Advantages and dangers of erbium laser application in stapedotomy

Conventional vs. diode laser stapedotomy: audiological outcomes and clinical safety

PURPOSE

To compare the hearing results and clinical safety of patients undergoing stapes surgery with conventional technique and diode laser.

METHODS

Retrospective observational study, which included patients treated with primary stapes surgery performed between January 2009 and January 2020. Three audiometric measurements (PTA, GAP and SDS) were evaluated as main results, evaluated by analysis of covariance (controlling the preoperative value). Intraoperative and postoperative complications were also analyzed. Outcomes were measured 6 months (± 1 month) after surgery.

RESULTS

153 cases were included, 97 operated with conventional technique and 56 with laser technique. Postoperative GAP ≤ 10 dB was obtained in 85.6% of the total sample, 82.5% in the conventional technique and 91.1% in the laser technique. Analysis of covariance showed no significant differences in the three surgery outcomes between the two groups (PTA, p = 0.277; GAP, p = 0.509 and SDS, p = 0.530). Regarding surgical complications, sensorineural damage was higher in the conventional technique group (p = 0.05). On the other hand, there were four cases of facial paresis, all in the laser group, three of them with the 980 nm laser.

CONCLUSIONS

Stapedotomy offered a high percentage of hearing success in the two groups studied. There were no significant differences in audiometric result, but there was a differential presentation of complications, being more frequent sensorineural hearing loss in the conventional technique group and facial paresis in the laser group.

Brazilian Society of Otology task force - Otosclerosis: evaluation and treatment

OBJECTIVES

To review and provide evidence-based recommendations for the diagnosis and treatment of otosclerosis.

METHODS

Task force members were educated on knowledge synthesis methods, including electronic database search, review and selection of relevant citations, and critical appraisal of selected studies. Articles written in English or Portuguese on otosclerosis were eligible for inclusion. The American College of Physicians' guideline grading system and the American Thyroid Association's guideline criteria were used for critical appraisal of evidence and recommendations for therapeutic interventions.

RESULTS

The topics were divided into 2 parts: 1) Diagnosis - audiologic and radiologic; 2) Treatment - hearing AIDS, pharmacological therapy, stapes surgery, and implantable devices - bone-anchored devices, active middle ear implants, and Cochlear Implants (CI).

CONCLUSIONS

The pathophysiology of otosclerosis has not yet been fully elucidated, but environmental factors and unidentified genes are likely to play a significant role in it. Women with otosclerosis are not at increased risk of worsening clinical condition due to the use of contraceptives or during pregnancy. Drug treatment has shown little benefit. If the patient does not want to undergo stapedotomy, the use of hearing aids is well indicated. Implantable systems should be indicated only in rare cases, and the CI should be indicated in cases of profound deafness.

Thulium laser in stapedotomy surgery

BACKGROUND

Thulium laser use in stapedotomy surgery is usually associated with many doubts regarding the thermal effect on the vestibular area and the production of acoustic shock waves, which may result in permanent complications.

OBJECTIVES

We aimed to evaluate the efficacy and safety of the Thulium laser use in stapedotomy and its long-term effects on the clinical and audiological results.

MATERIAL AND METHODS

It was a retrospective randomized case-series study. We included 148 otosclerosis patients. They were divided randomly into two groups; group A (multiple shots) included 62 patients and group B (one shot with a manual perforator) included 86 patients.

RESULTS

There was a statistically significant improvement of the ABG in both groups. ABG closure (<10 dB) occurred in 87.1% of patients in group A, and 89.5% of patients in group B. Intraoperative complications were more in group B (p-value = 0.038). The postoperative complications were more in group A (p-value = .017).

CONCLUSIONS

According to our experience on a relatively large number of cases, the Thulium laser is a safe tool to be used in stapedotomy either in multiple shots or one shot with a manual perforator. It improved functional hearing efficiently without showing signs of inner ear impairment.

Evaluation of Audiological Results and Cochleo-Vestibular Subclinical Injury After CO2 Laser Stapedotomy

BACKGROUND AND OBJECTIVES

Evaluation of the effectiveness and safety of CO₂ laser stapedotomy, focusing on the audiological results, and on the surgical cochleo-vestibular trauma.

STUDY DESIGN/MATERIALS AND METHODS

Retrospective clinical trial on 38 patients with the diagnosis of otosclerosis, who underwent CO₂ laser stapedotomy between January 2015 and October 2019. Postoperative air-bone gap (ABG), mean air conduction gain, and postoperative changes of high frequency threshold were evaluated 1, 3, 6, and 12 months after surgery. Videoculography (VOG) was performed to assess the vestibular impairment preoperatively and 1 day, 1 week, and 1 month after surgery.

RESULTS

Postoperative ABG closure within 10 dB was obtained in 35 cases (92.1%), with a mean postoperative ABG of 4.4 dB and a mean air conduction improvement of 32.3 dB. No significant worsening of high frequency threshold was observed. Spontaneous nystagmus was found preoperatively in 5/38 patients (13.2%), 1 day after surgery in 13/38 patients (34.2%), 1 week after surgery in 12/38 patients (31.6%), and 1 month after surgery in 4/38 patients (10.5%). Positional nystagmus was found preoperatively in 12/38 patients (31.6%), 1 day after surgery in 25/38 patients (65.8%), 1 week after surgery in 22/38 patients (57.9%), and 1 month after surgery in 10/38 patients (26.3%). The occurrence of nystagmus did not always correlate with vestibular symptoms: after surgery, 10 patients (26.3%) experienced vertigo associated with dizziness, 8 patients (21.1%) suffered from dizziness without vertigo, and 14 patients (36.8%) showed nystagmus without any symptomatology. At 1 month after surgery none of the patients complained about vestibular symptoms.

