Anomia or dysnomia is a deficit in naming or word-finding. This may be detected as abrupt cut-offs in spontaneous speech with circumlocutions and/or paraphasic substitutions. Formal tests of naming are also available (e.g., Graded Naming Test). Patients may be able to point to named objects despite being unable to name them, suggesting a problem in word retrieval but with preserved comprehension. They may also be able to say something about the objects they cannot name (e.g., "flies in the sky" for kite) suggesting preserved access to the semantic system.
Category-specific anomias have been described, e.g., for color (cf. achromatopsia). Anomia occurs with pathologies affecting the left temporoparietal area, but since it occurs in all varieties of aphasia is of little precise localizing or diagnostic value. The term anomic aphasia is reserved for unusual cases in which a naming problem overshadows all other deficits. Anomia may often be seen as a residual deficit following recovery from other types of aphasia. Anomia may occur as an early feature of Alzheimer’s disease, or with any dominant hemisphere space-occupying lesion.
Benson DF, Ardila A. Aphasia: a clinical perspective. New York: OUP, 1996: 252-261