Medicine – Vestibulocochlear Nerve (Cranial Nerve VIII): Rinne’s and Weber’s Tests

The vestibulocochlear nerve, cranial nerve VIII, has two main components:

Cochlear division → hearing.

Vestibular division → balance.

Bedside assessment of hearing commonly includes Rinne’s test and Weber’s test, both performed with a tuning fork, typically 512 Hz.

1. Rinne’s Test

Rinne’s test compares air conduction (AC) with bone conduction (BC) in each ear separately.

Normally, sound is transmitted more efficiently through the external auditory canal and middle ear than through direct vibration of the skull.

Therefore, in a normal ear:

Air conduction > bone conduction.

This is called Rinne positive.

2. Normal Rinne Test

In a normal ear:

AC > BC.

The patient hears the tuning fork longer or louder when it is held beside the ear than when it is placed on the mastoid process.

This is a normal finding.

3. Sensorineural Deafness and Rinne’s Test

In sensorineural hearing loss, both air and bone conduction are reduced because the cochlea or auditory nerve is impaired.

However, the normal relationship between the two pathways remains:

AC > BC.

Therefore, Rinne remains positive.

So:

Normal ear → Rinne positive.

Sensorineural deafness → Rinne positive.

The difference is that overall hearing is reduced in sensorineural loss.

4. Conductive Deafness and Rinne’s Test

In conductive hearing loss, sound transmission through the external or middle ear is impaired.

Bone conduction bypasses these structures and may therefore be heard better than air conduction.

Thus:

BC > AC.

This is called Rinne negative.

Therefore:

Conductive hearing loss → Rinne negative.

5. Rinne Test – Quick Note Form

Normal: AC > BC → Rinne positive.

Sensorineural hearing loss: AC > BC → Rinne positive, but hearing is reduced overall.

Conductive hearing loss: BC > AC → Rinne negative.

6. Weber’s Test

Weber’s test compares how sound is perceived between the two ears.

A vibrating tuning fork is placed in the midline, usually on the forehead or vertex of the skull.

The patient is asked whether the sound is heard:

Equally in both ears.

or

Louder in one ear.

7. Normal Weber Test

In a person with normal hearing, the sound is heard equally in both ears.

This is described as:

Weber does not lateralise.

8. Conductive Hearing Loss and Weber’s Test

In unilateral conductive hearing loss, Weber’s test lateralises to the affected ear.

So:

Conductive deafness → sound louder in the abnormal ear.

This may seem counterintuitive, but external environmental sounds are reduced in that ear, so bone-conducted sound is perceived relatively more strongly.

9. Sensorineural Hearing Loss and Weber’s Test

In unilateral sensorineural hearing loss, Weber’s test lateralises to the normal or better-hearing ear.

So:

Sensorineural deafness → sound louder in the opposite ear.

The affected cochlea or auditory nerve cannot perceive the bone-conducted vibration normally.

10. Meaning of Weber Lateralisation

If Weber’s test is heard louder on the right side, there are two main possibilities:

Right conductive hearing loss.

or

Left sensorineural hearing loss.

Similarly, if the sound is louder on the left:

Left conductive hearing loss.

or

Right sensorineural hearing loss.

This is why Weber should be interpreted together with Rinne’s test.

11. Combining Rinne and Weber

A useful bedside approach is to use both tests together.

If Weber lateralises to the right and Rinne is negative on the right:

Right conductive hearing loss.

If Weber lateralises to the right and Rinne remains positive on both sides:

Left sensorineural hearing loss is more likely.

12. Conductive Hearing Loss – Typical Pattern

In unilateral conductive hearing loss:

Rinne on affected side → negative, BC > AC.

Weber → lateralises to affected side.

Example:

Right conductive deafness → right Rinne negative + Weber louder on right.

13. Sensorineural Hearing Loss – Typical Pattern

In unilateral sensorineural hearing loss:

Rinne → positive on both sides, AC > BC.

Weber → lateralises to the better-hearing ear.

Example:

Right sensorineural deafness → Rinne positive bilaterally + Weber louder on left.

14. Important Limitation of Rinne’s Test

In very severe unilateral sensorineural deafness, a false-negative Rinne test may occasionally occur.

This happens because bone-conducted vibration placed on the mastoid of the deaf ear may cross the skull and be heard by the opposite normal cochlea.

Therefore, bedside tuning-fork tests are useful screening tools but do not replace formal audiometry when significant hearing loss is suspected.

15. Vestibulocochlear Nerve – Note Form

Cranial nerve VIII: vestibulocochlear nerve.

Cochlear division: hearing.

Vestibular division: balance.

Rinne test: compares air conduction with bone conduction.

Normal Rinne: AC > BC.

Sensorineural loss: AC > BC, so Rinne remains positive.

Conductive loss: BC > AC, so Rinne is negative.

Weber test: tuning fork placed in middle of forehead or vertex.

Normal Weber: sound heard equally on both sides.

Conductive loss: Weber lateralises to the affected ear.

Sensorineural loss: Weber lateralises to the normal/better ear.

Key Clinical Pattern

Remember:

Rinne = compare AIR with BONE.

Weber = compare RIGHT with LEFT.

Normal:

Rinne positive (AC > BC)

Weber central

Conductive hearing loss:

Rinne negative on affected side (BC > AC)

Weber goes TO the affected ear

Sensorineural hearing loss:

Rinne positive (AC > BC)

Weber goes AWAY from the affected ear

Easy Memory Rule

Conductive → Weber goes TO the bad ear.

Sensorineural → Weber goes to the GOOD ear.