Aphasia (redirected from aphasiac)

Aphasia 

Definition

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.

Description

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.

Broca's aphasia results from damage to the frontal lobe of the language-dominant area of the brain. Individuals with Broca's aphasia may become mute or may be able to use single-word statements or full sentences, although it may require great effort. Wernicke's aphasia is caused by damage to the temporal lobe of the language-dominant area of the brain. People with this condition speak in long, uninterrupted sentences, but the words used are often unnecessary and unintelligible.

(Illustration by Electronic Illustrators Group.)

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.

Causes and symptoms

Aphasia can develop after an individual sustains a brain injury from a stroke, head trauma, tumor, or infection, such as herpes encephalitis. As a result of this injury, the pathways for language comprehension or production are disrupted or destroyed. For most people, this means damage to the left hemisphere of the brain. (In 95 to 99% of right-handed people, language centers are in the left hemisphere, and up to 70% of left-handed people also have left-hemisphere language dominance.) According to the traditional classification scheme, each form of aphasia is caused by damage to a different part of the left hemisphere of the brain. This damage affects one or more of the basic language functions: speech, naming (the ability to identify an object, color, or other item with an appropriate word or term), repetition (the ability to repeat words, phrases, and sentences), hearing comprehension (the ability to understand spoken language), reading (the ability to understand written words and their meaning), and writing (the ability to communicate and record events with text).

Key terms

Anomic aphasia — A condition characterized by either partial or total loss of the ability to recall the names of persons or things as a result of a stroke, head injury, brain tumor, or infection.

Broca's aphasia — A condition characterized by either partial or total loss of the ability to express oneself, either through speech or writing. Hearing comprehension is not affected. This condition may result from a stroke, head injury, brain tumor, or infection.

Computed tomography (CT) — An imaging technique that uses cross-sectional x rays of the body to create a three-dimensional image of the body's internal structures.

Conduction aphasia — A condition characterized by the inability to repeat words, sentences, or phrases as a result of a stroke, head injury, brain tumor, or infection.

Frontal lobe — The largest, most forward-facing part of each side or hemisphere of the brain.

Global aphasia — A condition characterized by either partial or total loss of the ability to communicate verbally or using written words as a result of widespread injury to the language areas of the brain. This condition may be caused by a stroke, head injury, brain tumor, or infection. The exact language abilities affected vary depending on the location and extent of injury.

Hemisphere — One of the two halves or sides-the left and the right-of the brain.

Magnetic resonance imaging (MRI) — An imaging technique that uses a large circular magnet and radio waves to generate signals from atoms in the body. These signals are used to construct images of internal structures.

Subcortical aphasia — A condition characterized by either partial or total loss of the ability to communicate verbally or using written words as a result of damage to non language-dominated areas of the brain. This condition may be caused by a stroke, head injury, brain tumor, or infection.

Temporal lobe — The part of each side or hemisphere of the brain that is on the side of the head, nearest the ears.

Transcortical aphasia — A condition characterized by either partial or total loss of the ability to communicate verbally or using written words that does not affect an individual's ability to repeat words, phrases, and sentences.

Wernicke's aphasia — A condition characterized by either partial or total loss of the ability to understand what is being said or read. The individual maintains the ability to speak, but speech may contain unnecessary or made-up words.

The traditional classification scheme includes eight types of aphasia:

As researchers continue to learn more about the brain's structure and function, new types of aphasia are being recognized. One newly recognized type of aphasia, subcortical aphasia, mimics the symptoms of other traditional types of aphasia but involves language disorders that are not typical. This type of aphasia is associated with injuries to areas of the brain typically not identified with language and language processing.

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 (CT).

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:

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. The extent of recovery, however, in some cases, can be affected by an individual's willingness to cooperate and participate in speech therapy directly following the injury.

Resources

Books

Lyon, Jon G., and Marianne B. Simpson. Coping with Aphasia. San Diego: Singular Publishing Group, 1998.

Organizations

National Aphasia Association. 156 5th Ave., Suite 707, New York, NY 10010. (800) 922-4622. http://www.aphasia.org.

