Aphasia is a term used to describe a disturbance in the ability to use symbols, either written or spoken, to communicate information and is categorized into two types: expressive aphasia or receptive aphasia.
Aphasia affects about two million people in the U.S.
Nearly 180,000 people acquire the disorder every year in the U.S., 170,000 due to stroke.
These two types of aphasia can occur together.
Aphasia/dysphasia should be distinguished from dysarthria which results from impaired articulation.
Dysarthria, as opposed to aphasia, is a motor dysfunction due to disrupted innervation to the face, tongue, or soft palate that results in slurred speech but intact fluency and comprehension.
Aphasia is typically considered a cortical sign.
Its presence suggests dysfunction of the dominant cerebral cortex.
In aphasia a person may be unable to comprehend or unable to formulate language because of damage to specific brain regions.
The major causes are stroke and head trauma.
Aphasia is most often caused by stroke, where about a quarter of patients who experience an acute stroke develop aphasia.
Aphasia can also be the result of brain tumors, epilepsy, brain damage and 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.
The four aspects of communication are spoken language production and comprehension, and written language production and comprehension: the impairments in any of these aspects can impact on 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 is unaffected.
Expressive language and receptive language can both be affected as well.
Aphasia also affects visual language such as sign language.
The use of formulaic expressions in everyday communication is often preserved.
A prevalent deficit in the 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 that results in motor or sensory deficits, as it is not related to the mechanics of speech but rather the individual’s language cognition.
Often individuals with aphasia may have a difficulty with naming objects, so they might use words such as thing or point at the objects.
Behaviors often seen in people with aphasia as a result of attempted compensation for incurred speech and language deficits:
Self-repairs:
Struggle in non-fluent aphasias with an increase in effort to speak.
Preserved and automatic language in which some language or language sequences that were used so frequently prior to onset are still produced with more ease than other language post onset.
Possible sites of lesions include the thalamus, internal capsule, and basal ganglia.
Increasing evidence exists that many people with aphasia experience non-linguistic cognitive deficits in areas such as attention, memory, executive functions and learning.
The degree to which deficits in attention and other cognitive domains underlie language deficits in aphasia remains unclear.
People with aphasia often demonstrate short-term and working memory deficits in both the verbal domain as well as the visuospatial domain.
Such deficits may be associated with performance on language specific tasks such as naming, lexical processing, and sentence comprehension, and discourse.
Most 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 with mild aphasia, patients often demonstrate slower response times and interference effects in non-verbal attention abilities.
Deficits in short-term memory, working memory, attention, executive function, in initiation, planning, self-monitoring, cognitive flexibility, reduced speed and efficiency during completion executive function assessments can be seen with aphasia.
The severity of cognitive deficits in people with aphasia has been associated with lower quality of life, more so than the severity of the language deficit.
Cognitive deficits may impair rehabilitation and language treatment outcomes in aphasia.
Any disease or damage to the parts of the brain that control language can cause aphasia: brain tumors, traumatic brain injury, epilepsy and progressive neurological disorders, herpesviral encephalitis.
Aphasia can 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.
A small number of people can experience aphasia after damage to the right hemisphere only, and 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), 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 and progresses to a reduced ability to formulate grammatically correct sentences and impaired comprehension.
It is uncertain what initiates the onset of PPA in those affected by it.
Epilepsy can cause transient aphasia as a prodromal or episodic symptom.
Repeat 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.
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.
MRI scans may locate lesions or damage within brain tissue, particularly the left frontal and temporal regions- where a lot of language related areas are represented.
In fMRI studies shoe a 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, because a high percentage of aphasic patients develop it because of stroke and there can be infarcts present which is the total loss of blood flow, as fMRI relies on the BOLD response where the oxygen levels of the blood vessels, and this can create a false hyporesponse upon fMRI study.
In fMRI which relies on the BOLD response, it can create a false hyporesponse upon fMRI study.
