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

Effects of Varying Laser Parameters During Laser Stapedotomy on Intracochlear Pressures

OBJECTIVE

Sensorineural hearing loss is a known complication of stapes surgery. We previously showed that laser stapedotomy can result in intracochlear pressures that are comparable to high sound pressure levels. Optimizing laser settings to those that correspond with the lowest pressure changes may mitigate risk for postoperative hearing loss. Here we quantify the effects of various laser parameters on intracochlear pressures and test the hypothesis that intracochlear pressure changes are proportional to the laser energy delivered.

STUDY DESIGN

Basic and translational science.

SETTING

Cadaveric dissection and basic science laboratory.

METHODS

Cadaveric human heads underwent mastoidectomies. Intracochlear pressures were measured via fiber-optic pressure probes placed in scala vestibuli and tympani. Pulses of varied stimulus power and duration from a 980-nm diode laser were applied to the stapes footplate.

RESULTS

Sustained high-intensity pressures were observed in the cochlea during all laser applications. Observed pressure magnitudes increased monotonically with laser energy and rose linearly for lower stimulus durations and powers, but there was increased variability for laser applications of longer duration (200-300 ms) and/or higher power (8 W).

CONCLUSIONS

Results confirm that significant pressure changes occur during laser stapedotomy, which we hypothesize may cause injury. Overall energy delivered depends predictably on duration and power, but surgeons should use caution at the highest stimulus levels and longest pulse durations due to the increasing variability in intracochlear pressure under these stimulus conditions. While the risk to hearing from increased intracochlear pressures from laser stapedotomy remains unclear, these results affirm the need to optimize laser settings to avoid unintended injury.

Auditory Outcomes Following Transmastoid and Middle Cranial Fossa Approaches for Superior Semicircular Canal Dehiscence Repair

OBJECTIVE

To describe postoperative hearing outcomes following transmastoid (TM) and middle cranial fossa (MCF) approaches for semicircular canal dehiscence (SSCD) repair.

STUDY DESIGN

Retrospective review.

SETTING

Academic, tertiary referral center.

PATIENTS

Adults with SSCD who underwent repair between 2005 and 2019.

INTERVENTIONS

Pure tone audiometry pre- and postoperatively after SSCD repair.

MAIN OUTCOME MEASURES

Change in air-bone gap (ABG) at 250 and 500 Hz, pure tone average (PTA), bone conduction (BC), and air conduction (AC) thresholds at 500, 1000, 2000, and 4000 Hz for patients undergoing TM and MCF approaches for SSCD repair.

RESULTS

The average change in BC PTA for patients undergoing TM (n = 26) and MCF (n = 24) SSCD repair was not significantly different between the two groups. The first and final postoperative PTAs were recorded an average of 1.7 (range 0.30-3.0) and 29.1 (range 3.5-154) months postoperatively. For patients who underwent MCF repair, the average BC PTAs increased (+) by 2.2 dB HL (p 0.43) and 0.57 dB HL (p 0.88) at the first and final audiograms respectively compared to +1.27 dB HL (p 0.53) and a decrease (-) of 0.57 dB HL (p 0.63) for the TM group. The average changes in low frequency ABG for patients undergoing MCF repair were -4.7 dB (p 0.08) and -6.9 dB (p 0.15) at first and final audiograms respectively compared to -4.9 dB (p 0.06) and -4.1 dB (p 0.36) for patients who underwent TM repair. There was a high frequency hearing loss noted at 8000 Hz for the MCF (30.0 dB ± 18.7 preop; 41.7 dB ± 21.7 postop; p 0.01) and TM (32.1 dB ± 23.2 preop; 44.3 dB ± 29.6 postop; p 0.001) groups which persisted on long term follow up.

CONCLUSIONS

Both TM and MCF approaches to SSCD repair can be performed with long-term preservation of hearing. ABGs were reduced in each treatment group but did not reach significance. A high frequency hearing loss (8000 Hz) may be expected with either approach.

Hearing results after stapedotomy for otosclerosis: comparison of prosthesis variables

OBJECTIVE

To evaluate the influence of different piston variables on hearing following stapedotomy.

METHODS

Data were analysed in groups according to: piston material (titanium vs fluoroplastic), shaft diameter (0.4 mm vs 0.5 mm) and crimping style (manual crimping vs self-crimping). Pre- and post-operative average air-bone gap, air-bone gap difference, success rate and operative time were evaluated.