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aphasia /apha·sia/ (ah-fa´zhah) defect or loss of the power of expression by speech, writing, or signs, or of comprehending spoken or written language, due to injury or disease of the brain centers. See also agrammatism, dysphasia, and paraphasia. apha´sic

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amnesic aphasia , amnestic aphasia defective recall of specific names of objects or other words, with intact abilities of comprehension and repetition.

anomic aphasia  that in which recall of names is faulty.

auditory aphasia  a form of receptive aphasia in which sounds are heard but convey no meaning to the mind, due to disease of the auditory center of the brain.

Broca's aphasia  motor a.

conduction aphasia  aphasia believed to be due to a lesion of the path between sensory and motor speech centers; spoken language is comprehended normally but words cannot be repeated correctly.

expressive aphasia  motor a.

fluent aphasia  a type of receptive aphasia in which speech is well articulated and grammatically correct but is lacking in content.

global aphasia  total aphasia involving all the functions which go to make up speech or communication.

jargon aphasia  that with utterance of meaningless phrases, either neologisms or incoherently arranged known words.

mixed aphasia  global a.

motor aphasia  Broca's or nonfluent aphasia; that in which the ability to speak and write is impaired, due to a lesion in the insula and surrounding operculum.

nominal aphasia  anomic a.

nonfluent aphasia  motor a.

receptive aphasia  inability to understand written, spoken, or tactile speech symbols, due to disease of the auditory and visual word centers.

sensory aphasia  receptive a.

total aphasia  global a.

visual aphasia  alexia.

Wernicke's aphasia  receptive a.

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a·pha·sia (-fzh)

n.

Partial or total loss of the ability to articulate ideas or comprehend spoken or written language, resulting from brain damage due to injury or disease. Also called logagnosia, logamnesia, logasthenia.

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a·phasi·ac (-z-k) n.

a·phasic (-zk, -sk) adj. & n.

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aphasia (·fāˑ·zh),

n inability to speak or express oneself in words. Often caused by stroke.

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aphasia (fa´zh),

n a loss of power of expression through speech, writing, or signs of comprehension of spoken or written language resulting from disease or injury of the brain centers.

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aphasia Dysphasia Neurology Partial or total inability to understand or create speech, writing, or language due to damage to the brain's speech centers; loss of a previously possessed facility of language comprehension or production unexplained by sensory or motor defects or diffuse cerebral dysfunction Etiology Stroke, brain disease, injury; anomia–nominal or amnesic aphasia and impaired ability to communicate by writing-agraphia are usually present in all forms of aphasia. See Broca's/Motor aphasia, Sensory/Wernicke's aphasia, Tactile aphasia

Aphasia

Motor

Broca's aphasiaA primary deficit in language output or speech production, which ranges in severity from the mildest, cortical dysarthria, characterized by intact comprehension and ability to write, to a complete inability to communicate by lingual, phonetic, or manual activity

Sensory

Wernicke's aphasiaPts with sensory aphasia are voluble, gesticulate, and totally unaware of the total incoherency of their speech patterns; the words are nonsubstantive, malformed, inappropriate–paraphasia Sensory aphasia is characterized by 2 elements: Impaired speech comprehension–due largely to an inability to differentiate spoken and written phonemes–word elements-due to either involvement of the auditory association areas or separation from the 1º auditory complex Fluently articulated but paraphasic speech, which confirms the major role played by the auditory region in regulating language

Total

Global aphasia, complete aphasiaA form of aphasia caused by lesions that destroy significant amounts of brain tissue, eg occlusion of the middle cerebral or left internal carotid arteries, or tumors, hemorrhage, or other lesions; total aphasia is characterized by virtually complete impairment of speech and recognition thereof; afflicted Pts cannot read, write, or repeat what is said to them; although they may understand simple words or phrases, rapid fatigue and verbal and motor perseverence, they fail to carry out simple commands; total aphasia of vascular origin is almost invariably accompanied by right hemiplegia, hemianesthesia, hemianopia of varying intensity

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