Abstract
Scarring of the vocal folds leads to a deterioration of the highly complex micro-structure with consecutively impaired vibratory pattern and glottic insufficiency. The resulting dysphonia is predominantly characterized by a reduced vocal capacity. Despite the considerable progress in understanding of the underlying pathophysiology, the treatment of scarred vocal folds is still an unresolved chapter in laryngology and phonosurgery. Essential for a successful treatment is an individual, multi-dimensional concept that comprises the whole armamentarium of surgical and non-surgical (i.p. voice therapy) modalities. An ideal approach would be to soften the scar, because the reduced pliability and consequently the increased vibratory rigidity impede the easiness of vibration. The chosen phonosurgical method is determined by the main clinical feature: Medialization techniques for the treatment of glottic gap, or epithelium freeing techniques for improvement of vibration characteristics often combined with injection augmentation or implantation. In severe cases, buccal mucosa grafting can be an option. New developments, include treatment with anxiolytic lasers, laser technology with ultrafine excision/ablation properties avoiding coagulation (Picosecond infrared laser, PIRL), or techniques of tissue engineering. However, despite the promising results by in vitro experiments, animal studies and first clinical trials, the step into clinical routine application has yet to be taken.
Similar content being viewed by others
References
Allen J (2010) Cause of vocal fold scar. Curr Opin Otolaryngol Head Neck Surg 18:475–480
Hansen JK, Thibeault SL (2006) Current understanding and review of the literature: vocal fold scarring. J Voice 20:110–120
Hirano S, Minamiguchi S, Yamashita M, Ohno T, Kanemaru S, Kitamura M (2009) Histologic characterization of human scarred vocal folds. J Voice 23:399–407
Zapater E, Frias S, Perez A, Basterra J (2009) Comparative study on chronic tissue damage after cordectomies using either CO2 laser or microdissection electrodes. Head Neck 31:1477–1481
Hirano M (1975) Phonosurgery. Basic and clinical investigations, Otologia
Gray SD, Pignatari SS, Harding P (1994) Morphologic ultrastructure of anchoring fibers in normal vocal fold basement membrane zone. J Voice 8:48–52
Gray SD, Titze IR, Alipour F, Hammond TH (2000) Biomechanical and histologic observations of vocal fold fibrous proteins. Ann Otol Rhinol Laryngol 109:77–85
Remacle M, Degols JC, Delos M (1996) Exudative lesions of Reinke’s space. An anatomopathological correlation. Acta Otorhinolaryngol Belg 50:253–264
Friedrich G, Kainz J, Freidl W (1993) Functional structure of the human vocal cord. Laryngorhinootologie 72:215–224
Sato K, Hirano M, Nakashima T (2003) 3D structure of the macula flava in the human vocal fold. Acta Otolaryngol 123:269–273
Hirano M, Sato K, Nakashima T (1999) Fibroblasts in human vocal fold mucosa. Acta Otolaryngol 119:271–276
Hirano M (1988) Vocal mechanisms in singing: laryngological and phoniatric aspects. J Voice 2:51–69
Tillmann B, Paulsen F, Werner JA (1994) Structures of the anterior commissure of the larynx. Biomechanical and clinical aspects. Laryngorhinootologie 73:423–427
Gray SD, Chan KJ, Turner B (2000) Dissection plane of the human vocal fold lamina propria and elastin fibre concentration. Acta Otolaryngol 120:87–91
Sato K, Umeno H, Nakashima T (2010) Functional histology of the macula flava in the human vocal fold–Part 2: its role in the growth and development of the vocal fold. Folia Phoniatr Logop 62:263–270