CONCLUSION

CO₂ laser stapedotomy is a safe and effective technique, which allows to obtain good functional results with minimal perioperative cochleo-vestibular trauma.© 2021 Wiley Periodicals LLC.

Picosecond Infrared Laser (PIRL) Application in Stapes Surgery-First Experience in Human Temporal Bones

Objective:

Using a contact-free laser technique for stapedotomy reduces the risk of mechanical damage of the stapes footplate. However, the risk of inner ear dysfunction due to thermal, acoustic, or direct damage has still not been solved. The objective of this study was to describe the first experiences in footplate perforation in cadaver tissue performed by the novel Picosecond-Infrared-Laser (PIRL), allowing a tissue preserving ablation.

Patients and Intervention:

Three human cadaver stapes were perforated using a fiber-coupled PIRL. The results were compared with footplate perforations performed with clinically applied Er:YAG laser. Therefore, two different laser energies for the Er:YAG laser (30 and 60 mJ) were used for footplate perforation of three human cadaver stapes each.

Main Outcome Measure:

Comparisons were made using histology and environmental scanning electron microscopy (ESEM) analysis.

Results:

The perforations performed by the PIRL (total energy: 640–1070 mJ) revealed a precise cutting edge with an intact trabecular bone structure and no considerable signs of coagulation. Using the Er:YAG-Laser with a pulse energy of 30 mJ (total energy: 450–600 mJ), a perforation only in the center of the ablation zone was possible, whereas with a pulse energy of 60 mJ (total energy: of 195–260 mJ) the whole ablation zone was perforated. For both energies, the cutting edge appeared irregular with trabecular structure of the bone only be conjecturable and signs of superficial carbonization.

Conclusion:

The microscopic results following stapes footplate perforation suggest a superiority of the PIRL in comparison to the Er:YAG laser regarding the precision and tissue preserving ablation.

Stapedotomy with Microdrill or Carbon Dioxide Laser: Influence on Inner Ear Function

Objectives:

A prospective randomized audiological analysis of 336 otosclerosis operations was conducted to compare the evolution of bone conduction thresholds after primary stapedotomy with Two different techniques to open the footplate: microdrill and carbon dioxide laser stapedotomy.

Methods:

To monitor the inner ear function, we compared the preoperative bone conduction thresholds with the postoperative levels at day 2, week 2, week 6, and month 6. Evolution of the bone conduction was compared for the Two studied groups (laser versus microdrill).

Results:

An average bone conduction loss of 1.8 dB was measured at day 2 for the middle frequencies (0.5, 1, and 2 kHz). At 4 kHz, a bone conduction loss of 7 dB was found. The bone conduction thresholds measured in the first and second months after surgery showed a gradual recovery with overclosure as the end result.

Conclusions:

Our results confirm the transient depression of inner ear function in the immediate postoperative period, with recovery within the first weeks after surgery. In the studied population, no statistically significant difference was found between the Two techniques that were used to make the calibrated hole (laser versus microdrill). These results demonstrate that both techniques possess the same early effect regarding inner ear function. The authors hypothesize that an early inflammatory reaction could be the cause of the transient bone conduction shift.

Erbium: Yttrium-Aluminum-Garnet Laser Application in Stapedotomy

OBJECTIVE: To assess clinical safety and efficacy of the erbium: yttrium-aluminum-garnet (Er:YAG) laser in the stapes surgery; to define and optimize parameters that render the procedure safe for the inner ear.

STUDY DESIGN: Retrospective study.

MATERIAL AND METHODS: A microscope-integrated Er: YAG laser stapedotomy was performed on 29 patients and a conventional stapedotomy on 41 patients. An early (within 1 to 3 days after stapes surgery) and late (at least 6 weeks) pure-tone bone-conduction threshold audiogram was obtained.

RESULTS: No statistically significant differences were found by Student's t test over all measured frequencies between pre- and postoperative bone-conduction thresholds in each group. There was no statistically significant difference for all frequencies between early (3 days) and late postoperative mean bone-conduction thresholds.

CONCLUSIONS: The results of our preliminary clinical study showed that erbium laser poses no risk to inner ear function. However, the lack of standardization obliges further investigation to establish safe clinical parameters of the Er:YAG laser.

EBM RATING: B-3

CO2 Laser Stapedotomy with the “One-Shot” Technique— Clinical Results

OBJECTIVE: To further optimize the surgical technique with the CO2 laser in stapes surgery a scanner system was used to obtain a footplate perforation of 0.5 to 0.6 mm with only 1 laser application (“one-shot” stapedotomy).

STUDY DESIGN: 188 patients with otosclerosis were submitted to a primary CO2 laser stapedotomy with the SurgiTouch® scanner. This study surveys the surgical technique and clinical results.

RESULTS: An adequately large perforation diameter could be achieved with a single shot in 68% of the patients treated with the SurgiTouch® scanner. In 11% of the patients, a second laser application at the same site was necessary. In 21% of the patients, the perforation had to be enlarged by several slightly overlapping laser applications without scanner. The clinical data of this study clearly documents that there is no evidence of laser depending inner ear affections.

