Otolaryngology–Head and Neck Surgery (2008) 138, 507-512

ORIGINAL RESEARCH—OTOLOGY AND NEUROTOLOGY

Erbium: yttrium-aluminum-garnet laser

stapedotomy—A safe technique

Claudio Parrilla, MD, PhD, Jacopo Galli, MD, Anna Rita Fetoni, MD,

Mario Rigante, MD, and Gaetano Paludetti, MD, Rome, Italy

OBJECTIVE: To standardize the technical parameters of theerbium: yttrium-aluminum-garnet (Er:YAG) laser stapedotomy.STUDY DESIGN: Retrospective study of all patients with oto-sclerosis who underwent stapedotomy from January 2002 to Jan-uary 2006.SUBJECTS AND METHODS: The charts of 152 consecutivepatients who underwent stapedotomy were reviewed. The patientswere 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 foundover all measured frequencies, between pre- and postoperativebone conduction thresholds, in each group. At the last postopera-tive follow-up, vertigo and nystagmus were not detected; twopatients in group A and one patient in group B showed persistenttinnitus.CONCLUSION: Er:YAG laser stapedotomy is a safe and effec-tive procedure, with no damage of the inner ear when strict ad-herence to the safety parameters is observed. The Er:YAG laser isdefinitively suitable for stapes surgery, and represents a useful andsafe tool in the armamentarium of otological microsurgery.© 2008 American Academy of Otolaryngology–Head and NeckSurgery Foundation. All rights reserved.

Since the first Argon laser stapedotomy performed byPerkins in 1978,1 several laser systems have been clin-

ically adopted for otosclerosis, with the aim to minimizeinner ear damage, compared with that induced by conven-tional surgery.2-4 In fact, the main hypothetical cause ofsensorineural hearing loss in stapedectomy or stapedotomysurgery is secondary to an intraoperative trauma of thelabyrinth during footplate manipulation, particularly in thecase of a narrow oval window niche, in the presence of athin, fragile, and floating footplate, or in revision surgery.

Several laser systems have proven to be safe in stape-dotomy. Among them, visible light lasers (eg, argon andpotassium-titanyl-phosphate [KTP]) were first used.1,2-4

They are available with microhandpiece devices that allowdelivery of the energy directly through a curved fiber car-rier; these devices are a very useful tool in the armamen-tarium of stapes surgery in case of unfavorable anatomy.

Received August 4, 2007; revised December 5, 2007; accepted Decem-

ber 26, 2007.

0194-5998/$34.00 © 2008 American Academy of Otolaryngology–Head and Necdoi:10.1016/j.otohns.2007.12.033

The main disadvantage of these laser systems is representedby the thermal effects on deeper structures, a possible causeof carbonization of adjacent tissue, and penetration throughperilymph, with potential high risks of injury to inner earstructures.

On the other hand, many evidences in the literature showthat invisible light lasers (carbon dioxide [CO2] laser anderbium: yttrium-aluminum-garnet [Er:YAG] laser) are be-coming a widely accepted resource for stapes surgery, nowrepresenting a convincing option for stapedotomy, althoughthey are deficient in microhandpiece delivery system.5-8

In fact, because of their wavelengths, invisible lasersystems have near-optimal tissue absorption characteristics,being strongly absorbed by bone and allowing precise per-forations, thus reducing carbonization of the surroundingtissue and avoiding damage to middle and inner ear struc-tures. These characteristics allow the achievement of asharply defined perforation, with clean-cut edges. On thesegrounds, the CO2 laser with the SurgiTouch system (Lume-nis Co., Tel Aviv, Israel) and the “one-shot” technique areconsidered by some authors to be one of the best techno-logical improvements in the field of stapes surgery in thelast 5 years.8

With regard to the Er:YAG laser, it has the highestablation rate of bone, over 320 �g/J, among all other lasersystems used so far in otolaryngology9; therefore, veryprecise footplate perforation and minimal carbonization ofthe surrounding tissue are achieved.