Neural substrates of aphasia subtypes
MRI is often used to predict or confirm the subtype of aphasia present.
MRI is used to study the relationship between the type of aphasia and the age of the person with aphasia, with findings that patients with fluent aphasia are on average older than people with non-fluent aphasia.
Among patients with lesions confined to the anterior portion of the brain an unexpected portion of them have 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.
Apraxia is often correlated with aphasia, and is due to a subset of apraxia which affects 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: the anterior temporal lobe and the left inferior parietal lobe.
Aphasia is a collection of different disorders, rather than a single problem.
Each person with aphasia presents with a unique combination of language strengths and weaknesses.
Classifications of the aphasias tend to divide the various symptoms into broad classes distinguishing 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.
There are typical difficulties with speech and language that come with normal aging as well.
With age language can become more difficult to process resulting in a slowing of verbal comprehension, reading abilities and more likely word finding difficulties, though, functionality within daily life remains intact.
Major characteristics of different types of aphasia according to the Boston classification
Expressive aphasia (Broca’s aphasia)
Receptive aphasia (Wernicke’s aphasia)
Conduction aphasia
Mixed transcortical aphasia
Transcortical motor aphasia
Transcortical sensory aphasia
Global aphasia
Anomic aphasia
Individuals with expressive aphasia (Broca’s aphasia) frequently speak short, meaningful phrases that are produced with great effort, and
characterized as a nonfluent aphasia.
Individuals with expressive aphasia are able to understand the speech of others to varying degrees, are often aware of their difficulties and can become frustrated by their speaking problems.
While Broca’s aphasia appears to be solely an issue with language production, it may be rooted in an inability to process syntactical information.
Individuals with expressive aphasia may have a speech automatism, recurring or recurrent utterances: repeated lexical speech automatisms examples- I can’t…I can’t…, expletives/swearwords, numbers-one two, one two, or repeated consonant-vowel syllables.
In severe cases, the individual may be able to utter only the same speech automatism each time they attempt speech.
With anomic aphasia there is difficulty with naming: may have difficulties naming certain words, linked by their grammatical type-difficulty naming verbs and not nouns, or by their semantic category-difficulty naming words relating to a specific topic, or a more general naming difficulty.
Auditory comprehension tends to be preserved with anomic aphasia.
Anomic aphasia is the mildest form of aphasia.
Global aphasia is a severe impairment, impacting expressive and receptive language, reading, and writing.
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.
Individuals with conduction aphasia have deficits in the connections between the speech-comprehension and speech-production areas.
Expressive aphasia is characterized by halted, fragmented, effortful speech, but well-preserved comprehension relative to expression.
Expressive aphasia, (Broca’s aphasia), is a type of language disorder characterized by difficulty in producing spoken or written language.
Individuals with expressive aphasia typically struggle to form sentences, find the right words, and express their thoughts coherently.
This condition is often caused by damage to the language centers in the left hemisphere of the brain, such as Broca’s area.
People with expressive aphasia may understand language well and be aware of their communication difficulties.
Treatment for expressive aphasia may involve speech therapy to improve language production, communication strategies to compensate for difficulties, and rehabilitation to help with overall language skills.
Different approaches can be tailored to each individual based on the severity and underlying cause of the condition.
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 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.
Receptive aphasia subtype is 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: speech remains fluent, and comprehension is preserved, but there may have disproportionate difficulty repeating words or sentences.
Damage in conduction aphasia typically involves the arcuate fasciculus and the left parietal region.
Transcortical motor aphasia and transcortical sensory aphasia, are similar to Broca’s and Wernicke’s aphasia respectively, but the ability to repeat words and sentences is disproportionately preserved.
The existence of additional language disorder that may affect only a single language skill.
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.
Most patents do not fit neatly into one category or another, and there can be enormous variability in the types of difficulties they experience.
Primary progressive aphasia 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.
