Condition · Outer / middle ear

Otosclerosis

Stapes fixation — reflex absent on the probe side from the start

What is happening

Fenestral otosclerosis fixes the stapes footplate, raising ossicular stiffness and producing a low-frequency conductive hearing loss with an air–bone gap. Because the reflex is measured as a change in admittance, a fixed footplate abolishes the recordable response on the probe side regardless of which ear is stimulated.

Why the probe ear matters

Because the recorded response depends on the mechanics of the probe ear, a conductive lesion in the probe ear blocks measurement of an otherwise intact reflex arc. This is a measurement artefact, not a neural failure.

The reflex signature

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

Reflexes are absent for both conditions recorded with the probe in the affected ear, and present for both conditions recorded with the probe in the healthy ear — a vertical 'probe-ear' pattern.

Reflex decay

0s2s4s6s8s10s0%50%100%50% criterion
Negative (normal) decay — amplitude is well maintained across the 10-second hold. Decay testing is usually not interpretable because a reflex cannot be recorded on the affected side.

Pure-tone audiogram

0204060801002505001k2k4k8kFrequency (Hz)Hearing level (dB HL)
○ Right ear✕ Left ear
Right ear: low-frequency conductive loss with an air–bone gap and a Carhart notch around 2 kHz. Left ear normal.

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. Wilson RH, Margolis RH (1984). Acoustic-reflex measurements. In: Hearing Assessment (Rintelmann WF, Ed.), University Park Press.
Want to contrast this with another condition? The comparison tool places any two reflex signatures side by side.