A patient presents with right-sided lower motor neurone facial palsy, loss of taste over the anterior two-thirds of tongue, and hyperacusis. There is no evidence of vesicular eruption. The lesion is most likely located:

• A At the internal acoustic meatus
• B Between the geniculate ganglion and the nerve to stapedius ✓
• C Proximal to the geniculate ganglion
• D Between the nerve to stapedius and the chorda tympani

Explanation

The facial nerve's descending branch order in the mastoid (Fallopian canal) is: greater petrosal nerve at the geniculate ganglion → nerve to stapedius → chorda tympani → main trunk exits stylomastoid foramen. Loss of taste (chorda tympani, still intact below the lesion) AND hyperacusis (stapedial branch affected) localises the lesion between the geniculate ganglion and the nerve to stapedius, i.e., in the tympanic/horizontal segment, before the stapedius branch.

Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.