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Electrical promontory testing in differential diagnosis of sensori‐neural hearing impairment
Author(s) -
House William F.,
Brackmann Derald E.
Publication year - 1974
Publication title -
the laryngoscope
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.181
H-Index - 148
eISSN - 1531-4995
pISSN - 0023-852X
DOI - 10.1288/00005537-197412000-00007
Subject(s) - promontory , audiology , electrocochleography , hearing loss , sensation , auditory system , sensory system , auditory neuropathy , auditory cortex , medicine , neuroscience , psychology , archaeology , history
The possibility of rehabilitation of sensory deafness by a peripherally implantable prosthesis makes it very important to differentiate sensory from neural hearing impairment. We do this by a technique which we call electrical promontory testing, which includes measuring the electrical potentials generated in the auditory system and stimulating the inner ear electrically. Types of Sensori‐Neural Hearing Impairment. There are four or more types of sensori‐neural hearing impairment which in the past have collectively been termed sensori‐neural. They are: 1. sensory loss — deficiency in the hair cells; 2. neural loss — auditory nerve deficit; 3. brain stem loss — nuclear deficiency; and 4. central loss — auditory cortex defect. Method of Testing. Recording of the potentials evoked in the auditory system by the techniques of electrocochleography, brain stem audiometry and cortical evoked response audiometry is an important objective means of study of the auditory system. Characteristics of the potentials obtained such as wave form, latency, and amplitude help greatly in classifying types of partial hearing loss. In severe hearing loss no potentials are obtained from the auditory system. In these cases, a low‐voltage, low‐frequency electrical current is applied to the promontory. If the patient perceives an auditory sensation as a result of this stimulation, we believe that this demonstrates the presence of auditory neurons and the loss is classified as sensory. If an auditory sensation is not evoked, the deafness is classified as a neural or more central loss.