Experimental studies on the suitability of the erbium laser for stapedotomy in an animal model

Abstract

Animal experiments in mature guinea pigs were devised to determine whether and to what extent inner ear damage can be caused by in vivo use of the erbium laser for stapedotomy. The present study examined the laser effect in connection with perforation of the basal convolution of the cochlea and subsequent application in the opened cochlea. Acoustic evoked potentials as compound action potentials (CAP) were recorded for changes in inner ear function. Findings demonstrated that five applications of the erbium:YSGG (yttrium-scandium-gallium-garnet) laser (energy, 85 mJ/pulse; energy density, 36 J/cm2) were needed to create a footplate perforation of 500-600 microns and did not lead to CAP alteration in any animal (n = 20). An increase of the repetition rate from 1 to 5 Hz likewise caused no CAP alteration (n = 17). Application of high total energies in the open cochlea (n = 5) to determine the safety of the laser system for stapedotomy revealed that a 10-fold increase in the total energy required for adequate perforation led to irreversible CAP alterations and no CAP could be recorded at a 15-fold increase in total energy. In contrast, a 5-fold maximum increase in total energy caused no CAP alterations. These results demonstrate the safety of the Er:YSGG laser comparable to that of the CO2 laser for stapedotomy, supporting its utility as an alternative method for surgery.

Experimental in vivo fenestration of guinea pig cochlea using 2.79 Μm laser radiation

“…This value is much lower than the safety limit of 36 J cm-2 published by Jovanovic et al (34). The discrepancy might be explained by the larger diameter of the perforation (500-600/lm compared to 350ttm in the present study).…”

Experimental erbium laser surgery in the guinea pig cochlea: its use in the study of afferent cochlear neurotransmitters

“…As recently shown in similar animal models, the safety limit of erbium laser treatment was determined by changes in the CAP at an energy of 36 J/cm 2 per pulse with 25 applications at a repetition rate of 5 Hz [15]. In our experiments, however, there was a clear limitation below this value.…”

“…Recently, Jovanovic and co-workers [15] determined the relative safety of the erbium laser in animal experiments by means of changes in compound action potentials (CAP) of acoustic evoked potentials from the guinea pig cochlea.…”

Pressure and Temperature Changes inIn VitroApplications with the Laser and Their Implications for Middle Ear Surgery

“…Direct comparison shows all laser types to have specific advantages and disadvantages: whereas temperature increases are, accordingly, greater for the CO 2 laser [18], higher peak pressures can be expected with the Erbium laser [8, 14, 23]. The two latter systems have nevertheless become well established in routine clinical practice and have seen wide distribution and acceptance.…”