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 of naming and progresses to impaired grammar and comprehension.
The loss of language before the loss of memory differentiates primary progressive aphasia from typical dementias.
People with primary progressive aphasia i may have difficulties comprehending what others are saying.
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.
In Progressive Jargon Aphasia their speech appears to make sense to the patient, and the speech is fluent and effortless with intact syntax and grammar, but the person has problems with the selection of nouns.
In Progressive Jargon Aphasia patients 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.
Individuals with jargon aphasia often use neologisms, and may perseverate, picking another word starting with the same sound, pick another semantically related to the first, or pick one phonetically similar to the intended one.
There is a form of aphasia among deaf individuals: Sign languages are forms of language that have been shown to use the same areas of the brain as verbal forms of language.
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 humans perceive, to be faces of emotions.
Combining facial movements with speech, allows for a more full form of language which enables people 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 as vocal forms of communication and both are in jeopardy with severe forms of aphasia.
The 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.
Aphasia can range from mild to profound,and regardless of the severity of aphasia, people can make improvements due to spontaneous recovery and treatment in the acute stages of recovery.
Even with severe aphasia people are capable of making strong language gains in the chronic stage of recovery.
Aphasia is largely caused by unavoidable instances.
The two major causes of aphasia: stroke and traumatic brain injury (TBI).
Management
Most acute cases of aphasia recover some or most skills by participating in speech and language therapy.
Recovery and improvement of aphasia can continue for years after the stroke.
There is an approximate six-month period of spontaneous recovery in aphasia after a stroke.
Improvement in aphasia recovery varies widely, depending on the aphasia’s cause, type, and severity.
Recovery from aphasia depends on the person’s age, health, motivation, handedness, and educational level.
High intensity speech and language therapy provide significant better functional communication than lesser intensity care.
A total of 20-50 hours of speech and language therapy is required to achieve the best recovery.
People with aphasia who are younger than 55 years are the most likely to improve.
There is no one treatment proven to be effective for all types of aphasias.
Therapy for aphasia ranges from increasing functional communication to improving speech accuracy.
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.
Group therapy helps increase confidence and social skills in a comfortable setting.
Evidence supports the use of transcranial direct current stimulation (tDCS) for improving aphasia after stroke for nouns.
Specific treatment techniques include the following:
Copy and recall therapy (CART), which is repetition and recall of targeted words within therapy may strengthen orthographic representations and improve single word reading, writing, and naming names.
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), by encouraging normal interaction between people with aphasia and clinicians.
Melodic intonation therapy (MIT), uses the intact melodic/prosodic processing skills of the right hemisphere to help cue retrieval of words and expressive language.
Melodic intonation therapy is used to treat non-fluent aphasia and has proved to be help people with aphasia vocalize themselves through speech song, which is then transferred as a spoken word.
Semantic feature analysis (SFA) targets word-finding deficits:
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.
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.
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.
Involving family with the treatment of an aphasia loved assists in recovery, it will also make it easier for members of the family to learn how best to communicate with the patient.
When speech is insufficient, alternative communication could be considered such as alphabet boards, pictorial communication books, specialized software for computers or apps for tablets or smartphones.
If the symptoms of aphasia last longer than two or three months after a stroke, a complete recovery is unlikely, although some patients continue to improve over a period of years and even decades.
After a traumatic brain injury (TBI) or cerebrovascular accident (CVA), the brain undergoes healing and re-organization processes.
This is referred to as spontaneous recovery, where the brain begins to reorganize and change in order to recover.
Spontaneous recovery is the natural recovery the brain makes without treatment, and the brain begins to reorganize and change in order to recover.
Factors that contribute to a person’s chance of recovery caused by stroke, including stroke size and location.
Age, sex, and education have are not predictive of recovery.
There is also evidence the left hemisphere heals more effectively than the right.
People who are middle aged and older are the most likely to acquire aphasia.
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.