Comparison of laser induced effects on hyperplastic inferior nasal turbinates by means of scanning electron microscopy

Background and Objective: Various laser systems have been used for volume reduction of hyperplastic inferior nasal turbinates. Many studies have thus reported about clinical experiences concerning short and long term results. Although there are also some clinical investigations on histological changes after laser treatment, there is a lack of examinations by means of scanning electron microscopy (SEM) in order to especially investigate laser induced superficial tissue effects (ablation, carbonization, and coagulation). Materials and Methods: Directly following operative excision, three hyperplastic nasal turbinates were treated by laser light of five common medical laser systems and their corresponding wavelengths, using identical laser parameters (irradiance, laser spot diameter) and a reproducible application procedure. After passing through an ethanol dehydration process, the thermal effects on the tissue (carbonization, coagulation, and ablation) were investigated and photographed via SEM. Results: Depending on the laser wavelength used, tissue responses which could be observed by SEM greatly differ with respect to ablation, coagulation, and carbonization zones. While the CO2 laser showed a precise cutting of tissue via ablation with only slight thermal effects on the adjoining tissue, Argon-ion-, Nd:YAG-, and diode-lasers provided for an intense destruction of both the surrounding, superficial respiratory epithelium, and the tissue in the depth of the turbinates, resulting from the development of rather large carbonization and coagulation zones. Ho:YAG-laser light induced precise vaporization in addition to remarkable superficial coagulation of the tissue, which was of smaller extent than after treatment with Nd:YAG- and diode-laser, but comparable to the Argon-ion-laser. Conclusion: In the course of this study SEM proved to be especially suitable for the examination of tissue changes on the surface of laser treated turbinates (i.g., destruction of respiratory epithelium). According to our results, Argon-ion-, Nd:YAG-, and diode-lasers seem to be useful for an effective and bloodless reduction of hyperplastic turbinates. However, broad coagulation zones may lead to consecutive complications and side effects. Due to its good ablation and superficial coagulation capabilities, Ho:YAG-laser light also seems to be usable for an effective turbinate reduction, but its low thermal effects in the depth of the tissue may lead to bleedings during treatment. Laser light of the CO2 laser showed the lowest thermal tissue effects of the lasers investigated and therefore holds the risk of bleedings during treatment and the need of more than one therapeutic session to get a sufficient result. This investigation revealed that physicians, who are performing endonasal laser treatment, must be aware of the varying tissue effects of different medical laser systems to get a more aimed effect and to. avoid intra- and post-operative complications (e.g., Rhinitis sicca, bone sequestration of the turbinate, bleedings,...). (C) 2002 Wiley-Liss, Inc.