Which cranial nerve is affected by vertigo in syringobulbia?

In the context of syringobulbia, the correct answer is the vestibulocochlear nerve. Syringobulbia is characterized by the formation of a cystic expansion (syrinx) within the bulb (medulla oblongata) of the brainstem, which can impact various cranial nerves.

The vestibulocochlear nerve, responsible for both hearing and balance, plays a crucial role in the vestibular system, and its involvement is often linked to the sensation of vertigo. When the syrinx compresses or damages the pathways associated with the vestibulocochlear nerve, it can disrupt the transmission of balance-related information from the inner ear to the brain, leading to sensations of dizziness or vertigo.

In contrast, the vagus nerve primarily oversees autonomic functions like heart rate and digestion and does not directly relate to balance or vertigo. The optic nerve is responsible for vision and does not have a role in balance, while the hypoglossal nerve controls tongue movements and is also unrelated to vestibular function. Thus, the vestibulocochlear nerve's association with vertigo in syringobulbia is well-established due to its central role in the balance system.