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= Aphasia =
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Introduction
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Aphasia, also known as dysphasia, is an impairment in a person's
ability to comprehend or formulate language because of dysfunction in
specific brain regions. The major causes are stroke and head trauma;
prevalence is hard to determine, but aphasia due to stroke is
estimated to be 0.1-0.4% in developed countries. Aphasia can also be
the result of brain tumors, epilepsy, autoimmune neurological
diseases, brain infections, or neurodegenerative diseases (such as
dementias).
To be diagnosed with aphasia, a person's language must be
significantly impaired in one or more of the four aspects of
communication. In the case of progressive aphasia, a noticeable
decline in language abilities over a short period of time is required.
The four aspects of communication include spoken language production,
spoken language comprehension, written language production, and
written language comprehension. Impairments in any of these aspects
can impact functional communication.
The difficulties of people with aphasia can range from occasional
trouble finding words, to losing the ability to speak, read, or write;
intelligence, however, is unaffected. Expressive language and
receptive language can both be affected as well. Aphasia also affects
visual language such as sign language. In contrast, the use of
formulaic expressions in everyday communication is often preserved.
For example, while a person with aphasia, particularly expressive
aphasia (Broca's aphasia), may not be able to ask a loved one when
their birthday is, they may still be able to sing "Happy Birthday".
One prevalent deficit in all aphasias is anomia, which is a difficulty
in finding the correct word.
With aphasia, one or more modes of communication in the brain have
been damaged and are therefore functioning incorrectly. Aphasia is
'not' caused by damage to the brain resulting in motor or sensory
deficits, thus producing abnormal speech -- that is, aphasia is not
related to the 'mechanics' of speech, but rather the individual's
language cognition. However, it is possible for a person to have both
problems, e.g. in the case of a hemorrhage damaging a large area of
the brain. An individual's language abilities incorporate the socially
shared set of rules, as well as the thought processes that go behind
communication (as it affects both verbal and nonverbal language).
Aphasia is not a result of other peripheral motor or sensory
difficulty, such as paralysis affecting the speech muscles, or a
general hearing impairment.
Neurodevelopmental forms of auditory processing disorder (APD) are
differentiable from aphasia in that aphasia is by definition caused by
acquired brain injury, but acquired epileptic aphasia has been viewed
as a form of APD.
Signs and symptoms
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People with aphasia may experience any of the following behaviors due
to an acquired brain injury, although some of these symptoms may be
due to related or concomitant problems, such as dysarthria or apraxia,
and not primarily due to aphasia. Aphasia symptoms can vary based on
the location of damage in the brain. Signs and symptoms may or may not
be present in individuals with aphasia and may vary in severity and
level of disruption to communication. Often those with aphasia may
have a difficulty with naming objects, so they might use words such as
'thing' or point at the objects. When asked to name a pencil they may
say it is a "thing used to write".
* Inability to comprehend language
* Inability to pronounce, not due to muscle paralysis or weakness
* Inability to form words
* Inability to recall words (anomia)
* Poor enunciation
* Excessive creation and use of protologisms
* Inability to repeat a phrase
* Persistent repetition of one syllable, word, or phrase
(stereotypies, recurrent/recurring utterances/speech automatism) also
known as perseveration.
* Paraphasia (substituting letters, syllables or words)
* Agrammatism (inability to speak in a grammatically correct fashion)
* speaking in incomplete sentences
* Inability to read
* Inability to write
* Limited verbal output
* Difficulty in naming
* Speech disorder
* Speaking gibberish
* Inability to follow or understand simple requests
Related behaviors
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Given the previously stated signs and symptoms, the following
behaviors are often seen in people with aphasia as a result of
attempted compensation for incurred speech and language deficits:
* Self-repairs: Further disruptions in fluent speech as a result of
mis-attempts to repair erred speech production.
* Struggle in non-fluent aphasias: A severe increase in expelled
effort to speak after a life where talking and communicating was an
ability that came so easily can cause visible frustration.
* Preserved and automatic language: A behavior in which some language
or language sequences that were used frequently prior to onset are
still produced with more ease than other language post onset.
Subcortical
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* Subcortical aphasia's characteristics and symptoms depend upon the
site and size of subcortical lesion. Possible sites of lesions include
the thalamus, internal capsule, and basal ganglia.
Cognitive deficits
====================
While aphasia has traditionally been described in terms of language
deficits, there is increasing evidence that many people with aphasia
commonly experience co-occurring non-linguistic cognitive deficits in
areas such as attention, memory, executive functions and learning. By
some accounts, cognitive deficits, such as attention and working
memory constitute the underlying cause of language impairment in
people with aphasia. Others suggest that cognitive deficits often
co-occur, but are comparable to cognitive deficits in stroke patients
without aphasia and reflect general brain dysfunction following
injury. Whilst it has been shown that cognitive neural networks
support language reorganisation after stroke,
The degree to which deficits in attention and other cognitive domains
underlie language deficits in aphasia is still unclear.
