Nominal aphasia is a type of aphasia, or acquired language impairment, characterized by a severe difficulty recalling names or words. The condition is also sometimes called anomic, amnesic, or amnestic aphasia, or anomia. It is usually caused by brain trauma, such as a head injury, brain tumor, or stroke. A less severe difficulty recalling names or words is called dysnomia.
This form of aphasia is caused by damage to either the parietal lobe or the temporal lobe of the brain. The parietal lobe is responsible for integrating sensory information, while the temporal lobe is responsible for processing auditory information, as well as semantics in speech and vision. The damage involves a breakdown in the neural pathways within the brain.
Patients with nominal aphasia may use circumlocution, a roundabout way of speaking, to describe things that they cannot remember the word for. They typically recognize objects, and know what they are for or how to use them, even when they cannot recall their name. For example, a nominal aphasic may refer to scissors as "a tool used to cut paper or hair."
Those who have this form of aphasia typically understand what words refer to in other people's speech, even though they cannot remember them themselves. Hesitation when speaking, and displays of frustration are also common. The condition is not associated with any loss of intelligence or memory, besides the memory of words, and people who have this problem can usually perform non-speech-related tasks, like driving a car, as well as healthy people.
Nominal aphasia sometimes affects only one portion of a patient's ability to recall words and names. For example, the patient may only have difficulty recalling the names of objects on the right side of the visual field, but not the left, or vice versa. Some people have difficulty recalling content words, like the names of objects, while others have difficulty only with functional words like "in" and "the." Some patients have more trouble recalling proper names than they do with other nouns, or show equal difficulty recalling both. Some nominal aphasics are able to distinguish between colors, but cannot remember their names; this condition is called color anomia.
Another type of nominal aphasia is caused by damage to Broca's area in the frontal cortex of the brain. Broca's area is linked to speech production, but not to speech comprehension. If Broca's area is damaged, one type of aphasia that can result is called averbia. Averbia is characterized by a difficulty recalling only verbs, but not other types of speech.