Treatment of Poststroke Aphasia
Treatment of Poststroke Aphasia
Aphasia is an acquired neurologic disorder that impairs an individual's ability to use and/or understand language. It commonly occurs after stroke or other injury to the brain's language network. The authors present the current methods of diagnosis and treatment of aphasia. They include a review of the evidence for the benefits of speech–language therapy, the most widespread approach to aphasia treatment, and a discussion of newer interventions such as medication and brain stimulation. These methods hold much promise for improving patient outcomes in aphasia; however, additional research regarding the best approaches to aphasia treatment will greatly improve our clinical approach.
Approximately one million people in the United States are living with aphasia, an acquired neurologic disorder that affects the ability to use and/or understand language. Aphasia results from damage to any part of the language system in the brain; it is typically caused by stroke, tumor, or other brain injury. About two-thirds of individuals who experience a left-hemisphere stroke will develop aphasia and may have difficulty with any component of language, including word-finding, constructing grammatical speech, comprehending spoken words or sentences, reading, and/or writing. Although there is opportunity for both spontaneous recovery as well as therapeutic rehabilitation, approximately two-thirds of individuals with aphasia will experience a lifelong struggle with some aspects of communication. Living with aphasia can significantly affect life participation, and often has a negative impact on quality of life for both the patient and their family.
Language is a symbolic system that is used by humans for social interaction and functional communication. The various components of language, including meaning (semantics), sounds (phonology), and structure (syntax/morphology), are subserved by specific networks of brain regions. Aphasia can result from any kind of injury or illness that affects these brain areas, which lie mostly in the left hemisphere. Language is left lateralized in approximately 95% of right-handed individuals and 75% of left-handed individuals. The remaining individuals exhibit either right hemisphere (crossed) or bihemispheric (mixed) dominance. Many neurologists consider the brain's language network to be comprised of the Broca and Wernicke areas, with the arcuate fasciculus connecting them. However, the past few decades of research have revealed that language functions involve more extensive parts of the left temporal, parietal, and frontal lobes, along with subcortical gray matter structures. The nondominant hemisphere plays a smaller role in communication, contributing mostly to social or pragmatic aspects of language such as prosody and abstract language (e.g., humor or metaphor). Thus, damage to the nondominant hemisphere is unlikely to cause aphasia, but may cause difficulty with other cognitive–linguistic functions.
The most common cause of aphasia is a stroke affecting the lateral aspects of the left cerebral hemisphere (e.g., a left middle cerebral artery infarct). Aphasia can also result from damage to subcortical regions in the left hemisphere, and rarely from right cerebellar lesions, likely due to the connections between the right cerebellum and the left cerebral cortex. Because networks involved in various language functions are distributed widely throughout the brain, there is a wide range of specific language deficits that can be observed in an individual suffering from aphasia. These various impairments in spoken language production and/or comprehension may be accompanied by deficits in reading (alexia) and/or writing (agraphia). Additionally, although aphasia itself is a disorder of language and individuals with aphasia may have no other discernable cognitive or motor deficits, aphasia is often comorbid with deficits in executive function or with verbal and/or ideomotor apraxia. There is also a high incidence of depression in this population, with some estimates indicating that nearly two-thirds of patients with aphasia suffer from depression. Persons with aphasia are thus complex patients who benefit from thorough diagnostic assessment and careful development of a treatment plan that will maximize their ability to recover language function.
Just as there is substantial variability in the symptoms and signs of aphasia, there is considerable variability in the course of recovery. As with other stroke-related deficits, recovery is fastest early on and slows down over time. Although the common wisdom is that all spontaneous recovery has occurred by 12 months after the injury, many studies have demonstrated that additional gains can be made after this time. In general, the initial severity of aphasia predicts the outcome. Other factors such as age, sex, premorbid language lateralization, and involvement of deep white-matter tracts also predict recovery to some degree, although our ability to predict early on who will recover well from aphasia is limited. Specific language deficits may improve at different rates, and the type of the aphasia may subsequently change over time. As a result, the treatment plan of an individual with aphasia will also change over time.
