CN VIII – Vestibulocochlear Nerves

Testing can begin with the client sitting on the exam table. Before testing the vestibulocochlear nerves, ask the client about any history of impaired hearing and use of hearing devices. If the client has a hearing aid, they should keep it on.

1. General ability: Begin by noting the client’s general ability to hear you throughout your ongoing assessment process. For example, have you noticed any difficulties in hearing as manifested by leaning forward, lip reading, or consistently asking you to repeat what you say?

2. Finger/thumb rub test: this test helps evaluate the cochlear nerve. Ask the client to look straight forward and place their index finger on the tragus of the right ear and push the tragus in and move in a circular motion until you ask the client to stop. It may be simplest to demonstrate this for them. Ask them to close their eyes so you are specifically testing hearing and not their ability to see your hand moving. Then, place your hand in front of the opposite ear (left ear) and rub your fingers and thumbs together and ask them if they can hear it. Repeat on the other side. See Video 11.

• • Normally, the client should be able to hear this sound on both ears with a similar intensity.
  • Abnormal findings are when the client cannot hear the sounds or they sound different in intensity

Video 11: Finger/thumb rub test.

3. Whisper voice test: this test also helps evaluate the cochlear nerve. Tell the client that you are going to whisper a mixture of three numbers and letters and you want them to repeat what you say. Ask them to look straight forward and place their index finger on the tragus of the right ear and push the tragus in and move your finger over the tragus in a circular motion until you ask the client to stop. Stand on their left side (slightly behind them and about an arm’s length away) to test the left ear. Take a breath in, and as you breathe out, whisper a mixture of three numbers/letters (e.g., 8, E, 4). The client should repeat what you say. If they don’t, whisper another set of three numbers/letters (e.g., 2, K, 10). Repeat on the opposite ear with a different set of numbers/letters. See Video 12.

• • Normal findings are when the client can repeat what you say with both ears. If you need to repeat the set of numbers/letters on one ear (for a total of six), a normal finding is if the client is able to repeat at least half of the numbers/letters.
  • Abnormal findings are when the client is unable to repeat the set of numbers/letters on one or both ears or unable to repeat at least half of them if repeated twice.

Video 12: Whisper voice test.

4. Past pointing test: this test specifically focuses on the vestibular portion of the cochlear nerve. It evaluates the client’s proprioceptive sensation of the vestibular portion of the nerve, i.e., body’s awareness that helps an individual perceive their location and movement. Ask the client to place both arms straight out in front of them with palms down. You will then do the same, but with your palms up: allow the client’s hands to rest on yours and then ask them to raise their arms above their head, and then come back to the same position to touch your hands. Next, ask them to close their eyes and again raise their arms above their head, and then come back to the same position to touch your hands (repeating this twice). See Video 13.

• • Normal findings are when the client can raise their arms and then return to the same position to touch your hands with eyes closed (this is considered a negative past pointing test).
  • Abnormal findings are when the client is unable to return their hands to the same position to touch your hands with eyes closed. They might deviate to the side with one or both hands or overshoot your hands (this is considered a positive past pointing test).

Video 13: Past pointing test.

• Note the findings:
  • Normal findings might be documented as: “Cochlear nerve test: With whispered voice test, client able to hear and repeat numbers and letters in both ears, able to hear examiner rubbing fingers together beside both ears. Past pointing test: client able to raise arms above head and return and touch examiner’s hands with eyes closed.”
  • Abnormal findings might be documented as: “Client unable to hear and repeat numbers and letters whispered in left ear. Positive past pointing test.”