In particular, people with aphasia often demonstrate short-term and
working memory deficits. These deficits can occur in both the verbal
domain as well as the visuospatial domain. Furthermore, these deficits
are often associated with performance on language specific tasks such
as naming, lexical processing, and sentence comprehension, and
discourse production. Other studies have found that most, but not all
people with aphasia demonstrate performance deficits on tasks of
attention, and their performance on these tasks correlate with
language performance and cognitive ability in other domains. Even
patients with mild aphasia, who score near the ceiling on tests of
language often demonstrate slower response times and interference
effects in non-verbal attention abilities.
In addition to deficits in short-term memory, working memory, and
attention, people with aphasia can also demonstrate deficits in
executive function. For instance, people with aphasia may demonstrate
deficits in initiation, planning, self-monitoring, and cognitive
flexibility. Other studies have found that people with aphasia
demonstrate reduced speed and efficiency during completion of
executive function assessments.
Regardless of their role in the underlying nature of aphasia,
cognitive deficits have a clear role in the study and rehabilitation
of aphasia. For instance, the severity of cognitive deficits in people
with aphasia has been associated with lower quality of life, even more
so than the severity of language deficits. Furthermore, cognitive
deficits may influence the learning process of rehabilitation and
language treatment outcomes in aphasia. Non-linguistic cognitive
deficits have also been the target of interventions directed at
improving language ability, though outcomes are not definitive. While
some studies have demonstrated language improvement secondary to
cognitively-focused treatment, others have found little evidence that
the treatment of cognitive deficits in people with aphasia has an
influence on language outcomes.
One important caveat in the measurement and treatment of cognitive
deficits in people with aphasia is the degree to which assessments of
cognition rely on language abilities for successful performance. Most
studies have attempted to circumvent this challenge by utilizing
non-verbal cognitive assessments to evaluate cognitive ability in
people with aphasia. However, the degree to which these tasks are
truly "non-verbal" and not mediated by language is unclear. For
instance, Wall et al. found that language and non-linguistic
performance was related, except when non-linguistic performance was
measured by "real life" cognitive tasks.
Causes
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Aphasia is most often caused by stroke, where about a quarter of
patients who experience an acute stroke develop aphasia. However, any
disease or damage to the parts of the brain that control language can
cause aphasia. Some of these can include brain tumors, traumatic brain
injury, epilepsy and progressive neurological disorders. In rare
cases, aphasia may also result from herpesviral encephalitis. The
herpes simplex virus affects the frontal and temporal lobes,
subcortical structures, and the hippocampal tissue, which can trigger
aphasia. In acute disorders, such as head injury or stroke, aphasia
usually develops quickly. When caused by brain tumor, infection, or
dementia, it develops more slowly.
Substantial damage to tissue anywhere within the region shown in blue
(on the figure in the infobox above) can potentially result in
aphasia. Aphasia can also sometimes be caused by damage to subcortical
structures deep within the left hemisphere, including the thalamus,
the internal and external capsules, and the caudate nucleus of the
basal ganglia. The area and extent of brain damage or atrophy will
determine the type of aphasia and its symptoms. A very small number of
people can experience aphasia after damage to the right hemisphere
only. It has been suggested that these individuals may have had an
unusual brain organization prior to their illness or injury, with
perhaps greater overall reliance on the right hemisphere for language
skills than in the general population.
Primary progressive aphasia (PPA), while its name can be misleading,
is actually a form of dementia that has some symptoms closely related
to several forms of aphasia. It is characterized by a gradual loss in
language functioning while other cognitive domains are mostly
preserved, such as memory and personality. PPA usually initiates with
sudden word-finding difficulties in an individual and progresses to a
reduced ability to formulate grammatically correct sentences (syntax)
and impaired comprehension. The etiology of PPA is not due to a
stroke, traumatic brain injury (TBI), or infectious disease; it is
still uncertain what initiates the onset of PPA in those affected by
it.
Epilepsy can also include transient aphasia as a prodromal or episodic
symptom. However, the repeated seizure activity within language
regions may also lead to chronic, and progressive aphasia. Aphasia is
also listed as a rare side-effect of the fentanyl patch, an opioid
used to control chronic pain.
Neuroimaging methods
======================
Magnetic resonance imaging (MRI) and functional magnetic resonance
imaging (fMRI) are the most common neuroimaging tools used in
identifying aphasia and studying the extent of damage in the loss of
language abilities. This is done by doing MRI scans and locating the
extent of lesions or damage within brain tissue, particularly within
areas of the left frontal and temporal regions- where a lot of
language related areas lie. In fMRI studies a language related task is
often completed and then the BOLD image is analyzed. If there are
lower than normal BOLD responses that indicate a lessening of blood
flow to the affected area and can show quantitatively that the
cognitive task is not being completed.
There are limitations to the use of fMRI in aphasic patients
particularly. Because a high percentage of aphasic patients develop it
because of stroke there can be infarct present which is the total loss
of blood flow. This can be due to the thinning of blood vessels or the
complete blockage of it. This is important in fMRI as it relies on the
BOLD response (the oxygen levels of the blood vessels), and this can
create a false hyporesponse upon fMRI study. Due to the limitations of
fMRI such as a lower spatial resolution, it can show that some areas
of the brain are not active during a task when they in reality are.
Additionally, with stroke being the cause of many cases of aphasia the
extent of damage to brain tissue can be difficult to quantify
therefore the effects of stroke brain damage on the functionality of
the patient can vary.
