pathology specializes in communication disorders.The main components of speech production include: phonation, the process of sound production; resonance, opening and closing of the vocal folds; intonation, the variation of pitch; and voice, including aeromechanical components of...
will administer oral evaluations to determine the extent of a patient’s comprehension and speech capability. The following standardized testing techniques are most commonly used in the diagnosis of transcortical sensory aphasia.
Clinical Assessment
Initial assessment will determine if the cause of linguisticLinguistics
Linguistics is the scientific study of human language. Linguistics can be broadly broken into three categories or subfields of study: language form, language meaning, and language in context....
deficiency is aphasia. If the diagnosis is then confirmed, testing will next address the type of aphasia and its severity. The Boston Diagnostic Aphasia Examination
Boston Diagnostic Aphasia Examination
The Boston Diagnostic Aphasia Examination or BDAE is a test used to evaluate adults suspected of having aphasia, and is currently in its third edition. It was created by Harold Goodglass and Edith Kaplan...
specializes in determining the severity of a sensory aphasia through the observation of conversational behaviors. Several modalities of perception and response are observed in conjunction with the subject’s ability to process sensory information. The location of the brain lesion and type of the aphasia can then be inferred from the observed symptoms. The Minnesota Test for Differential Diagnosis is the most lengthy and thorough assessment. It pinpoints the subject’s strengths and weaknesses in the areas of audio, vision, reading comprehension, speech, and writing. From this differential diagnosis, a patient’s course of treatment can be determined. After treatment planning, the Porch Index of Communicative Ability is the best test of prognosis and the degree of recovery.
Characteristics
Transcortical sensory aphasia is characterized as a fluent aphasia. FluencyFluency
Fluency is the property of a person or of a system that delivers information quickly and with expertise.-Speech:...
is determined by direct qualitative observation of the patient’s speech to determine the length of spoken phrases, and is usually characterized by a normal or rapid rate; normal phrase length, rhythm
Rhythm
Rhythm may be generally defined as a "movement marked by the regulated succession of strong and weak elements, or of opposite or different conditions." This general meaning of regular recurrence or pattern in time may be applied to a wide variety of cyclical natural phenomena having a periodicity or...
, melody, and articulatory agility; and normal or paragrammatic speech. Transcortical sensory aphasia is a disorder in which there is a discrepancy between phonological processing
Phonological rule
A phonological rule is a formal way of expressing a systematic phonological or morphophonological process or diachronic sound change in language. Phonological rules are commonly used in generative phonology as a notation to capture sound-related operations and computations the human brain performs...
, which remains intact, and lexical-semantic processing
Lexical semantics
Lexical semantics is a subfield of linguistic semantics. It is the study of how and what the words of a language denote . Words may either be taken to denote things in the world, or concepts, depending on the particular approach to lexical semantics.The units of meaning in lexical semantics are...
, which is impaired. This disconnect occurs since Wernike’s area is not damaged in patients with TSA, therefore repetition is spared while comprehension is affected. In addition to problems in comprehension, Transcortical sensory aphasia is further characterized based on deficits in naming and paraphasia.
Comprehension
When clinically examined, patients with TSA will exhibit poor comprehension of verbal commands. Based on the extent of the comprehension deficiency, patients will have difficulty following simple commands such as “close your eyes.” Depending on the extent of affected brain area, patients are able to follow simple commands but may not be able to comprehend more difficult, multistep commands such as, “point to the ceiling, then touch your left ear with your right hand." When increasing the complexity of verbal commands comprehension is often tested by varying the grammatical structure of the command to determine whether or not the patient understands different grammatical variations of the same sentence.Naming
Naming involves the ability to recall an object. Patients with TSA, as well as patients with all other aphasia subtypes, exhibit poor naming. Clinical assessment of naming involves the observer first asking the patient to name high frequency objects such as clock, door, and chair. TSA patients who name common objects with ease generally have difficulty naming both uncommon objects and specific parts of objects such as lapel, or the dial on a watch.Paraphasia
Patients with TSA typically exhibit paraphasia; their speech is fluent but often error-prone. Their speech is often unintelligible as they tend to use the wrong words, e.g. tree instead of train or uses words in senseless and incorrect combinations.Wernicke-Lichtheim connectionist model
In 1874, Carl Wernicke claimed that thought and language were supported by two distinct regions in the brain. He believed that disturbances in language due to brain damage resulted from damage to psycholinguistic functions that were represented by these specific areas. These areas are the center for acoustic images, found in the temporal lobe cortex, and the center for motor images, located in the inferior frontal region, which are connected by subcortical fiber tracts. According to Wernicke, sounds were sent to the center for acoustic images via the acoustic nerveVestibulocochlear nerve
The vestibulocochlear nerve is the eighth of twelve cranial nerves, and is responsible for transmitting sound and equilibrium information from the inner ear to the brain...