CONCLUSION: The CO2 laser combined with modern scanner systems is well suited for application in stapes surgery.

High frequency bone conduction auditory evoked potentials in the guinea pig: Assessing cochlear injury after ossicular chain manipulation

Permanent high frequency (>4 kHz) sensorineural hearing loss following middle ear surgery occurs in up to 25% of patients. The aetiology of this loss is poorly understood and may involve transmission of supra-physiological forces down the ossicular chain to the cochlea. Investigating the mechanisms of this injury using animal models is challenging, as evaluating cochlear function with evoked potentials is confounded when ossicular manipulation disrupts the normal air conduction (AC) pathway. Bone conduction (BC) using clinical bone vibrators in small animals is limited by poor transducer output at high frequencies sensitive to trauma. The objectives of the present study were firstly to evaluate a novel high frequency bone conduction transducer with evoked auditory potentials in a guinea pig model, and secondly to use this model to investigate the impact of middle ear surgical manipulation on cochlear function. We modified a magnetostrictive device as a high frequency BC transducer and evaluated its performance by comparison with a calibrated AC transducer at frequencies up to 32 kHz using the auditory brainstem response (ABR), compound action potential (CAP) and summating potential (SP). To mimic a middle ear traumatising stimulus, a rotating bur was brought in to contact with the incudomalleal complex and the effect on evoked cochlear potentials was observed. BC-evoked potentials followed the same input-output function pattern as AC potentials for all ABR frequencies. Deterioration in CAP and SP thresholds was observed after ossicular manipulation. It is possible to use high frequency BC to evoke responses from the injury sensitive basal region of the cochlea and so not rely on AC with the potential confounder of conductive hearing loss. Ongoing research explores how these findings evolve over time, and ways in which injury may be reduced and the cochlea protected during middle ear surgery.

Lasers in stapes surgery: a review

Background:

Lasers in stapes surgery are used to divide the anterior and posterior crus of the stapes, divide the stapedius tendon and perforate the footplate. The ideal laser should not penetrate deeply into the perilymph (thereby increasing its temperature). It should be conducted through optical fibres, allowing easy manipulation, and should have good water absorption, equating to high bone ablation efficiency.

Objectives:

This review discusses the various different lasers used in stapes surgery with regard to their properties and suitability for this type of surgery. In particular, the laser parameters used are discussed to facilitate their clinical use.

Long-term results of the Er-Yag laser used in stapes surgery

Stapes surgery is performed using both conventional techniques and a variety of laser systems. The Er-Yag laser is a type of pulsation laser deemed by many to be the safest for ear surgery. The aim of this study was to assess the long-term effects of using the Er-Yag laser in stapes surgery and its impact on inner ear function. The study was conducted on 95 ears (48 right and 47 left) that had undergone Er-Yag laser-assisted stapedotomy. The follow-up time was at least 3 years. Pure tone audiometry was performed on all patients. The frequency ranged from 125 to 8,000 Hz. Air conduction and bone conduction were both assessed. Moreover, all patients had their stapedius reflex assessed and were given a Rinne test. The results were evaluated according to the Committee on Hearing and Equilibrium guidelines and then statistically analyzed using the Wilcoxon sequence pair test with a p value of <0.05. A decrease in the hearing threshold of 0.5, 1, and 3 kHz, for both bone and air conduction was observed for all patients (p < 0.0001). The Wilcoxon sequence pair test revealed a statistically significant correlation between the pre- and postoperative treatment mean air-bone gap values (p < 0.0001). No facial nerve paralysis was observed. No Er-Yag laser side effects were observed on inner ear function. The patients also had lower hearing thresholds. These observations demonstrate the usefulness of Er-Yag lasers in stapes surgery.

Comparison of KTP, Thulium, and CO2 laser in stapedotomy using specialized visualization techniques: thermal effects

High-speed thermal imaging enables visualization of heating of the vestibule during laser-assisted stapedotomy, comparing KTP, CO2, and Thulium laser light. Perforation of the stapes footplate with laser bears the risk of heating of the inner ear fluids. The amount of heating depends on absorption of the laser light and subsequent tissue ablation. The ablation of the footplate is driven by strong water absorption for the CO2 and Thulium laser. For the KTP laser wavelength, ablation is driven by carbonization of the footplate and it might penetrate deep into the inner ear without absorption in water. The thermal effects were visualized in an inner ear model, using two new techniques: (1) high-speed Schlieren imaging shows relative dynamic changes of temperatures up to 2 ms resolution in the perilymph. (2) Thermo imaging provides absolute temperature measurements around the footplate up to 40 ms resolution. The high-speed Schlieren imaging showed minimal heating using the KTP laser. Both CO2 and Thulium laser showed heating below the footplate. Thulium laser wavelength generated heating up to 0.6 mm depth. This was confirmed with thermal imaging, showing a rise of temperature of 4.7 (±3.5) °C for KTP and 9.4 (±6.9) for Thulium in the area of 2 mm below the footplate. For stapedotomy, the Thulium and CO2 laser show more extended thermal effects compared to KTP. High-speed Schlieren imaging and thermal imaging are complimentary techniques to study lasers thermal effects in tissue.

