Approach to Aphasia

Aphasia is a disturbance of language due to brain damage. This damage can affect comprehension (listening and reading) and/or expression (speaking and writing). In aphasia, the ability is name objects is always impaired to some degree. Aphasia most commonly develops after a brain injury, such as a stroke or head trauma. However, it can also develop due to neurodegenerative diseases, such as Alzheimer’s disease or frontotemporal dementia, leading to syndromes such as primary progressive aphasia.

  • Aphasia may result from lesions in and around the perisylvian language area of the brain, which includes the lateral sulcus (Sylvian fissure) of the left hemisphere and includes Broca's area and Wernicke's area.[1]
  • Language is generated in the left hemisphere (generally), left cerebral cortex
    • Thus, lesions/abnormalities in the cortex produce abnormalities of language, known as aphasias
    • Thus, to test language function, one tests for fluency, naming, comprehension, and naming
  • Speech is generated at the level of the brainstem, through the articulation of the mouth and its movements
    • Thus, lesions/abnormalities in the brainstem produce abnormalities of speech, called dysarthria (i.e. - a problem of articulation)
    • Thus, to test speech function, one tests for motor output of speech
    • Apraxia of speech is another issue involving speech and not language centres of the brain. In apraxia of speech, individuals have inconsistencies in their speech error, and there is a phenomenon called “groping,” where the individual is trying to move their tongue and lips to get them into the right place to the make the sounds. There is typically a halting, effortful quality of speech, and there is typically difficulty with verb endings.
  • It is important to note that it is possible for brain injury and neurodegeneration to cause all three speech and language problems: aphasia, dysarthria, and apraxia of speech (depending on which areas of the brain are affected).

How Do I Test for Dysarthria?

Dysarthria is predictable pattern of typical difficulty with pronunciation of a sound. To test for dysarthria, ask the patient to say a word several times repeatedly. Some common words (the NIH Stroke Scale/Score [NIHSS] Dysarthria Words) used to test for dysarthria include:
  • MAMA
  • Most language functions (grammar, vocabulary and literal meaning) are usually lateralized to the left hemisphere in right-handed individuals (up to 90% of individuals). In left-handed individuals, language lateralization is either bilateral, or lateralized to the right hemisphere.[2]

When we say someone has normal speech or fluency in a neurologic/psychiatric context, it means they have good phrase length, rate, and an abundance of spontaneous speech. It also means they have no paraphasic errors (inappropriately substituted words or syllables), no neologisms (nonexistent words), and no errors in grammar. Normal prosody is a term also frequently used, meaning there is normal range of rhythm, pitch, stress, intonation.

Foreign Accent Syndrome

Acquired Neurogenic Foreign Accent Syndrome (ANFAS) is a motor speech disorder in which, after brain damage such as a traumatic brain injury or stroke, patients start speaking with a new accent, which sounds like a foreign accent to listeners. This typically occurs after damage to the language-dominant, left hemisphere (affecting the primary motor cortex, the premotor cortex, the internal capsule, the corona radiata, or the basal ganglia nuclei).[3] Although impaired expression of emotion through pitch, loudness, rate, and rhythm of speech can occur after right-hemisphere (RH) strokes, these rarely result in FAS.[4]

When speech is impaired and not normal, it is called aphasic speech. Aphasias are first categorized as either fluent or non-fluent. They can then be further sub-characterized by whether there are deficits in repetition, comprehension, and naming.

  • Fluency
    • Fluent Aphasia: Patient is able to produce connected speech. Sentence structure is relatively intact but lacks meaning.
    • Non-fluent Aphasia: Speech production is halting and effortful. Grammar is impaired; content words may be preserved.
  • Repetition: Patient is able to repeat words over and over again
  • Language Comprehension: Patient is able to understand the context and meaning behind sentences and words
  • Naming: Patient is able to recognize and name and object
  • Paraphasia: inappropriately substituted words or syllables
    • Phonemic paraphasias: “baby flitter” instead of “baby sitter”
    • Semantic paraphasias: “clock” instead of “watch,” “pen” instead of “pencil,” “apple” instead of “orange.”
    • Neologisms: a completely new word (e.g. - “bobfrest” instead “tree”)
    • Perseveration: returning to a same topic or word, over and over again
  • Anomia
    • Anomia is a symptom of all forms of aphasia, but patients whose primary deficit is word retrieval are diagnosed with anomic aphasia. Some level of anomia is seen in all of the aphasias.
  • Fluency Tasks
    • Semantic fluency (also known as category fluency): is a task that involve producing words belonging to a predetermined semantic category (e.g. - animals, fruits and vegetables)
    • Phonemic fluency (also known as lexical or letter fluency): is a task that involves producing words beginning with a given letter (e.g. - F, A and S being the most commonly)

Syntax Errors and Semantic Errors

  • A syntax (or synatactic) error is a violation of the grammatical rules of a language
    • e.g. - “I is going to the store.”
    • e.g. - “people elderly” instead of “elderly people”
  • A semantic error is a violation of the rules of meaning of a language.
    • e.g. - “My banana just flew a car to Chicago”
    • e.g. - “time-telling thing” instead of “watch”)
    • Although the syntax (grammar) above is perfectly correct, the semantics (meaning) does not make sense!

