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StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-.

StatPearls [Internet].

Aphasia

Huykien Le ; Mickey Y. Lui .

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Last Update: March 27, 2023 .

Continuing Education Activity

Aphasia is an impairment of language caused by damage to the language area of the brain, primarily Broca and Wernicke areas. Injury to the brain can be caused by various disease processes such as cerebrovascular accident (CVA), traumatic brain injury (TBI), brain mass, or neurodegenerative diseases. Patients can develop symptoms that include difficulties articulating words or sentences, deficits of comprehension, or both. This activity highlights the evaluation and treatment of aphasia and outlines the role of the interprofessional team in the care of patients with this condition.

Describe interprofessional team strategies for improving care coordination and communication to advance the care of patients with aphasia and improve outcomes.

Introduction

Aphasia is an impairment of comprehension or formulation of language caused by damage to the cortical center for language. It can be caused by many different brain diseases and disorders; however, cerebrovascular accident (CVA) is the most common reason for a person to develop aphasia. The symptoms of aphasia can range from mild impairment to complete loss of any fundamental components of language such as semantic, grammar, phonology, morphology, and syntax.

The function of language is the ability to express and comprehend spoken and written words. The language area of the brain is typically located in the dominant hemisphere. These structures include Wernicke area, Broca area, and arcuate fasciculus.[1] The Wernicke area is located at the posterior end of the superior temporal gyrus. Its function is to process visual and auditory information, and it is the center for comprehension and planning of words. Broca area is located in the inferior frontal area and is the center for motor execution of speech and sentence formation.[2] Arcuate fasciculus is the neural pathway connecting Wernicke area to the Broca area.

Specific aphasia syndromes are dependent on the location of the lesion in the brain.[3] In fluent aphasia, the patient can speak in sentences that sound like normal speech, but some of the words are made-up words or have some sounds that are not correct. People with non-fluent aphasia struggle to get words out, omit words, and speak in very short sentences. Specific non-fluent aphasia syndromes include Broca, transcortical motor, mixed transcortical, and global. Fluent aphasia syndromes include Wernicke, transcortical sensory, conduction, and anomic.

Etiology

Aphasia is most commonly seen in patients who have had a cerebrovascular accident but can be seen in neurodegenerative diseases (Alzheimer disease, frontotemporal lobar degeneration, etc.), vascular dementia, brain tumor, or traumatic brain injury.

Aphasia is not secondary to damage to motor or sensory function. It is not a result of peripheral motor or sensory difficulties including paralysis affecting the speech muscles or general hearing impairment.

Epidemiology

According to the National Institute on Deafness and Other Communication Disorders (NIDCD), in the United States, there are 180,000 new aphasia cases a year, and 1 of every 272 Americans are affected with aphasia. Approximately one-third of the cases are attributed to cerebrovascular accidents.[4] The most common type is global aphasia.[5] There is an equal incidence of aphasia caused by CVA between men and women.[6] However, the incidence is age-dependent. Those younger than 65 years old have a 15% chance of being affected compared to those older than 85 years old and have a 43% chance of developing the condition.[7] 25% to 40% of stroke survivors develop aphasia due to damage to the language-processing regions of the brain.

Pathophysiology

Aphasia is caused by lesions to the language areas of the brain, which are typically located in the dominant hemisphere. For the majority of the population, the dominant hemisphere is on the left side.[8] These areas are Wernicke area, Broca area, and arcuate fasciculus. The most common cause of aphasia is due to CVA. CVA occurs when the blood supply to a certain part of the brain is greatly diminished or stopped due to an ischemic event (i.e., embolism or thrombosis) or from a hemorrhagic event (i.e., intracerebral hemorrhage, subarachnoid hemorrhage). In some cases, aphasia can be caused by damage to subcortical structures deep within the left hemisphere, including the internal and external capsules, the thalamus, and the caudate nucleus.[9]

In addition, aphasia can be caused by progressive deterioration of brain tissue such as Alzheimer, Pick disease, vascular dementia, some forms of Parkinson disease, or from direct physical injuries, as seen in traumatic brain injury. Other causes of injuries to language areas can include infection and mass effects from brain tumors.[10]

History and Physical

There are many different types of aphasia syndromes with signs and symptoms that may overlap with each other. A clinician with the insight to differentiate and recognize the differences in each type of aphasia can carefully formulate an individualized treatment plan.

Wernicke Aphasia (Receptive)

Broca Aphasia (Expressive)

Conduction Aphasia

Transcortical Sensory Aphasia

The lesion is located around Wernicke area, however, sparing Wernicke area and isolating it. Patients have an inability to comprehend but can repeat with fluent speech. At the same time, patients display the presence of semantic paraphasia.

Transcortical Motor Aphasia

The lesion is located around Broca area, however, sparing Broca area and isolating it. Patients have a non-fluent speech but are able to repeat long, complex phrases. Patients tend to remain silent but may speak with 1 to 2 words.

Mixed Transcortical Aphasia

The lesion is located around Wernicke area, Broca area, and arcuate fasciculus, but these areas are spared and are isolated. Patients would have severe speaking and comprehension impairment; however, they can repeat long, complex sentences.