Pressure and temperature changes in in vitro applications with the laser and their implications for middle ear surgery

Background. The purpose of this study was to evaluate the thermal and pressure effects using a Titan Sapphire chirped-pulse amplifier system configured to deliver ultrashort pulses of 180 femtoseconds (fs) in an inner ear model. Materials and Methods. Temperature increases and heat exchange processes in the fluid (physiological saline) were examined in a calorically and physiologically approximated cochlea model for applying laser parameters effective in the creation of footplate perforations. Results. In the effective energy density range, the highest temperature increases achieved with the Carbon dioxide (CO₂) laser were about 11 degrees C. The lowest temperature maxima were 6 degrees C with the Er:YAG laser (Yttrium-Aluminum-Oxide doted with Erbium3+-ions) and <5 degrees C with the femtosecond laser. Comparison of the laser-induced pressure with the limit graph published by Pfander indicated that the use of the fs laser is unobjectionable for fluences <1 J/cm². Conclusions. Our investigations demonstrated that the application of the fs laser in middle ear surgery presents a new and promising addition to the range of ultrashort wavelength lasers used for this purpose.

A comparison of the hearing results of KTP and Erbium YAG laser stapedotomy

CONCLUSION

Our data prove that lasers are safe and useful instruments in stapes surgery. Good postoperative results can be attained in both KTP and Er: YAG lasers. There was no significant inner ear damage related to the Er: YAG laser use.

OBJECTIVE

To compare the postoperative results of stapedotomies performed with KTP and Erbium: YAG lasers in patients with otosclerosis in order to assess the risk of Er: YAG for the inner ear.

PATIENTS AND METHODS

The charts of 152 consecutive adult patients who underwent primary laser stapedotomies for otosclerosis from 1999 to 2005 were reviewed. One hundred and thirty-seven stapedotomies (98 patients) were performed using the KTP laser and 54 stapedotomies (54 patients) were performed with Er: YAG laser. All the patients were separated in two groups according to the type of laser, which was used. Hearing results were analyzed according to the Committee on Hearing and Equilibrium Guidelines of the American Academy of Otolaryngology-Head and Neck Surgery. Pure-tone audiometry was performed before the surgery, three months and one year postoperatively.

RESULTS

The study indicated that KTP and Er: YAG stapedotomies have similar rates of the air-bone gap closure. There was no significant postoperative sensorineural hearing loss found in both techniques.

Experimental study on thermic effects, morphology and function of guinea pig cochlea: a comparison between the erbium:yttrium-aluminum-garnet laser and carbon dioxide laser

BACKGROUND AND OBJECTIVE

Surgery of the inner ear requires atraumatic techniques to preserve the morphology of the inner ear. Recent experiment and clinical studies have demonstrated that several laser systems are suitable for cochleostomy. The goal of this study was to quantify the thermic effects, morphology and function of guinea pig cochlea in vivo by comparing the erbium:yttrium-aluminum-garnet (Er:YAG) laser and carbon dioxide (CO(2)) laser and to determine the optimum laser parameters for safe clinical treatment.

STUDY DESIGN/MATERIALS AND METHODS

A fenestration in the basal cochlear turn of guinea pigs was created. A type K thermocouple was placed on the membrane of round window to detect the local temperature change during laser irradiation. The auditory evoked brainstem response (ABR) was measured before and after laser application. Confocal laser microscopy and scanning electron microscopy (SEM) was used for cochlear morphology.

RESULTS

An increased hearing loss immediately and 4 weeks later after irradiation was observed in animals with the higher power CO(2) laser in accordance with a higher temperature increase during laser application. In contrast, a wider safety scope of Er:YAG application in cochleostomy was presented with little temperature increase. These findings were correlated with the ultrastructural changes in guinea pig cochlea.

CONCLUSION

The Er:YAG and CO(2) lasers are shown to be safe if the total amount of energy is kept within the limits applied in this study. In addition, on this preliminary basis by guinea pig laser cochleostomy, Er:YAG laser maybe less damaging to inner ear structures than CO(2) laser with a larger safety scope and less thermic effects.

Erbium: yttrium-aluminum-garnet laser stapedotomy—A safe technique

Objective

To standardize the technical parameters of the erbium: yttrium-aluminum-garnet (Er:YAG) laser stapedotomy.

Study Design

Retrospective study of all patients with otosclerosis who underwent stapedotomy from January 2002 to January 2006.

Subjects and Methods

The charts of 152 consecutive patients who underwent stapedotomy were reviewed. The patients were stratified into two groups, according to the instrument used. Stapedotomies were performed in group A, with the OPMI®TwinEr: YAG laser; and in group B with manual microperforators.

Results

No statistically significant differences were found over all measured frequencies, between pre- and postoperative bone conduction thresholds, in each group. At the last postoperative follow-up, vertigo and nystagmus were not detected; two patients in group A and one patient in group B showed persistent tinnitus.

Conclusion

Er:YAG laser stapedotomy is a safe and effective procedure, with no damage of the inner ear when strict adherence to the safety parameters is observed. The Er:YAG laser is definitively suitable for stapes surgery, and represents a useful and safe tool in the armamentarium of otological microsurgery.

