A patient with an acoustic neuroma (vestibular schwannoma) pressing in the cerebellopontine angle develops hoarseness, ipsilateral loss of the gag reflex, and ipsilateral vocal cord palsy. Which cranial nerve is MOST likely affected by direct extension of the tumour?

• A Glossopharyngeal nerve (CN IX)
• B Hypoglossal nerve (CN XII)
• C Vagus nerve (CN X) ✓
• D Spinal accessory nerve (CN XI)

Explanation

The vagus nerve (CN X) exits the skull via the jugular foramen and is susceptible to compression by lesions in the cerebellopontine angle or at the jugular foramen. Its branches supply the pharynx (gag reflex via pharyngeal plexus) and the larynx (via recurrent laryngeal nerve, causing vocal cord palsy and hoarseness). CN IX contributes to the afferent limb of the gag reflex but its isolated loss does not produce hoarseness. CN XI and XII would produce trapezius/sternomastoid weakness and tongue deviation respectively.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.