Cortical deafness is caused by bilateral cortical lesions in the primary auditory cortex located in the temporal lobes of the brain. In most instances, the cause is bilateral embolic stroke to the area of Heschl's gyri. Cortical deafness is extremely rare, with only twelve reported cases.
Patients with cortical deafness cannot hear any sounds, that is, they are not aware of sounds including non-speech, voices, and speech sounds.
It is thought that cortical deafness could be a part of a spectrum of an overall cortical hearing disorder. In some cases, patients with cortical deafness have had recovery of some hearing functions, resulting in partial auditory deficits such as auditory verbal agnosia. Auditory verbal agnosia is the inability to recognize speech while hearing remains intact. This syndrome might be difficult to distinguish from a bilateral temporal lesion such as described above.
^ abIngram, John Henry (2007). Neurolinguistics: an introduction to spoken language processing and its disorders. Cambridge, UK: Cambridge University Press. pp. 160–171. ISBN0-521-79190-1. OCLC297335127.