Laser stapedotomy – the up-to-date solution of otosclerotic stapes fixation

A vezetéses halláscsökkenést okozó otoscleroticus stapesfixatio műtéti megoldásának folyamatos fejlődése az elmúlt fél évszázad egyik fülsebészeti sikertörténete. A stapedectomia, illetve parciális stapedectomia mellett manapság a stapedotomia is elterjedt műtéti megoldásnak tekinthető. Cél: A minimálisan invazív lézerstapedotomia hazai bevezetése, tapasztalatok szerzése, valamint a műtéti halláseredmények és a posztoperatív komplikációk elemzése. Módszer: A szerzők közleményükben KTP-lézerrel asszisztált, Nitinol-pisztonnal végzett 14 esetük kapcsán ismertetik lézerstapedotomiákkal szerzett első tapasztalataikat. 2006 márciusa és 2007 áprilisa között 11 nőbeteget és 3 férfi beteget operáltak. A betegek átlagéletkora 42,2 év volt, 6 esetben bal, 8 esetben jobb fülön történt a műtét. A betegek átlagos követési ideje 9 hónap volt. Eredmények: A posztoperatív audiogramok értékelésekor az 500–1000–2000–3000 Hz frekvenciákat figyelembe véve a légvezetés átlagos javulása 21,5 dB volt. Ugyanezen frekvenciákon a csontlégközértékek átlagos javulása 18,7 dB volt. Kilenc hónap átlagos követési idő mellett az eddigi esetekben a műtéteket követően a betegek 85%-ában az átlagos csontlégköz < 10 dB, de valamennyi beteg esetében < 20 dB. Az átlagos légvezetés értéke egy beteg kivételével < 30 dB. Belsőfül-károsodásra utaló, a magashang-frekvenciákat érintő csontvezetéses romlást, facialis paresist nem észleltek. Következtetések: A szerzők tapasztalatai és az irodalmi adatok alapján a Nitinol-pisztonnal végzett lézerstapedotomiáknak számos előnyük van: 1) a piszton hurkának hőre aktiválódó memóriaeffektusa kiküszöböli az incus hosszú szárára két ponton történő rászorítás hátrányait; 2) a posztoperatív szédülés mértéke enyhébb, időtartama rövidebb, ezért az ápolási idő csökken; 3) a műtét költséghatékony, és minimálisan invazív; 4) a lézer alkalmazása minimális cochlearis traumát, vérmentes környezetet biztosít; 5) a protézis migrációja kiküszöbölhető, körülötte a granuláció mérsékeltebb; 6) magas frekvenciákon tartósan jó halláseredmény érhető el; 7) a komplikációk súlyossága, gyakorisága csökken, ezért a technika jó megoldás kevésbé gyakorlott operatőrök számára is; 8) problémás esetekben (arteria stapedialis jelenléte, obliterativ otosclerosis, úszó stapestalp, rendellenesen futó n. facialis a dobüregben, revíziós műtétek) is alkalmazható; 9) a halláseredmények interindividuális különbsége kisebb. – Eddigi kedvező tapasztalataik alapján a szerzők lézerstapedotomián átesettek hosszú távú követését tervezik nagyobb beteganyagon.

Er:YAG laser osteotomy for removal of impacted teeth: Clinical comparison of two techniques

BACKGROUND AND OBJECTIVES

In contrast to many techniques currently employed for osteotomy, like saws, drills or modulated ultrasound, lasers offer non-contact and low-vibration bone cutting. Therefore, this report examines the benefits to laser osteotomy in oral surgery using two different short-pulsed Er:YAG laser systems.

MATERIALS AND METHODS

Er:YAG lasers, using either a fiber-optic delivery system and an articulated arm delivery system, were used to remove impacted teeth in 30 patients. In 15 patients an Er:YAG laser utilizing a fiber-optic delivery system was applied for cutting bone, with a pulse energy of 500 mJ, a pulse duration of 250 microseconds and frequency of 12 Hz (energy density 177 J/cm(2)). The other 15 patients were treated with an Er:YAG laser utilizing an articulated arm delivery system, with a pulse energy of 1,000 mJ, a pulse duration of 300 microseconds and a frequency of 12 Hz (energy density 157 J/cm(2)).

RESULTS

In all cases the lasers allowed precise bone ablation without any visible, negative, thermal side-effects. Since the laser tip was used in a non-contact mode and could be positioned freely, unrestricted cut geometries were feasible. Adjacent soft tissue structures could be preserved and were not harmed by the laser beam. However, osteotomies were time consuming, especially if teeth had to be separated. The level of water irrigation limited the use of the laser. In 20% of the cases in which the articulated arm delivery laser was used to section teeth, it was necessary to use a conventional dental drill to finish the procedure.

CONCLUSION

This bone ablation technique, using short Er:YAG laser pulses and water spray, produced good clinical results without any impairment to wound healing. However, for now, the lack of depth control and the time required to perform the necessary osteotomy limit routine clinical application.

„Ein-Schuss-CO2-Laser-Stapedotomie“

BACKGROUND

In order to further optimize the surgical technique with CO(2) laser in stapes surgery, a scanner system was used to obtain a footplate perforation of 0.5-0.6 mm with only one laser application ("one-shot" stapedotomy).

PATIENTS AND METHODS

A total of 255 patients with otosclerosis were submitted to primary CO(2) laser stapedotomy with a SurgiTouch scanner. This study discusses the surgical technique and clinical results.

RESULTS

An adequately large perforation diameter could be achieved with a single shot in 68% of the patients treated. In 14% of the patients, a second laser application at the same site was necessary. In 18% the perforation had to be enlarged by several slightly overlapping laser applications without using the scanner. There was no evidence of laser dependent inner ear affections.

