Learning curve of medialization thyroplasty using a Montgomery™ implant

Eur Arch Otorhinolaryngol DOI 10.1007/s00405-014-3292-z LARYNGOLOGY Learning curve of medialization thyroplasty using a MontgomeryTM implant G. Desuter • S. Henrard • D. Boucquey • M. Van Boven • Q. Gardiner • M. Remacle Received: 16 July 2014 / Accepted: 12 September 2014 Ó Springer-Verlag Berlin Heidelberg 2014 Abstract Type I thyroplasty—also called medialization thyroplasty (MT)—is considered as an effective treatment for glottic incompetence in general and for abductor vocal fold palsy in particular. In the past there have been some concerns about the experience a laryngeal framework surgeon should have in order achieve an acceptable voice outcome. To assess the learning curve of MT performed using the MontgomeryÒ hard silicone implant. A retrospective study involving 36 patients divided into three consecutive groups (1, 2, 3) of 12 MT patients or six consecutive groups (1a, 1b, 2a, 2b, 3a, 3b) of six MT patients. Outcome measures: acoustic and aerodynamic outcome improvements (d) compared to the duration of intervention [operative times (OT)]. Data were analysed by G. Desuter (&)
D. Boucquey Otolaryngolgy, Head and Neck Surgery Department, Voice and Swallowing Clinic, Cliniques Universitaires Saint-Luc, Université Catholique de Louvain, 10 avenue Hippocrate, 1200 Brussels, Belgium e-mail: [email protected]; [email protected] S. Henrard Institute of Health and Society (IRSS), Université Catholique de Louvain, Brussels, Belgium M. Van Boven Anesthesiology Department, Cliniques Universitaires Saint-Luc, Université Catholique de Louvain, Brussels, Belgium Q. Gardiner Otolaryngology, Head and Neck Surgery Department, Ninewells Hospital, University of Dundee, Dundee DD19SY, UK M. Remacle Otolaryngology, Head and Neck Surgery Department, Cliniques Universitaires de Mont-Godinne, Université Catholique de Louvain, Yvoir, Belgium Anova, Kuskal Wallis and v2 statistical tests, according to data distributions. OT decreased significantly between groups 1, 2 and 3 with a mean OT of 90.50 , 71.50 and 560 (p \ 0.001), respectively. Objective d such as maximum phonation time (MPT) (p 0.376), Estimated Sub-Glottic Pressure (ESPG) (p: 0.675) Shimmer (p: 0.543) and Jitter (p: 0.709) did not show significant improvement. Only the voice handicap index (VHI) d of group 2 showed significant improvement (p 0.005) compared with the two other groups 1 and 3. Surgeon experience decreases the OT significantly. On the other hand, our study did not show a correlation between surgeon experience and voice outcome measures improvemnts (MPT, ESGP, Shimmer, Jitter). Keywords Type 1 thyroplasty
Medialization thyroplasty
Learning curve
Montgomery prosthesis Introduction Many techniques and materials for performing type I thyroplasties–also called medialization thyroplasty (MT)-have been proposed over the years, with similar outcomes. There is no evidence in the literature to support the use of one or other technique nor material, although silicone (self-carved or PhonoformTM), MontgomeryTM prosthesis and GoretexTM appear to be the most utilized materials in the US. In Europe, the Friederich’s titanium implant is also widely used. Presently, the choice of technique and material used to perform MT is mostly determined by the surgeon’s degree of confidence in using it. Little has been published in the English literature on how this confidence is gained. Similarly, there has been some concern about the experience a laryngeal framework surgeon should have in order achieve an acceptable voice outcome. 123 Eur Arch Otorhinolaryngol Fig. 1 Number of MT performed per year This study examines the learning curve of a novice phonosurgeon performing MT using the MontgomeryTM hard silicone implant. Patient recruitment started after a 3 day medialization thyroplasty (MT) course providing hands-on teaching using cadaver larynges. The surgeon had not attended other similar courses nor had additional mentoring. Patient referrals were mostly triggered by mouth to mouth reputation among the local physician community. Materials and methods The case notes of 36 patients treated by MT using a MontgomeryTM hard silicone implant were studied retrospectively. All patients were operated on by the same surgeon (GD) between May 2004 and March 2013 for unilateral adductor vocal fold palsy causing dysphonia and respiratory fatigue during speech (Fig. 1). All patients were operated on at least 6 months after the initial consultation confirming a vocal fold palsy. The duration of dysphonia before MT was variable, from 6 to 204 months. The patient cohort showed a sex ratio of 15 males to 21 females. There were 6 right vocal fold palsies and 30 left vocal fold palsies. The mean age in the cohort was 56 years (min 18 years, max 88 years). No MTs using another material was performed in this group. All MTs were performed under light intravenous sedation and cutaneous local anaesthesia with per-operative voice feedback as the sole outcome control. The procedures were conducted as described by Montgomery et al. [1, 2].The only operative change during this study consisted of a modification in the patient’s draping. From 2009, the patient’s mouth and nose were left 123 uncovered and included in the operative field to allow better per-operative voice feedback. Check flexible laryngoscopy was performed at day 3 and 10 to rule out any complications. No patient needed an additional fibrerscopic examination. Cefuroxime 1 g IV was administered to the patient before the skin incision. Steroids were not given. No other treatment was given to the patient and a relative voice rest was advised for 48 h post-op. Patients were discharged at day 2 or 3 after drain removal. Extensive voice assessment was performed within a month pre-operatively and 1 month post-operatively. Pre-operative voice assessment and a 1 month postoperative voice assessment were performed according to the Basic Protocol for Functional assessment of Voice Pathology as described by the European Laryngological Society. Outcome measures consisted of: (1) the operative time (OT) from skin incision to skin closure as noted in the electronic anesthesiology record, (2) the 120 voice handicap index (VHI), (3) the estimated sub-glottic pressure recorded with (ESGP), (4) the maximum phonation time (MPT), (5) the Shimmer index (Shimmer), and (6) the Jitter index (Jitter) [3]. The ESGP were obtained by using a phonatory aerodynamic system 6600 (Kay Pentax, Montvale New Jersey USA). The MPT (best of three attempts), the Jitter and the Shimmer were obtained using a computerized speech lab model 4150B (Kay Pentax, Montvale New Jersey, USA). Patients were aggregated into ‘‘batches’’ of 3 (12 patients each) and 6 (6 patients each, each group of 12 being divided into two groups) chronological subgroups and compared with each other. Patients were aggregated into 3 ‘‘batches’’ (12 patients each). The first batch, group 1, consisted of 12 patients Eur Arch Otorhinolaryngol operated between 2004 and 2007. The second batch of 12 patients, group 2, were operated between 2009 and 2011 and the third batch of 12, group 3, were operated in 2012 and 2013. Then to avoid any temporal effects, each group of 12 was divided into two groups of 6 patients hereafter referred to as groups 1a, 1b, 2a, 2b, 3a and 3b. The operating time and the difference in pre- and post-operative voice outcomes of the chronological subgroups were compared with each other. The OT was determined in minutes (Fig. 2). The pre-op compared to post-op outcome measure differences were reported as dVHI in unit/120, dESPG in cmH2O, dMPT in seconds, dShimmer in %, dJitter in %, respectively and compared by groups. Data were analysed by Anova, Kuskal Wallis and v2 statistical tests according to patient distribution. Results Table 1 summarizes the outcome results when the cohort is split into three consecutive sub-cohorts of 12 patients and Table 2 shows similar results when the cohort is split into six consecutive sub-cohorts of 6 patients. The mean VHI decrease was 39.9 units. The mean gain of MPT was 4 s. The mean Shimmer and Jitter decrease were respectively, of 1.23 and 1.90 %. The mean change in ESGP was a decrease of 1.86 cmH2O, although increases were found in many patients of various sub-groups. Overall outcome results were comparable to other series of MT whatever the material used, especially in terms of VHI and MPT. OT decreased significantly between the chronological groups 1, 2 and 3 with a mean OT of respectively, 90.50 , 71.50 and 560 (p \ 0.001). Objective outcome differences such as maximum phonation Time (p: 0.376), estimated sub-glottic pressure (p: 0.675) Shimmer (p: 0.543) and Jitter (p: 0.709) remained unchanged between groups. Only the dVHI, difference in pre and postoperative VHI of group 2 showed significant improvement (p: 0.005) No major complications such as infection, granulation, bleeding, prosthetic extrusion needing revision or dyspnoea were noted. Discussion Fig. 2 Graph showing the evolution of OT (min), MPT (s) and VHI (U/120) along the six consecutive groups of patients Most articles written on MT underscore the difficulty of comparing MT outcomes due to the lack of standardized outcome measures. In a recent article, Shen et al. proposed Table 1 Outcome by groups in batches of 12 patients Variable Total N (%) or median [P25; P75] or mean ± SD Group 1 n (%) or median [P25; P75] or mean ± SD Group 2 n (%) or median [P25; P75] or mean ± SD Group 3 n (%) or median [P25; P75] or mean ± SD p Male 21 (58.3) 8 (66.7) 6 (50.0) 7 (58.3) 0.710 Female 15 (41.7) 4 (33.3) 6 (50.0) 5 (41.7) Age (years) 60.7 [47.0; 70.2] 49.2 [33.8; 56.0] 63.6 [52.1; 73.0] 65.5 [58.7; 71.0] 0.042a OT (min) 71.5 [58.0; 85.5] 90.5 [74.0; 97.0] 71.5 [63.5; 82.8] 56.0 [51.8; 64.5] \0.001a -39.9 ± 24.1 -34.4 ± 26.6 -57.3 ± 26.6 -28.2 ± 19.7 Gender dVHI (units/120) 0.005b 2 dPSG (cmH O) -0.58 [-1.86; 1.73] -0.88 [-1.44; 0.06] -0.23 [-2.56; 2.39] -0.47 [-1.86; 2.94] 0.675 dTMP (s) dShimer (%) 4.0 [2.0; 9.5] -1.23 [-4.52; 0.25] 3.5 [1.8; 5.3] -1.20 [-4.15; -0.05] 7.0 [2.8; 14.3] -2.12 [-4.73; -0.18] 4.9 [-1.5; 11.3] -1.07 [-1.76; 1.83] 0.376 0.543 dJitter (%) -1.90 [-3.29; -0.78] -2.20 [-2.95; -1.90] -1.35 [-3.29; -0.65] -1.40 [-3.76; -0.56] 0.709 a Group 1 different of 3 b Group 1 different of group 2 and group 2 different of group 3 123 123 Table 2 Outcomes by groups in batches of 6 patients Variable Total N (%) or median [P25; P75] or mean ± SD Group 1a n (%) or median [P25; P75] or mean ± SD Group 1b n (%) or median [P25; P75] or mean ± SD Group 2a n (%) or median [P25; P75] or mean ± SD Group 2b n (%) or median [P25; P75] or mean ± SD Group 3a n (%) or median [P25; P75] or mean ± SD Group 3b n (%) or median [P25; P75] or mean ± SD Female 21 (58.3) 3 (50.0) 5 (83.3) 2 (33.3) 4 (66.7) 4 (66.7) 3 (50.0) Male 15 (41.7) 3 (50.0) 1 (16.7) 4 (66.7) 2 (33.3) 2 (33.3) 3 (50.0) Age (years) 56.1 ± 18.2 48.2 ± 22.9 45.1 ± 9.8 66.1 ± 6.1 48.7 ± 26.3 59.6 ± 15.4 68.8 ± 11.5 0.087 OT (min) dVHI (units/ 120) 72.6 ± 16.6 -39.9 ± 24.1 84.7 ± 17.5 -31.7 ± 16.2 87.3 ± 12 -37.2 ± 15.6 67.2 ± 13.2 -58.7 ± 30.3 75.3 ± 10.7 -55.8 ± 25.2 63.8 ± 15.1 -33.5 ± 11.4 57.2 ± 10.4 -22.8 ± 25.7 0.003 0.048a dPSG (cmH2O) -0.57 [-1.86; 1.73] -0.99 [-1.25; -0.22] -0.67 [-1.68; 0.80] -3.38 [-11.85; -0.10] 2.19 [-0.12; 2.78] -0.60 [-3.04; 0.52] 2.38 [-1.55; 6.00] 0.311 dTMP (s) dShimer (%) 4.00 [2.00; 9.5] -1.23 [-4.52; 0.25] 3.00 [1.25; 7.75] -0.75 [-1.68; 0.78] 3.5 [3.00; 4.00] -2.85 [-6.17; -0.54] 7.00 [4.00; 7.00] -2.52 [-4.78; -0.36] 9.00 [3.00; 21.00] -2.12 [-4.13; 0.14] 7.05 [2.73; 11.75] -1.23 [-10.97; -1.03] 2.88 [-3.29; 8.40] 0.76 [-1.32; 2.36] 0.719 0.473 dJitter (%) -1.90 [-3.29; -0.78] -2.20 [-2.20; -1.98] -2.35 [-3.55; -1.90] -1.80 [-3.12; -1.19] -1.09 [-2.79; -0.36] -4.21 [-7.47; -1.52] -0.94 [-1.44; -0.52] 0.448 p value Gender a Differences: groups 3b-1a, 3b-1b Eur Arch Otorhinolaryngol Eur Arch Otorhinolaryngol Table 3 Comparison of VHI and MPT outcomes after MT according to Van Ardenne et al. publication [12] Cohort and material n Mean VHI difference (decrease, in units/120) Mean MPT difference (increase, in seconds) Van Ardenne et al. [12] 10 13.4 2.7 14 29.5 8.1 36 39.9 4 Carved silicone Van Ardenne et al. [12] Friedriech’s titanium implant Desuter et al. (present study) Montgomery implant a voice-related quality of life inventory—the VHI as a primary outcome and an aerodynamic measure—the MPT as a secondary outcome to evaluate the efficacy of surgery for glottic insufficiency [4]. Some other authors also consider the NHR, the Shimmer index and the glottal flow rate as good outcome measures but there is a lack of consensus on these last three indicators [5, 6]. Likewise, if the ESGP measure should hypothetically reflect the best glottic competence measure in terms of aerodynamics, measurement issues and the high variability of the ESGP 1 month after MT rules it out as a valid outcome measure. This is confirmed by our results which show that the ESPG can increase or decrease after surgery. Indeed, patients presenting a barely measurable ESGP pre-operatively can show a dramatic increase post-operatively, but other patients show a decrease of their ESGP, the MT allowing them to lower the subglottic pressure that they previously required to force air through the larynx to cause phonation. Only direct subglottic pressure, the use of which peroperatively has been tested by Remacle et al. [7] could potentially represent a third valid outcome measure. For our series of 36 cases of MT, the overall decrease of VHI index score (39.9 ± 26.6) and the overall increase of MPT (4 [2.0; 9.5] s) measured at 1 month post-operatively are comparable to other series results, whichever material was utilized [8–11]. Table 3 compares our results with the results published by Van Ardenne et al. [12], whose study is the most comparable with ours in terms of patient characteristics, surgeon experience, cohort size and voice analysis timing