RESULTS AND CONCLUSION

Fifty-one patients (58 ears) were included. A post-operative air-bone gap of 10 dB or lower was achieved in 44 cases, with a success rate of 75.9 per cent; 52 cases (89.7 per cent) had an air-bone gap of 20 dB or lower. The success rate was higher, but not significantly, in fluoroplastic than in titanium pistons (85 per cent vs 70 per cent). Pistons with shaft diameters of 0.5 mm and 0.4 mm had success rates of 79 per cent and 72 per cent, respectively. No significant differences were found for any audiometric parameters. There were no significant differences between manual crimping and self-crimping pistons in terms of audiometric results or success rate.

The impact of intra-operative factors in otosclerosis outcomes: retrospective study in a tertiary centre

The aim of the study was to assess results from a large cohort of patients undergoing otosclerosis surgery with respect to the impact of intra-operative variables on post-operative hearing function and complications. We enrolled 384 patients affected by otosclerosis who were subjected to stapes surgery between 2004 and 2013 at a single institution. Surgery was performed in all cases under local anaesthesia, using a manual perforator and/or microdrill. Teflon-piston prosthesis was used in all patients. Audiological data obtained preoperatively and at last follow-up examination (minimum 12 months) were compared. Statistical analysis was performed using the multiple regression model. Peripheral rim otosclerosis and diffuse otosclerosis were associated with better functional results compared to the obliterative pattern (p < 0.05). Mean post-operative Air-Bone Gap was significantly higher in the 0.4 mm, compared to 0.6 mm piston group at 0.5 kHz (p < 0.001) and 1 kHz (p < 0.02); in the stapedotomy group a statistically significant difference was found between 0.4 and 0.6 mm piston groups, in favour of the latter (p < 0.05). No differences were encountered in terms of average hearing threshold and complications. Intra-operative variables cannot be fully predictable and our data could help in stratification of the results and as a landmark for the surgeon’s decisions.

[The role of stapedoplasty in the treatment of hearing impairment in the patients presenting with tympanosclerosis]

The present study included the examination and surgical treatment of 50 adult patients presenting with tympanosclerotic fixation of the stirrup. The patients comprising the first subgroup (n=25) underwent the two-stage treatment during the period from 1990 to 2009. The final phase of the treatment consisted of the implantation of different kinds of stirrup prostheses placed on the venous autograft that closed the oval window of the vestibule following partial or total instrumental stapedectomy. The second subgruop was composed of the patients (n=25) who were given the two- or three-stage surgical treatment during the period from 2009 till 2014 the final phase of which was performed following the same procedures as in the first subgroup but with the use of the surgical CO₂-laser instead of the conventional instrumental methods. The pathomorphological studies carried out at different stages of the surgical treatment have demonstrated the necessity of isolation of the vestibular fluid for the purpose of implantation of the stirrup prostheses with a view to preventing cochlear complications. The results of the present study give evidence of the efficiency of stapedoplasty with the application of the autocartilaginous prostheses of the stirrup implanted on the venous autografts to close the oval window of the vestibule with the reduction of the bone-air interval down to less than 20 dB. The performance of this procedure with the use of the instrumental technique produced a favourable outcome of the treatment in 71.4% of the patients presenting with tympanosclerosis. The use of the laser-assisted approach further increased the efficiency of the treatment up to 76%. Moreover, the latter method allows to avoid the reaction of the inner ear to the surgical intervention during the early postoperative period and results in the faster averaged reduction of the bone-air interval in comparison with the patients treated with the application of the instrumental technique.

Design of a resilient ring for middle ear's chamber stapes prosthesis

This paper presents the process of designing a new elastic element replacing a membrane in the chamber stapes prosthesis (ChSP). The results of the study are volume displacement characteristics obtained for the prosthesis and physiological stapes. Simulation tests on a 3D CAD model have confirmed that a properly designed ring can stimulate perilymph with the same or greater efficacy as the physiological stapes footplate placed on the elastic annular ligament. The ChSP with a new elastic element creates a good chance of improving hearing in patients suffering from otosclerosis.

New chamber stapes prosthesis - A preliminary assessment of the functioning of the prototype

Piston-stapedotomy is the most common method for hearing restoration in patients with otosclerosis. In this study, we have experimentally examined a prototype of a new chamber stapes prosthesis. The prototype was implanted in a human cadaver temporal bone. The round window vibrations before and after implantation were measured for the acoustic signal (90 dB SPL, 0.8–8 kHz) in the external auditory canal. In comparison with a 0.4-mm piston prosthesis, the chamber prosthesis induced significantly higher vibration of the round window, especially for frequencies above 1.5 kHz. Based on the results, it can be surmised that stapedotomy with a chamber stapes prosthesis could provide better hearing results in comparison with the piston-stapedotomy.

