No abstract
Laser stapedotomy has now become an established method in the surgical treatment of otoscierosis. Recent experimental studies have demonstrated that, apart from the continuous wave lasers, several pulsed laser systems are also suitable for stapes management. Experiments were performed in guinea pigs to clarify which, if any, of the pulsed lasers used can damage the inner ear on application of the laser parameters required for the stapedotomy. The basal convolution of the guinea-pig cochlea was chosen as the application site. Acoustic evoked potentials (compound action potentials (CAP)) yielded information on inner-ear function. With the Er:YSGG laser (energy:85 J/pulse, energy density:36 J/cm2, total energy: 0.425 J), five applications to the cochlea are necessary for a foot plate perforation of 500-600i.tm. With the Ho:YAG laser, an adequately large perforation can be achieved with at least 10 applications of an energy of 210 mJ per pulse (energy density: 90 J/cm2, total energy: 2.1 J).The aim of this study was: (1st) to clarify whether the Er:YSGG and Ho:YAG laser could cause morphological changes in the organ of Corti of the guinea pig on application of the laser parameters required for stapedotomy, and SPIE Vol. 3193 . 0277-786X/98/$1O.OO 27 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/27/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx 28 (2nd) to verify our experimental electrophysiological results and correlate them with the morphological changes detected in the organ of Corti in the guinea pig cochlea by scanning-electron-microscopic examination. It shows that the effective laser parameters (5 x 85 mJ) of the Er:YSGG-laser cause no changes of the guinea pig cochlea. Even with the application of 25 pulses with the same energy the guinea pig cochlea shows normal appearance. The effective laser parameters of the Ho:YAG laser (10 x 210 mJ) show changes in the outer hair cells in the form of stereocilie fusion and giant hair cell formation while the inner hair cells and supporting cells are showing normal appearance. Ourresults clearly demonstrate a high application safety for the Er:YSGG laser, while the Ho:YAG-laser is not well tolerated in the animal experiment and has only a low application safety. Its application in stapedotomy would be unreliable and dangerous for the inner ear. Our results also clearly show that the electrophysiological data correlate well with the scanning-electron-microscopic data.
Hintergrund Bei plötzlich aufgetretener einseitiger hochgradiger sensorineuraler Hörstörung bzw. Ertaubung können Patienten nach frustraner intravenöser Glukokortikoidtherapie einer explorativen Tympanotomie mit Abdeckung des runden und/oder ovalen Fensters (RF und/oder OF) wegen des Verdachts einer Rundfenstermembranruptur mit Perilymphfistel (PLF) oder einer Fissula ante fenestram (FAF) behandelt werden. Die Studie untersucht, ob die zusätzliche Abdeckung des ovalen Fensters im Vergleich zur alleinigen Abdeckung des runden Fensters einen zusätzlichen Hörgewinn bringt. Methodik Die retrospektive Studie untersucht 54 Patienten mit akuter Ertaubung und durchgeführter Tympanoskopie, bei denen Audiogramme von 3 Zeitpunkten (präoperativ, nach Detamponade sowie mindestens 3–6 Monate postoperativ) vorlagen. Bei 28 Patienten erfolgte neben der Rundfensterabdeckung die zusätzliche Abdeckung des ovalen Fensters. Ergebnis Eine intraoperativ sichtbare PFL bzw. FAF wurde in keinem Operationsbericht beschrieben. Die Hörschwellen waren im frühen postoperativen Zeitraum bereits hoch signifikant geringer und verbesserten sich im weiteren Verlauf. Zwischen den Subgruppen RF und RF + OF zeigte sich in beiden postoperativen Zeiträumen kein signifikanter Unterschied. Bei 65 % (Kriterien nach Kanzaki) und 74 % (Kriterien nach Siegel) der Patienten konnte postoperativ eine partielle bzw. komplette Hörverbesserung nachgewiesen werden. Beim Vergleich der Patientengruppen mit bzw. ohne postoperative Hörverbesserung zeigten sich keine statistischen Unterschiede bezüglich Geschlecht, Alter, Nebendiagnosen oder Latenz der Operation bis zum Symptombeginn. Schlussfolgerung In dieser Studie zeigte die zusätzliche Abdeckung des OF keine signifikante Hörverbesserung. Die postoperative Hörverbesserung entspricht den publizierten Spontanremissionsraten. Nur eine prospektive multizentrische Studie mit Kontrollgruppe kann den Stellenwert der Tympanoskopie und mit Rund- bzw. ovaler Fensterabdeckung bei einer akuten hochgradigen sensorineuralen Schwerhörigkeit vor dem Hintergrund der Spontanremissionen klären.
Successful restoration of audition in revision stapedotomies involves precise identification and correction of the pathological condition without traumatizing the inner ear. Conventional surgical procedures often lead to unsatisfactory audition results and inner ear damages. In revision stapedotomy, the CO2 laser provides the ear surgeon with three important advantages over the conventional technique: 1 . improved diagnostic and therapeutic precision, 2. better stabilization of the new prosthesis in the oval niche, and 3 . reduction of inner ear trauma through non-contact atraumatic management.The surgical procedure of revision stapedotomies with the CO2 laser is discussed, and case examples are used to illustrate the diversity of pathological conditions that can be treated by CO2 laser surgery. Our experience with revision CO2 laser stapedotomy suggests an improvement of postoperative audition compared to the conventional technique and demonstrates a significant elimination of sensorineural deafness. The CO2 laser enables the ear surgeon to precisely and reliably correct conduction deafness recurring after stapedotomy.
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