Sato K, Nakashima T, Nonaka S, Harabuchi Y (2008) Histopathologic investigations of the unphonated human vocal fold mucosa. Acta Otolaryngol 128:694–701
Sato K, Hirano M, Nakashima T (2001) Stellate cells in the human vocal fold. Ann Otol Rhinol Laryngol 110:319–325
Yamashita M, Hirano S, Kanemaru S, Tsuji S, Suehiro A, Ito J (2007) Side population cells in the human vocal fold. Ann Otol Rhinol Laryngol 116:847–852
Gugatschka M, Kojima T, Ohno S, Kanemaru S, Hirano S (2011) Recruitment patterns of side population cells during wound healing in rat vocal folds. Laryngoscope 121:1662–1667
Kumai Y, Kobler JB, Herrera VL, Zeitels SM (2010) Perspectives on adipose-derived stem/stromal cells as potential treatment for scarred vocal folds: opportunity and challenges. Curr Stem Cell Res Ther 5:175–181
Thibeault SL, Gray SD, Bless DM, Chan RW, Ford CN (2002) Histologic and rheologic characterization of vocal fold scarring. J Voice 16:96–104
Rousseau B, Hirano S, Scheidt TD et al (2003) Characterization of vocal fold scarring in a canine model. Laryngoscope 113:620–627
Rousseau B, Ge PJ, Ohno T, French LC, Thibeault SL (2008) Extracellular matrix gene expression after vocal fold injury in a rabbit model. Ann Otol Rhinol Laryngol 117:598–603
Rousseau B, Hirano S, Chan RW et al (2004) Characterization of chronic vocal fold scarring in a rabbit model. J Voice 18:116–124
Gray SD, Titze IR, Chan R, Hammond TH (1999) Vocal fold proteoglycans and their influence on biomechanics. Laryngoscope 109:845–854
Chan RW, Gray SD, Titze IR (2001) The importance of hyaluronic acid in vocal fold biomechanics. Otolaryngol Head Neck Surg 124:607–614
Thibeault SL, Rousseau B, Welham NV, Hirano S, Bless DM (2004) Hyaluronan levels in acute vocal fold scar. Laryngoscope 114:760–764
Hirano S, Bless DM, Rousseau B, Welham N, Scheidt T, Ford CN (2003) Fibronectin and adhesion molecules on canine scarred vocal folds. Laryngoscope 113:966–972
Ferdous Z, Peterson SB, Tseng H, Anderson DK, Iozzo RV, Grande-Allen KJ (2010) A role for decorin in controlling proliferation, adhesion, and migration of murine embryonic fibroblasts. J Biomed Mater Res A 93:419–428
Bouchayer M, Cornut G (1992) Microsurgical treatment of benign vocal fold lesions: indications, technique, results. Folia Phoniatr (Basel) 44:155–184
Monday LA, Cornut G, Bouchayer M, Roch JB (1983) Epidermoid cysts of the vocal cords. Ann Otol Rhinol Laryngol 92:124–127
Ford CN, Inagi K, Khidr A, Bless DM, Gilchrist KW (1996) Sulcus vocalis: a rational analytical approach to diagnosis and management. Ann Otol Rhinol Laryngol 105:189–200
Giovanni A, Chanteret C, Lagier A (2007) Sulcus vocalis: a review. Eur Arch Otorhinolaryngol 264:337–344
Sunter AV, Yigit O, Huq GE, Alkan Z, Kocak I, Buyuk Y (2011) Histopathological characteristics of sulcus vocalis. Otolaryngol Head Neck Surg 145:264–269
Itoh T, Kawasaki H, Morikawa I, Hirano M (1983) Vocal fold furrows. A 10-year review of 240 patients. Auris Nasus Larynx 10(Suppl):S17–S26
Nakayama M, Ford CN, Brandenburg JH, Bless DM (1994) Sulcus vocalis in laryngeal cancer: a histopathologic study. Laryngoscope 104:16–24
Sato K, Hirano M (1998) Electron microscopic investigation of sulcus vocalis. Ann Otol Rhinol Laryngol 107:56–60
Friedrich G (1995) Basic principles for indications in phonosurgery. Laryngorhinootologie 74:663–665
Friedrich G, Remacle M, Birchall M, Marie JP, Arens C (2007) Defining phonosurgery: a proposal for classification and nomenclature by the phonosurgery committee of the European laryngological society (ELS). Eur Arch Otorhinolaryngol 264:1191–1200
Martinez Arias A, Remacle M, Lawson G (2010) Treatment of vocal fold scar by carbon dioxide laser and collagen injection: retrospective study on 12 patients. Eur Arch Otorhinolaryngol 267:1409–1414
Benninger MS (2000) Microdissection or microspot CO2 laser for limited vocal fold benign lesions: a prospective randomized trial. Laryngoscope 110:1–17
Remacle M, Lawson G, Watelet JB (1999) Carbon dioxide laser microsurgery of benign vocal fold lesions: indications, techniques, and results in 251 patients. Ann Otol Rhinol Laryngol 108:156–164
Benninger MS, Alessi D, Archer S et al (1996) Vocal fold scarring: current concepts and management. Otolaryngol Head Neck Surg 115:474–482
Arens C, Remacle M (2010) Scarred larynx. In: Remacle M, Eckel H (eds) Surgery of the Larynx and Trachea, 1st edn. Springer Verlag, Berlin, pp 171–176
Dejonckere PH, Bradley P, Clemente P et al (2001) A basic protocol for functional assessment of voice pathology, especially for investigating the efficacy of (phonosurgical) treatments and evaluating new assessment techniques. Guideline elaborated by the committee on phoniatrics of the European laryngological society (ELS). Eur Arch Otorhinolaryngol 258:77–82
Isshiki N (2000) Progress in laryngeal framework surgery. Acta Otolaryngol 120:120–127
Friedrich G, de Jong FI, Mahieu HF, Benninger MS, Isshiki N (2001) Laryngeal framework surgery: a proposal for classification and nomenclature by the phonosurgery committee of the European laryngological society. Eur Arch Otorhinolaryngol 258:389–396
Isshiki N, Morita H, Okamura H, Hiramoto M (1974) Thyroplasty as a new phonosurgical technique. Acta Otolaryngol 78:451–457
Friedrich G (1999) Titanium vocal fold medializing implant: introducing a novel implant system for external vocal fold medialization. Ann Otol Rhinol Laryngol 108:79–86
Giovanni A, Vallicioni JM, Gras R, Zanaret M (1999) Clinical experience with Gore-Tex for vocal fold medialization. Laryngoscope 109:284–288
McCulloch TM, Hoffman HT (1998) Medialization laryngoplasty with expanded polytetrafluoroethylene. Surgical technique and preliminary results. Ann Otol Rhinol Laryngol 107:427–432
Montgomery WW, Montgomery SK (1997) Montgomery thyroplasty implant system. Ann Otol Rhinol Laryngol Suppl 170:1–16
van Ardenne N, Vanderwegen J, Van Nuffelen G, De Bodt M, Van de Heyning P (2011) Medialization thyroplasty: vocal outcome of silicone and titanium implant. Eur Arch Otorhinolaryngol 268:101–107
Schneider B, Denk DM, Bigenzahn W (2003) Functional results after external vocal fold medialization thyroplasty with the titanium vocal fold medialization implant. Laryngoscope 113:628–634
Isshiki N, Shoji K, Kojima H, Hirano S (1996) Vocal fold atrophy and its surgical treatment. Ann Otol Rhinol Laryngol 105:182–188
Zeitels SM, Mauri M, Dailey SH (2003) Medialization laryngoplasty with Gore-Tex for voice restoration secondary to glottal incompetence: indications and observations. Ann Otol Rhinol Laryngol 112:180–184
Friedrich G (1998) External vocal fold medialization: surgical experiences and modifications. Laryngorhinootologie 77:7–17
Friedrich G (1998) External vocal cord medialization: functional outcome. Laryngorhinootologie 77:18–26
Koufman JA (1989) Surgical correction of dysphonia due to bowing of the vocal cords. Ann Otol Rhinol Laryngol 98:41–45
Sittel C, Friedrich G, Zorowka P, Eckel HE (2002) Surgical voice rehabilitation after laser surgery for glottic carcinoma. Ann Otol Rhinol Laryngol 111:493–499
Sulica L, Blitzer A (2006) Treatment. In: Sulica L, Blitzer A (eds) Vocal Fold Paralysis, 1st edn. Springer Verlag, Berlin, pp 77–85
Sulica L, Rosen CA, Postma GN et al (2010) Current practice in injection augmentation of the vocal folds: indications, treatment principles, techniques, and complications. Laryngoscope 120:319–325
Carroll TL, Rosen CA (2011) Long-term results of calcium hydroxylapatite for vocal fold augmentation. Laryngoscope 121:313–319
Sittel C, Echternach M, Federspil PA, Plinkert PK (2006) Polydimethylsiloxane particles for permanent injection laryngoplasty. Ann Otol Rhinol Laryngol 115:103–109
Rosen CA, Gartner-Schmidt J, Casiano R et al (2007) Vocal fold augmentation with calcium hydroxylapatite (CaHA). Otolaryngol Head Neck Surg 136:198–204
Gillespie MB, Dozier TS, Day TA, Martin-Harris B, Nguyen SA (2009) Effectiveness of calcium hydroxylapatite paste in vocal rehabilitation. Ann Otol Rhinol Laryngol 118:546–551
Bergamini G, Alicandri-Ciufelli M, Molteni G et al (2010) Therapy of unilateral vocal fold paralysis with polydimethylsiloxane injection laryngoplasty: our experience. J Voice 24:119–125
Mallur PS, Morrison MP, Postma GN, Amin MR, Rosen CA (2012) Safety and efficacy of carboxymethylcellulose in the treatment of glottic insufficiency. Laryngoscope 122:322–326
Mikaelian DO, Lowry LD, Sataloff RT (1991) Lipoinjection for unilateral vocal cord paralysis. Laryngoscope 101:465–468
Prodinger PM, Windisch G, Hammer GP, Anderhuber F, Friedrich G (2009) Lipoaugmentation of the vocal folds: a survey on alternative donor sites for graft harvesting. J Voice 23:625–630
Wexler DB, Jiang J, Gray SD, Titze IR (1989) Phonosurgical studies: fat-graft reconstruction of injured canine vocal cords. Ann Otol Rhinol Laryngol 98:668–673
Chan RW, Titze IR (1998) Viscosities of implantable biomaterials in vocal fold augmentation surgery. Laryngoscope 108:725–731
Sanderson JD, Simpson CB (2009) Laryngeal complications after lipoinjection for vocal fold augmentation. Laryngoscope 119:1652–1657
Young VN, Wijewickrama RC, Pizzuto MA, Rosen CA (2012) An unusual complication of vocal fold lipoinjection: case report and review of the literature. Arch Otolaryngol Head Neck Surg 138:418–420
Neuenschwander MC, Sataloff RT, Abaza MM, Hawkshaw MJ, Reiter D, Spiegel JR (2001) Management of vocal fold scar with autologous fat implantation: perceptual results. J Voice 15:295–304
Brandenburg JH, Kirkham W, Koschkee D (1992) Vocal cord augmentation with autogenous fat. Laryngoscope 102:495–500
Hsiung MW, Woo P, Minasian A, Schaefer Mojica J (2000) Fat augmentation for glottic insufficiency. Laryngoscope 110:1026–1033
Rihkanen H (1998) Vocal fold augmentation by injection of autologous fascia. Laryngoscope 108:51–54
Reijonen P, Leivo I, Nevalainen T, Rihkanen H (2001) Histology of injected autologous fascia in the paralyzed canine vocal fold. Laryngoscope 111:1068–1074
Reijonen P, Lehikoinen-Soderlund S, Rihkanen H (2002) Results of fascial augmentation in unilateral vocal fold paralysis. Ann Otol Rhinol Laryngol 111:523–529
Cheng Y, Li ZQ, Huang JZ et al (2009) Combination of autologous fascia lata and fat injection into the vocal fold via the cricothyroid gap for unilateral vocal fold paralysis. Arch Otolaryngol Head Neck Surg 135:759–763
Kimura M, Mau T, Chan RW (2010) Viscoelastic properties of phonosurgical biomaterials at phonatory frequencies. Laryngoscope 120:764–768
Hertegard S, Hallen L, Laurent C et al (2004) Cross-linked hyaluronan versus collagen for injection treatment of glottal insufficiency: 2-year follow-up. Acta Otolaryngol 124:1208–1214