;Neural substrates of aphasia subtypes
MRI is often used to predict or confirm the subtype of aphasia
present. Researchers compared three subtypes of aphasia --
nonfluent-variant primary progressive aphasia (nfPPA),
logopenic-variant primary progressive aphasia (lvPPA), and
semantic-variant primary progressive aphasia (svPPA), with primary
progressive aphasia (PPA) and Alzheimer's disease. This was done by
analyzing the MRIs of patients with each of the subsets of PPA. Images
which compare subtypes of aphasia as well as for finding the extent of
lesions are generated by overlapping images of different participant's
brains (if applicable) and isolating areas of lesions or damage using
third-party software such as MRIcron. MRI has also been used to study
the relationship between the type of aphasia developed and the age of
the person with aphasia. It was found that patients with fluent
aphasia are on average older than people with non-fluent aphasia. It
was also found that among patients with lesions confined to the
anterior portion of the brain an unexpected portion of them presented
with fluent aphasia and were remarkably older than those with
non-fluent aphasia. This effect was not found when the posterior
portion of the brain was studied.
;Associated conditions
In a study on the features associated with different disease
trajectories in Alzheimer's disease (AD)-related primary progressive
aphasia (PPA), it was found that metabolic patterns via PET SPM
analysis can help predict progression of total loss of speech and
functional autonomy in AD and PPA patients. This was done by comparing
an MRI or CT image of the brain and presence of a radioactive
biomarker with normal levels in patients without Alzheimer's Disease.
Apraxia is another disorder often correlated with aphasia. This is due
to a subset of apraxia which affects speech. Specifically, this subset
affects the movement of muscles associated with speech production,
apraxia and aphasia are often correlated due to the proximity of
neural substrates associated with each of the disorders. Researchers
concluded that there were 2 areas of lesion overlap between patients
with apraxia and aphasia, the anterior temporal lobe and the left
inferior parietal lobe.
;Treatment and neuroimaging
Evidence for positive treatment outcomes can also be quantified using
neuroimaging tools. The use of fMRI and an automatic classifier can
help predict language recovery outcomes in stroke patients with 86%
accuracy when coupled with age and language test scores. The stimuli
tested were sentences both correct and incorrect and the subject had
to press a button whenever the sentence was incorrect. The fMRI data
collected focused on responses in regions of interest identified by
healthy subjects. Recovery from aphasia can also be quantified
using diffusion tensor imaging. The accurate fasciculus (AF) connects
the right and left superior temporal lobe, premotor regions/posterior
inferior frontal gyrus. and the primary motor cortex. In a study which
enrolled patients in a speech therapy program, an increase in AF
fibers and volume was found in patients after 6-weeks in the program
which correlated with long-term improvement in those patients. The
results of the experiment are pictured in Figure 2. This implies that
DTI can be used to quantify the improvement in patients after speech
and language treatment programs are applied.
Classification
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Aphasia is best thought of as a collection of different disorders,
rather than a single problem. Each individual with aphasia will
present with their own particular combination of language strengths
and weaknesses. Consequently, it is a major challenge just to document
the various difficulties that can occur in different people, let alone
decide how they might best be treated. Most classifications of the
aphasias tend to divide the various symptoms into broad classes. A
common approach is to distinguish between the fluent aphasias (where
speech remains fluent, but content may be lacking, and the person may
have difficulties understanding others), and the nonfluent aphasias
(where speech is very halting and effortful, and may consist of just
one or two words at a time).
However, no such broad-based grouping has proven fully adequate, or
reliable. There is wide variation among people even within the same
broad grouping, and aphasias can be highly selective. For instance,
people with naming deficits (anomic aphasia) might show an inability
only for naming buildings, or people, or colors. Unfortunately,
assessments that characterize aphasia in these groupings have
persisted. This is not helpful to people living with aphasia, and
provides inaccurate descriptions of an individual pattern of
difficulties.
There are typical difficulties with speech and language that come with
normal aging as well. As we age, language can become more difficult to
process, resulting in a slowing of verbal comprehension, reading
abilities and more likely word finding difficulties. With each of
these, though, unlike some aphasias, functionality within daily life
remains intact.
Boston classification
=======================
Major characteristics of different types of aphasia according to the
Boston classification
Type of aphasia Speech repetition Naming Auditory comprehension
Fluency
Expressive aphasia (Broca's aphasia) Moderate-severe Moderate-severe
Mild difficulty Non-fluent, effortful, slow
Receptive aphasia (Wernicke's aphasia) Mild-severe Mild-severe
Defective Fluent paraphasic
Conduction aphasia Poor Poor Relatively good Fluent
Mixed transcortical aphasia Moderate Poor Poor Non-fluent
Transcortical motor aphasia Good Mild-severe Mild Non-fluent
Transcortical sensory aphasia Good Moderate-severe Poor Fluent
Global aphasia Poor Poor Poor Non-fluent
Anomic aphasia Mild Moderate-severe Mild Fluent
* Individuals with receptive aphasia (Wernicke's aphasia), also
referred to as fluent aphasia, may speak in long sentences that have
no meaning, add unnecessary words, and even create new "words"
(neologisms). For example, someone with receptive aphasia may say,
"delicious taco", meaning "The dog needs to go out so I will take him
for a walk". They have poor auditory and reading comprehension, and
fluent, but nonsensical, oral and written expression. Individuals with
receptive aphasia usually have great difficulty understanding the
speech of both themselves and others and are, therefore, often unaware
of their mistakes. Receptive language deficits usually arise from
lesions in the posterior portion of the left hemisphere at or near
Wernicke's area. It is often the result of trauma to the temporal
region of the brain, specifically damage to Wernicke's area. Trauma
can be the result from an array of problems, however it is most
commonly seen as a result of stroke
* Individuals with expressive aphasia (Broca's aphasia) frequently
speak short, meaningful phrases that are produced with great effort.
