Condition · Neural

Facial Nerve Palsy

Efferent-limb lesion — reflex absent on the probe side, lesion-dependent

The efferent limb and the stapedial branch

The stapedius is innervated by the stapedial branch of the facial nerve. A facial nerve lesion proximal to (above) the take-off of this branch abolishes the reflex on that side; a lesion distal to it leaves the reflex intact.

Probe-side dependence

An efferent-limb lesion abolishes the reflex recorded from the affected ear in both ipsilateral and contralateral conditions, because the muscle on that side cannot contract regardless of which ear is stimulated.

The reflex signature

Stim. Right
Stim. Left
Probe Right
Absent
Absent
Probe Left
Present
95 dB HL
Present
90 dB HL
The characteristic four-cell grid for this condition.

Absent responses fill the affected-probe-ear column; the lesion lies proximal to the stapedial branch on that side.

Reflex decay

0s2s4s6s8s10s0%50%100%50% criterion
Negative (normal) decay — amplitude is well maintained across the 10-second hold. Where the lesion is proximal to the stapedial branch, no reflex is recordable on the affected side, so decay cannot be assessed.

Pure-tone audiogram

0204060801002505001k2k4k8kFrequency (Hz)Hearing level (dB HL)
○ Right ear✕ Left ear
Hearing is typically normal — facial palsy does not affect the auditory pathway itself.

Frequencies plotted: 250, 500, 1k, 2k, 4k, 8k Hz.

References for this page

  1. Hall JW (2014). Introduction to Audiology Today. Pearson, Boston.
  2. Katz J (Ed.) (2015). Handbook of Clinical Audiology (7th ed.). Wolters Kluwer, Philadelphia.
  3. Musiek FE, Baran JA (2007). The Auditory System: Anatomy, Physiology and Clinical Correlates. Pearson, Allyn & Bacon, Boston.
Want to contrast this with another condition? The comparison tool places any two reflex signatures side by side.