Global aphasia
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
The symptoms of global aphasia are those of severe Broca's aphasia and Wernicke's aphasia combined. There is an almost total reduction of all aspects of spoken and written language, in expression as well as comprehension. Improvement may occur in one or both areas (expressive and receptive) over time with rehabilitation. What is interesting to point out is that in patients of global aphasia other cognitive skills remain functioning - a phenomenon affirming that language faculty is indeed a separate domain.
Global aphasia is a type of aphasia that is usually associated with a large lesion in the presylvian area. It involves a "left side blowout" which includes Broca's area, Wernicke's area and the Arcuate fasciculus.
When injury initially occurs to all of these areas, the progression starts out with Global aphasia in the first 1-2 days due brain swelling (Edema). From there it evolves into Brocas or Wernicke's aphasia for 1-3 months (usually Broca's), then it resolves into a presidual anomic aphasia. Studies show that spontaneous improvement, if it happens, occurs within six months, but complete recovery is rare.
Persons with global aphasia are usually mute or use repetitive vocalization. The person frequently uses simple words such as expletives. They are marked by a severe impairment of both understanding and expression of language. Although, they can maintain communication through gestures.
Historical Perspective
Global aphasia was recognized to be a universal damage to both the speech receptive, and producing areas of the brain. However, it's understanding did not come into existence, until Paul Broca described Broca's aphasia(a component of Global aphasia), and Carl Wernicke described Wernicke's aphasia. A collective understanding of the two seperate components of aphasia led to the description of Global aphasia.[1]
Classification
According to the Cognitive Neuropsychological Model, which classifies aphasia based on the specific function lost, Global Aphasia can be classified as a non-fluent aphasia, with poor repetition, naming and auditory comprehension. This stems from diffuse global damage to both the frontal lobe, and the temporal lobe. Both areas responsible for production, and reception of speech.
Pathophysiology
Like most forms of Aphasia, damage to the Broca's Area, in addition to Wernicke's Area, is responsible for the combination of symptoms seen in Global Aphasia. Since both areas are involved in understanding and production of speech, a cluster of symptoms encompassing both will be present. Patient can barely comprehend, or make sense, out of spoken or written language.
Causes
Global Aphasia like most aphasias, usually results from damage to the dominant speech producing hemisphere. Massive intracerebral bleeding, tumors, and medications have been implicated as causative factors of Global Aphasia. Of them all, stroke seems to be the most common cause
* Stroke * Cerebral Tumors * Infection * Trauma * Neurodegenerative Disease
However, stroke, seems to be the commonest cause of Global aphasia, and occurs alongside weakened limbs, which is usually an indication of other areas of the brain being involved. For this reason alone, Global Aphasia is generally more common in the elderly.
Differentiating Global Aphasia from Other Diseases
Epidemiology and Demographics
Risk Factors
Screening
Natural History, Complications, and Prognosis
Diagnosis
Diagnostic Study of Choice
History and Symptoms
- Impaired Comprehension and interpretation of language.
- Impaired understanding and Formulation of language.
- Paralysis of unilateral limbs(Stroke patients)
- Impaired pronunciation of language and certain sounds.
- Poor control of mouth, voice box, and tongue.
Physical Examination
Laboratory Findings
Electrocardiogram
X-ray
Echocardiography and Ultrasound
CT scan
MRI
Other Imaging Findings
Other Diagnostic Studies
Prognosis
Prognosis for Aphasic patients can be determined by cause of aphasia, age of patient, and presence of other co-morbidities. Older patients have a harder time recovering. Aphasia caused by stroke has a better prognosis, than that caused by a tumor, or neurodegenerative disease. Of critical importance is the ability of patients to live independently following diagnosis. This is rarely achieved, as Aphasia can persist for months to years.
Treatment
Medical Therapy
Surgery
Primary Prevention
Secondary Prevention
Multiple treatment modalities exist for Global Aphasia which includes:
1)Repetitive Transcranial Magnetic Simulation(rTMS): Usually used in post-stroke rehabilitation.[2]
2)Speech and Language Therapy(SLT): Has been known to be beneficial in Aphasic patients.
3) Transcranial Direct Current Simulation: When used in conjunction with speech therapy was known to be effective, rather than when used alone.
4)Piracetam: Known pharmacological agent used in global aphasia. Studies have shown little benefit in improving overall severity of aphasia, however, the writing ability of patients had a slight improvement. Overall, there has been no significant data, to support benefits of piracetam.[3]
References
Template:Psych-stub Template:WikiDoc Sources
- ↑ Henderson VW (June 1986). "Paul Broca's less heralded contributions to aphasia research. Historical perspective and contemporary relevance". Arch Neurol. 43 (6): 609–12. doi:10.1001/archneur.1986.00520060071021. PMID 3521554.
- ↑ Ren C, Zhang G, Xu X, Hao J, Fang H, Chen P, Li Z, Ji Y, Cai Q, Gao F (2019). "The Effect of rTMS over the Different Targets on Language Recovery in Stroke Patients with Global Aphasia: A Randomized Sham-Controlled Study". Biomed Res Int. 2019: 4589056. doi:10.1155/2019/4589056. PMC 6699349 Check
|pmc=value (help). PMID 31467892. - ↑ Berthier ML (2005). "Poststroke aphasia : epidemiology, pathophysiology and treatment". Drugs Aging. 22 (2): 163–82. doi:10.2165/00002512-200522020-00006. PMID 15733022.