Nominal aphasia (anomia) is a severe problem with recalling words or names. It is also known as:
Anomia is usually caused by brain trauma, such as an accident, stroke, or tumor. Dysnomia refers to a less severe form of this word-recall dysfunction. Learning disabilities caused by name-recall problems are usually diagnosed as Dysnomia rather than anomia, but a review of the literature shows significant confusion between the two terms.
Sometimes subjects may know what to do with an object, but still not be able to give a name to the object. A subject is shown an orange, and asked what it is called. The subject may be well aware that the object can be peeled and eaten, and may be able to demonstrate this by actions or even verbal responses. Whether such a subject could name the color of the orange is unknown. Responses may differ depending on whether objects are shown in the right or left hand side of the visual field.
Anomia is caused by damage to various parts of the parietal lobe or the temporal lobe of the brain. This type of phenomenon can be quite complex, and usually involves a breakdown in one or more pathways between regions in the brain.
"Averbia" is a specific type of anomia in which the subject has trouble remembering only verbs. This is caused by damage to the frontal cortex, in or near Broca's area.