CONCLUSION

CO(2) laser, combined with modern scanner systems, is well suited for application in stapes surgery.

The influence of Er. YAG laser application in fenestration to the inner ear

OBJECTIVE

Erbium (Er.) YAG laser may be usable for middle ear surgery because of its ability to ablate bony tissue. We investigated the inner ear damage caused by the fenestration to the inner ear with Er. YAG laser.

DESIGN

We investigated the influence of Er. YAG laser on the inner ear using electrophysiological technique.

RESULTS

Several cases had a decrease in endocochlear potential (EP) and cochlear microphonics (CM) after the fenestration to the inner ear.

CONCLUSIONS

Er. YAG laser is safe if it is used for the small and superficial fenestration to the stapes footplate. However, a few extra pulses after fenestration are dangerous.

Clinical results after stapedotomy: a comparison between the erbium: yttrium-aluminum-garnet laser and the conventional technique

OBJECTIVE

The objective of this study was to assess whether the use of the erbium: yttrium-aluminum-garnet (Er:YAG) laser has negative effects on inner ear function and to compare the short- and long-term hearing outcome of patients undergoing conventional stapedotomy versus laser stapedotomy.

STUDY DESIGN

Retrospective review of prospectively collected audiometric data of patients with otosclerosis operated on by one experienced surgeon.

SETTING

Academic tertiary referral center.

PATIENTS

A total of 266 stapes surgeries were evaluated for intraoperative findings, of which 209 patients were evaluated for preoperative and postoperative hearing thresholds after a 6- to 452-week (mean, 22 wk) audiological follow-up.

INTERVENTION

One hundred fifteen (43%) of the operations were performed conventionally, using manual perforators for stapedotomy (Group A); in 115 (43%) surgeries, the perforators were used in combination with the Er:YAG laser (Group B), and in 36 (14%) operations, the Er:YAG was used exclusively for footplate perforation (Group C).

MAIN OUTCOME MEASURES

Pure-tone audiometry was performed before surgery, 2 days postoperatively (bone conduction only) and at 5, 26, and 57 weeks postoperatively.

RESULTS

A postoperative temporary threshold shift of the bone conduction could be found in all groups. In Group C, where the laser was used exclusively for footplate perforation, this threshold shift was not only the most significant, but also-in contrast to the other groups-not totally reversible. In all techniques, a satisfactory air-bone gap closure could be achieved. The best long-term results (96% of the patients had <or=20 dB air-bone gap after 57 wk) could be found in Group B.

CONCLUSION

If certain rules to minimize inner ear trauma are followed, the Er:YAG laser is a safe tool in middle ear surgery. Combining both the laser and the conventional technique, instead of the separate use of either technique, leads to superior postoperative hearing results.

Morphological effects of nanosecond- and femtosecond-pulsed laser ablation on human middle ear ossicles

We evaluate the feasibility of nanosecond-pulsed and femtosecond-pulsed lasers for otologic surgery. The outcome parameters are cutting precision (in micrometers), ablation rate (in micrometers per second), scanning speed (in millimeters per second), and morphological effects on human middle ear ossicles. We examine single-spot ablations by a nanosecond-pulsed, frequency-tripled Nd:YAG laser (355 nm, beam diameter 10 microm, pulse rate 2 kHz, power 250 mW) on isolated human mallei. A similar system (355 nm, beam diameter 20 microm, pulse rate 10 kHz, power 160-1500 mW) and a femtosecond-pulsed CrLi:SAF-Laser (850 nm, pulse duration 100 fs, pulse energy 40 microJ, beam diameter 36 microm, pulse rate 1 kHz) are coupled to a scanner to perform bone surface ablation over a defined area. In our setups 1 and 2, marginal carbonization is visible in all single-spot ablations of 1-s exposures and longer: With an exposure time of 0.5 s, precise cutting margins without carbonization are observed. Cooling with saline solution result is in no carbonization at 1500 mW and a scan speed of 500 mms. Our third setup shows no carbonization but greater cutting precision, although the ablation volume is lower. Nanosecond- and femtosecond-pulsed laser systems bear the potential to increase cutting precision in otologic surgery.

Prospective clinical study on cochlear function after erbium:yttrium-aluminum-garnet laser stapedotomy

OBJECTIVE

To assess whether the application of the emitting erbium:yttrium-aluminum-garnet (Er:YAG) laser in stapedotomy has negative effects on vestibular and cochlear functions.

DESIGN

Prospective, with 12 to 14 months follow-up.

SETTING

Academic tertiary referral center.

PATIENTS

Twenty-four patients undergoing stapedotomy (primary surgery) in otosclerosis.

INTERVENTION

All patients underwent Er:YAG laser-assisted stapedotomy for otosclerosis between January 2000 and June 2002.

MAIN OUTCOME MEASURES

Early (1-3 days after surgery) and late (12-14 months after surgery) postoperative bone-conduction thresholds and the presence of post-operative tinnitus and vertigo were analyzed. In addition, the relation between applied laser energy and postoperative bone-conduction thresholds was calculated.