Is it Aphasia or Something Else?

Keep in mind that aphasia is a separate disorder from dysarthria, an impairment of the motor functions of speech (i.e. - the actual muscles involved in speech). To distinguish aphasia from dysarthria, remember that aphasia by definition requires difficulties with naming (e.g. - naming common daily objects).
  • Fluency: the smoothness or flow in which sounds, syllables, words, and phrases are joined when speaking quickly
  • Repetition: (e.g. - “No ifs ands or buts” in the MMSE“)
  • Comprehension: assesses understanding (e.g. - the 3-step command in MMSE)
  • Naming: (e.g. - naming watch, pen)

Aphasia Syndromes

N = Normal or relatively spared, Imp = Impaired, * = with paraphasia, † = with echolalia
Aphasia Fluency Repetition Comprehension Naming
Broca's (Expressive) Imp Imp N Imp
Transcortical Motor Imp N N Imp
Mixed Transcortical Imp N Imp Imp
Global Imp Imp Imp Imp
Wernicke's (Receptive) N* Imp Imp Imp
Transcortical Sensory N N Imp Imp
Conduction (Arcuate) N* Imp N Imp
Anomic N N N Imp

Fluent and Non-Fluent Aphasias Fig. 1

Non-fluent aphasias usually involve damage or a lesion affecting the anterior portion of the language centre in the left hemisphere.

The patient knows what they want to say, but struggles to get it out.

Broca's Aphasia (also known as “expressive aphasia”) is often referred to as a non-fluent aphasia because of the halting and effortful quality of speech.

Transcortical Motor Aphasia is a type of of non-fluent aphasia similar to Broca's aphasia, but repetition skills are intact. The deficit is usually due to a small subcortical lesion superior to Broca's area, or the anterior superior frontal lobe in the perisylvian area of the left hemisphere.[5] The patient may have difficulty spontaneously answering a question but can repeat long utterances without difficulty.

Mixed Transcortical Aphasia is a combination of the two transcortical aphasias (transcortical motor aphasia and transcortical sensory aphasia), where both reception and expression are severely impaired. Repetition remains intact.

Global Aphasia is a non-fluent aphasia with severe impairment of both expressive and receptive skills (hence the term global). This aphasia is usually associated with a large left hemisphere lesion that affects both the receptive (Wernicke's) and expressive (Broca's) areas of the brain. Despite these deficits, individuals may be able to express themselves through facial expressions, gestures, and intonations.

Fluent aphasias usually involve damage or a lesion affecting the posterior portion of the language centre in the left hemisphere.

The patient can speak effortlessly, but the speech lacks meaning, and they cannot understand the written or spoken language.

Wernicke's aphasia (also known as “receptive aphasia”) is a fluent aphasia where the ability to grasp the meaning of spoken/written words is impaired, but fluent speech is still produced. However, this does not mean spoken speech is normal by any means. Although the speech is fluent (i.e. - smooth), there are paraphasias such as jumbled words and meaningless sentences. An individual may be unable to understand spoken or written words, or may read and not understand what they are reading. Sometimes, an individual pretends to understand and even nods in agreement, known as “cover-up aphasia.”

Transcortical Sensory Aphasia is similar to Wernicke's aphasia, with the exception of a strong ability to repeat words and phrases. The patient may repeat questions rather than answer them (also known as “echolalia”).

Conduction Aphasia is a fluent aphasia with a significant impairment with repetition. The lesion involves the arcuate fasciculus and the left parietal region. The patient can express themselves reasonably well, with some word-finding issues, and comprehension can be good. However, the patient will show significant difficulty repeating phrases, particularly as they increase in length and complexity. They may stumble over words they are attempting to pronounce.

Anomic Aphasia is a fairly mild form of aphasia. The patient will use generic fillers, such as nonspecific nouns and pronouns (e.g., “thing”), or circumlocution, where the person describes the intended word in a roundabout way. Comprehension and repetition is typically intact, but the patient may not always recognize the retrieved word is the correct one, indicating difficulty with word recognition as well.