It is thus characterized as a nonfluent aphasia. Affected people often
omit small words such as "is", "and", and "the". For example, a person
with expressive aphasia may say, "walk dog", which could mean "I will
take the dog for a walk", "you take the dog for a walk" or even "the
dog walked out of the yard." Individuals with expressive aphasia are
able to understand the speech of others to varying degrees. Because of
this, they are often aware of their difficulties and can become easily
frustrated by their speaking problems. While Broca's aphasia may
appear to be solely an issue with language production, evidence
suggests that it may be rooted in an inability to process syntactical
information. Individuals with expressive aphasia may have a speech
automatism (also called recurring or recurrent utterance). These
speech automatisms can be repeated lexical speech automatisms; 'e.g.',
modalisations ('I can't ..., I can't ...'), expletives/swearwords,
numbers ('one two, one two') or non-lexical utterances made up of
repeated, legal, but meaningless, consonant-vowel syllables (e.g..,
/tan tan/, /bi bi/). In severe cases, the individual may be able to
utter only the same speech automatism each time they attempt speech.
* Individuals with anomic aphasia have difficulty with naming. People
with this aphasia may have difficulties naming certain words, linked
by their grammatical type ('e.g.', difficulty naming verbs and not
nouns) or by their semantic category ('e.g.', difficulty naming words
relating to photography, but nothing else) or a more general naming
difficulty. People tend to produce grammatic, yet empty, speech.
Auditory comprehension tends to be preserved. Anomic aphasia is the
aphasial presentation of tumors in the language zone; it is the
aphasial presentation of Alzheimer's disease. Anomic aphasia is the
mildest form of aphasia, indicating a likely possibility for better
recovery.
* Individuals with transcortical sensory aphasia, in principle the
most general and potentially among the most complex forms of aphasia,
may have similar deficits as in receptive aphasia, but their
repetition ability may remain intact.
* Global aphasia is considered a severe impairment in many language
aspects since it impacts expressive and receptive language, reading,
and writing. Despite these many deficits, there is evidence that has
shown individuals benefited from speech language therapy. Even though
individuals with global aphasia will not become competent speakers,
listeners, writers, or readers, goals can be created to improve the
individual's quality of life. Individuals with global aphasia usually
respond well to treatment that includes personally relevant
information, which is also important to consider for therapy.
* Individuals with conduction aphasia have deficits in the connections
between the speech-comprehension and speech-production areas. This
might be caused by damage to the arcuate fasciculus, the structure
that transmits information between Wernicke's area and Broca's area.
Similar symptoms, however, can be present after damage to the insula
or to the auditory cortex. Auditory comprehension is near normal, and
oral expression is fluent with occasional paraphasic errors.
Paraphasic errors include phonemic/literal or semantic/verbal.
Repetition ability is poor. Conduction and transcortical aphasias are
caused by damage to the white matter tracts. These aphasias spare the
cortex of the language centers, but instead create a disconnection
between them. Conduction aphasia is caused by damage to the arcuate
fasciculus. The arcuate fasciculus is a white matter tract that
connects Broca's and Wernicke's areas. People with conduction aphasia
typically have good language comprehension, but poor speech repetition
and mild difficulty with word retrieval and speech production. People
with conduction aphasia are typically aware of their errors. Two forms
of conduction aphasia have been described: 'reproduction conduction
aphasia' (repetition of a single relatively unfamiliar multisyllabic
word) and 'repetition conduction aphasia' (repetition of unconnected
short familiar words.
* Transcortical aphasias include transcortical motor aphasia,
transcortical sensory aphasia, and mixed transcortical aphasia. People
with transcortical motor aphasia typically have intact comprehension
and awareness of their errors, but poor word finding and speech
production. People with transcortical sensory and mixed transcortical
aphasia have poor comprehension and unawareness of their errors.
Despite poor comprehension and more severe deficits in some
transcortical aphasias, small studies have indicated that full
recovery is possible for all types of transcortical aphasia.
Classical-localizationist approaches
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Localizationist approaches aim to classify the aphasias according to
their major presenting characteristics and the regions of the brain
that most probably gave rise to them. Inspired by the early work of
nineteenth-century neurologists Paul Broca and Carl Wernicke, these
approaches identify two major subtypes of aphasia and several more
minor subtypes:
* Expressive aphasia (also known as "motor aphasia" or "Broca's
aphasia"), which is characterized by halted, fragmented, effortful
speech, but well-preserved comprehension 'relative to expression'.
Damage is typically in the anterior portion of the left hemisphere,
most notably Broca's area. Individuals with Broca's aphasia often have
right-sided weakness or paralysis of the arm and leg, because the left
frontal lobe is also important for body movement, particularly on the
right side.