However, as with all pulsed lasers, the Er:YAG laser canpotentially cause a mechanical injury of the cochlea, attrib-utable to a shock wave created by explosive bone ablation.10

In this respect, two recently published clinical reports in-vestigated the safety of the Er:YAG laser for inner earfunction, judging this system not fully recommendable forstapes surgery because of the early and transient postoper-ative bone conduction (BC) threshold shift (although a com-plete recovery was observed 6 hours after the surgical pro-cedure),11 and to the poor clinical substantiations.8

Nevertheless, several clinical and experimental studiesreported that the Er:YAG laser stapedotomy is safe and

k Surgery Foundation. All rights reserved.

508 Otolaryngology–Head and Neck Surgery, Vol 138, No 4, April 2008

effective,12-15 although the accurate analysis of these reportsshows that the clinical parameters for a safe Er:YAG laserstapedotomy are not sufficiently standardized, as we havealready outlined in a previous paper.16

The aim of this study was to confirm the efficacy ofmicroscope-integrated Er:YAG laser stapedotomy in oto-sclerosis, by means of an analysis of late postoperative airconduction (AC) and bone conduction (BC) hearing thresh-olds, and to standardize parameters for this procedure, so asto achieve clinical safety for inner ear function.

MATERIALS AND METHODS

A total of 152 stapes surgeries, consecutively performedbetween January 2002 and January 2006 at our institutionby the same trained surgeon, were retrospectively analyzed.Audiometric data of patients were prospectively collectedfor the study.

In our department the Er:YAG laser has been in use forstapes surgery since 2002. Since 2004 this technique hasbeen used to perform almost all stapes surgeries. Over theperiod of study, a microscope-integrated Er:YAG laser sta-pedotomy was performed on 101 patients (group A) and aconventional stapedotomy on 51 patients (group B). GroupA consisted of 39 males and 62 females, aged between 26and 65 years (mean age 38 years); group B consisted of 16males and 35 females, aged between 28 and 67 year (meanage 37 years). The choice of a conventional or laser tech-nique was determined randomly; the surgeon’s trendpointed more and more often toward the laser technique,thus explaining the different number of patients in the twogroups.

In group A, all stapedotomies were performed withthe OPMI®TwinEr:YAG laser (wavelength, 2.94 �m;Oberkochen, Germany) mounted to a Zeiss operating mi-croscope (focal length 300 mm; Oberkochen, Germany).The laser pulses are applied by the micromanipulator-drivenbeam from the optic of the microscope. Pulses of 30 mJ(footplate perforation) to 40 mJ (ablation of stapes super-structure) were used. The laser spot diameter was set to 0.38mm2, resulting in an energy density of 4.6 J/cm2 per laserpulse, and a pulse duration of 200 �s. The Er:YAG laserwas used to cut the posterior crus of the stapes and toperforate the footplate in the posterior third. A multishottechnique was always used. The number of shots deliveredwas correlated with the footplate thickness.

In group B, stapedotomies were performed convention-ally with manual microperforators.

This study was approved by the Ethics Committee of theMedical Faculty of the Catholic University in Rome, andpatients gave their informed consent before participation.The functional results were evaluated according to theguidelines of the Committee on Hearing and Equilibrium ofthe American Academy of Otolaryngology–Head and Neck

Surgery.17

Preoperative and postoperative AC and BC values at0.25, 0.5, 1, 2, 3, and 4 KHz were recorded.

Pure-tone average (PTA) was calculated as the mean of0.5, 1, 2, and 3 KHz thresholds. The four-frequency PTAwas used to compute the postoperative air-bone gap. Animpairment of the inner ear function due to Er:YAG lasersurgery could be overlooked in the cases with Carhart ef-fect, which is defined as BC depression in the presence of aconductive hearing loss. To avoid this kind of biasing in theclosure gap evaluation, we calculated the postoperativeABG as a result of postoperative air conduction AC-PTAminus postoperative BC-PTA. Postoperative hearing gainwas calculated as ABG before the operation minus ABG ofthe last follow-up examination.

