A motor aphasia is a type of nonfluent or expressive aphasia and is characterized by difficult-to-understand articulation and speech patterns. Motor aphasia and other related language problems, such as pure or fluent aphasias, originate in the brain and can be caused by trauma, stroke, or other problems that affect the brain. There are many different language disorders that can affect everything from the comprehension of written or spoken language to the ability to speak or write. Motor aphasia tends to leave the ability to comprehend language intact while damaging the ability to articulate language in a completely understandable manner. In some cases, different aphasias present together, and an individual may simultaneously lose the ability to comprehend language and develop difficult-to-understand speech patterns.
There are several different specific types of motor aphasias. Broca's aphasia, for instance, causes nonfluent speech, characterized by a slow pace, limited coherence, and perceptible difficulty in putting thoughts into words. In some cases, this form of motor aphasia severely limits an individual's vocabulary to a few words or syllables. While comprehension of simple speech is generally retained, individual's with Broca's aphasia may find it difficult to understand complex or convoluted sentence structures. This difficulty in understanding applies to both spoken and written sentences and phrases.
Another type of motor aphasia called transcortical motor aphasia (TMA) is characterized by speech and comprehension difficulties similar to that of Broca's aphasia. Individuals with TMA, however, retain the ability to repeat phrases or lists of words while those with Broca's aphasia tend not to. TMA is usually caused by a stroke.
In some cases of severe brain injury, global aphasia may occur. Global aphasia is characterized by a nearly-complete loss of ability to comprehend or to produce written or spoken language. Other mental skills, such as mathematical reason and non-linguistic social comprehension, tend to remain intact in individuals with global aphasia, indicating that the "language centers" of the brain are distinct from other reasoning areas of the brain.
Many different options are available for the treatment of motor aphasia. One particularly popular form of treatment, called melodic intonation therapy, is based on the observation that individuals with aphasias preventing them from speaking lines of text in conversation are often able to sing the same words or phrases. The aim of the therapy is to teach individuals with motor aphasia to comprehend and produce language based on its melodic qualities. The parts of the brain responsible for music and melody are, in essence, substituted for the damaged language centers.