Global Aphasia

Lesions vary in size and location but tend to follow the left middle cerebral artery distribution. This is the most severe form of aphasia. Patients can only produce a few recognizable words and have little to no understanding of written or spoken language. Patients are unable to read or write.

The lesion is at the angular gyrus and is the mildest form of aphasia. Patients have difficulties with word finding.

Related Behaviors

Self-repairs are disruptions in fluent speech resulting from mis-attempts to repair erred production of speech.

Speech disfluencies include repetitions and prolongations at the phonemic, syllable, and word level with pathological frequency.

Preserved and automatic language are when some language or language sequences that were utilized frequently prior to onset are still produced with more ease.

Evaluation

Patients with aphasia usually are evaluated with computed tomography (CT) without contrast initially if a CVA is suspected, and subsequently, magnetic resonance imaging (MRI) to identify the precise location of the lesion. Then they are evaluated by speech/language pathologists to assess and help identify areas of a language deficit. Several formal exams are used to identify aphasia, such as the Boston diagnostic aphasia exam and Western aphasia battery. Boston diagnostic aphasia exam provides a severity rating from slight to severe. The Western aphasia battery helps assess if the patient is aphasic and if so, determines the type and severity. Furthermore, it provides a baseline and should be repeated to trend improvements, all the while identifying strengths and weaknesses.

For the evaluation of aphasia, three parts of language assessments are used to distinguish the different types of aphasia syndromes. This includes fluency of speech, comprehension, and repetition. Fluency of speech entails a typical speech rate, intact syntactic ability, and effortless speech output. Comprehension is the patient's ability to understand written and spoken words. Finally, repetition is the patient's ability to repeat written or spoken words.

Fluent Aphasia Syndromes

Non-fluent Aphasia Syndromes

A cognitive neuropsychological approach attempts to identify the key language skills that are not functioning properly. These are called modules. A patient may have difficulty with just one module or a number of modules.

Treatment / Management

The initial treatment of aphasia is dependent on its cause. Immediate management follows the ABCs of critical care: airway, breathing, and circulation. In patients with acute CVA, patients may receive intravenous thrombolytic therapy with tissue plasminogen activator (tPA), intra-arterial mechanical thrombectomy, or carotid endarterectomy.[13] Surgical decompression is used for patients with hemorrhagic CVA, TBI, or brain tumors. If the cause is due to an infection, initiation of steroids, antivirals, or antibiotics may be indicated.

While there is no standardized treatment, the primary goal is for patients to regain their greatest level of independence. To achieve this goal, the patient’s physical comorbidities, mental health, and deficits need to be addressed and properly managed. In addition, caregiver education and social support greatly impact a patient’s recovery outcome.

Patients suffering from aphasia have difficulties communicating their wants and needs. Some patients with aphasia are cognizant of their deficit and situation, which can be frustrating and may lead to severe depression and lack of participation in therapy. Therefore, early diagnosis of depression is instrumental in treating the aphasic patient. The patient will require emotional support from family, friends, and/or spiritual leaders. Referral to a psychiatrist, neuropsychologist, and/or psychologist for evaluation and management may be indicated. In addition, the treatment of depression includes pharmacological management.[14] First-line medications include selective serotonin reuptake inhibitors (SSRIs), as well as tricyclic antidepressants (TCAs). However, SSRIs are generally preferred due to lower side effect profiles.

Patients will be evaluated by speech-language pathologists to determine their strengths and weaknesses to individually customize a treatment plan. However, it has been shown that patients have better improvement with short, intense treatment sessions compared to longer but less intense treatment sessions.[15] Patients will be provided with different compensatory strategies, also known as augmentative and alternative communication (AAC). These strategies can include providing patients with a whiteboard, pen, and paper for writing, photos of common items for identification, or more advanced devices, such as tablets with common phrases or pictures.

Patients with non-fluent aphasias, such as Broca aphasia, have impaired fluency when it comes to sentence generation but tend to have intact singing abilities. Melodic intonation therapy (MIT) utilizes melody and rhythm to improve a patient’s fluency. The theory behind MIT is to utilize the undamaged non-dominant hemisphere that is responsible for intoning and reducing the use of the dominant hemisphere. MIT can only be used in patients with intact auditory comprehension.[16]

Advances in neuroimaging technology now can appreciate the activation of the language areas of the brain, allowing for further advances in aphasia research and treatment.[4][17] Studies on transcranial stimulation by direct electrical current (TES) and transcranial magnetic stimulation (TMS) have shown promising results.[18] Along with therapy, there has been an improvement in word-finding, function, and activity outcomes.[19] It should be noted that using neuroimaging to isolate optimal stimulation sites for the use of TES is expensive and time-consuming; therefore, it is currently more applicable in research rather than clinical treatment. Stimulation of ancillary systems is easier and has shown to be promising.[20] Studies on pharmacological therapy have yielded mixed results and tend to coincide with the treatment of CVAs. Drug therapies have included dopaminergic agents, and catecholaminergic agents can facilitate neural plasticity and recovery but require further research.[21]

Differential Diagnosis

Aphasia can present insidiously or acutely and is caused by several disease processes that need to be ruled out such as CVA, brain tumor, brain hemorrhage, traumatic brain injury (TBI), and dementia due to toxin, infection, or vascular.

Other differential diagnoses to consider include: