Eur Arch Otorhinolaryngol DOI 10.1007/s00405-014-3014-6
Otology
A comparison of hearing results following stapedotomy under local versus general anesthesia Maureen Loewenthal · Nathan Jowett · Chia‑Jung Busch · Rainald Knecht · Carsten V. Dalchow
Received: 18 December 2013 / Accepted: 16 March 2014 © Springer-Verlag Berlin Heidelberg 2014
Abstract Advances in operative technique, instrumentation, and prosthesis design in otosclerosis surgery continue since Shea performed the first successful surgery. This is the first analysis to specifically compare post-operative hearing outcomes following stapedotomy surgery performed under local versus general anesthesia. Hearing outcomes were further stratified by comparing conventional perforator and Er:YAG laser ablation perforation techniques. Pre- and post-operative audiograms were retrospectively analyzed together with the method of anesthesia and the perforation technique for all patients with otosclerosis who underwent stapedotomy between 1998 and 2007. Pre-operative individual standard audiometry frequency thresholds (IFTs), air (AC) and bone conduction pure tone averages (PTA), and air bone gaps (ABG) were compared against post-operative results. Differences between pre- and post-operative PTAs and ABGs were compared between patients who received stapedotomy under local versus general anesthesia, as well as for patients who underwent conventional versus Er:YAG laser ablation perforations. Eighty-six patients were identified of which 24 % (n = 21) received local and 76 % (n = 65) received general anesthesia. Post-operative audiograms were available for 84 and 48 patients, respectively. Significant improvements were seen across all groups for standard 4-frequency AC-PTA and ABG and for IFTs up to 3 kHz. No significant difference was seen for IFTs between M. Loewenthal (*) · C.-J. Busch · R. Knecht · C. V. Dalchow Department of Otorhinolaryngology, Head and Neck Surgery, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246 Hamburg, Germany e-mail: [email protected] N. Jowett Department of Otorhinolaryngology, Head and Neck Surgery, McGill University, Montréal, Canada
4 and 6 kHz. A significant decline in post-operative hearing thresholds was seen at 8 kHz. Significant improvements in PTA and ABG were seen for all groups. There was a trend toward general compared to local anesthesia post-operative hearing results furthermore in combination with conventional perforation technique then with laser technique. Keywords Otosclerosis · Stapedotomy · Stapes surgery · Local and general anesthesia · Laser · Footplate perforation
Introduction Stapes footplate surgery is the treatment of choice for otosclerosis-induced hearing loss. Since the introduction of modern reconstructive stapes surgery by Shea in 1956 [1–3], the technique of stapedioplasty has evolved [4]. Stapedotomy was first described in the early 1960s by Plester [5] who performed partial stapedectomy by resecting the posterior third of the stapes footplate. To reduce the risk of sensorineural hearing loss that may result from footplate manipulation, the technique was further refined by Shea and Marquet, who in 1965 pioneered the technique of creating a single central stapes footplate perforation through which a 0.6 mm Teflon prosthesis piston could be fitted. This novel technique led to improved post-operative hearing results, especially at higher frequencies [6, 7]. Since that time, surgical technique, and stapes prosthesis innovation have continued to advance, with a wide range of stapes prostheses and perforation methods currently available to the otologic surgeon. At present, the Fisch incus stapedotomy is generally accepted as the standard operative procedure [8]. Stapes footplate perforation methods include conventional perforators, microdrill, and laser ablation techniques, with the latter being increasingly used by otologic surgeons
13
[9, 10]. Lasers provide a precise and non-contact means for footplate perforation, with the aim of minimizing the risk of inner ear damage [11]. Laser systems may be operated in continuous or pulsed modes. Lasers typically operated in a continuous mode—such as some CO2 and argon lasers— ablate by means of slow photothermal vaporization, which may result in significant thermal injury to inner ear structures with improper use. The CO2 laser emits, in the infrared spectrum at 10.6 μm, a wavelength that does not penetrate deeply through intact tissues due to strong water absorption [12]. The argon laser is typically tuned to emit visible wavelengths at 488 or 514 nm in stapes surgery. Such wavelengths fall within the ‘optical window’ where deep penetration can occur that may result in unapparent thermal injury to inner ear structures. Short pulse systems—such as the microsecond pulsed erbium:yttrium–aluminum–garnet (Er:YAG) laser—ablate tissue by means of fast photothermal vaporization and photomechanical effects [13], which pose negligible risk of thermal injury, yet significant risk of acoustic shockwave-induced mechanical injury to inner ear structures, predominantly affecting higher frequencies [14]. The Er:YAG laser emits in the infrared at 2,940 nm, which like CO2 laser emission is strongly absorbed by water and hence does not penetrate deeply into tissues. Hearing outcomes following surgery for otosclerosis may be dependent on numerous factors. Previous studies have examined surgical technique, surgeon experience, method of perforation, and type of prosthesis [15–22]. It has long been accepted that stapes surgery may be performed under local (LA) or general anesthesia (GA); no prior study has explicitly compared outcomes based on the method of anesthesia. Despite previous consensus among otologic surgeons in some countries that LA should be the technique of choice, many surgeons continue to perform the procedure with the patient under GA [23]. As will be discussed, LA and GA have contrasting advantages and disadvantages, each of which may play an important role in post-operative hearing outcomes. Remarkably, only a handful of studies have compared outcomes based on the method of anesthesia, with conflicting results [24, 25]. In the present study, the potential impact of the anesthesia technique on hearing outcomes following stapedotomy for otosclerosis is assessed. Additionally, sub-group analysis comparing Er:YAG laser ablation with conventional footplate perforation is assessed for procedures done under local and general anesthesia.
Materials and methods Patient demographics A retrospective review was performed of all patients with otosclerosis who underwent primary stapedotomy between
13
Eur Arch Otorhinolaryngol
September 1998 and February 2007 at the Philipps University Medical Centre (Marburg, Germany) and the Parkklinik (Berlin, Germany) by the same experienced otologic surgeon. Revision surgery procedures were excluded. A total of 88 patients were identified, consisting of 52 women (59 %) and 36 men (41 %) with a median age of 43 years, standard deviation of 13 years, and range of 11–73 years. Primary stapedotomy was performed in 21 patients (24 %) under LA and in 65 patients (76 %) under GA. Procedure A tympanomeatal flap was elevated in the standard fashion using an endaural or transcanal approach. When necessary, a transmeatal flap was developed to widen the external canal with a diamond burr. Also when necessary, a limited anterosuperior canalplasty was performed using a curette or a drill to provide adequate exposure of the anterior tympanic spine, stapes footplate, the oval window niche, and surrounding structures, while preserving the chorda tympani. The mobility of the ossicular chain and fixation of the stapes footplate were confirmed. Central stapes footplate perforation was then performed either by Er:YAG laser ablation (single shot 20 mJ, 6–10 shots; n = 42, 49 %) or by manual perforation technique (n = 44, 51 %). A piston prosthesis was introduced after appropriate trimming and fixed to the long process of the incus with the incudostapedial joint and stapes arch intact. With the prosthesis in place, the stapes arch was then divided using either conventional crurotomy scissors or Er:YAG laser ablation. The mobility of the ossicular chain with attached piston prosthesis was then confirmed with a fine pick. Following reposition of the tympanomeatal flap and sealing of the stapedotomy margins, the wound was closed. Hearing evaluation Pure tone audiometry to determine individual frequency thresholds (IFTs) for air conduction (AC) at 0.5, 1.0, 2.0, 3.0, 4.0, 6.0, and 8.0 kHz and for bone conduction (BC) at 0.5, 1.0, 2.0, 3.0, and 4.0 kHz measured in terms of the decibel hearing level (dB HL) scale was conducted for all patients pre-operatively and at least once post-operatively. Early (≤3 months) post-operative audiograms were conducted following surgery for 84 patients (mean 2 months, range 0.2–3.4 months). In addition, late (>3 months) postoperative audiograms were also available for 48 patients (mean 21 months, range 3.6–77.6 months). Pure tone averages (PTAs) and air bone gaps (ABGs) for AC and BC were calculated for each set of corresponding IFTs based on the American Academy of Otolaryngology and Head and Neck Surgery’s (AAO-HNS) Committee on Hearing and Equilibrium [26]. Changes in AC and BC between
Eur Arch Otorhinolaryngol Table 1 Hearing parameters and hearing benefit after incus stapedotomy (n = 84), ΔABG = p ≤ 0.005
M (dB) mean value, Md (dB) median, SW (dB) range, Min (dB) minimum, Max (dB) maximum, SD (dB) standard deviation, AC air conduction, BC bone conduction
n
M (dB)
Md (dB)
SW (dB)
Mln (dB)
Max (dB)
SD (dB)
p
Δ PTA 1 AC Δ PTA 2 AC Δ PTA 3 AC Δ PTA 1 BC
84 84 84 84
16.3 11.4 12.9 1.8
15.9 13.8 12.5 3.3
83.3 76.3 83.8 41.7
48.3 42.5 46.3 20.0
13.2 12.7 13.6 7.1
0.0001 0.0001 0.0001 0.12
Δ PTA 2 BC Δ PTA 3 BC Δ PTA 4 BC Δ ABG 1 Δ ABG2
84 84 84 84 84
1.6 0.5 0.4 14.4 12.8
2.5 0.7 1.7 13.3 12.5
38.8 37.6 40.0 56.6 48.8
−35.0 −33.8 −37.5 −21.7
17.5 16.3 15.0 43.4 36.3
6.9 6.8 7.5 11.2 10.3
0.10 0.50 0.37 0.0001 0.0001
Δ ABG 3
84
12.4
11.3
55.1
−16.3
38.8
11.3
0.0001
pre- and post-operative IFTs (ΔIFT), PTAs (ΔPTA), and ABGs (ΔABG) were calculated in dB HL for each patient. PTA 1 = Ø 0.5, 1.0, 2.0 kHz PTA 2 = Ø 0.5, 1.0, 2.0, 3.0 kHz PTA 3 = Ø 0.5, 1.0, 2.0, 4.0 kHz PTA 4 = Ø 1.0, 2.0, 4.0 kHz (only BC). The post-operative hearing benefit was measured by subtracting the post-operative bone conduction (dB HL) from the post-operative air conduction (dB HL) (ABG = air bone gap). The following combinations of frequencies were determined: ABG 1 = Ø 0.5, 1.0, 2.0 kHz = [(AC 0.5 kHz–BC 0.5 kHz) + (AC 1.0 kHz–BC 1.0 kHz) + (AC 2.0 kHz– BC 2.0 kHz)]/4 ABG 2 = Ø 0.5, 1.0, 2.0, 3.0 kHz = [(AC 0.5 kHz–BC 0.5 kHz) + (AC 1.0 kHz–BC 1.0 kHz) + (AC 2.0 kHz– BC 2.0 kHz) + (AC 3.0 kHz–BC 3.0 kHz)]/4 ABG 3 = Ø 0.5, 1.0, 2.0, 4.0 kHz = [(AC 0.5 kHz–BC 0.5 kHz) + (AC 1.0 kHz–BC 1.0 kHz) + (AC 2.0 kHz– BC 2.0 kHz) + (AC 4.0 kHz–BC 4.0 kHz)]/4. Statistical analysis Pre-operative AC and BC IFTs, PTAs, and ABGs were compared against early post-operative results for each individual using the Wilcoxon matched-pairs signed-rank test. Differences between pre- and early post-operative PTAs and ABGs were compared using the Mann–Whitney U test between patients who received stapedotomy under local versus general anesthesia, as well as for patients who underwent conventional versus Er:YAG laser ablation perforations. Plots were used to compare early and late postoperative ABGs. Means (M), medians (Md), and standard deviations (SD) were reported. Significance level (α) was set at 0.05 and non-parametric tests were used. Results were analyzed using Microsoft Excel 2003 (Microsoft
−21.3 −21.3 −25.0 −13.3 −12.5
Inc., Seattle, USA) and SPSS 15.0 (Statistical Package for Social Sciences version 15.0, IBM Inc., Armonk, USA).
Results IFTs against pre-operative values (Tables 1, 2) revealed significant improvements in AC from 0.5 to 3.0 kHz (mean 14.4 dB HL, p
Otology
A comparison of hearing results following stapedotomy under local versus general anesthesia Maureen Loewenthal · Nathan Jowett · Chia‑Jung Busch · Rainald Knecht · Carsten V. Dalchow
Received: 18 December 2013 / Accepted: 16 March 2014 © Springer-Verlag Berlin Heidelberg 2014
Abstract Advances in operative technique, instrumentation, and prosthesis design in otosclerosis surgery continue since Shea performed the first successful surgery. This is the first analysis to specifically compare post-operative hearing outcomes following stapedotomy surgery performed under local versus general anesthesia. Hearing outcomes were further stratified by comparing conventional perforator and Er:YAG laser ablation perforation techniques. Pre- and post-operative audiograms were retrospectively analyzed together with the method of anesthesia and the perforation technique for all patients with otosclerosis who underwent stapedotomy between 1998 and 2007. Pre-operative individual standard audiometry frequency thresholds (IFTs), air (AC) and bone conduction pure tone averages (PTA), and air bone gaps (ABG) were compared against post-operative results. Differences between pre- and post-operative PTAs and ABGs were compared between patients who received stapedotomy under local versus general anesthesia, as well as for patients who underwent conventional versus Er:YAG laser ablation perforations. Eighty-six patients were identified of which 24 % (n = 21) received local and 76 % (n = 65) received general anesthesia. Post-operative audiograms were available for 84 and 48 patients, respectively. Significant improvements were seen across all groups for standard 4-frequency AC-PTA and ABG and for IFTs up to 3 kHz. No significant difference was seen for IFTs between M. Loewenthal (*) · C.-J. Busch · R. Knecht · C. V. Dalchow Department of Otorhinolaryngology, Head and Neck Surgery, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246 Hamburg, Germany e-mail: [email protected] N. Jowett Department of Otorhinolaryngology, Head and Neck Surgery, McGill University, Montréal, Canada
4 and 6 kHz. A significant decline in post-operative hearing thresholds was seen at 8 kHz. Significant improvements in PTA and ABG were seen for all groups. There was a trend toward general compared to local anesthesia post-operative hearing results furthermore in combination with conventional perforation technique then with laser technique. Keywords Otosclerosis · Stapedotomy · Stapes surgery · Local and general anesthesia · Laser · Footplate perforation
Introduction Stapes footplate surgery is the treatment of choice for otosclerosis-induced hearing loss. Since the introduction of modern reconstructive stapes surgery by Shea in 1956 [1–3], the technique of stapedioplasty has evolved [4]. Stapedotomy was first described in the early 1960s by Plester [5] who performed partial stapedectomy by resecting the posterior third of the stapes footplate. To reduce the risk of sensorineural hearing loss that may result from footplate manipulation, the technique was further refined by Shea and Marquet, who in 1965 pioneered the technique of creating a single central stapes footplate perforation through which a 0.6 mm Teflon prosthesis piston could be fitted. This novel technique led to improved post-operative hearing results, especially at higher frequencies [6, 7]. Since that time, surgical technique, and stapes prosthesis innovation have continued to advance, with a wide range of stapes prostheses and perforation methods currently available to the otologic surgeon. At present, the Fisch incus stapedotomy is generally accepted as the standard operative procedure [8]. Stapes footplate perforation methods include conventional perforators, microdrill, and laser ablation techniques, with the latter being increasingly used by otologic surgeons
13
[9, 10]. Lasers provide a precise and non-contact means for footplate perforation, with the aim of minimizing the risk of inner ear damage [11]. Laser systems may be operated in continuous or pulsed modes. Lasers typically operated in a continuous mode—such as some CO2 and argon lasers— ablate by means of slow photothermal vaporization, which may result in significant thermal injury to inner ear structures with improper use. The CO2 laser emits, in the infrared spectrum at 10.6 μm, a wavelength that does not penetrate deeply through intact tissues due to strong water absorption [12]. The argon laser is typically tuned to emit visible wavelengths at 488 or 514 nm in stapes surgery. Such wavelengths fall within the ‘optical window’ where deep penetration can occur that may result in unapparent thermal injury to inner ear structures. Short pulse systems—such as the microsecond pulsed erbium:yttrium–aluminum–garnet (Er:YAG) laser—ablate tissue by means of fast photothermal vaporization and photomechanical effects [13], which pose negligible risk of thermal injury, yet significant risk of acoustic shockwave-induced mechanical injury to inner ear structures, predominantly affecting higher frequencies [14]. The Er:YAG laser emits in the infrared at 2,940 nm, which like CO2 laser emission is strongly absorbed by water and hence does not penetrate deeply into tissues. Hearing outcomes following surgery for otosclerosis may be dependent on numerous factors. Previous studies have examined surgical technique, surgeon experience, method of perforation, and type of prosthesis [15–22]. It has long been accepted that stapes surgery may be performed under local (LA) or general anesthesia (GA); no prior study has explicitly compared outcomes based on the method of anesthesia. Despite previous consensus among otologic surgeons in some countries that LA should be the technique of choice, many surgeons continue to perform the procedure with the patient under GA [23]. As will be discussed, LA and GA have contrasting advantages and disadvantages, each of which may play an important role in post-operative hearing outcomes. Remarkably, only a handful of studies have compared outcomes based on the method of anesthesia, with conflicting results [24, 25]. In the present study, the potential impact of the anesthesia technique on hearing outcomes following stapedotomy for otosclerosis is assessed. Additionally, sub-group analysis comparing Er:YAG laser ablation with conventional footplate perforation is assessed for procedures done under local and general anesthesia.
Materials and methods Patient demographics A retrospective review was performed of all patients with otosclerosis who underwent primary stapedotomy between
13
Eur Arch Otorhinolaryngol
September 1998 and February 2007 at the Philipps University Medical Centre (Marburg, Germany) and the Parkklinik (Berlin, Germany) by the same experienced otologic surgeon. Revision surgery procedures were excluded. A total of 88 patients were identified, consisting of 52 women (59 %) and 36 men (41 %) with a median age of 43 years, standard deviation of 13 years, and range of 11–73 years. Primary stapedotomy was performed in 21 patients (24 %) under LA and in 65 patients (76 %) under GA. Procedure A tympanomeatal flap was elevated in the standard fashion using an endaural or transcanal approach. When necessary, a transmeatal flap was developed to widen the external canal with a diamond burr. Also when necessary, a limited anterosuperior canalplasty was performed using a curette or a drill to provide adequate exposure of the anterior tympanic spine, stapes footplate, the oval window niche, and surrounding structures, while preserving the chorda tympani. The mobility of the ossicular chain and fixation of the stapes footplate were confirmed. Central stapes footplate perforation was then performed either by Er:YAG laser ablation (single shot 20 mJ, 6–10 shots; n = 42, 49 %) or by manual perforation technique (n = 44, 51 %). A piston prosthesis was introduced after appropriate trimming