Weber and Rinne Tuning Fork tests for USMLE
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Conductive hearing loss includes the area from the external ear to the stapes.
Sensorineural hearing loss includes the cochlea and the cranial nerve eight. Using weber and rine tuning fork test you can determine whether the problem is conduction hearing loss or sensorineural hearing loss.
Air conduction occurs when the sounds waves go through the external ear to the cochlea and the senorineural area. Therefore air conduction tests conduction and sensorineural hearing loss.
Bone conduction the sound waves travel through the mastoid and bypasses the external ear and activates the cochlea directly. Therefore bone conduction only tests sensorineural.
Place tuning fork on mastoid until patient can no longer hear. Then place tuning fork next to external auditory meatus and see if the patient can continue to hear.
Normally air conduction is two times longer than bone conduction. If bone conduction is greater than air conduction then it is called a negative Rinne Test and there is a conduction hearing loss. If air conduction is greater than bone conduction then it is a positive rinne test then the patient is either normal or there is sensorineural hearing loss.
If there is severe damage to cochlea than there can be a false positive.
Strike tuning fork on the mideline of fore head.
Normally the sound will travel to both cochlea equally and the sound will be heard equally (no lateralization).
In sensorineural hearing loss the lateralization will go to the good ear. However, if there is conductive hearing loss the sound will lateralize to the bad ear.
ABSOLUTE BONE CONDUCTION (ABC)
Comparing patients bone conduction to the bone conduction of the examiner. Tragus must be occluded to rule out any air conduction. Place tuning fork on mastoid and ask when the patient can't hear any long and then place on yourself. If abnormal then there is a sensorineural hearing loss.
Same as absolute bone conduction test but ear is not occluded. If shorter then sensorineural hearing loss. But if it is longer than it is conductive hearing loss.