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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.
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.
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).
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:
- Broca's aphasia, also called motor aphasia, results from damage to the front portion or frontal lobe of the language-dominant area of the brain. Individuals with Broca's aphasia may be completely unable to use speech (mutism) or may be able to use single-word statements or even full sentences, though these sentences may require a great deal of effort to construct. Small words, such as conjunctions (and, or, but) and articles (the, an, a), may be omitted, leading to a "telegraph" quality in their speech. Hearing comprehension is usually not affected, so they are able to understand other people's speech and conversation and can follow commands. Often, they may experience weakness on the right side of their bodies, which can make it difficult to write. Reading ability is impaired, and they may have difficulty finding the right word when speaking. Individuals with Broca's aphasia may become frustrated and depressed because they are aware of their language difficulties.
- Wernicke's aphasia is caused by damage to the side portion or temporal lobe of the language-dominant area of the brain. Individuals with Wernicke's aphasia speak in long, uninterrupted sentences; however, the words used are frequently unnecessary or even made-up. They have a great deal of difficulty understanding other people's speech, sometimes to the point of being unable to understand spoken language at all. Reading ability is diminished, and although writing ability is retained, what is written may be abnormal. No physical symptoms, such as the right-sided weakness seen with Broca's aphasia, are typically observed. Also, in contrast to Broca's aphasia, individuals with Wernicke's aphasia are not aware of their language errors.
- Global aphasia is caused by widespread damage to the language areas of the left hemisphere. As a result, all basic language functions are affected, but some areas may be more affected than others. For example, an individual may have difficulty speaking but may be able to write well. The individual may experience weakness and loss of feeling on the right side of their body.
- Conduction aphasia, also called associative aphasia, is rather uncommon. Individuals with conduction aphasia are unable to repeat words, sentences, and phrases. Speech is fairly unbroken, although individuals may frequently correct themselves and words may be skipped or repeated. Although able to understand spoken language, it may also be difficult for the individual with conduction aphasia to find the right word to describe a person or object. The impact of this condition on reading and writing ability varies. As with other types of aphasia, right-sided weakness or sensory loss may be present.
- Anomic or nominal aphasia primarily influences an individual's ability to find the right name for a person or object. As a result, an object may be described rather than named. Hearing comprehension, repetition, reading, and writing are not affected, other than by this inability to find the right name. Speech is fluent, except for pauses as the individual tries to recall the right name. Physical symptoms are variable, and some individuals have no symptoms of one-sided weakness or sensory loss.
- Transcortical aphasia is caused by damage to the language areas of the left hemisphere outside the primary language areas. There are three types of aphasia: transcortical motor aphasia, transcortical sensory aphasia, and mixed transcortical aphasia. All of the transcortical aphasias are distinguished from other types by the individual's ability to repeat words, phrases, or sentences. Other language functions may also be impaired to varying degrees, depending on the extent and particular location of brain damage.
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.
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).
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.
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.
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.
Lyon, Jon G., and Marianne B. Simpson. Coping with Aphasia. San Diego: Singular Publishing Group, 1998.
National Aphasia Association. 156 5th Ave., Suite 707, New York, NY 10010. (800) 922-4622. http://www.aphasia.org.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.
a type of speech disorder consisting of a defect or loss of the power of expression by speech, writing, or signs, or of comprehension of spoken or written language, due to disease or injury of the brain centers, such as after stroke syndrome on the left side.
Patient Care. Aphasia is a complex phenomenon manifested in numerous ways. The recovery period is often very long, even months or years. Because communication is such a vital part of everyday living, loss of the ability to communicate with words, whether in speaking or writing, can profoundly affect the personality and behavior of a patient. Although aphasic persons usually require extensive treatment by specially trained speech patholigists or therapists, all persons concerned with the care of the patient should practice techniques that will help minimize frustration and improve communication with such patients.
amnestic aphasia anomic aphasia.
anomic aphasia inability to name objects, qualities, or conditions. Called also amnestic or nominal aphasia.
ataxic aphasia expressive aphasia.
auditory aphasia loss of ability to comprehend spoken language. Called also word deafness.
Broca's aphasia motor aphasia.
conduction aphasia aphasia due to a lesion of the pathway between the sensory and motor speech centers.
expressive aphasia motor aphasia.
fluent aphasia that in which speech is well articulated (usually 200 or more words per minute) and grammatically correct but is lacking in content and meaning.
global aphasia total aphasia involving all the functions that go to make up speech and communication.
jargon aphasia that with utterance of meaningless phrases, either neologisms or incoherently arranged known words.
motor aphasia aphasia in which there is impairment of the ability to speak and write, owing to a lesion in the insula and surrounding operculum including Broca's motor speech area. The patient understands written and spoken words but has difficulty uttering the words. See also receptive aphasia. Called also logaphasia and Broca's, expressive, or nonfluent aphasia.
nominal aphasia anomic aphasia.
nonfluent aphasia motor aphasia.
receptive aphasia inability to understand written, spoken, or tactile speech symbols, due to disease of the auditory and visual word centers, as in word blindness. See also motor aphasia. Called also logamnesia and sensory or Wernicke's aphasia.
sensory aphasia receptive aphasia.
visual aphasia alexia.
Wernicke's aphasia receptive aphasia.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.
Impaired or absent comprehension or production of, or communication by, speech, reading, writing, or signs, caused by an acquired lesion of the dominant cerebral hemisphere.
Synonym(s): alogia (1)
[G. speechlessness, fr. a- priv. + phasis, speech]
Farlex Partner Medical Dictionary © Farlex 2012
Partial or total loss of the ability to articulate ideas or comprehend spoken or written language, resulting from damage to the brain from injury or disease.
a·pha′si·ac′ (-zē-ăk′) n.
a·pha′sic (-zĭk, -sĭk) adj. & n.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.
aphasiaDysphasia 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.
- 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
- 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
- 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
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.
Impaired or absent comprehension or production of, or communication by, speech, writing, or signs; due to an acquired lesion of or injury to a language center of the brain; may be transient if cerebral swelling subsides.
Compare: alalia, aphonia
Synonym(s): alogia (1) , dysphasia, dysphrasia, logagnosia, logamnesia, logasthenia.
Compare: alalia, aphonia
Synonym(s): alogia (1) , dysphasia, dysphrasia, logagnosia, logamnesia, logasthenia.
[G. speechlessness, fr. a- priv. + phasis, speech]
Medical Dictionary for the Health Professions and Nursing © Farlex 2012
aphasiaAn acquired speech disorder resulting from brain damage which affects the understanding and production of language rather than the mechanical aspects of articulation. Aphasia is a common feature of STROKE affecting usually the left side of the brain. In sensory aphasia the essential problem is in understanding information input as in speech, writing or gesture. In motor aphasia, reception of input information may be normal but the ability to express thoughts, which may be entirely normal, is lost or defective both in speech and in writing. Various combinations of disability occur. Names may be forgotten while relationships or functions may be retained. Vocabulary may be severely reduced and circumlocution engaged in. Speech may be hesitant or confined to expletives. Motor aphasia often causes depressing frustration. Speech aphasia does not necessarily deprive the patient of arithmetical ability.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005
Impaired or absent comprehension or production of, or communication by, speech, reading, writing, or signs.
[G. speechlessness, fr. a- priv. + phasis, speech]
Medical Dictionary for the Dental Professions © Farlex 2012