and fixed to the long process of the incus with the incudostapedial joint and stapes arch intact. With the prosthesis in place, the stapes arch was then divided using either conventional crurotomy scissors or Er:YAG laser ablation. The mobility of the ossicular chain with attached piston prosthesis was then confirmed with a fine pick. Following reposition of the tympanomeatal flap and sealing of the stapedotomy margins, the wound was closed. Hearing evaluation Pure tone audiometry to determine individual frequency thresholds (IFTs) for air conduction (AC) at 0.5, 1.0, 2.0, 3.0, 4.0, 6.0, and 8.0 kHz and for bone conduction (BC) at 0.5, 1.0, 2.0, 3.0, and 4.0 kHz measured in terms of the decibel hearing level (dB HL) scale was conducted for all patients pre-operatively and at least once post-operatively. Early (≤3 months) post-operative audiograms were conducted following surgery for 84 patients (mean 2 months, range 0.2–3.4 months). In addition, late (>3 months) postoperative audiograms were also available for 48 patients (mean 21 months, range 3.6–77.6 months). Pure tone averages (PTAs) and air bone gaps (ABGs) for AC and BC were calculated for each set of corresponding IFTs based on the American Academy of Otolaryngology and Head and Neck Surgery’s (AAO-HNS) Committee on Hearing and Equilibrium [26]. Changes in AC and BC between
Eur Arch Otorhinolaryngol Table 1 Hearing parameters and hearing benefit after incus stapedotomy (n = 84), ΔABG = p ≤ 0.005
M (dB) mean value, Md (dB) median, SW (dB) range, Min (dB) minimum, Max (dB) maximum, SD (dB) standard deviation, AC air conduction, BC bone conduction
n
M (dB)
Md (dB)
SW (dB)
Mln (dB)
Max (dB)
SD (dB)
p
Δ PTA 1 AC Δ PTA 2 AC Δ PTA 3 AC Δ PTA 1 BC
84 84 84 84
16.3 11.4 12.9 1.8
15.9 13.8 12.5 3.3
83.3 76.3 83.8 41.7
48.3 42.5 46.3 20.0
13.2 12.7 13.6 7.1
0.0001 0.0001 0.0001 0.12
Δ PTA 2 BC Δ PTA 3 BC Δ PTA 4 BC Δ ABG 1 Δ ABG2
84 84 84 84 84
1.6 0.5 0.4 14.4 12.8
2.5 0.7 1.7 13.3 12.5
38.8 37.6 40.0 56.6 48.8
−35.0 −33.8 −37.5 −21.7
17.5 16.3 15.0 43.4 36.3
6.9 6.8 7.5 11.2 10.3
0.10 0.50 0.37 0.0001 0.0001
Δ ABG 3
84
12.4
11.3
55.1
−16.3
38.8
11.3
0.0001
pre- and post-operative IFTs (ΔIFT), PTAs (ΔPTA), and ABGs (ΔABG) were calculated in dB HL for each patient. PTA 1 = Ø 0.5, 1.0, 2.0 kHz PTA 2 = Ø 0.5, 1.0, 2.0, 3.0 kHz PTA 3 = Ø 0.5, 1.0, 2.0, 4.0 kHz PTA 4 = Ø 1.0, 2.0, 4.0 kHz (only BC). The post-operative hearing benefit was measured by subtracting the post-operative bone conduction (dB HL) from the post-operative air conduction (dB HL) (ABG = air bone gap). The following combinations of frequencies were determined: ABG 1 = Ø 0.5, 1.0, 2.0 kHz = [(AC 0.5 kHz–BC 0.5 kHz) + (AC 1.0 kHz–BC 1.0 kHz) + (AC 2.0 kHz– BC 2.0 kHz)]/4 ABG 2 = Ø 0.5, 1.0, 2.0, 3.0 kHz = [(AC 0.5 kHz–BC 0.5 kHz) + (AC 1.0 kHz–BC 1.0 kHz) + (AC 2.0 kHz– BC 2.0 kHz) + (AC 3.0 kHz–BC 3.0 kHz)]/4 ABG 3 = Ø 0.5, 1.0, 2.0, 4.0 kHz = [(AC 0.5 kHz–BC 0.5 kHz) + (AC 1.0 kHz–BC 1.0 kHz) + (AC 2.0 kHz– BC 2.0 kHz) + (AC 4.0 kHz–BC 4.0 kHz)]/4. Statistical analysis Pre-operative AC and BC IFTs, PTAs, and ABGs were compared against early post-operative results for each individual using the Wilcoxon matched-pairs signed-rank test. Differences between pre- and early post-operative PTAs and ABGs were compared using the Mann–Whitney U test between patients who received stapedotomy under local versus general anesthesia, as well as for patients who underwent conventional versus Er:YAG laser ablation perforations. Plots were used to compare early and late postoperative ABGs. Means (M), medians (Md), and standard deviations (SD) were reported. Significance level (α) was set at 0.05 and non-parametric tests were used. Results were analyzed using Microsoft Excel 2003 (Microsoft
−21.3 −21.3 −25.0 −13.3 −12.5
Inc., Seattle, USA) and SPSS 15.0 (Statistical Package for Social Sciences version 15.0, IBM Inc., Armonk, USA).
Results IFTs against pre-operative values (Tables 1, 2) revealed significant improvements in AC from 0.5 to 3.0 kHz (mean 14.4 dB HL, p
