EFFECTS OF PULSED-LASER SYSTEMS ON STAPES FOOTPLATE

Background and Objective: The aim of the present study was to investig ate the tissue ablation capacity of various pulsed lasers at the stape s footplate. Study Design/Materials and Methods: Isolated human stapes and bovine compact-bone platelets were used to determine the effectiv e laser parameters and appropriate application technique for achieving a perforation measuring 500-600 mu m in diameter. Of interest were al so the shape and quality of the perforations, the reproducibility of t he perforation effect, and the thermically altered marginal zones occu rring at the footplate. Three pulsed laser systems were used: excimer, holmium:YAG (Ho:YAG), and erbium:YSGG (Er:YSGG) lasers. Results: The tissue-ablating effect of pulsed laser systems permits a precise and c ontrolled management of the stapes footplate through low and readily r eproducible ablation rates. The extent of thermic side effects at the footplate is lower in comparison to the purely thermically acting cw a nd superpulse laser systems. The Er:YSGG laser exhibits the highest ab lation rate at the stapes and is thus the most effective laser for per foration of the stapes footplate. Though somewhat less effective, the Ho:YAG laser also appears to be suitable for stapedotomy. On the other hand, we do not consider the applied excimer laser (308 nm) to be par ticularly appropriate at the stapes because of its low ablation rates. Conclusion: Thus, the erbium laser could represent an alternative to the argon, KTP 532, and CO2 lasers, already clinically successful in s tapes surgery. However, further studies are neccessary to examine the transmission of thermic energy into the vestibule and the acoustic str ess to the inner ear during laser stapedotomy, to be able to make a de finitive statement about the safest and most effective laser system fo r stapes surgery. (C) 1997 Wiley-Liss, Inc.