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Dysphasia is a partial or complete impairment of the ability to communicate resulting from brain injury.
Approximately one million Americans currently suffer from one of the various forms of dysphasia, and an additional 80,000 new cases occur annually. The term "dysphasia" is more frequently used by European health professionals, whereas in North American the term, aphasia is more commonly preferred. These two terms, however, can be and are used interchangeably. They both refer to the full or partial loss of verbal communication skills due to damage or degeneration of the brain's language centers. Developmental Dysphasia is considered to be a learning disability, but will not be the focus of this article.
Verbal communication is derived from several regions located in the language-dominant hemisphere of the brain. These include the adjacent inferior parietal lobe, the inferolateral lobe, and the posterosuperior temporal lobe, as well as the subcortical connection between these areas. Disease, direct trauma, lesion, or infarction involving one or more of these regions can disrupt or prevent proper language function. Dysphasia does not necessarily prevent proper cognitive function, so the patient can think and feel with perfect clarity. This can be extremely frustrating for the patient, as they cannot express these thoughts and feelings to others.
Dysphasia can occur in a variety of forms, depending on how the communicative disruption manifests. Classically, dysphasia can affect one or more of the basic language functions: comprehension (understanding spoken language), naming (identifying items with words), repetition (repeating words or phrases), and speech. Although there are several subtypes of dysphasias, they most commonly manifest in one of three syndromes: expressive dysphasia, receptive dysphasia, or global dysphasia.
Expressive dysphasia, also known as motor dysphasia, produces a conscious and recognizable disruption of a patient's speech production and language output. This includes the impairment of speech initiation, proper grammatical sequencing, and proper word forming and articulation. Although patients can perfectly understand what is said to them, they have great difficulty communicating their thoughts.
BROCA'S DYSPHASIA. Broca's dysphasia is the most common type of expressive dysphasia. It is caused by damage to the lower area of the premotor cortex, located just in front of the primary motor cortex. This region is most commonly referred to as the Broca's area. Speech for patients suffering from Broca's dysphasia may be completely impossible. Others may be able to form single words or full sentences, but only through great effort. "Telegraphing," the omission of articles and conjunctions, may also be exhibited.
TRANSCORTICAL DYSPHASIA. Also known as isolation syndrome, transcortical dysphasia is caused by damage to the language-dominant brain that separates all or parts of the central region from the rest of the brain. There are three sub-classes of transcortical dysphasia, which define the impairments to a patient's ability to repeat words, sentences, and phrases: transcortical motor dysphasia, transcortical sensory dysphasia, and mixed transcortical dysphasia. Additional impairments may occur depending on the extent and location of the damage.
Receptive dysphasia, also known as sensory dysphasia, impairs the patient's comprehension and meaning of language. Unlike expressive dysphasia, the patient can speak fluently and articulately, but will utilize meaningless words, nonsensical grammar, and unnecessary phrases to the point of becoming incomprehensible. However, they will be completely unaware of their mistakes. Additionally, the patient will find it difficult to comprehend spoken language and/or word-object relation.
WERNICKE'S DYSPHASIA. Also known as semantic dysphasia, Wernicke's dysphasia is the most common of the receptive dysphasia. It is caused by damage to the Wernicke's area, located in the posterior superior temporal lobe of the language-dominant hemisphere. Although the patient can speak clearly and at length, many of their words, phases, and sentences will be nonsensical in nature. Additionally, they will experience difficulty in understanding spoken language, if not suffer a complete lack of comprehension. Semantic distinctions between words may become mixed up and jumbled, furthering confusion.
ANOMIC DYSPHASIA. Anomic dysphasia, also referred to as amnesic dysphasia, is caused by damage to the temporal parietal area and/or the angular gyrus region. Although very similar to Wernicke's dysphasia, anomic dysphasia is distinguished by its disruption of a patient's word-retrieval skills. They will be unable to correctly name people or objects, causing them to pause or substitute generalized words (like "thing"). Otherwise, the patient will exhibit few, if any, language impairments.
CONDUCTION DYSPHASIA. Also known as associative dysphasia, conduction dysphasia is a relatively uncommon disease (representing only 10% of the cases). Damage to the upper temporal lobe, lower parietal, or connection between the Wernicke's and Broca's areas can result in the inability to repeat words, phrases, or sentences. The patient may also suffer the inability to describe people or objects in the proper terms.
Global dysphasia, the third most common form of dysphasia, results from damage to both the anterior and posterior regions of the language-dominant hemisphere. In global dysphasia, all of the patient's language skills are disrupted; however, some may be disrupted more severely than others.
Causes & symptoms
Currently, over one million people in the United States suffer a permanent type of dysphasia. Although dysphasia may manifest in several ways, the common cause for its onset is damage or trauma to the brain. Stroke, in particular, is the most common cause for dysphasia. Of the half million stroke victims reported annually in the United States, approximately 100,000 will suffer some form of dysphasia. Infection, direct trauma, transient ischemic attack (TIA), brain tumors, and degeneration can also instigate the onset of dysphasia.
