Cortical deafness is a rare form of sensorineural hearing loss caused by damage to the primary auditory cortex. Cortical deafness is an auditory disorder where the patient is unable to hear sounds but has no apparent damage to the anatomy of the ear (see  auditory system), which can be thought of as the combination of auditory verbal agnosia and auditory agnosia. Patients with cortical deafness cannot hear any sounds, that is, they are not aware of sounds including non-speech, voices, and speech sounds. Although patients appear and feel completely deaf, they can still exhibit some reflex responses such as turning their head towards a loud sound. Cause
Cortical deafness is caused by bilateral cortical lesions in the primary auditory cortex located in the temporal lobes of the brain. The ascending auditory pathways are damaged, causing a loss of perception of sound. Inner ear functions, however, remains intact. Cortical deafness is most often caused by stroke, but can also result from brain injury or birth defects. More specifically, a common cause is bilateral embolic stroke to the area of Heschls gyri. Cortical deafness is extremely rare, with only twelve reported cases. Each case has a distinct context and different rates of recovery. 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 function, resulting in partial auditory deficits such as auditory verbal agnosia.
The following are three case studies with different reasons for cortical deafness. A case published in 2001 describes the patient as 20-year-old man referred for cochlear implants because of bilateral deafness following a motorcycle accident two years earlier. His CT shows hemorrhagic lesions involving both internal capsules. He was comatose for several weeks and awoke quadriparetic, cognitively impaired and completely deaf. He exhibited a response towards the occasional sudden, loud sound, however, by turning his head. Reading and writing capabilities were maintained, and he was able to communicate by lip-reading. His own speech was dysarthric, but comprehensible. Normal tympanograms and stapedial reflexes imply that the middle and inner ear remained functioning and the auditory nerve was intact. His auditory nerve was tested by evoking responses with normal auditory nerve potentials at 10 dB bilaterally. The results of the BAER waves were normal, but an abnormal complex IV-V suggested that the pathways were functioning through the brainstem, but there was a lesion present in the mid-brain. With these findings, it was determined the patient had cortical deafness due to bilateral interruption of the ascending auditory pathway associated with hemorrhagic lesions of both internal capsules. Therefore, cochlear implantation was not performed. Published in 1994, this patient was monitored over the course of almost 20 years after exhibiting signs of hearing impairment as an infant. Audiologic and related test results in concurrence with MRI confirmed bilateral absence of considerable portions of her temporal lobes resulting in cortical deafness.