Central Hearing Loss Causes And Symptoms

What is Central Hearing Loss?

Central hearing loss is a rare form of hearing impairment resulting from damage to the auditory nerve or the brain pathways leading to it, as well as lesions on the brainstem. Patients with this type of condition are often misdiagnosed due to inconsistent auditory behavior, whereby patients may react to environmental sounds, but show no reaction to sudden loud sounds.

Causes:

• Bilateral brainstem lesions (tumors)


• Damage to brainstem structures


• Right sided temporal lesions


• Head trauma

Brainstem Injuries: Although lesions of the brainstem are a rare factor of central hearing loss, a lesion must be present on both sides of the brainstem in order for central deafness to occur. It must also be noted that severe head trauma can result in central hearing loss.

Symptoms:

• Word Deafness: Patients have no problem speaking, but do have difficulty with word comprehension


• Auditory hallucinations leading to a misdiagnosis of psychological problems such as schizophrenia


• Inability to recognize nonword stimuli such as a telephone ringing (auditory agnosia) or music (amusia)


• Sudden hearing loss

Persons afflicted with this condition often consider themselves to be deaf even while having reactions to sounds in their environment.

Diagnosis:

These patients have normal pure tone ability, therefore, pure tone audiogram alone will not identify the problem. To correctly diagnose central hearing loss, a combination of of pure tone audiogram and Comprehensive Aphasia Test (CAT), consisting of a cognitive screen, a language battery, and a disability questionnaire.

Treatment:

Central hearing loss is not helped by medication or surgery, rather the focus is on preventing progression of the disease.

When compared to conductive and senorineural hearing loss, central hearing loss is very rare, and involves damage to the nerves of hearing. It is not easily diagnosed and most often is misdiagnosed as a psychological disturbance, when in fact the person is suffering from central hearing loss.

Cortical Deafness: Is a combination of word deafness and auditory agnosia. The person is unable inability to comprehend verbal or nonverbal sounds such as the startle reaction to a clap, and is the result of bilateral lesions to the brainstem. The initial symptom of sudden deafness, that progress to the person being able to hear sound but can not recognize their meaning. Cortical deafness is the result of a lesion in the cerebral cortex.

Auditory hallucinations are most often found in schizophrenia, but can actually be due to brain damage. This most often due to an injury to the superior temporal auditory association areas. Stimulation of this area provokes an auditory sensation that seems real to patients. Auditory hallucinations can also be due to temporal lobe seizures, and occasionally due to damage to brainstem structures, such as the auditory cortex.

If you or anyone you know has been diagnosed with a psychological disturbance such as schizophrenia, there is a slight chance that the real problem is central hearing loss or nerve damage. Specific testing may be able to bring a misdiagnosis to a correct diagnosis.

by Barb Hicks, RN/LMT