Symptoms of dysphasia will quickly manifest after damage to the brain has occurred, and will present in accordance to the particular type of dysphasia suffered. Due to the proximity to areas of the brain that control motor function, expressive dysphasias can be accompanied by noticeable motor impairment. The majority of symptoms will be language related, including:
- Difficulty remembering words
- Difficulty naming objects and/or people
- Difficulty speaking in complete and/or meaningful sentences
- Difficulty speaking in any fashion
- Difficulty reading or writing
- Difficulty expressing thoughts and feelings
- Difficulty understanding spoken language
- Using incorrect or jumbled words
- Using words in the wrong order
Dysphasia is frequently diagnosed while the patient is being treated for injury to the brain, be it from trauma or disease. The health professional, typically a neurologist, will conduct standard cognitive tests, including tests to determine whether the patient's language centers have been affected. If the patient exhibits signs of difficulty communicating, they will often be referred to a speech-language pathologist. In turn, the pathologist will conduct a comprehensive examination of the patient's ability language and comprehension skills. This examination may begin with evaluating the patient's ability to repeat words and phrases, recognize and describe objects, and comprehend what is said to them. More extensive and standardized language-based tests may be required, including the Porch Index of Speech Ability and the Boston Diagnostic Aphasia Examination. Based on the result of the examinations, the health professional will be able to determine the type of dysphasia inflicting the patient. More extensive damage may require the use of computed tomography or magnetic resonance imaging for an effective diagnosis.
Initially it is necessary to treat and stabilize the injury underlying the development of the patient's dysphasia. In some cases, such as with damage caused by TIA, a full recovery can be expedient and take only a few days. Unfortunately, most dysphasias can take months, if not years, to recover from. Even after prolonged therapy, many patients never achieve a full recovery. Efficacy of treatment greatly depends on the promptness with which it begins. For this reason, many medical facilities have speech-language pathologists on staff to begin the initial treatment process as quickly as possible.
There is no medical or surgical cure for dysphasia. Treatment, instead, relies strongly upon the use of various speech therapies. Much like physical therapy strengthens muscles and bones back to normalcy, speech therapy allow the patient to regain language function, as well as rebuild their communications skills. Treatment is typically conducted with a trained speech therapist. However, group sessions are common and allow the patient to practice their language skills in a non-threatening environment with others sharing their disability. Although much of therapeutic work is conducted by a speech therapist, friends and family also play a vital role in the patient's recovery. They can help the patient continually practice and exercise language skills while outside the therapeutic setting. Many times, family members are included on therapy sessions to teach them how to communicate with and understand the patient.
There are several treatments available, which utilize the patient's remaining language abilities to rebuild and compensate for those that were lost. These include out-put focused therapy (stimulationresponse), psycholinguistic therapy (cognitive), cognitive neurorehabilitation, and combinations thereof. Although these treatments approach aphasia differently, they all share a common thread by identifying the specific communication deficits and then targeting them with various modalities (computer-aided therapy, picture cards, reading and writing exercises, speech practice, etc.). These techniques stimulate the various parts of the brain associated with language, memory, and understanding, and thus allow it to heal.
Fortunately, about half of patients will suffer from transient dysphasia, in which the symptoms fade completely after only a few days. However, a patient's prognosis will greatly depend on several factors, such as the location and extent of the underlying damage. Additional factors of importance are the patient's age, general health, and mental health and motivation. Handedness may also be an indicator for recovery, as left-handed individuals have language centers located in both hemispheres of the brain (not just the left). As such, left-handed patients have access to language skills from either side of the brain, which can expedite their recovery. Even with therapy, dysphasia may take several years to overcome. Indeed, some patients will never regain their pre-trauma skill level of communication and speech.
Dysphasia can be prevented by avoiding the causes of brain injury and stroke, such as high blood pressure. In particular, eating a healthy diet and not smoking to maintain proper blood pressure will help prevent damaging strokes. Although it is impossible to predict head trauma, the use of head protection while participating in dangerous sports or activities can reduce the risk of serious brain damage.
Transient ischemic attack — Also known as a ministroke, a transient ischemic attack is caused by a temporary interruption of blood flow in an area of the brain. Unlike in a true stroke, normal brain function will return with 24 hours.
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Impairment in the production of speech and failure to arrange words in an understandable way; caused by an acquired lesion of the brain.
[dys- + G. phasis, speaking]
Impairment of speech and verbal comprehension, especially when associated with brain injury.
dys·pha′sic (-zĭk) adj. & n.
dysphasiaDysphrasia Neurology A speech impairment and/or inability to produce recognizable speech Clinical Defects in perception, sound discrimination, auditory memory, comprehension, word-finding, dysplexia Etiology Tumors of dominant cerebral hemisphere–ie, frontal, temporal, parietal lobes. See Aphrasia.
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]
dysphasiaImpairment of speech or of the production or comprehension of spoken or written language. Dysphasia is due mainly to damage to the temporoparietal and prerolandic parts of the brain, usually from STROKE. Seven major sub-types of aphasia, including motor, sensory, conduction and ANOMIC DYSPHASIA, have been described but it is a complex disorder which cannot readily be divided into neat categories. Much can often be done to help by intensive devoted therapy. See also APHASIA.
Impairment in the production of speech and failure to arrange words in an understandable way.
[dys- + G. phasis, speaking]