Normative data of incus and stapes displacement during middle ear surgery using laser Doppler vibrometry.

OBJECTIVES

To report normative data for incus and stapes motion using laser Doppler vibrometry (LDV) during middle ear surgery and to discuss possible limitations of the procedure.

STUDY DESIGN

Institutional review board-approved, retrospective study of data from patients undergoing the Envoy Esteem implantable device at 3 institutions.

SETTING

Quaternary referral health system.

ELIGIBILITY CRITERIA

patients sucsessfully implanted with an Esteem device.

METHODS

Data from 70 patients undergoing the Envoy Esteem procedure were reviewed. Sound at 100 dB and 50 frequencies ranging from 125 to 8,000 Hz were used during the procedure. LDV was performed to measure the displacment of the body of the incus and the posterior crus of the stapes to assess whether there was sufficient ossicular mobility to allow for implantation.

RESULTS

The average displacement of the ossicles for all 70 patients was collected and analyzed. The trend was an average displacement around 100 nm from 125 to 500 Hz for both the incus and stapes with a linear decline starting at 1,000 Hz for the incus and 500 Hz for the stapes, with slightly greater displacement of the stapes at higher frequencies.

CONCLUSION

This is the first article to report in vivo measures of ossicular mobility. These data help to understand the micromechanics of ossicular motion as well as the use and limitations of LDV. This information may lead to a prescreening process for implanted middle ear devices that function by overdriving the stapes.