Disorders of Speech & Language
Aphasia is the term used to describe an acquired loss of language that causes problems with any or all of the following: speaking, listening, reading and writing. Some people with aphasia have trouble using words and sentences (expressive aphasia). Some have problems understanding others (receptive aphasia). Others with aphasia struggle with both using words and understanding (global aphasia). Aphasia can cause problems with spoken language (talking and understanding) and written language (reading and writing). Typically, reading and writing are more impaired than talking or understanding. The severity of the aphasia depends on the amount and location of the damage to the brain.
Broca’s (expressive or motor) Aphasia
Damage to a discrete part of a the brain in the left frontal lobe (Broca’s area) of the language-dominant hemisphere has been shown to significantly affect use of spontaneous speech and motor speech control. Words may be uttered very slowly and poorly articulated. Speech may be labored and consist primarily of nouns, verbs or important adjectives. Speech takes on a telegraphic character. People suffering from Broca’s aphasia have great difficulty with repetition and a severe impairment in writing. In some patients, however, the understanding of spoken and written language may be relatively well-preserved. The non-fluent variant of primary progressive aphasia (nfvPPA) is a type of expressive aphasia.
If damage encompasses both Wernicke’s and Broca’s areas, global aphasia can occur. In this case, all aspects of speech and language are affected. Patients can say a few words at most and understand only a few words and phrases. They usually cannot carry out commands or name objects. They cannot read or write or repeat words said to them.
Logopenic Primary Progressive Aphasia (lvPPA)
Degeneration of the angular gyrus in the temporal lobe and inferior parietal lobe can lead to lvPPA. Typical symptoms include slowed speech with normal articulation, impaired comprehension of sentence syntax as well as impaired naming of things. lvPPA is probably associated with Alzheimer’s disease pathology.
Primary Progressive Aphasia (PPA)
PPA is caused by degeneration in the parts of the brain that control speech and language (the left, or “dominant,” side of the brain in the frontal, temporal and parietal regions that normally control language function). This type of aphasia begins gradually, with speech or language symptoms that reflect the normal role for the site of initial degeneration. Eventually, problems spread throughout the broader language network. PPA subtypes include non-fluent primary progressive aphasia (nfvPPA), semantic variant primary progressive aphasia (svPPA) and logopenic primary progressive aphasia (lvPPA). These syndromes result from a variety of underlying diseases, but most often frontotemporal lobar degeneration (FTLD) (both tau and TDP-43 subtypes) or Alzheimer’s disease.
Damage to the posterior superior areas of the language dominant temporal lobe (often called Wernicke’s area) has been shown to significantly affect speech comprehension. In other words, information is heard through an intact auditory cortex in the anterior temporal lobe, however, when it arrives at the posterior association areas, the information cannot be sufficiently “translated.” In contrast to Broca’s aphasia, the person with Wernicke’s aphasia talks volubly and gestures freely. Speech is produced without effort, and sentences are of normal length. However, the person’s speech is devoid of meaning.
This pattern of receptive aphasia is marked by:
- Fluent, grammatically correct speech with little meaning
- Poor comprehension
- Paraphasic errors:
- calling a spoon a “fork” (semantic)
- calling a spoon a “spood” (literal)
- Neologisms (or nonsense words)