A nurse is performing a cranial nerve assessment on a client following a head injury. Which of the following findings should the nurse expect if the client has impaired function of the vestibulocochlear nerve (cranial nerve VIII)?
A.
Disequilibrium with movement
B.
Deviation of the tongue from midline
C.
Loss of peripheral vision
D.
mobility to smell
The Correct Answer and Explanation is:
The correct answer is A. Disequilibrium with movement.
The vestibulocochlear nerve, also known as cranial nerve VIII, is responsible for transmitting sound and equilibrium (balance) information from the inner ear to the brain. It has two main branches: the cochlear nerve, which deals with hearing, and the vestibular nerve, which deals with balance. Impairment of the vestibulocochlear nerve can result in a variety of symptoms related to hearing and balance.
Explanation:
- Disequilibrium with movement: This is the most relevant symptom associated with vestibulocochlear nerve impairment. The vestibular portion of cranial nerve VIII is responsible for maintaining balance by transmitting sensory information from the inner ear’s semicircular canals and vestibules to the brain. These structures detect changes in head position and movement, helping the body maintain its sense of equilibrium. If this nerve is damaged, the client may experience dizziness, vertigo, or a sense of disequilibrium (a feeling of unsteadiness or imbalance), especially when moving.
- Deviation of the tongue from midline: This symptom is linked to damage to the hypoglossal nerve (cranial nerve XII), which controls the muscles of the tongue. When the hypoglossal nerve is damaged, the tongue deviates toward the injured side. Since this has no connection to hearing or balance, it is not related to vestibulocochlear nerve function.
- Loss of peripheral vision: This is associated with damage to the optic nerve (cranial nerve II) or the visual pathways in the brain. The optic nerve is responsible for transmitting visual information from the eyes to the brain, and its impairment affects vision, not hearing or balance.
- Inability to smell: This symptom is associated with damage to the olfactory nerve (cranial nerve I), which is responsible for the sense of smell. Cranial nerve VIII, the vestibulocochlear nerve, is unrelated to the sense of smell.
In conclusion, damage to the vestibulocochlear nerve primarily affects balance and hearing, with disequilibrium being a hallmark symptom. Therefore, A is the correct answer.