RESULTS

In 22 patients, unchanged preoperative minus early postoperative pure-tone bone-conduction averages at 1, 2, and 4 kHz were observed. In one patient, a slight early deterioration between 10 and 20 dB was seen. In 18 patients, unchanged preoperative minus late postoperative pure-tone bone-conduction averages at 1, 2, and 4 kHz were observed. In two patients, a slight late deterioration between 10 and 20 dB was seen. In two patients, a new postoperative tinnitus was observed. No patient suffered from vertigo at the time of second evaluation. No correlation between applied laser energy and both postoperative bone-conduction thresholds was found.

CONCLUSIONS

The Er:YAG laser stapedotomy in otosclerosis is a safe technique. Vestibular and cochlear function is not significantly disturbed after Er:YAG laser stapedotomy.

Application of carbon dioxide and erbium:yttrium-aluminum-garnet lasers in inner ear surgery: an experimental study

BACKGROUND

Surgery of the inner ear requires atraumatic techniques to preserve the sensory structures of the inner ear. With modern laser technology, surgery can be performed without mechanical contact, reducing the risk of direct mechanical trauma. However, energy transfer by laser light has the potential to induce damage by heating, pressure waves, or direct irradiation, depending on the properties of the laser and parameters of application.

HYPOTHESIS

The application of laser systems in inner ear surgery may have an advantage over traditional techniques; the carbon dioxide laser in continuous mode with an automated scanning procedure and the erbium:yttrium-aluminum-garnet laser were compared with a mechanical technique, using a diamond drill.

METHODS

A cochleostomy in the basal cochlear turn of guinea pigs was created. Thresholds in response to frequency-specific stimuli and clicks were established by recording compound action potentials, both before and after the procedure.

RESULTS

The best results in terms of preservation of cochlear function were obtained with the diamond drill. However, a single ear had a complete loss after fracture of the cochlear wall. Mean threshold shifts observed with the carbon dioxide laser were slightly greater, showing mild high-frequency losses, although differences to the group of drilling were not statistically significant. Results with the erbium:yttrium-aluminum-garnet laser showed significantly higher degrees of hearing loss than the other two groups, predominantly in the high-frequency region.

CONCLUSIONS

Mechanical opening of the inner ear using a microdrill can be performed with minimal hearing loss; however, it carries the risk of direct trauma to the inner ear. The carbon dioxide laser with a new scanning technology as a noncontact procedure is shown to be effective and safe. It can be regarded as a useful tool in inner ear surgery. The erbium:yttrium-aluminum-garnet laser has a greater potential to cause damage.

[Stapedotomy, stapedectomy and revision surgery performed with laser techniques. Revision of literature]

The usefulness of laser in otologic surgery, and specifically the suitability of its use in stapes surgery, is still under discussion. We intend to support the use of this method in the surgical treatment of otosclerosis, as well as to elucidate which type of laser is the most advisable one, establishing also in which stages of surgery it should be used. For this, we carry out a revision of the main opinions published in this regard in the international literature, commenting on the results and observations gathered in it. We end by setting out a number of conclusions which are the result of the analysis of the criteria put forward in the bibliography.

Ultrashort pulse laser ossicular ablation and stapedotomy in cadaveric bone

BACKGROUND AND OBJECTIVE

The purpose of this study was to evaluate the ablation of ossicular tissue using a 1,053 nm Ti:Sapphire chirped pulse amplifier laser system configured to deliver ultrashort pulses of 350 femtoseconds (fs) (3.5x10(-13) seconds) in cadaver temporal bone.

STUDY DESIGN/MATERIALS AND METHODS

Ablation of the formalin-fixed incus and stapes was performed using an ultrashort pulse laser (USPL) (0.4 mm beam diameter, pulse fluence of 2.0 J/cm2, and pulse repetition rate of 10 Hz). The ablation rate was measured using optical micrometry, and crater surface morphology examined using scanning electron microscopy.

RESULTS

The laser produced precise bone ablation at a rate of 1.26 microm/pulse, with almost no evidence of thermal damage, and very little evidence of photomechanical injury.

CONCLUSIONS

Ultrashort pulse lasers may provide a useful clinical tool for otologic and skull base surgery, where precise hard tissue ablation is required adjacent to critical structures.

A study of the intra-operative effect of the Argon and KTP laser in stapes surgery

The intraoperative effect of the Argon and KTP laser was studied on 20 patients who had primary stapes surgery under local anaesthetic; 10 had Argon and 10 had KTP laser stapedotomy. Symptoms of inner ear disturbance such as dizziness and tinnitus were systematically recorded during the laser procedure. Both dizziness and tinnitus were relatively uncommon when the laser was used on the promontory. When the laser was used to transect the posterior crus, all the patients reported transient dizziness, probably from the thermal effect through the posterior crus into the inner ear. However, tinnitus was unusual during this stage. When the laser was used to fenestrate the footplate, only 30% of patients reported a transient dizziness as less laser energy was used. On the other hand, 55% of the patients experienced tinnitus during this stage, which indicates an acoustic effect on the inner ear. There is no difference between the Argon and KTP laser.

Safety of the erbium:yttrium-aluminum-garnet laser in stapes surgery in otosclerosis

OBJECTIVE

The purpose of this study was to present early and late bone-conduction hearing thresholds and data about cochlear and vestibular disturbances in patients after erbium:yttrium-aluminum-garnet (Er:YAG) laser stapedotomy in otosclerosis.

STUDY DESIGN

The study design was a retrospective study.

SETTING

The study was conducted at an academic tertiary referral center.

PATIENTS

In this study, audiologic data of 117 patients undergoing Er:YAG laser-assisted stapedotomy for otosclerosis between 1993 and 1999 were included.