An audiogram of BC-PTA was obtained at least 6 weeksafter stapes surgery. For the postoperative audiogram, thedifference between preoperative and postoperative BC-PTAaverage at 0.5, 1, 2, 3, and 4 KHz was calculated as ameasure of closure, or operative damage to hearing.

To evaluate the inner ear function, preoperative BCthresholds (obtained within 10 days before surgery) werecompared with postoperative BC hearing thresholds (ob-tained at least 6 months after surgery). Occurrence of nystag-mus was assessed by means of physical examination; vertigoand tinnitus were assessed by means of patient reporting.

Measurements were performed in a soundproof room. Asuitable masking of the contralateral ear during BC mea-surement was always applied.

Statistical analysis of the results was performed withStudent’s t and �2 tests. Significance was set at P � 0.05.

RESULTS

The initial mean threshold of AC-PTA was 54.13 dB ingroup A and 51.41 dB in group B, with no statisticallysignificant difference between the two. At least 6 monthsafter the operation, AC-PTA in group A was 28.73 dB(Fig 1); after conventional stapedotomy (group B), the AC-PTA was 27.42 dB (Fig 1). By Student’s t test, a statisticallysignificant improvement (P � 0.05) in postoperative ACthreshold was found in all frequencies, both in group A andgroup B.

Before laser stapedotomy, the patients showed a meanBC-PTA of 27.66 dB, at 0.5, 1, 2, 3, and 4 KHz frequencies.

Figure 1 The histogram shows the pre- and postoperative PTA

air conduction, in group A and in group B. *P � 0.05.

509Parrilla et al Erbium: yttrium-aluminum-garnet laser . . .

Twelve months after surgery, BC-PTA improved by 2.73dB (range �3.75 to 10 dB). The patients who underwentconventional stapedotomy gained in BC-PTA by 1.4 dB(range �7.5 to 6.25 dB). However, in comparison of pre-and postoperative BC thresholds in each group, no statisti-cally significant differences were found by Student’s t testover all measured frequencies (Figs 2 and 3).

The sensorineural hearing loss (SNHL) was defined as apostoperative BC threshold of 10 dB higher than the pre-operative average of BC values at 1, 2, and 4 KHz. Theoverall rate of SNHL was 1.97 percent (3 of 152 patients).The laser group had a 1.98 percent rate of SNHL, comparedwith 1.96 percent in the conventional technique group. Thisdifference was not statistically significant.

The mean preoperative ABG was 27.3 dB in group A and26.9 dB in group B, with no statistically significant differ-ence between the two. At the last follow-up (12 months),group A showed a mean ABG of 7.7 dB and group B of 8.3dB. The Student’s t test revealed a significant differencebetween preoperative and postoperative ABG in each group(Fig 4). Mean ABG improved in group A by 19.6 dB and by18.6 dB in group B. The difference between the gains of thetwo groups was not significant (P � 0.160).

Figure 5 shows the number and the percentage of sub-jects with mean preoperative ABG within the ranges of 0 to10 dB, 11 to 20 dB, 21 to 40 dB, and �40 dB HL, beforeand after the operation, in the two groups. The number ofpatients with an ABG between 0 to 20 dB improved aftersurgery in both groups: 94.50 percent in group A and 92.15percent in group B (75.24% and 74.50% closed ABG towithin 0 to 10 DB, respectively; P � 0.05).

In 97.02 percent of patients in group A (98 of 101) andin 96.07 percent of patients in group B (49 of 51), no

Figure 3 The picture shows the mean BC thresholds before and

Figure 2 The picture shows the mean BC thresholds before andafter laser stapedotomy (group A).

after conventional stapedotomy (group B).

spontaneous vertigo, nystagmus, and tinnitus were observedduring the first 3 postoperative days. At the last postopera-tive follow-up (12 months), vertigo and nystagmus disap-peared in all patients, but two of three patients in group Aand one of two patients in group B showed persistent tin-nitus (Table 1).