* Receptive aphasia (also known as "sensory aphasia" or "Wernicke's
aphasia"), which is characterized by fluent speech, but marked
difficulties understanding words and sentences. Although fluent, the
speech may lack in key substantive words (nouns, verbs, adjectives),
and may contain incorrect words or even nonsense words. This subtype
has been associated with damage to the posterior left temporal cortex,
most notably Wernicke's area. These individuals usually have no body
weakness, because their brain injury is not near the parts of the
brain that control movement.
* Conduction aphasia, where speech remains fluent, and comprehension
is preserved, but the person may have disproportionate difficulty
repeating words or sentences. Damage typically involves the arcuate
fasciculus and the left parietal region.
* Transcortical motor aphasia and transcortical sensory aphasia, which
are similar to Broca's and Wernicke's aphasia respectively, but the
ability to repeat words and sentences is disproportionately preserved.
Recent classification schemes adopting this approach, such as the
Boston-Neoclassical Model, also group these classical aphasia subtypes
into two larger classes: the nonfluent aphasias (which encompasses
Broca's aphasia and transcortical motor aphasia) and the fluent
aphasias (which encompasses Wernicke's aphasia, conduction aphasia and
transcortical sensory aphasia). These schemes also identify several
further aphasia subtypes, including: anomic aphasia, which is
characterized by a selective difficulty finding the names for things;
and global aphasia, where both expression and comprehension of speech
are severely compromised.
Many localizationist approaches also recognize the existence of
additional, more "pure" forms of language disorder that may affect
only a single language skill. For example, in pure alexia, a person
may be able to write, but not read, and in pure word deafness, they
may be able to produce speech and to read, but not understand speech
when it is spoken to them.
Cognitive neuropsychological approaches
=========================================
Although localizationist approaches provide a useful way of
classifying the different patterns of language difficulty into broad
groups, one problem is that most individuals do not fit neatly into
one category or another. Another problem is that the categories,
particularly the major ones such as Broca's and Wernicke's aphasia,
still remain quite broad and do not meaningfully reflect a person's
difficulties. Consequently, even amongst those who meet the criteria
for classification into a subtype, there can be enormous variability
in the types of difficulties they experience.
Instead of categorizing every individual into a specific subtype,
cognitive neuropsychological approaches aim to identify the key
language skills or "modules" that are not functioning properly in each
individual. A person could potentially have difficulty with just one
module, or with a number of modules. This type of approach requires a
framework or theory as to what skills/modules are needed to perform
different kinds of language tasks. For example, the model of Max
Coltheart identifies a module that recognizes phonemes as they are
spoken, which is essential for any task involving recognition of
words. Similarly, there is a module that stores phonemes that the
person is planning to produce in speech, and this module is critical
for any task involving the production of long words or long strings of
speech. Once a theoretical framework has been established, the
functioning of each module can then be assessed using a specific test
or set of tests. In the clinical setting, use of this model usually
involves conducting a battery of assessments, each of which tests one
or a number of these modules. Once a diagnosis is reached as to the
skills/modules where the most significant impairment lies, therapy can
proceed to treat these skills.
Progressive aphasias
======================
Primary progressive aphasia (PPA) is a neurodegenerative focal
dementia that can be associated with progressive illnesses or
dementia, such as frontotemporal dementia / Pick Complex Motor neuron
disease, Progressive supranuclear palsy, and Alzheimer's disease,
which is the gradual process of progressively losing the ability to
think. Gradual loss of language function occurs in the context of
relatively well-preserved memory, visual processing, and personality
until the advanced stages. Symptoms usually begin with word-finding
problems (naming) and progress to impaired grammar (syntax) and
comprehension (sentence processing and semantics). The loss of
language before the loss of memory differentiates PPA from typical
dementias. People with PPA may have difficulties comprehending what
others are saying. They can also have difficulty trying to find the
right words to make a sentence. There are three classifications of
Primary Progressive Aphasia : Progressive nonfluent aphasia (PNFA),
Semantic Dementia (SD), and Logopenic progressive aphasia (LPA).
Progressive Jargon Aphasia is a fluent or receptive aphasia in which
the person's speech is incomprehensible, but appears to make sense to
them. Speech is fluent and effortless with intact syntax and grammar,
but the person has problems with the selection of nouns. Either they
will replace the desired word with another that sounds or looks like
the original one or has some other connection or they will replace it
with sounds. As such, people with jargon aphasia often use neologisms,
and may perseverate if they try to replace the words they cannot find
with sounds. Substitutions commonly involve picking another (actual)
word starting with the same sound (e.g., clocktower - colander),
picking another semantically related to the first (e.g., letter -
scroll), or picking one phonetically similar to the intended one
(e.g., lane - late).