MAIN OUTCOME MEASURES

The preoperative minus 2 postoperative (early, 1-3 days; late, at least 6 weeks) average pure-tone bone-conduction thresholds at 1, 2, and 4 kHz and 0.5, 1, 2, and 3 kHz were calculated. The postoperative appearance of nystagmus, vertigo, and tinnitus was analyzed.

RESULTS

A total of 91 of 117 patients showed unchanged preoperative minus postoperative pure-tone bone-conduction averages at 1, 2, and 4 kHz in the late postoperative measurement. A slight deterioration was observed in 8 of 117 patients. Regarding the frequencies 0.5, 1, 2, and 3 kHz, 97 of 117 patients showed unchanged preoperative minus postoperative pure-tone bone-conduction averages. A new transient tinnitus appeared in 37 of 117 patients, and a new persistent tinnitus was found in 3 of 117 patients. Most of the patients had no postoperative dizziness (63/117 patients) and no postoperative nystagmus (109/117 patients).

CONCLUSION

The study did not show significant sensorineural hearing loss at or below 3 kHz. Vestibular and cochlear function has no clinically relevant suppression after Er:YAG laser stapedotomy.

Implications of sound levels generated by otologic devices

OBJECTIVE

Exposure to loud noise can result in sensorineural hearing loss. In otology, a wide variety of devices are used that have significant noise output, both to the operator and the patient. This study quantifies and compares the sound pressure levels (SPL) of a variety of otologic instruments.

METHODS

Using a calibrated sound pressure level meter, the peak and impulse sound pressure levels of several otologic instruments were determined at 1 cm from their application to human temporal bones. Devices measured were an air-powered drill with a cutting burr, an electric micro-drill, and KTP, CO(2), and erbium lasers.

RESULTS

Impulse sound pressure levels for the KTP laser, CO(2) laser, microdrill, air-powered drill and erbium laser were 67, 71, 90, 105, and 105 dBA, respectively. Peak sound pressure levels were 81, 89, 102, 118, and 132 dBA, respectively.

CONCLUSIONS

Use of the KTP laser, CO(2) laser, and microdrill result in impulse levels of less than 100 dBA. Although the impulse levels of the erbium laser and the air-powered drill were equivalent, the peak sound pressure levels of the erbium laser were significantly higher. These high sound pressure levels may increase the chance for hearing loss. Like any tool, lasers and drills have benefits and risks. The results of this study demonstrate significant differences in SPLs of common otologic lasers and drills. Although noise-induced hearing loss is a function of both SPL and duration of exposure, surgeons should consider these differences when selecting and applying these tools, especially when used on or adjacent to the ossicular chain and stapes footplate.

Experimental and clinical results of Er:YAG laser stapedotomy

BACKGROUND AND OBJECTIVE

At the beginning of the 1980s, different laser types were used for stapes surgery to reduce potential harm to inner ear structures through manipulation with conventional instruments during stapedotomy. Most clinical studies were carried out with the CO2 or the argon laser. The Er:YAG laser has been used rarely in patients with otosclerosis.

STUDY DESIGN/MATERIALS AND METHODS

In an experimental study on 54 human petrous bones, the optimal laser energy parameter for dissection of the posterior stapes crus and the footplate perforation were determined. With these parameters, stapedotomy was carried out with the Er:YAG laser in 29 patients with otosclerosis with a conventional dissection of the incudostapedial joint and the stapedius muscle tendon. The Er:YAG laser was used (60 or 100 mJ, 3-6 pulses) for dissection of the posterior stapes crus and footplate perforation.

RESULTS

No intra- or postoperative complications were observed in all 29 patients. Vertigo and hearing loss were not observed intra- or postoperatively. The postoperative hearing results (improvement of the air-bone gap) was in all cases satisfactory (median remaining air bone gap, 8.1 dB). The median operation time was 29 minutes (15-42 minutes) and did not show a significant prolongation in comparison to the conventional technique. In 1 of the 29 patients, the footplate perforation needed to be carried out conventionally.

CONCLUSION

For the first time, Er:YAG laser parameters have been optimized and refined in a human petrous bone model and were then used in a clinical setting. According to the presented results, the Er:YAG laser seemed to be a very suitable instrument for stapedotomy.

Is the Er:YAG Laser Damaging to Inner Ear Function?

OBJECTIVE

To assess whether the use of the Er:YAG laser in middle ear surgery has negative effects on inner ear function.

STUDY DESIGN

Prospective.

PATIENTS

Forty-nine patients with a 4- to 18-month postoperative audiologic follow-up were included in the study (24 stapedotomies, 23 malleostapedotomies, 1 surgery for congenital ear atresia, and 1 tympanoplasty). Twenty patients with conventional stapedotomy formed a control group.

RESULTS

No statistically significant differences in preoperative and postoperative bone conduction thresholds and no impairment of postoperative air conduction thresholds were found. There was no significant difference between the results of the laser and the conventional stapedotomy. In addition, no relevant correlation between applied laser energy and postoperative hearing results were found. In summary, the authors were unable to find a negative effect of the Er:YAG laser on inner ear function at the 4- to 18-month audiometric follow-up.

CONCLUSION

The clinical use of the Er:YAG laser with the system used in this study poses no risk to inner ear function if the total amount of energy is kept within the limits applied in this study.