In the laser-operated patients (group A), we obtainedfootplate perforations by delivering 13 � 17 single pulses of30 mJ (mean 15 pulses), resulting in a mean total amount ofenergy of 450 mJ. We used a total amount of energy higherthan 500 mJ in three patients only; two of them (1.98%)complained of persistent tinnitus, postoperatively (Table 2).

DISCUSSION

The main advantage of the laser in stapes surgery is tocreate an atraumatic opening in the fixed or mobile footplate

Figure 4 Pre- and postoperative ABGs in group A and in groupB. *P � 0.05.

Figure 5 The picture shows the percentage of patients stratifiedaccording to the ABG, in group A and in group B, before (A) and

after (B) surgery.

510 Otolaryngology–Head and Neck Surgery, Vol 138, No 4, April 2008

that does not involve use of the hands, thus avoiding me-chanical manipulation. This noncontact laser vaporizationhas been proposed as the gold standard technique in stapessurgery, particularly in cases of a narrow oval windowniche; in the presence of a thin, fragile, and most of all,floating foot-plate6,7; and in revision surgery.18

However, several laser-related risks for the membranousinner ear, such as heat dispersion, direct irradiation energy,and acoustic shock, have represented strong deterrents to thecommon adoption of this technique.

Therefore, over the last 2 decades, visible (argon andKTP) and invisible (CO2 and Er:YAG) laser systems havebeen proposed as the “perfect” tool to achieve a risk-freestapedotomy, supported by the results of several clinicalstudies.3,4,14

In our previous report16 we showed the safety of theEr:YAG laser system, with no change in the early (1-3 dayspostoperatively) and late BC thresholds, but we questionedthe lack of standardization of clinical parameters in theEr:YAG laser stapedotomy.

In fact, analysis of the literature shows that previousreports did not provide precise and standardized informationabout both the number of pulses and the total amount ofenergy used.6,13,14

Considering the results of our preliminary experience(inner ear damage in one patient with total amount of energygreater than 750 mJ),16 the philosophy followed by ourdepartment was to minimize the total amount of energy.Therefore, we perforated the footplate stapes by 13 � 17single pulses of 30 mJ, and we used a total amount of energygreater than 500 mJ in three cases only. All three patientsreceived such high energy because of an unusually thickfootplate.

Table 1

Number of patients in both groups showing nystagmu

after surgery

Ny

Group A Group B

Within 3 days 2 012 months 0 0

Table 2

Signs of transient and/or permanent inner ear damage

the total amount of laser energy (LE)

Nystagmus Vertig

3 days 12 months 3 days 12

LE � 500 mJ 0 0 0LE � 500 mJ 2 0 3

All patients in the manual technique group who had athick footplate and required a traditional drillout techniquedid not show any inner ear damage. The choice of the optionfor the treatment of a thick footplate or obliterative otoscle-rosis was not discussed in our study because of the smallnumber of patients with this finding. This may represent anissue of debate in the future, through further studies.

Our experience confirms that limiting the total amount ofdelivered energy to less than 500 mJ is of paramount im-portance, although experimental studies show that the initialsigns of cochlear damage begin after an energy delivery of2.1 J.19

The analysis of our results seems to outline the validityof these issues. The comparison of preoperative and post-operative (12 months) BC, assessed up to 4000 Hz, did notshow any significant differences in 99 of 101 patients whounderwent laser stapedotomy. Only two patients showeddeterioration higher than 10 dB. No difference in BCthresholds was found between patients who underwent la-ser stapedotomy and those who underwent conventionalstapedotomy.

In the laser stapedotomy group, tinnitus was detected in3 of 101 patients at the early follow-up, and in 2 of 101patients at the late follow-up (1.98%). A transient postop-erative dizziness occurred in 3 of 101 patients. However, atthe late follow-up, neither persistent postoperative vertigonor nystagmus was observed.