. Wernicke also proposed the idea that these two centers, along with the commissure
Commissure
A commissure is the place where two things are joined. The term is used especially in the fields of anatomy and biology.In anatomy, commissure refers to a bundle of nerve fibers that cross the midline at their level of origin or entry .* The most common usage of the term refers to the brain's...
linking the acoustic nerve with the center for motor images, were the first structures used when a child is beginning to acquire language abilities through imitation of what he hears.
Ludwig Lichtheim
Ludwig Lichtheim
Ludwig Lichtheim was a German physician. He was educated at the gymnasium in Breslau, and studied medicine at the universities of Berlin, Zurich, and Breslau, graduating in 1868...
, another German physician, was influenced by the work of Wernicke and Broca
Paul Broca
Pierre Paul Broca was a French physician, surgeon, anatomist, and anthropologist. He was born in Sainte-Foy-la-Grande, Gironde. He is best known for his research on Broca's area, a region of the frontal lobe that has been named after him. Broca’s Area is responsible for articulated language...
and is responsible for developing the localizationalist concept of aphasia. He had a great interest in aphasia, especially those that he believed could not be explained by Wernicke’s model. He proposed that these types of aphasia were due to disturbances in the pathways that connect major speech centers instead of the speech centers themselves. According to Lichtheim, there were specific centers in the brain for auditory images and motor images, and these centers were connected by a commissure that passes through the insula, similar to Wernicke’s proposal. However, Lichtheim postulates the existence of a third center where concepts are elaborated because he believed that other parts of the brain had to be accessed when less automatic characteristics of language, such as comprehension, were involved. Pathways that link the auditory center to non-language areas where concepts are determined accomplish this. Lichtheim also presents the idea that the phonological information that is used in verbal output is controlled by not only the direct connections linking the center for auditory images and the center of motor images, but also by an indirect connection linking these two centers with the non-language concept center. According to his model, the commissural pathways that link the concept center with the sensory and motor speech centers include two separate commissures and a set of converging fiber tracts that come from various regions of the cerebral cortex to the sensory and motor centers.
Lichtheim suggested that a lesion interrupting the commissures between the auditory image center and the concept center would cause a sensory aphasia with fluent paraphasic speech and difficulty in understanding both spoken and written language, similar to Wernicke’s aphasia. However, unlike Wernicke’s aphasia, the lesion would not disrupt the capacity to repeat, read aloud, or write to dictation, although there is a loss of intelligence regarding what the patient comprehends. Lichtheim discusses a patient in an 1885 article who could repeat what was spoken to him and had fluent expression of language but had poor comprehension of what was spoken to him. Lichtheim first refers to this as inner-commissural word-deafness. In 1908, Wernicke recognizes aphasias in which repetition remains intact and refers to them as transcortial aphasias, using transcortical sensory aphasia to refer to Lichtheim’s “inner-commissural word-deafness.”
Management of the Disorder
Due to advances in modern neuroimaging, scientists have been able to gain a better understanding of how language is learned and comprehended. Based on the new data from the world of neuroscience, improvements can be made in coping with the disorder.Therapy
Therapists have have been developing multiple methods of improving speech and comprehension.One such method involves focusing on the relationship between learning and how if an individual learns something at the same time as something else, these two ‘events’ can be wired together in the brain. As a result, if a therapist can find and improve correlations or coincidences that have been either damaged or deleted by severe cases of aphasia such as transcortical sensory aphasia, can be important in brain function and recovery. This can be achieved with intensive therapy hours in order to maximize time where correlation is emphasized.
Through careful analysis of neuroimaging studies, a correlation has been developed with motor function and the understanding of action verbs. For example, leg and motor areas were seen to be activated words such as "kick", leading scientists to understand the connection between motor and language processes in the brain. This is yet another example of using relationships that are related in the brain for the purpose of rehabilitating speech and comprehension.
Of huge importance in aphasia therapy is the need to start practicing as soon as possible. Better recovery occurs when a patient has attempted to improve their comprehension and speaking early on. There is a relationship between the length of time spent not practicing and level of recovery. The patient should be pushed to their verbal communication limits in order to get the patient to get comfortable with making full use of residual language skills that remain.
One effective therapy technique is using what are known as language games in order to encourage verbal communication. One famous example is known as "Builder's Game", where a builder and a helper must communicate in order to effectively work on a project. The helper must hand the builder the tools he or she may need, which requires effective oral communication. Furthermore, when the helper hands the block to the builder, the game incorporates action with language, a key therapy technique.