Aphasia

Description:
Aphasia is the name given to a collection of language disorders caused by damage to the brain.  The word aphasia comes from the wordn aphasia, in Ancient Greek, which means A requirement for a diagnosis of aphasia is that, prior to the illness or injury, the person’s language skills were normal . The difficulties of people with aphasia can range from occasional trouble finding words to losing the ability to speak, read, or write, but does not affect intelligence. This also affects visual language such as sign language. The term “aphasia” implies a problem with one or more functions that are essential and specific to language function. It is not usually used when the language problem is a result of a more peripheral motor or sensory difficulty, such as paralysis affecting the speech muscles or a general hearing impairment.
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Stroke is the most common cause of aphasia in the United States. Approximately 500,000 individuals suffer strokes each year, and 20% of these individuals develop some type of aphasia. Other causes of brain damage include head injuries, brain tumors, and infection. About half of the people who show signs of aphasia have what is called temporary or transient aphasia and recover completely within a few days. An estimated one million Americans suffer from some form of permanent aphasia. As yet, no connection between aphasia and age, gender, or race has been found.
Aphasia is sometimes confused with other conditions that affect speech, such as dysarthria and apraxia. These condition affect the muscles used in speaking rather than language function itself. Dysarthria is a speech disturbance caused by lack of control over the muscles used in speaking, perhaps due to nerve damage. Speech apraxia is a speech disturbance in which language comprehension and muscle control are retained, but the memory of how to use the muscles to form words is not.

Symptoms:
Aphasia is condition characterized by either partial or total loss of the ability to communicate verbally or using written words. A person with aphasia may have difficulty speaking, reading, writing, recognizing the names of objects, or understanding what other people have said. Aphasia is caused by a brain injury, as may occur during a traumatic accident or when the brain is deprived of oxygen during a stroke. It may also be caused by a brain tumor, a disease such as Alzheimer’s, or an infection, like encephalitis. Aphasia may be temporary or permanent. Aphasia does not include speech impediments caused by loss of muscle control.
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To understand and use language effectively, an individual draws upon word memory-stored information on what certain words mean, how to put them together, and how and when to use them properly. For a majority of people, these and other language functions are located in the left side (hemisphere) of the brain. Damage to this side of the brain is most commonly linked to the development of aphasia. Interestingly, however, left-handed people appear to have language areas in both the left and right hemispheres of the brain and, as a result, may develop aphasia from damage to either side of the brain.

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 will try to hide their inability to name objects by using words like thing. So 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 speak spontaneously
*inability to form words
*inability to name objects (anomia)
*poor enunciation
*excessive creation and use of personal neologisms
*inability to repeat a phrase
*persistent repetition of one syllable, word, or phrase (stereotypies)
*paraphasia (substituting letters, syllables or words)
*agrammatism (inability to speak in a grammatically correct fashion)
*dysprosody (alterations in inflexion, stress, and rhythm)
*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

Causes:
Aphasia is most commonly caused by stroke. It can also be caused by other brain diseases, including cancer (brain tumor), epilepsy, and Alzheimer’s disease, or by a head injury. 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. Aphasia usually develops more slowly from a brain tumor, infection, or dementia.

Although all of the disease listed above are potential causes, aphasia will generally only result when there is substantial damage to the left hemisphere of the brain, either the cortex (outer layer) and/or the underlying white matter. Substantial damage to tissue anywhere within the region shown in blue on the figure below 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.

Finally, certain chronic neurological disorders, such as epilepsy or migraine, can also include transient aphasia as a prodromal or episodic symptom.  Aphasia is also listed as a rare side-effect of the fentanyl patch, an opioid used to control chronic pain.

Classification:
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. There is a huge variation among patients within the same broad grouping, and aphasias can be highly selective. For instance, patients with naming deficits (anomic aphasia) might show an inability only for naming buildings, or people, or colors.

Classical-Localizationist approaches:
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:

*Broca’s aphasia (also known as Motor aphasia or Expressive aphasia), which is characterized by halted, fragmented, effortful speech, but relatively well-preserved comprehension. It has been associated with damage to the posterior left prefrontal cortex, 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.

*Wernicke’s aphasia (also known as Sensory aphasia or Receptive 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.

*Other, more minor subtypes include Conduction aphasia, a disorder where speech remains fluent, and comprehension is preserved, but the person may have disproportionate difficulty where repeating words or sentences. Other include 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 disroportionately 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 a sizeable number of 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. Consequently, even amongst individuals who meet the criteria for classification into a subtype, there can be enormous variability in the types of difficulties they experience.

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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. One 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.

