Condition · Outer / middle ear

Ossicular Discontinuity

Disconnected ossicular chain — reflex absent, often a hypermobile tympanogram

A broken chain cannot transmit the reflex

Ossicular discontinuity — for example a disrupted incudostapedial joint — decouples the stapedius from the rest of the chain. The contraction cannot stiffen the system the probe is monitoring, so no reflex is recorded on that side.

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.

A probe-ear column of absent responses, accompanied by a hypermobile tympanogram on the affected side.

Reflex decay

0s2s4s6s8s10s0%50%100%50% criterion
Negative (normal) decay — amplitude is well maintained across the 10-second hold. Not assessable on the affected side.

Pure-tone audiogram

0204060801002505001k2k4k8kFrequency (Hz)Hearing level (dB HL)
○ Right ear✕ Left ear
Right ear: large conductive loss, often with a wide air–bone gap exceeding the loss seen in otosclerosis.

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

References for this page

  1. Wilson RH, Margolis RH (1984). Acoustic-reflex measurements. In: Hearing Assessment (Rintelmann WF, Ed.), University Park Press.
  2. Hall JW (2014). Introduction to Audiology Today. Pearson, Boston.
  3. Katz J (Ed.) (2015). Handbook of Clinical Audiology (7th ed.). Wolters Kluwer, Philadelphia.
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