A patient with an acute right lower motor neuron facial palsy has loss of taste over the anterior two-thirds of the tongue and hyperacusis on the right, but tear secretion is normal. The lesion is localized:

• A Proximal to the geniculate ganglion
• B Distal to the geniculate ganglion but proximal to the origin of the chorda tympani ✓
• C Distal to the stylomastoid foramen
• D At the internal acoustic meatus

Explanation

Normal lacrimation means the greater petrosal nerve, given off at the geniculate ganglion, is intact, excluding lesions at or proximal to the geniculate ganglion. Loss of taste and hyperacusis mean the chorda tympani and the nerve to stapedius, both arising in the mastoid segment, are affected. The lesion therefore sits in the facial canal between the geniculate ganglion and the origin of these branches. A lesion distal to the stylomastoid foramen would spare taste, hearing, and lacrimation entirely.

Reference: Gray's Anatomy, 42nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.