Dec 02 2011

Deciphering the Weber and Rinne Tuning Fork Tests

The Weber and Rinne tests have been known to show up on boards, and are notoriously confusing and hard to remember. This post addresses what the tests are and how to perform them, interpret them, and remember them.

The Weber and Rinne tests are more than just a way to evaluate the Vestibulocochlear nerve (cranial nerve VIII). They are screening tests to determine the presence of hearing loss. They are performed using tuning forks at the frequencies of 512- and 1024-Hz. Tuning forks with these different frequencies are utilized so that both low (512-Hz) and high (1024-Hz) frequency hearing loss may be revealed. The Weber test is able to test for and distinguish between conductive hearing loss (CHL) and sensorineural hearing loss (SNHL), while the Rinne test assesses for the presence of CHL only.

The Weber test is executed by hitting the tuning fork and then holding it in the middle of the patient’s forehead. If the patient is unable to hear the tuning fork in this position, it can also be placed on the nasal bone or in the middle of the front two teeth. The patient is then asked to determine where the sound is heard the best. A normal result is when the sound is the same in both ears. If the sound is louder in one ear, it is indicative of conductive hearing loss (CHL) in that ear or sensorineural hearing loss (SNHL) in the opposite ear. The reverse is also true. If the sound is quieter in one ear, it is indicative of SNHL in that ear or CHL in the opposite ear.

At first glance, the results of the Weber test seem opposite to what you would normally think. However, the key to understanding it is realizing that the tuning fork is measuring how well the sound conducts through the bone (termed bone conduction), and the patient reports how well this sound is heard. Additionally, outside sound is still being conducted through the air (termed air conduction) to the patient’s ear (if no CHL is present). The bone conduction is a measure of SNHL, while the air conduction is a measure of CHL.

If bone conduction is intact on both sides (therefore no SNHL), the patient will report a louder sound in the ear with CHL. This is because the ear with the CHL is only receiving input from the bone conduction and no air conduction, and the sound is perceived as louder in that ear.

If air conduction is intact on both sides (therefore no CHL), the patient will report a quieter sound in the ear with the SNHL. This is because the ear with the SNHL is not receiving input from the bone conduction, and the sound is perceived as louder in the normal ear.

The Rinne test (pronounced like the name Renée) is executed by hitting the tuning fork and then holding it on the patient’s mastoid process. After the patient states the sound can no longer be heard, the tuning fork is then moved to just outside the external auditory meatus. If the sound is able to be heard again, it is a normal result. This is termed a positive test because the air conduction (AC) is greater than the bone conduction (BC). A negative test is when the sound cannot be heard again, and the BC > AC. If there is no air conduction, then CHL must be present.

A mnemonic you can use to help you to not mix up the tests is to think of Rinne as a woman screaming right into your ear, and Weber as a level-headed man who doesn’t sway from the center. For the Rinne test, the normal result is a good “positive” result and is also in alphabetical order (AC > BC).

Reference:
Beasley, Donald J., and Ronald G. Amedee. “Hearing Loss.” Expert Guide to Otolaryngology. By Karen H. Calhoun, Mark K. Wax, and David E. Eibling. Philadelphia, PA: American College of Physicians-American Society of Internal Medicine, 2001. 59. Print. ACP Expert Guide Series.

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