FRCS (ORL-HNS) · SECTION 1 SBA

Facial nerve localisation

A patient has complete unilateral lower-motor-neurone facial weakness, hyperacusis, loss of taste from the anterior tongue and reduced lacrimation. Where is the lesion most likely?

CHOOSE ONE ANSWER

Best of five

  1. A. At the stylomastoid foramen
  2. B. Within the parotid gland
  3. C. At the chorda tympani alone
  4. D. Proximal to the geniculate ganglion
  5. E. In the contralateral motor cortex
ANSWER AND REASONING

D. Proximal to the geniculate ganglion

Reduced lacrimation localises proximal to the greater superficial petrosal nerve; hyperacusis and taste loss also indicate involvement proximal to stapedius and chorda tympani branches.

Why every option is right or wrong

A. At the stylomastoid foramen: A distal lesion spares taste, stapedius and lacrimation.

B. Within the parotid gland: Parotid lesions affect motor branches after the nerve exits the skull.

C. At the chorda tympani alone: This would affect taste but not facial movement or lacrimation.

D. Proximal to the geniculate ganglion: Reduced lacrimation localises proximal to the greater superficial petrosal nerve; hyperacusis and taste loss also indicate involvement proximal to stapedius and chorda tympani branches.

E. In the contralateral motor cortex: An upper-motor-neurone lesion typically spares the forehead and does not cause this branch pattern.

What if the scenario changed?

If lacrimation were preserved but taste and stapedius function were lost, localisation would move distal to the geniculate ganglion but proximal to the nerve to stapedius.

EDUCATIONAL USE

Independent Clinora educational preparation material; not official JCIE content, an accredited programme, clinical advice, or a substitute for current guidance, local policy and specialist judgement.

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