Is there a difference in the effect on the bone conduction threshold of two different techniques of penetrating the stapes footplate during otosclerosis surgery?
Background: Surgery for otosclerosis has changed little over the past 50 years. The addition of surgical lasers has allowed creation of a hole in the stapes footplate with less physical contact than with a surgical instrument such as a straight pick. A laser interaction with the footplate still involves a transfer of energy, however. Comparisons of surgical outcomes with or without the use of lasers have shown comparable results.
Study design: Retrospective review of 302 patients from a tertiary medical center. One hundred eighty patients underwent stapedectomy with the use of a CO2 laser, and 122 patients underwent stapedectomy using a manual technique of footplate perforation, with no randomization. Bone conduction thresholds were measured pre-operatively, then again on the first and fourth post-operative day, one month post-operatively and one year post-operatively.
Synopsis: Three hundred two patients had post-operative testing on the first and fourth post-operative days. There was a small but statistically significant decline in bone conduction thresholds at 0.5, 1, 2 and 4 kHz for both time points and for both techniques. Two hundred eighty patients had testing at the one-month post-operative stage. There was a return to the pre-operative bone conduction level at 0.5 and 1 kHz, but a persisting decline at 2 and 4 kHz. One hundred twenty-five patients had post-operative testing at one year. All frequencies tested showed that the bone conduction thresholds had returned to or surpassed pre-operative levels. Their data suggest a slightly greater “overclosure” of the bone conduction threshold for the patients undergoing laser penetration of the footplate at the one year post-operative evaluation. However, this outcome has to be tempered by the significant decline in the number of patients evaluated at one-year post-operatively—fewer than 50 percent of the original patients.
Bottom line: There does not appear to be a difference in the post-operative bone conduction thresholds between the techniques of laser or manual penetration of the stapes footplate. Early testing within four days of surgery may detect a decline in bone conduction thresholds, but these thresholds appear to return to the pre-operative level over a period of one month to one year.
Citation: Brase C, Keil I, Schwitulla J, et al. Bone conduction after stapes surgery: comparison of CO2 laser and manual perforation. Otol Neurotol. 2013;34:821-826.
—Reviewed by George T. Hashisaki, MD