Moreover, functional results show that a postoperativeABG within the range of 0 to 20 dB was attempted in 94.5percent of Er:YAG laser–treated patients. In the literature,closure of the postoperative ABG to 20 dB or less wasachieved by 85 percent to 99 percent of the patients whounderwent laser stapedotomy.4,20

), vertigo, or tinnitus, within 3 days and 12 months

Vertigo Tinnitus

p A Group B Group A Group B

1 3 20 2 1

) in the laser group patients, stratified according to

Tinnitus Patients with IED

ths 3 days 12 months 3 days 12 months

0 0 0 03 2 3 2

s (Ny

Grou

30

(IED

o

mon

00

511Parrilla et al Erbium: yttrium-aluminum-garnet laser . . .

The most original and important finding of our study wasthat all the signs of inner ear damage (persistent tinnitus,transient dizziness, and deterioration of BC �10 dB) wereobserved in the three patients who received a total amountof energy greater than 500 mJ, because of the presence of aparticularly thick footplate.

In our opinion, although the safety and efficacy of theEr:YAG laser stapedotomy is assumed, the main limit of thislaser technique is represented by the application of slightlyoverlapping pulses directly to the perilymph, through an exist-ing fenestration of the stapes footplate (ie, multiple-shot tech-nique). For this reason we strongly suggest performing a ro-sette formation with the laser for stapedotomy calibration.This technical procedure is useful to minimize direct appli-cation to the perilymph, while not avoiding it. Some authorsencourage the combination of the laser-assisted techniquewith the conventional one to set the original perforation andto enlarge the stapedotomy, respectively.5 We found thecombined technique particularly indicated in the case ofobliterative otosclerosis or of an unusually thick footplate,so as to minimize the total amount of energy delivered. Inparticular, a traditional drillout technique (to obtain a “bluethin footplate”) should be combined with a final laser per-foration of the footplate: The total amount of energy wouldtherefore be reduced.

Recent clinical reports show that an adequately large andcircular perforation with no negative effect on the inner earfunction is achieved by one-shot stapedotomy with CO2

laser.8 If these results are confirmed by other clinical re-ports, this technique could represent a considerable advancein laser stapes surgery.

CONCLUSIONS

Our findings suggest that, in the hands of a skillful surgeon,both the Er:YAG laser–assisted stapedotomy and the con-ventional technique yield acceptable and long-lasting func-tional results.

In particular, our results show that Er:YAG laser stape-dotomy is a safe and effective procedure, with no damage tothe inner ear when adherence to the safety parameters isstrictly observed.

Patients with an unusually thick footplate who receivedlaser energy greater than 500 mJ had a higher complicationrate, related to inner ear damage. So far, no data are avail-able concerning use of the Er:YAG laser in cases of anunusually thick footplate or obliterative otosclerosis. Inthese cases the authors suggest the use of a combinedtechnique.

These data, as well as the data in the literature, allow usto conclude that Er:YAG laser is definitively suitable forstapes surgery, and represent a useful and safe tool in thearmamentarium of otological microsurgery, especially inmanaging some particular intraoperative findings such as anarrow oval window niche or a fragile and floating foot-

plate.

AUTHOR INFORMATION

From the Institute of Otolaryngology, Catholic University of Sacred Heart(Drs Parrilla, Galli, Fetoni, Rigante, and Paludetti).

Corresponding author: Claudio Parrilla, MD, Institute of Otolaryngology,Catholic University of Sacred Heart, Largo Gemelli n.8, 00168, Rome,Italy.

E-mail address: claudioparrilla@yahoo.com.

AUTHOR CONTRIBUTIONS

Claudio Parrilla: design of the clinical record, writing the paper; JacopoGalli: participated in writing the paper; Anna Rita Fetoni: data collection;Mario Rigante: data collection; Gaetano Paludetti: participated in writ-ing the paper, supervisor.

FINANCIAL DISCLOSURE

None.

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