Rinne test is used to evaluate the loss of hearing in one ear. It is helpful in comparing the perception of sound transmitted by air conduction to those transmitted through bone conduction through the mastoid process. Simply we can say the Rinne test is used to differentiate conductive deafness from neural ie non-conductive deafness.
Requirements for Rinne’s Test:
- You need a tuning fork having a frequency of about 512Hz.
- Note: Don’t use 128Hz or 256Hz tuning forks as these are used to assess vibration sensations in neural deafness examinations.
- The room where the test is performed must be reasonably quiet, otherwise, the test can not be performed.
The procedure of Rinne’s Test:
You must get consent from the patient about performing the test. Must explain the test before the performance, no documents are required for this verbal agreement by the patient is enough.
How to start a tuning fork vibration correctly:
- Firstly hold the flattened part of the shaft of tuning fork loosely between your thumb and first finger. By holding it too firmly can dampen the vibrations of the tuning fork.
- Strike the tuning fork against a firm surface which may be a table or anything else about a third of the way down the tines of the fork.
- The knee cap or a firm rubbery surface makes a good surface to be hit against these. Hitting against the very hard surface sometime may produce multiple harmonics and distort the frequency.
- Practice your technique for this, as a smooth, even reasonable duration and loudness is key factors in performing these clinical tests.
Procedure for Rinne test:
- The vibrating tuning fork is presented firstly with the tine of the external auditory meatus (i.e at the external ear or nearby it) for a few seconds and then the base is pressed firmly on the mastoid process (i.e a part of temporal bone) behind the ear.
- Then ask the patient which heard is louder.
- Hold the tuning fork in a range about 1-2cm from the ear with tines in a line with the ear canal ( not it must not be at right angles).
- When you are pressing the base firmly on one side of the head it is best to support the other side of the patient’s head with your other hand or by your assistant. Ensure you avoid the side of the spectacle of the arms.
- If you are not pressing reasonably firmly. Then you will only vibrate the soft tissues of the scalp of the head and not the bones of the skull.
Rinne Test Results:
The tuning fork should be heard louder when you presented at the external auditory meatus and this situation is normal. This patient is said to be Rinne positive on that side ( the ossicular chain is doing what it should do and acting as an amplifier which is its major function).
If the bone conduction through the mastoid process of the temporal bone is heard louder. Then that of the air then the patient is Rinne’s negative. Which always suggests about abnormality.
Rinne Negative Test:
- If the patient is Rinne negative (i.e abnormal) then this shows that something is preventing air to be transmitted through the external auditory canal, the eardrum or the oval window of the ear.
- Rinne’s Negative shows that bone conduction is better than air conduction ( it may be any side that is left side or maybe right).
Causes in the external auditory canal abnormalities:
- Presence of the wax in the external auditory canal.
- Infection in the outer auditory canal (i.e otitis externa).
- Presence of foreign bodies in the ear canal.
Causes due to the drum include:
- Perforation in the eardrum ( secondary to trauma or infections).
Read also about : Montelukast
Causes in the middle ear are:
- Infection in the middle ear ( i.e otitis media).
- Sometime Serous otitis media (i.e glue ear) caused. As the end result of repeated bouts of acute otitis media (i.e middle ear infection).
Causes at the oval window of the ear:
Otosclerosis, where there is a failure in the transmission of the sound from the stapes (i.e ossicle) through the oval window due to abnormal bone growth.
Cautions of Rinne Test:
A patient with profound sensorineural deafness may found as a false Rinne’s Negative.
The reasons being that with complete loss of innervation to that ear the patient should not be able to hear anything whether the tuning fork is presented to the external auditory canal or mastoid process of the temporal bone.
However, they may hear the sound being transmitted through the other skull bone to the remaining good ear on the other side. And they may not be able to recognize which ear they are hearing th sound in.
This may give the appearance of the bone conduction is being better. Than that of the air conduction when in fact the eas may be completely dead (damaged).
There is another test which helps in distinguishing between a true and a false Rinne negative test is to perform another test, known as Weber’s test.