Deaf aphasia
==============
There have been many instances showing that there is a form of aphasia
among deaf individuals. Sign languages are, after all, forms of
language that have been shown to use the same areas of the brain as
verbal forms of language. Mirror neurons become activated when an
animal is acting in a particular way or watching another individual
act in the same manner. These mirror neurons are important in giving
an individual the ability to mimic movements of hands. Broca's area of
speech production has been shown to contain several of these mirror
neurons resulting in significant similarities of brain activity
between sign language and vocal speech communication. People use
facial movements to create, what other people perceive, to be faces of
emotions. While combining these facial movements with speech, a more
full form of language is created which enables the species to interact
with a much more complex and detailed form of communication. Sign
language also uses these facial movements and emotions along with the
primary hand movement way of communicating. These facial movement
forms of communication come from the same areas of the brain. When
dealing with damages to certain areas of the brain, vocal forms of
communication are in jeopardy of severe forms of aphasia. Since these
same areas of the brain are being used for sign language, these same,
at least very similar, forms of aphasia can show in the Deaf
community. Individuals can show a form of Wernicke's aphasia with sign
language and they show deficits in their abilities in being able to
produce any form of expressions. Broca's aphasia shows up in some
people, as well. These individuals find tremendous difficulty in being
able to actually sign the linguistic concepts they are trying to
express.
Severity
==========
The severity of the type of aphasia varies depending on the size of
the stroke. However, there is much variance between how often one type
of severity occurs in certain types of aphasia. For instance, any type
of aphasia can range from mild to profound. Regardless of the severity
of aphasia, people can make improvements due to spontaneous recovery
and treatment in the acute stages of recovery. Additionally, while
most studies propose that the greatest outcomes occur in people with
severe aphasia when treatment is provided in the acute stages of
recovery, Robey (1998) also found that those with severe aphasia are
capable of making strong language gains in the chronic stage of
recovery as well. This finding implies that persons with aphasia have
the potential to have functional outcomes regardless of how severe
their aphasia may be. While there is no distinct pattern of the
outcomes of aphasia based on severity alone, global aphasia typically
makes functional language gains, but may be gradual since global
aphasia affects many language areas.
Prevention
======================================================================
Aphasia is largely caused by unavoidable instances. However, some
precautions can be taken to decrease risk for experiencing one of the
two major causes of aphasia: stroke and traumatic brain injury (TBI).
To decrease the probability of having an ischemic or hemorrhagic
stroke, one should take the following precautions:
* Exercising regularly
* Eating a healthy diet, avoiding cholesterol in particular
* Keeping alcohol consumption low and avoiding tobacco use
* Controlling blood pressure
* Going to the emergency room immediately if you begin to experience
unilateral extremity (especially leg) swelling, warmth, redness,
and/or tenderness as these are symptoms of a deep vein thrombosis
which can lead to a stroke
To prevent aphasia due to traumatic injury, one should take
precautionary measures when engaging in dangerous activities such as:
* Wearing a helmet when operating a bicycle, motor cycle, ATV, or any
other moving vehicle that could potentially be involved in an accident
* Wearing a seatbelt when driving or riding in a car
* Wearing proper protective gear when playing contact sports,
especially American football, rugby, and hockey, or refraining from
such activities
* Minimizing anticoagulant use (including aspirin) if at all possible
as they increase the risk of hemorrhage after a head injury
Additionally, one should always seek medical attention after
sustaining head trauma due to a fall or accident. The sooner that one
receives medical attention for a traumatic brain injury, the less
likely one is to experience long-term or severe effects.
Management
======================================================================
Most acute cases of aphasia recover some or most skills by
participating in speech and language therapy. Recovery and improvement
can continue for years after the stroke. After the onset of aphasia,
there is approximately a six-month period of spontaneous recovery;
during this time, the brain is attempting to recover and repair the
damaged neurons. Improvement varies widely, depending on the aphasia's
cause, type, and severity. Recovery also depends on the person's age,
health, motivation, handedness, and educational level.
Speech and language therapy that is higher intensity, higher dose or
provided over a long duration of time leads to significantly better
functional communication, but people might be more likely to drop out
of high intensity treatment (up to 15 hours per week). A total of
20-50 hours of speech and language therapy is necessary for the best
recovery. The most improvement happens when 2-5 hours of therapy is
provided each week over 4-5 days. Recovery is further improved when
besides the therapy people practice tasks at home. Speech and language
therapy is also effective if it is delivered online through video or
by a family member who has been trained by a professional therapist.
Recovery with therapy is also dependent on the recency of stroke and
the age of the person. Receiving therapy within a month after the
stroke leads to the greatest improvements. Three or six months after
the stroke more therapy will be needed, but symptoms can still be
improved. People with aphasia who are younger than 55 years are the
most likely to improve, but people older than 75 years can still get
better with therapy.
There is no one treatment proven to be effective for all types of
aphasias. The reason that there is no universal treatment for aphasia
is because of the nature of the disorder and the various ways it is
presented. Aphasia is rarely exhibited identically, implying that
treatment needs to be catered specifically to the individual. Studies
have shown that, although there is no consistency on treatment
methodology in literature, there is a strong indication that
treatment, in general, has positive outcomes. Therapy for aphasia
ranges from increasing functional communication to improving speech
accuracy, depending on the person's severity, needs and support of
family and friends. Group therapy allows individuals to work on their
pragmatic and communication skills with other individuals with
aphasia, which are skills that may not often be addressed in
individual one-on-one therapy sessions. It can also help increase
confidence and social skills in a comfortable setting.
