Learning Disability

Aphasia

 

Aphasia: Is the disturbance in formulation and comprehension of language. This class of language disorder ranges from having difficulty remembering words to being completely unable to speak, read, or write. Aphasia is usually linked to brain damage, most commonly by stroke. The brain damage which links aphasia can also cause further brain diseases such as cancer, epilepsy and Alzheimer's disease.

Acute aphasia disorders usually develop quickly as a result of head injury or stroke, and progressive forms of aphasia develop slowly from a brain tumor, infection, or dementia. The area and extent of brain damage or atrophy will determine the type of aphasia and its symptoms. Aphasia types include expressive aphasia, receptive aphasia, conduction aphasia, anomic aphasia, global aphasia, primary progressive aphasias and many others (see Category:Aphasias). Medical evaluations for the disorder range from clinical screenings by a neurologist to extensive tests by a Speech-Language Pathologist.

Classifying the different subtypes of aphasia is difficult and has led to disagreements among experts. The localizationist model is the original model, but modern anatomical techniques and analyses have shown that precise connections between brain regions and symptom classification do not exist. The neural organization of language is complicated; language is a comprehensive and complex behavior and it makes sense that it is not the product of some small, circumscribed region of the brain.

No classification of patients in subtypes and groups of subtypes is adequate. Only about 60% of patients will fit in a classification scheme such as fluent/nonfluent/pure aphasias. There is a huge variation among patients with the same diagnosis, 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.

Primary and secondary cognitive processes

Aphasias can be divided into primary and secondary cognitive processes.

• Primary aphasia is due to problems with cognitive language-processing mechanisms, which can include: Transcortical sensory aphasia, Semantic Dementia, Apraxia of speech, Progressive nonfluent aphasia, and Expressive aphasia
• Secondary aphasia is the result of other problems, like memory impairments, attention disorders, or perceptual problems, which can include: Transcortical motor aphasia, Dynamic aphasia, Anomic aphasia, Receptive aphasia, Progressive jargon aphasia, Conduction aphasia, and Dysarthria^.

Cognitive neuropsychological model

The cognitive neuropsychological model builds on cognitive neuropsychology. It assumes that language processing can be broken down into a number of modules, each of which has a specific function. Hence there is a module which recognises phonemes as they are spoken and a module which stores formulated phonemes before they are spoken. Use of this model clinically involves conducting a battery of assessments (usually from the PALPA, the "psycholinguistic assessment of language processing in adult acquired aphasia ... that can be tailored to the investigation of an individual patient's impaired and intact abilities"), each of which tests one or a number of these modules. Once a diagnosis is reached as to where the impairment lies, therapy can proceed to treat the individual module.

Signs and symptoms

 

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.

• 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
• poor enunciation
• excessive creation and use of personal neologisms
• inability to repeat a phrase
• persistent repetition of phrases

• 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

Causes

 Aphasia usually results from lesions to the language-relevant areas of the frontal, temporal and parietal lobes of the brain, such as Broca's area, Wernicke's area, and the neural pathways between them. These areas are almost always located in the left hemisphere, and in most people this is where the ability to produce and comprehend language is found. However, in a very small number of people, language ability is found in the right hemisphere. In either case, damage to these language areas can be caused by a stroke, traumatic brain injury, or other brain injury.

References

 

1. ^ ἀφασία, Henry George Liddell, Robert Scott, A Greek-English Lexicon, on Perseus
2. ^ [1], Domasio Antonio, "Aphasia", on N engl J Med
3. ^ Carenotes, "General Information: Aphasia", Truven Health Analytics Inc., 2012
4. ^ ^{a b c} "Aphasia". MedicineNet.com. Retrieved 2011-05-23.
5. ^ "American Speech-Language-Hearing Association (ASHA):- Aphasia Causes and Number".
6. ^ "American Speech-Language-Hearing Association (ASHA):- Aphasia".
7. ^ Kolb, Bryan; Whishaw, Ian Q. (2003). Fundamentals of human neuropsychology. [New York]: Worth. pp. 502, 505, 511. ISBN 0-7167-5300-6. OCLC 464808209.
8. ^ Dronkers NF, Plaisant O, Iba-Zizen MT, Cabanis EA (May 2007). "Paul Broca's historic cases: high resolution MR imaging of the brains of Leborgne and Lelong". Brain 130 (Pt 5): 1432–41. doi:10.1093/brain/awm042. PMID 17405763.
9. ^ Masdeu, Joseph (June 2000). "Aphasia". Archives of Neurology 57 (6).
10. ^ Taylor Sarno, M. (2007). Neurogenic disorders of speech and language. In: O’Sullivan, S.B. & Schmitz, T.J. (2007). Physical Rehabilitation (5th ed.). Philadelphia (PA): F.A. Davis Company.