Abstract and Introduction
Abstract
Aphasia is an acquired neurologic disorder that impairs an individual's ability to use and/or understand language. It commonly occurs after stroke or other injury to the brain's language network. The authors present the current methods of diagnosis and treatment of aphasia. They include a review of the evidence for the benefits of speech–language therapy, the most widespread approach to aphasia treatment, and a discussion of newer interventions such as medication and brain stimulation. These methods hold much promise for improving patient outcomes in aphasia; however, additional research regarding the best approaches to aphasia treatment will greatly improve our clinical approach.
Introduction
Approximately one million people in the United States are living with aphasia, an acquired neurologic disorder that affects the ability to use and/or understand language. Aphasia results from damage to any part of the language system in the brain; it is typically caused by stroke, tumor, or other brain injury. About two-thirds of individuals who experience a left-hemisphere stroke will develop aphasia and may have difficulty with any component of language, including word-finding, constructing grammatical speech, comprehending spoken words or sentences, reading, and/or writing. Although there is opportunity for both spontaneous recovery as well as therapeutic rehabilitation, approximately two-thirds of individuals with aphasia will experience a lifelong struggle with some aspects of communication. Living with aphasia can significantly affect life participation, and often has a negative impact on quality of life for both the patient and their family.
Language is a symbolic system that is used by humans for social interaction and functional communication. The various components of language, including meaning (semantics), sounds (phonology), and structure (syntax/morphology), are subserved by specific networks of brain regions. Aphasia can result from any kind of injury or illness that affects these brain areas, which lie mostly in the left hemisphere. Language is left lateralized in approximately 95% of right-handed individuals and 75% of left-handed individuals. The remaining individuals exhibit either right hemisphere (crossed) or bihemispheric (mixed) dominance. Many neurologists consider the brain's language network to be comprised of the Broca and Wernicke areas, with the arcuate fasciculus connecting them. However, the past few decades of research have revealed that language functions involve more extensive parts of the left temporal, parietal, and frontal lobes, along with subcortical gray matter structures. The nondominant hemisphere plays a smaller role in communication, contributing mostly to social or pragmatic aspects of language such as prosody and abstract language (e.g., humor or metaphor). Thus, damage to the nondominant hemisphere is unlikely to cause aphasia, but may cause difficulty with other cognitive–linguistic functions.
The most common cause of aphasia is a stroke affecting the lateral aspects of the left cerebral hemisphere (e.g., a left middle cerebral artery infarct). Aphasia can also result from damage to subcortical regions in the left hemisphere, and rarely from right cerebellar lesions, likely due to the connections between the right cerebellum and the left cerebral cortex. Because networks involved in various language functions are distributed widely throughout the brain, there is a wide range of specific language deficits that can be observed in an individual suffering from aphasia. These various impairments in spoken language production and/or comprehension may be accompanied by deficits in reading (alexia) and/or writing (agraphia). Additionally, although aphasia itself is a disorder of language and individuals with aphasia may have no other discernable cognitive or motor deficits, aphasia is often comorbid with deficits in executive function or with verbal and/or ideomotor apraxia. There is also a high incidence of depression in this population, with some estimates indicating that nearly two-thirds of patients with aphasia suffer from depression. Persons with aphasia are thus complex patients who benefit from thorough diagnostic assessment and careful development of a treatment plan that will maximize their ability to recover language function.
Just as there is substantial variability in the symptoms and signs of aphasia, there is considerable variability in the course of recovery. As with other stroke-related deficits, recovery is fastest early on and slows down over time. Although the common wisdom is that all spontaneous recovery has occurred by 12 months after the injury, many studies have demonstrated that additional gains can be made after this time. In general, the initial severity of aphasia predicts the outcome. Other factors such as age, sex, premorbid language lateralization, and involvement of deep white-matter tracts also predict recovery to some degree, although our ability to predict early on who will recover well from aphasia is limited. Specific language deficits may improve at different rates, and the type of the aphasia may subsequently change over time. As a result, the treatment plan of an individual with aphasia will also change over time.
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