Evidence does not support the use of transcranial direct current
stimulation (tDCS) for improving aphasia after stroke. Moderate
quality evidence does indicate naming performance improvements for
nouns, but not verbs using tDCS
Specific treatment techniques include the following:
* Copy and recall therapy (CART) - repetition and recall of targeted
words within therapy may strengthen orthographic representations and
improve single word reading, writing, and naming
* Visual communication therapy (VIC) - the use of index cards with
symbols to represent various components of speech
* Visual action therapy (VAT) - typically treats individuals with
global aphasia to train the use of hand gestures for specific items
* Functional communication treatment (FCT) - focuses on improving
activities specific to functional tasks, social interaction, and
self-expression
* Promoting aphasic's communicative effectiveness (PACE) - a means of
encouraging normal interaction between people with aphasia and
clinicians. In this kind of therapy, the focus is on pragmatic
communication rather than treatment itself. People are asked to
communicate a given message to their therapists by means of drawing,
making hand gestures or even pointing to an object
* Melodic intonation therapy (MIT) - aims to use the intact
melodic/prosodic processing skills of the right hemisphere to help cue
retrieval of words and expressive language
* Centeredness Theory Interview (CTI) - Uses client centered goal
formation into the nature of current patient interactions as well as
future / desired interactions to improve subjective well-being,
cognition and communication.
* Other - 'i.e.', drawing as a way of communicating, trained
conversation partners
Semantic feature analysis (SFA) -- a type of aphasia treatment that
targets word-finding deficits -- is based on the theory that neural
connections can be strengthened by using related words and phrases
that are similar to the target word, to eventually activate the target
word in the brain. SFA can be implemented in multiple forms such as
verbally, written, using picture cards, etc. The SLP provides
prompting questions to the individual with aphasia in order for the
person to name the picture provided. Studies show that SFA is an
effective intervention for improving confrontational naming.
Melodic intonation therapy is used to treat non-fluent aphasia and has
proved to be effective in some cases. However, there is still no
evidence from randomized controlled trials confirming the efficacy of
MIT in chronic aphasia. MIT is used to help people with aphasia
vocalize themselves through speech song, which is then transferred as
a spoken word. Good candidates for this therapy include people who
have had left hemisphere strokes, non-fluent aphasias such as Broca's,
good auditory comprehension, poor repetition and articulation, and
good emotional stability and memory. An alternative explanation is
that the efficacy of MIT depends on neural circuits involved in the
processing of rhythmicity and formulaic expressions (examples taken
from the MIT manual: "I am fine," "how are you?" or "thank you");
while rhythmic features associated with melodic intonation may engage
primarily left-hemisphere subcortical areas of the brain, the use of
formulaic expressions is known to be supported by right-hemisphere
cortical and bilateral subcortical neural networks.
Systematic reviews support the effectiveness and importance of partner
training. According to the National Institute on Deafness and Other
Communication Disorders (NIDCD), involving family with the treatment
of an aphasic loved one is ideal for all involved, because while it
will no doubt assist in their recovery, it will also make it easier
for members of the family to learn how best to communicate with them.
When a person's speech is insufficient, different kinds of
augmentative and alternative communication could be considered such as
alphabet boards, pictorial communication books, specialized software
for computers or apps for tablets or smartphones.
When addressing Wernicke's aphasia, according to Bakheit et al.
(2007), the lack of awareness of the language impairments, a common
characteristic of Wernicke's aphasia, may affect the rate and extent
of therapy outcomes. Robey (1998) determined that at least 2 hours of
treatment per week is recommended for making significant language
gains. Spontaneous recovery may cause some language gains, but without
speech-language therapy, the outcomes can be half as strong as those
with therapy.
When addressing Broca's aphasia, better outcomes occur when the person
participates in therapy, and treatment is more effective than no
treatment for people in the acute period. Two or more hours of therapy
per week in acute and post-acute stages produced the greatest results.
High-intensity therapy was most effective, and low-intensity therapy
was almost equivalent to no therapy.
People with global aphasia are sometimes referred to as having
irreversible aphasic syndrome, often making limited gains in auditory
comprehension, and recovering no functional language modality with
therapy. With this said, people with global aphasia may retain
gestural communication skills that may enable success when
communicating with conversational partners within familiar conditions.
Process-oriented treatment options are limited, and people may not
become competent language users as readers, listeners, writers, or
speakers no matter how extensive therapy is. However, people's daily
routines and quality of life can be enhanced with reasonable and
modest goals. After the first month, there is limited to no healing to
language abilities of most people. There is a grim prognosis, leaving
83% who were globally aphasic after the first month that will remain
globally aphasic at the first year. Some people are so severely
impaired that their existing process-oriented treatment approaches
offer no signs of progress, and therefore cannot justify the cost of
therapy.
Perhaps due to the relative rareness of conduction aphasia, few
studies have specifically studied the effectiveness of therapy for
people with this type of aphasia. From the studies performed, results
showed that therapy can help to improve specific language outcomes.
One intervention that has had positive results is auditory repetition
training. Kohn et al. (1990) reported that drilled auditory repetition
training related to improvements in spontaneous speech, Francis et al.
(2003) reported improvements in sentence comprehension, and
Kalinyak-Fliszar et al. (2011) reported improvements in
auditory-visual short-term memory.