Effectiveness of stapedotomy in improving hearing sensitivity for 53 otosclerotic patients: retrospective review

BACKGROUND

Otosclerosis is a common cause of progressive hearing impairment that causes fixation of the stapes. Surgical intervention is the preferred treatment approach to ameliorate the conductive hearing loss associated with stapedial otosclerosis. However, given that it is a difficult and delicate procedure, the surgery may fail for a number of reasons. Therefore, it is very important to evaluate the success rate of the surgical approach used in each regional center.

OBJECTIVE

To examine the effectiveness of stapedotomy in improving hearing sensitivity for otosclerotic patients at King Abdul Aziz University Hospital in Riyadh.

DESIGN

Retrospective chart review with an analysis of pre- and postoperative surgical treatment.

SETTING

Tertiary referral otolaryngology clinic.

PATIENTS AND METHODS

All cases who underwent stapedotomy between 1997 and 2009 were retrospectively reviewed. Preoperative and postoperative audiometric assessments were conducted using conventional pure tone audiometry. Differences were analyzed by two-way repeated measures ANOVA.

MAIN OUTCOME MEASURE(S)

Pre- and postoperative pure tone thresholds for air and bone conduction.

RESULT

Fifty-three patients underwent stapedotomy. Stapedotomy yielded significant improvements in mean (SD) postoperative air-conduction thresholds of about 18.7 (11.7) dB (P < .0001) and mean (SD) post.operative bone-conduction thresholds of about 2 (7.2) dB (P < .05). Additionally, a significant correlation was found between improvement in air-conduction thresholds and the size of preoperatve air-bone gap (P < .01) About 70%of patients achieved an air-bone gap of 20 dB or better. None of the cases examined in this study exhibited sensorineural hearing loss or adverse complications following stapedotomy.

CONCLUSIONS

Stapedotomy is a safe and effective treatment option for patients with otosclerosis. Given that the majority of participants in this study exhibited mixed hearing loss preoperatively, the results further suggest that stapedotomy can also be effective in improving thresholds for these patients.

LIMITATIONS

The sample size was relatively small.

Outcomes following Semicircular Canal Plugging

Objectives

To examine audiometric outcomes, symptom control rates, and complication rates following semicircular canal plugging for superior semicircular canal dehiscence syndrome.

Study Design

Retrospective chart review.

Setting

Private, neurotologic tertiary referral center.

Subjects and Methods

Patients undergoing semicircular canal plugging for superior semicircular canal dehiscence syndrome from January 1, 2007, to December 31, 2012. Pre- and postoperative audiometry, vestibular testing, operative findings, and clinical symptoms were assessed through chart review.

Results

A total of 24 ears underwent a canal plugging procedure during the study period for superior canal dehiscence syndrome. Pre- and postoperative air conduction pure-tone averages were 21.1 and 22.5 dB ( P = .42, not significant [NS]). The average pre- and postoperative word recognition scores were 95.8% and 95.1% ( P = .48, NS). Vestibular evoked myogenic potential data showed reduced thresholds in 7 patients with canal dehiscence. Complications were limited to a single, temporary facial weakness. Complete symptom improvement was noted in 35.7% of all patients, while at least partial symptom improvement was found in over 80% of patients.

Conclusion

Semicircular canal plugging procedures are associated with excellent hearing outcomes and may reduce preoperative symptoms in patients with superior semicircular canal dehiscence.

Effect of different stapes prostheses on the passive vibration of the basilar membrane

The effect of different stapes prostheses on the basilar membrane (BM) motion was determined. To that end, a three dimensional finite element (FE) model of the passive human cochlea was developed. Passive responses of the BM were found based on coupled fluid-structure interactions between the cochlear solid structures and the scala fluids. The passive BM vibrations in normal (healthy) cochlea were compared with vibrations in the cochlea in which a 0.4-mm piston or a proposed new type of prosthesis was implanted. The proposed chamber prosthesis was not experimentally implanted, but only numerically simulated. Design of the new chamber stapes prosthesis is presented for the first time in this paper. The simulation results showed 10-20 dB decrease in BM displacement amplitude in the case of the piston. In contrast, the BM responses in the cochlea with the new prosthesis are higher with respect to the healthy ear. The results obtained in this study are promising for further research to optimize the design of the new chamber stapes prosthesis.

