Aphasia

Article Author:
Huykien Le
Article Editor:
Mickey Lui
Updated:
6/16/2020 8:21:36 PM
PubMed Link:
Aphasia

Introduction

Aphasia is an impairment to 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] Wernicke area is located at the posterior end of the superior temporal gyrus. Its function is to process visual and auditory information and 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 Broca area. 

Specific aphasia syndromes are dependent on the location of the lesion in the brain and are broadly classified as fluent or non-fluent.[3] Specific fluent aphasia syndromes include Broca, transcortical motor, mixed transcortical, and global. Non-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.

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 who are younger than 65 years old have a 15% chance of being affected compared to those who are older than 85 years old have a 43% chance of developing the condition.[7]

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 (ie. embolism or thrombosis) or from a hemorrhagic event (i.e., intracerebral hemorrhage, subarachnoid hemorrhage). 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 effect from brain tumors.[9]

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)

  • The lesion is located in the Wernicke area (Brodmann area 22), which is the center for comprehension and planning of words.[10][11] Although patients are unable to understand written and/or spoken words, their speech remains fluent. At the same time, however, their speech is meaningless and can include paraphasia, both phonemic and semantics, neologism, and jargon. Phonemic paraphasia involves words that sound alike (i.e., sap and map), while semantics paraphasia pertains to words that relate to each other (i.e., sofa for couch). Neologisms are made-up words. Jargon is a string of made-up words in combination with real words that do not make sense together in context. These patients are unaware of their errors and do not recognize that their speech lacks meaning.
    • Example:
      • Examiner: Hi, how are you doing today?
      • Patient: I’m happy, are you pretty.
      • Examiner: What are you doing today?
      • Patient: We stayed with the water today.

Broca Aphasia (Expressive)

  • The lesion is located in Broca area, which is the center for the motor part of speech and sentence formation.[11] Patients are unable to formulate grammatically correct spoken and written language properly. Although their speech is non-fluent and lacks words with grammatical significance such as prepositions and articles, patients are able to include important content words such as nouns, verbs, and some adjectives. Therefore, patients are usually able to convey the message that they are trying to express.
    • Example:
      • Examiner: Hi, Mr. Smith, when did you graduate college?
      • Patient: I was umm… 7 years… ago
      • Examiner: What do you use to do?
      • Patient: well… work… um… work… on desk… uh… marketing… very good…

Conduction Aphasia

  • The lesion is located at the arcuate fasciculus, which is the neural pathway connecting Wernicke area to Broca area [1]. Patients have difficulties or unable to repeat what is spoken to them. They recognize their paraphasic errors and try to correct them.
    • Example:
      • Examiner: Please repeat after me; boy.
      • Patient: Boy.
      • Examiner: Seventy-nine.
      • Patient: Ninety-seven…no… seventy sine… seventy-nice

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.

Anomia

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

Evaluation

Aphasic patients usually are evaluated with computed tomography (CT) without contrast initially if a CVA is suspected, and subsequently, a 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 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. On the other hand, 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 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

  • Wernicke- fluent, impaired comprehension, unable to repeat
  • Transcortical sensory- fluent, impaired comprehension, able to repeat
  • Conduction- fluent, intact comprehension, unable to repeat
  • Anomic- fluent, intact comprehension, able to repeat

Non-fluent Aphasia Syndromes

  • Broca- non-fluent, intact comprehension, unable to repeat
  • Transcortical motor- non-fluent, intact comprehension, able to repeat
  • Mixed transcortical- non-fluent, impaired comprehension, able to repeat
  • Global- non-fluent, impaired comprehension, unable to repeat

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.[12] 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 aphasic patients 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.[13] First-line medications include selective serotonin reuptake inhibitor (SSRI), as well as tricyclic antidepressants (TCA). 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.[14] 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 can also learn Amer-Ind gestures or American Sign Language for communication. Ameri-Ind is easier to imitate and may be preferred.[15]

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 reduce 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).[18] have shown some promising results. 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 are easier and have 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:

  • Altered mental status from encephalopathy or delirium 
  • Dysphonia
  • Dysarthria
  • Apraxia of speech
  • Cognitive-communication disorder

