Cranial Nerve VIII
Auditory Nerve
There are two components: auditory and vestibular.
AUDITORY
WHAT TO DO
Test the hearing
Test one ear at a time. Block the opposite ear; either cover it with your hand or produce a blocking white noise, e.g. crumpling paper.
Hold your watch by the patient’s ear. Discover how far away from the ear it is still heard. Alternative sounds are whispering or rubbing your fingers together. Increase in volume to normal speech or loud speech until your patient hears.
If the hearing in one ear is reduced, perform Rinne’s and Weber’s tests.
Rinne’s test
WHAT YOU FIND
| Rinne test in deaf ear | Weber test | |
| Conductive deafness | BC > AC | Deaf ear |
| Sensorineural deafness | AC > BC | Good ear |
N.B. With complete sensorineural deafness in one ear, bone conduction from the other ear will be better than air conduction.
WHAT IT MEANS
– Lesion of the cochlea (common): otosclerosis, Ménière’s disease, drug- or noise-induced damage.
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