A three-dimensional finite element model of round window membrane vibration before and after stapedotomy surgery

Piston stapes prostheses are implanted in patients with refractory conductive or mixed hearing loss due to stapes otosclerosis to stimulate the perilymph with varying degrees of success. The overclosure effect described by the majority of researchers affects mainly low and medium frequencies, and a large number of patients report a lack of satisfactory results for frequencies above 2 kHz. The mechanics of perilymph stimulation with the piston have not been studied in a systematic manner. The objective of this study was to assess the influence of stapedotomy surgery on round window membrane vibration and to estimate the postoperative outcomes using the finite element (FE) method. The study hypothesis is that the three-dimensional FE model developed of the human inner ear, which simulates the round window (RW) membrane vibration, can be used to assess the influence of stapedotomy on auditory outcomes achieved after the surgical procedure. An additional objective of the study was to enable the simulation of RW membrane vibration after stapedotomy using a new type of stapes prosthesis currently under investigation at Warsaw University of Technology. A three-dimensional finite element (FE) model of the human inner ear was developed and validated using experimental data. The model was then used to simulate the round window membrane vibration before and after stapedotomy surgery. Functional alterations of the RW membrane vibration were derived from the model and compared with the results of experimental measurements from temporal bones of a human cadaver. Piston stapes prosthesis implantation causes an approximately fivefold (14 dB) lower amplitude of the RW membrane vibrations compared with normal anatomical conditions. A satisfactory agreement between the FE model and the experimental data was found. The new prosthesis caused an increase of 20–30 dB in the RW displacement amplitude compared with the 0.4-mm piston prosthesis. In all frequencies, the FE model predicted a RW displacement curve that was above the experimental curves for the normal ear. The stapedotomy can be well simulated by the FE model to predict the auditory outcomes achieved following this otosurgery procedure. The 3D FE model developed in this study may be used to optimize the geometry of a new type of stapes prosthesis in order to achieve a similar sound transmission through the inner ear as for a normal middle ear. This should provide better auditory outcomes for patients with stapedial otosclerosis.

Comparison of round-window membrane mechanics before and after experimental stapedotomy

BACKGROUND

Surgical intervention within the area of the middle ear always leads to alteration of conditions in its biomechanical system. This fact may provide an explanation for the lack of expected auditory outcome, although an apparently good anatomic outcome was obtained. In the case of stapedotomy, the majority of patients report lack of satisfactory results for frequencies above 2,000 Hz. The effect has not been experimentally investigated yet.

METHODS

This study, conducted in four human temporal bones, yielded a record of round-window membrane vibration amplitude and phase in the frequency function (400 Hz-10 kHz) at the sound intensity level of 90 dB administered to the external auditory canal in a physiologic condition and following implantation of a Teflon piston stapes prosthesis. The procedure of experimental stapedotomy was performed with the tympanic membrane preserved from the maximally dilated approach through the posterior tympanotomy.

RESULTS

Stapes Teflon piston prosthesis implantation was found to cause approximately fivefold lower amplitude of round-window membrane vibrations compared to a physiologic situation for frequencies above 2 kHz in particular.

CONCLUSIONS

After stapedotomy, with the use of a Teflon piston prosthesis, stimulation of inner ear structures diminishes, especially in higher frequencies.

Microdrill, CO2-laser, and piezoelectric stapedotomy: a comparative study

OBJECTIVE

To compare 3 different devices used to perforate the stapes footplate in otosclerotic patients.

STUDY DESIGN

The study design was a prospective unblinded study. It was conducted at the ENT Department of a general hospital.

MATERIALS AND METHODS

Ninety subjects undergoing primary stapedotomy for otosclerosis by a senior surgeon participated. A stapedotomy operation was performed under local anesthesia with reversed sequence of surgical steps. Three different devices were used to perforate the posterior half of the footplate: a microdrill (MD), a CO2 laser (CO2), and a Piezosurgery bone device (PZS). The hole diameter was 0.7 mm. Three consecutive samples of unselected patients were recruited. All patients of each sample were operated with the same device. Main outcome measures were preoperative and postoperative air- (AC) and bone-conduction (BC) audiometry, intraoperative findings, and postoperative complications. Postoperative pure-tone audiometry was done 1 month after surgery.