Prognosis

Recovery of aphasia varies depending on the type, severity, cause, motivation of the patients, etc.[22] Most improvement can be seen two to three months after onset and tend to peak at six months with recovery rates drastically decreasing thereafter. There is minimal improvement after two years. Broca aphasia has better recovery when compared to Global aphasia and Global aphasia has better recovery compared to Wernicke aphasia.[23]

Complications

Patients suffering from aphasia, who were once educated and literate, are now unable to communicate their basic wants and needs. Many have intact awareness of their deficit and may become frustrated, even violent. They may feel that they have lost control of their life and feel isolated, which will lead to severe depression.[24] In addition, many will suffer from other deficits seen in CVA, TBI, etc., such as the loss of mobility, ability to perform activities of daily living, or potentially bedridden. Patients may be incontinent in bowel or bladder, and unable to communicate whether they have urinated or defecated. This will increase the likelihood of infections or pressure ulcers. They may have pain that is undertreated. In summary, complications of aphasia are related or dependent ultimately on the underlying cause.

Consultations

  • Physiatrist (physical medicine and rehabilitation)
  • Psychiatrist
  • Neurologist
  • Speech-language pathologist
  • Neuropsychologist

Deterrence and Patient Education

The most common cause of aphasia is CVA, and patients should be educated on correcting modifiable risk factors that may lead to a CVA. The most important modifiable risk factor is hypertension, and patients should follow various guidelines such as the American College of Cardiology (ACC), or the Joint National Committee (JNC-7, 8) to keep their blood pressure under control.[25] Patients with atrial fibrillation should be on anticoagulation based on CAD VASC2 Score, and those with diabetes need their blood sugar controlled.[26] Patients should be encouraged to quit smoking. Ultimately, patient education depends on the underlying cause.

Pearls and Other Issues

It is important to understand that patients with aphasia have an impairment of language due to injury from the brain and not a cognitive deficit. When communicating with patients with aphasia, speak clearly, and use simple and short sentences. Another technique is repeating or writing down keywords. Also, allow patients time to talk and finish their thoughts and avoid correcting their speech.

Enhancing Healthcare Team Outcomes

Aphasia is caused by different disease processes and consists of many syndromes. Because of this, it is easily misdiagnosed. The initial challenge of diagnosing aphasia is that patients are unable to communicate to provide an adequate history for diagnosis. This may require a history from family members or friends, which can be unreliable or unavailable. Therefore, the healthcare professional needs to be familiar with the signs and symptoms of aphasia.

Initially, patients will present to primary care or emergency physicians. The ability to recognize aphasia can aide in the diagnosis of its underlining cause. For example, patients with an acute stroke can present initially with aphasia and can be misdiagnosed as delirium. Aphasia has many underlining causes and requires an interdisciplinary team that includes a physiatrist, psychiatrist, neurologist, speech-language pathologist, and a neuropsychologist to manage comorbidities and deficits.[14] Interdisciplinary team members need to know how to properly communicate and interact with aphasic patients to avoid frustration and encourage patient participation.

The speech-language pathologist plays a vital role in identifying the type of aphasia syndrome and formulate an individualized rehabilitation regimen with the assistance of the physiatrist. Depending on the patient’s comorbidities, other specialists are required. Patients who suffered from a stroke may have cardiac, pulmonary, renal, or integumentary issues requiring a cardiologist, pulmonologist, nephrologist, and wound care physician. Physical therapists and occupational therapists will be a part of the interdisciplinary team to treat physical deficit and aid in aphasia treatment. Patients with neurodegenerative disease will require a neurologist, while patients with an infectious cause require infectious disease specialists.

Patients with aphasia will likely suffer from depression and require support from healthcare professionals such as a neuropsychologist, psychologist, and psychiatrist. Patients will also require social support. Family members, friends, and/or religious leaders will require extensive education to assist patients in their recovery process.

There is no specific protocol in treating patients with aphasia. The treatment and rehabilitation regimen is highly individualized and requires an extensive interdisciplinary team. Proper consultation of specialists and education of family members and friends is required to optimize patient treatment and allow patients to regain their greatest level of independence.


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