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Comparing Mechanical Effects and Sound Production of KTP, Thulium, and CO2 Laser in Stapedotomy

Kamalski, Digna M. A.*†; Verdaasdonk, Rudolf M.; de Boorder, Tjeerd§; Vincent, Robert; Versnel, Huib*†; Grolman, Wilko*†

doi: 10.1097/MAO.0000000000000465
Otosclerosis

Hypothesis: The mechanical and acoustic effects that occur during laser-assisted stapedotomy differ among KTP, CO2, and thulium lasers.

Background: Making a fenestration in stapedotomy with a laser minimizes the risk of a floating footplate caused by mechanical forces. Theoretically, the lasers used in stapedotomy could inflict mechanical trauma because of absorption in the perilymph, causing vaporization bubbles. These bubbles can generate a shock wave, when imploding.

Methods: In an inner ear model, we made a fenestration in a fresh human stapes with KTP, CO2, and thulium laser. During the fenestration, we performed high-speed imaging from different angles to capture mechanical effects. The sounds produced by the fenestration were recorded simultaneously with a hydrophone; these recordings were compared with acoustics produced by a conventional microburr fenestration.

Results: KTP laser fenestration showed little mechanical effects, with minimal sound production. With CO2 laser, miniscule bubbles arose in the vestibule; imploding of these bubbles corresponded to the acoustics. Thulium laser fenestration showed large bubbles in the vestibule, with a larger sound production than the other two lasers. Each type of laser generated significantly less noise than the microburr. The microburr maximally reached 95 ± 7 dB(A), compared with 49 ± 8 dB(A) for KTP, 68 ± 4 dB(A) for CO2, and 83 ± 6 dB(A) for thulium.

Conclusion: Mechanical and acoustic effects differ among lasers used for stapedotomy. Based on their relatively small effects, KTP and CO2 lasers are preferable to thulium laser.

*Department of Otorhinolaryngology and Head & Neck Surgery, †Brain Center Rudolf Magnus, University Medical Center Utrecht; ‡Department of Physics and Medical Technology, VU University Medical Center Amsterdam; §Department of Medical Technology and Clinical Physics, University Medical Center Utrecht, The Netherlands; and ∥Jean Causse Ear Clinic, Transverse de Béziers, Colombiers, France

Address correspondence and reprint requests to Digna M. A. Kamalski, M.D., Department of Otorhinolaryngology, University Medical Center Utrecht: Heidelberglaan 100, G05.1293584 CX Utrecht, The Netherlands; E-mail: ent-research@umcutrecht.nl

Some of the laser equipment used for this study was provided by Omniguide, Cambridge, MA, USA.

The authors disclose no conflicts of interest.

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