RESULTS

The CO2 laser was used in 30 stapedotomies, the PZS in 30, and the MD was used in 30. Bone-conduction pure-tone averages did not worsen in the MD and CO2 groups. CO2 laser shows a trend toward less residual air-bone gap and more functional gain at low frequencies. Piezosurgery bone device patients lost approximately 10 dB in BC at 4,000 Hz. Significant differences in AC thresholds gain and in the residual air-bone gap were found between groups. Piezosurgery bone device patients had less gain and more residual gap at high frequencies as a result of a slight deterioration of BC threshold. A higher rate of postoperative vertigo was also found in PZS patients.

CONCLUSION

The use of the CO2 laser seems associated with the best functional results, although on a statistical basis, they do not differ significantly from that obtained with the standard MD platinotomy. The PZS stapedotomy is effective from a surgical point of view for most patients. However, it is associated with a slight but significant deterioration of BC at high frequency and at higher vertigo rate. More basic validation of the stimulation parameters is necessary for safe use of this new technology.

The Effect of CO(2) and KTP laser on the cat saccule and utricle

OBJECTIVES/HYPOTHESIS

To assess the potential carbon dioxide (CO(2)) and potassium-titanyl-phosphate (KTP) laser-related trauma to the saccule and utricle in a cat model.

STUDY DESIGN

Basic science experiment utilizing cat model.

METHODS

Twelve adult male cats were divided into two groups-CO(2) and KTP-to assess the potential saccule and/or utricle trauma with direct discharge of laser energy into the vestibule after the stapes was removed. Both groups were subdivided to assess the effects with acute sacrifice and three-month survival. Bone conduction auditory brain-stem response thresholds were used to monitor auditory function. Clinical observation was used to monitor vestibular function. The temporal bones were harvested, processed, and stained with hematoxylin and eosin (H&E) in all animals with the uninvolved side serving as the control.

RESULTS

None of the animals demonstrated changes in bone conduction auditory brain-stem responses. None of the animals in the survival group demonstrated clinical vestibular dysfunction. Saccular and utricular wall rupture was observed in all animals sacrificed acutely. None of the saccular and utricular wall ruptures were of a size and location that could be attributed to laser trauma, and none of the saccular and utricular wall ruptures were associated with neuroepithelial trauma.

CONCLUSIONS

There is no evidence of a difference between the CO(2) and KTP laser in potential laser-related trauma. Using bone-conducting auditory brain-stem response threshold and clinical monitoring of vestibular function, there was no evidence of clinical auditory or vestibular dysfunction. The histologic evidence of saccular and utricular wall rupture is more consistent with stapes extraction trauma than laser-related trauma.

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.

Outcome and lack of prognostic factors in stapes surgery

OBJECTIVE

To analyze predictive factors of outcome after primary stapes surgery for otosclerosis.

STUDY DESIGN

Retrospective review of 139 patients with otosclerosis and 147 operations performed by the same senior surgeon with the same surgical technique.

SETTING

Academic hospital and tertiary referral center.

PATIENTS

All patients had documented preoperative and peroperative audiologic assessments and preoperative records. The mean age of patients was 44.31 years.

INTERVENTION

Stapedotomy with diode laser using Teflon prosthesis.

MAIN OUTCOME MEASURES

The bone conduction threshold changes, the improvement of pure-tone average air-bone gaps (PTA-ABGs), and ABGs for each frequency were analyzed using 0.5, 1, 2, and 4 kHz. Success rate was defined by postoperative ABG. Log-rank test was used to define significant factors.

RESULTS

At 24 hours postoperative, there was a significant deterioration in bone conduction threshold at 1, 2, and 4 kHz. However, at 4 kHz, the threshold remained significantly worse at longer term. There was a significant improvement of the PTA-ABG. Eighty-six percent of patients obtained a PTA-ABG of 20 dB or less. We also obtained a significant ABG closure on every frequency except on 4 kHz. Multivariate statistical analysis had not identified a predictive factor of hearing outcomes such as the anatomy of the facial nerve, the incus, the stapes footplate and the external auditory canal, the prosthesis crimping, bleeding, and surgical damage of the tympanic membrane.

CONCLUSION

In experienced hands, we observed a significantly transient depression of bone conduction hearing levels that was definitively present at 4 kHz. Peroperative difficult or abnormal situations did not seem to have an influence on the hearing outcome. Those statements will enable accurate preoperative counseling. It will also permit precise matching of future series to allow accurate comparisons.