In practice, the cognitive neuropsychological approach can be unwieldy due to the wide variety of skills that can potentially be tested. Also, it is perhaps best suited to milder cases of aphasia: If the person has little expressive or receptive language ability, sometimes test performance can be difficult to interpret. In practice, clinicians will often use a blend of assessment approaches, which include broad subtyping based on a localizationist framework, and some finer exploration of specific language skills based on the cognitive neuropsychological framework.
Other forms of aphasia:

Progressive aphasias:
Primary progressive aphasia (PPA) is 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. It is characterized by the gradual loss of the ability to name objects. People suffering from 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 patient’s speech is incomprehensible, but appears to make sense to them. Speech is fluent and effortless with intact syntax and grammar, but the patient 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, patients 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 language is, after all, a form of communication that has been shown to use the same areas of the brain as verbal forms of communication. 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. Facial communication is a significant portion of how animals interact with each other. Humans use facial movements to create, what other humans perceive, to be faces of emotions. While combining these facials 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 patients, as well. These individuals find tremendous difficulty in being able to actually sign the linguistic concepts they are trying to express

Diagnosis:
Following brain injury, an initial bedside assessment is made to determine whether language function has been affected. If the individual experiences difficulty communicating, attempts are made to determine whether this difficulty arises from impaired language comprehension or an impaired ability to speak. A typical examination involves listening to spontaneous speech and evaluating the individual’s ability to recognize and name objects, comprehend what is heard, and repeat sample words and phrases. The individual may also be asked to read text aloud and explain what the passage means. In addition, writing ability is evaluated by having the individual copy text, transcribe dictated text, and write something without prompting.
A speech pathologist or neuropsychologist may be asked to conduct more extensive examinations using in-depth, standardized tests. Commonly used tests include the Boston Diagnostic Aphasia Examination, the Western Aphasia Battery, and possibly, the Porch Index of Speech Ability.

The results of these tests indicate the severity of the aphasia and may also provide information regarding the exact location of the brain damage. This more extensive testing is also designed to provide the information necessary to design an individualized speech therapy program. Further information about the location of the damage is gained through the use of imaging technology, such as magnetic resonance imaging (MRI) and computed tomography scans.
Treatment:
Initially, the underlying cause of aphasia must be treated or stabilized. To regain language function, therapy must begin as soon as possible following the injury. Although there are no medical or surgical procedures currently available to treat this condition, aphasia resulting from stroke or head injury may improve through the use of speech therapy. For most individuals, however, the primary emphasis is placed on making the most of retained language abilities and learning to use other means of communication to compensate for lost language abilities.
Speech therapy is tailored to meet individual needs, but activities and tools that are frequently used include the following:

Exercise and practice. Weakened muscles are exercised by repetitively speaking certain words or making facial expressions, such as smiling.
Picture cards. Pictures of everyday objects are used to improve word recall and increase vocabulary. The names of the objects may also be repetitively spoken aloud as part of an exercise and practice routine.

Picture boards. Pictures of everyday objects and activities are placed together, and the individual points to certain pictures to convey ideas and communicate with others.
Workbooks. Reading and writing exercises are used to sharpen word recall and regain reading and writing abilities. Hearing comprehension is also redeveloped using these exercises.
Computers. Computer software can be used to improve speech, reading, recall, and hearing comprehension by, for example, displaying pictures and having the individual find the right word.

Prognosis:
The degree to which an individual can recover language abilities is highly dependent on how much brain damage occurred and the location and cause of the original brain injury. Other factors include the individual’s age, general health, motivation and willingness to participate in speech therapy, and whether the individual is left or right handed. Language areas may be located in both the left and right hemispheres in left-handed individuals. Left-handed individuals are, therefore, more likely to develop aphasia following brain injury, but because they have two language centers, may recover more fully because language abilities can be recovered from either side of the brain. The intensity of therapy and the time between diagnosis and the start of therapy may also affect the eventual outcome.

Prevention:
Because there is no way of knowing when a stroke, traumatic head injury, or disease will occur, very little can be done to prevent aphasia. However  it can be adviced to be careful in movement of aged person specially for those having high bloodpressure, diabetis and other form of diseases.

Following are some precautions that should be taken to avoid aphasia, by decreasing the risk of stroke, the main cause of aphasia:

*Exercising regularly
*Eating a healthy diet
*Keeping alcohol consumption low and avoiding tobacco use
*Controlling blood pressure

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 in the field of psychology.

Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose.

Resources:
http://en.wikipedia.org/wiki/Aphasia
http://medical-dictionary.thefreedictionary.com/aphasia

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