Individualized service delivery
=================================
Intensity of treatment should be individualized based on the recency
of stroke, therapy goals, and other specific characteristics such as
age, size of lesion, overall health status, and motivation. Each
individual reacts differently to treatment intensity and is able to
tolerate treatment at different times post-stroke. Intensity of
treatment after a stroke should be dependent on the person's
motivation, stamina, and tolerance for therapy.
Outcomes
======================================================================
If the symptoms of aphasia last longer than two or three months after
a stroke, a complete recovery is unlikely. However, it is important to
note that some people continue to improve over a period of years and
even decades. Improvement is a slow process that usually involves both
helping the individual and family understand the nature of aphasia and
learning compensatory strategies for communicating.
After a traumatic brain injury (TBI) or cerebrovascular accident
(CVA), the brain undergoes several healing and re-organization
processes, which may result in improved language function. This is
referred to as spontaneous recovery. Spontaneous recovery is the
natural recovery the brain makes without treatment, and the brain
begins to reorganize and change in order to recover. There are several
factors that contribute to a person's chance of recovery caused by
stroke, including stroke size and location. Age, sex, and education
have not been found to be very predictive. There is also research
pointing to damage in the left hemisphere healing more effectively
than the right.
Specific to aphasia, spontaneous recovery varies among affected people
and may not look the same in everyone, making it difficult to predict
recovery.
Though some cases of Wernicke's aphasia have shown greater
improvements than more mild forms of aphasia, people with Wernicke's
aphasia may not reach as high a level of speech abilities as those
with mild forms of aphasia.
Prevalence
======================================================================
Aphasia affects about two million people in the U.S. and 250,000
people in Great Britain. Nearly 180,000 people acquire the disorder
every year in the U.S., 170,000 due to stroke. Any person of any age
can develop aphasia, given that it is often caused by a traumatic
injury. However, people who are middle aged and older are the most
likely to acquire aphasia, as the other etiologies are more likely at
older ages. For example, approximately 75% of all strokes occur in
individuals over the age of 65. Strokes account for most documented
cases of aphasia: 25% to 40% of people who survive a stroke develop
aphasia as a result of damage to the language-processing regions of
the brain.
History
======================================================================
The first recorded case of aphasia is from an Egyptian papyrus, the
Edwin Smith Papyrus, which details speech problems in a person with a
traumatic brain injury to the temporal lobe.
During the second half of the 19th century, aphasia was a major focus
for scientists and philosophers who were working in the beginning
stages of the field of psychology.
In medical research, speechlessness was described as an incorrect
prognosis, and there was no assumption that underlying language
complications existed. Broca and his colleagues were some of the first
to write about aphasia, but Wernicke was the first credited to have
written extensively about aphasia being a disorder that contained
comprehension difficulties. Despite claims of who reported on aphasia
first, it was F.J. Gall that gave the first full description of
aphasia after studying wounds to the brain, as well as his observation
of speech difficulties resulting from vascular lesions. A recent book
on the entire history of aphasia is available (Reference: Tesak, J.
& Code, C. (2008) 'Milestones in the History of Aphasia: Theories
and Protagonists'. Hove, East Sussex: Psychology Press).
Etymology
===========
'Aphasia' is from Greek 'a-' ("without", negative prefix) + 'phásis'
('φάσις', "speech").
The word 'aphasia' comes from the word ἀφασία 'aphasia', in Ancient
Greek, which means "speechlessness", derived from ἄφατος 'aphatos',
"speechless" from ἀ- 'a-', "not, un" and φημί 'phemi', "I speak".
Further research
======================================================================
Research is currently being done using functional magnetic resonance
imaging (fMRI) to witness the difference in how language is processed
in normal brains vs aphasic brains. This will help researchers to
understand exactly what the brain must go through in order to recover
from Traumatic Brain Injury (TBI) and how different areas of the brain
respond after such an injury.
Another intriguing approach being tested is that of drug therapy.
Research is in progress that will hopefully uncover whether or not
certain drugs might be used in addition to speech-language therapy in
order to facilitate recovery of proper language function. It's
possible that the best treatment for Aphasia might involve combining
drug treatment with therapy, instead of relying on one over the other.
One other method being researched as a potential therapeutic
combination with speech-language therapy is brain stimulation. One
particular method, Transcranial Magnetic Stimulation (TMS), alters
brain activity in whatever area it happens to stimulate, which has
recently led scientists to wonder if this shift in brain function
caused by TMS might help people re-learn language. Another type of
external brain stimulation is transcranial Direct Current Stimulation
(tDCS), but existing research has not shown it to be useful for
improving aphasia after a stroke.
See also
======================================================================
* Agnosia, inability to process sensory information (e.g. inability to
recognize objects)
* Aphasiology, study of language impairment (usually from brain
damage)
* Apraxia of speech, difficulty connecting speech messages from the
brain to the mouth
* Aprosodia
* Auditory processing disorder
* Lethologica
* Lists of language disorders
* 'My Beautiful Broken Brain', a 2014 documentary
* Origin of speech
Notes
======================================================================
{{notelist|refs=
}}
External links
======================================================================
* [
https://www.aphasia.org/ National Aphasia Association]
License
=========
All content on Gopherpedia comes from Wikipedia, and is licensed under CC-BY-SA
License URL:
http://creativecommons.org/licenses/by-sa/3.0/
Original Article:
http://en.wikipedia.org/wiki/Aphasia