and techniques. The purpose of this study being the learning curve for MT, we split the entire cohort into three consecutive groups and compared the outcome results of each of the three chronological groups of 12 patients. No statistical differences were found except for the VHI of group 2 showing a statistical improvement compared to the two other groups (p \ 0.005). To avoid any temporal effects, we split the cohort into six consecutive groups of six patients and found the same results (p \ 0.048). No clear explanation was found to explain the better outcome of VHI in group 2. The etiology of the vocal fold palsy, age, gender and time between onset of palsy and surgery—time before treatment (TBT)—were investigated. None of these parameters showed significant differences. To summarize, these results suggest that the experience of the surgeon using a Montgomery prosthesis does not correlate with the functional outcome. As no major complications were noted, the reduction of adverse effects related to a surgeon’s experience could not be investigated further. Figure 1 shows the number of MT procedures performed per year. Group 1 procedures were performed within a larger frame of time than groups 2 and 3. The frequency of procedures performed were also very different within the three groups with an overall frequency of three procedures/year for group 1, six procedures/year for group 2 and eventually nine procedures/year for group 3. As can be seen, the frequency of performance of the procedure does not appear to have an impact on either the functional outcome or the complication rate. The sole factor that statistically improves with surgeon experience is the operative time that was considerably reduced between group 1 and 3 (p \ 0.001). It is interesting to compare these results to the two large surveys of laryngeal framework surgery in the US conducted in 1998 and 2010 [13, 14]. The more recent survey showed that MT accounts for the vast majority of laryngeal framework surgery (85 %) where as, perhaps surprisingly, only 50 % of respondents to the survey report obtaining preoperative voice recordings. In comparison to the 1998 survey, data from the 2010 survey suggests that surgeons are using less self-carved silicon, the same amount of Goretex and more pre-moulded US market available implants such as MontgomeryÒ, PhonoformÒ or VocoMÒ prosthesis. Whether the relative decrease of the MT/arytenoid adduction combination procedures, as shown by the 2010 survey, could be related to this increased use of pre-moulded prostheses—supposedly treating the posterior glottis—is still debated. The same survey indicates that 55 % of 936 respondents had performed fewer than 14 MT in total and 33 % have less than 6 years of experience with MT. Despite the fact that the 1998 survey demonstrated the opposite, the survey performed one decade later could not statistically demonstrate a decrease in complication rate with increasing experience, both annually as well as overall. Similarly, we had no major complications within the study period. According to the 2010 survey, this is also the 123 Eur Arch Otorhinolaryngol case for the vast majority of US surgeons performing less than 5 MT a year. Our results support the common opinion that the use of pre-moulded prostheses—when correctly utilized—provides good subjective and objective voice results when performed by a novice surgeon. These good results do not improve with experience. The sole measure that statistically improved with experience was the OT that was reduced by more than half an hour after 36 procedures while maintaining the voice results. 4. 5. 6. Conclusions To our knowledge, this study is the first to investigate the learning curve for MT performed by a sole surgeon with a single technique and material. According to the study results, MT procedures utilizing a Montgomery hard silicone prosthesis appear to be rapidly effective in terms of outcome and safety. On the other hand, surgical experience does not change the efficacy of the procedure but rather the efficiency of it, reaching the same outcome but requiring less operative time. Further retrospective studies should investigate the learning curve of MT performed with other prosthetic materials or techniques 10. Conflict of interest Authors deny any conflict of interest or financial interest with mentioned organization or company. 11. 7. 8. 9. References 12. 1. Montgomery WW, Blaugrund SM, Varvares MA (1993) Thyroplasty: a new approach. Ann Otol Rhinol Laryngol 102(8 Pt 1):571–579 2. Montgomery WW, Montgomery SK (1997) Montgomery thyroplasty implant system. 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