title: Penetration of CO2 laser into the otic capsule using a hand-held, flexible-fiber delivery system.
abstract: OBJECTIVE
  Recently, a new, flexible-fiber, CO2 laser delivery system has been FDA-cleared for clinical use. However, for otologic surgery, no data have been reported correlating power settings to depth of penetration into the otic capsule-the bone that covers the inner ear. This was the goal of our study.
  
  
  METHODS
  Eight cadaveric temporal bones were procured as per our institution's protocols. For each specimen, nine different laser holes were burned into the otic capsule using the flexible-fiber CO2 laser delivery system. Power settings were varied from 10 to 20 W in 2 W increments, and duration of exposure was 100, 200, 300, 400, or 600 milliseconds. Each setting (power and duration) was tested on two specimens. Following laser exposure, each specimen was scanned in a microCT scanner, and the depth of penetration measured from these images.
  
  
  RESULTS
  Of the 72 laser shots, 8 were excluded due to double hits (4), oblique hits (3), or complete penetration (1). After excluding these 8, bone penetration was found to vary from 160 to 670 microm based on power and time settings. Spearman analysis on ranked data showed that time had a greater impact on depth than power. The correlation coefficients for time and power were 0.84 (P = 0.013) and 0.40 (P<0.001), respectively.
  
  
  CONCLUSIONS
  The flexible-fiber CO2 laser is effective for otic capsule ablation in this model. High power setting and long pulse duration can lead to complete penetration of the otic capsule potentially causing damage of underlying structures such as the facial nerve, horizontal semicircular canal, and cochlea.
authors.affiliation: Department of Otolaryngology, Medical University of Hannover, Hannover 30659, Germany.
authors.forename: Omid
authors.initials: O
authors.lastname: Majdani
authors.forename: Justin
authors.initials: J
authors.lastname: Wittkopf
authors.forename: Mary S
authors.initials: MS
authors.lastname: Dietrich
authors.forename: Robert F
authors.initials: RF
authors.lastname: Labadie
mesh_terms: D002102:Cadaver; D007758:Ear, Inner / Q000601:surgery*; D004867:Equipment Design; D004869:Equipment Safety; D005260:Female; D005336:Fiber Optic Technology; D006801:Humans; D053685:Laser Therapy / Q000379:methods*; D054020:Lasers, Gas / Q000627:therapeutic use*; D008297:Male; D013506:Otologic Surgical Procedures / Q000295:instrumentation / Q000379:methods; D013701:Temporal Bone / Q000601:surgery*