Ford CN, Bless DM, Loftus JM (1992) Role of injectable collagen in the treatment of glottic insufficiency: a study of 119 patients. Ann Otol Rhinol Laryngol 101:237–247
Remacle M, Marbaix E (1988) Collagen implants in the human larynx. Pathological examinations of two cases. Arch Otorhinolaryngol 245:203–209
Larsen NE, Pollak CT, Reiner K, Leshchiner E, Balazs EA (1993) Hylan gel biomaterial: dermal and immunologic compatibility. J Biomed Mater Res 27:1129–1134
Hertegard S, Cedervall J, Svensson B et al (2006) Viscoelastic and histologic properties in scarred rabbit vocal folds after mesenchymal stem cell injection. Laryngoscope 116:1248–1254
Hertegard S, Dahlqvist A, Goodyer E (2006) Viscoelastic measurements after vocal fold scarring in rabbits–short-term results after hyaluronan injection. Acta Otolaryngol 126:758–763
Molteni G, Bergamini G, Ricci-Maccarini A et al (2010) Auto-crosslinked hyaluronan gel injections in phonosurgery. Otolaryngol Head Neck Surg 142:547–553
Thibeault SL, Klemuk SA, Chen X, Quinchia Johnson BH (2011) In Vivo engineering of the vocal fold ECM with injectable HA hydrogels-late effects on tissue repair and biomechanics in a rabbit model. J Voice 25:249–253
Choi JS, Kim NJ, Klemuk S et al (2012) Preservation of viscoelastic properties of rabbit vocal folds after implantation of hyaluronic Acid-based biomaterials. Otolaryngol Head Neck Surg 147(3):515–521
Courey MS, Gardner GM, Stone RE, Ossoff RH (1995) Endoscopic vocal fold microflap: a three-year experience. Ann Otol Rhinol Laryngol 104:267–273
Sataloff RT, Spiegel JR, Heuer RJ et al (1995) Laryngeal mini-microflap: a new technique and reassessment of the microflap saga. J Voice 9:198–204
Kass ES, Hillman RE, Zeitels SM (1996) Vocal fold submucosal infusion technique in phonomicrosurgery. Ann Otol Rhinol Laryngol 105:341–347
Sataloff RT, Hawkshaw MJ, Divi V, Heman-Ackah YD (2007) Voice surgery. Otolaryngol Clin North Am 40:1151–1183
Bouchayer M, Cornut G (1988) Microsurgery for benign lesions of the vocal folds. Ear Nose Throat J. 67:446–449 452–4, 456–64 passim
Bouchayer M, Cornut G, Witzig E, Loire R, Roch JB, Bastian RW (1985) Epidermoid cysts, sulci, and mucosal bridges of the true vocal cord: a report of 157 cases. Laryngoscope 95:1087–1094
Fleming DJ, McGuff S, Simpson CB (2001) Comparison of microflap healing outcomes with traditional and microsuturing techniques: initial results in a canine model. Ann Otol Rhinol Laryngol 110:707–712
Duflo S, Thibeault SL, Li W, Shu XZ, Prestwich G (2006) Effect of a synthetic extracellular matrix on vocal fold lamina propria gene expression in early wound healing. Tissue Eng 12:3201–3207
Zhang F, Sprecher AJ, Wei C, Jiang JJ (2010) Implantation of gelatin sponge combined with injection of autologous fat for sulcus vocalis. Otolaryngol Head Neck Surg 143:198–203
Amini-Nik S, Kraemer D, Cowan ML et al (2010) Ultrafast mid-IR laser scalpel: protein signals of the fundamental limits to minimally invasive surgery. PLoS One 5:e13053
Finck CL, Harmegnies B, Remacle A, Lefebvre P (2010) Implantation of esterified hyaluronic acid in microdissected Reinke’s space after vocal fold microsurgery: short- and long-term results. J Voice 24:626–635
Tsunoda K, Takanosawa M, Niimi S (1999) Autologous transplantation of fascia into the vocal fold: a new phonosurgical technique for glottal incompetence. Laryngoscope 109:504–508
Tsunoda K, Kondou K, Kaga K et al (2005) Autologous transplantation of fascia into the vocal fold: long-term result of type-1 transplantation and the future. Laryngoscope 115:1–10
Dedo HH (1975) A technique for verticle hemilaryngectomy to prevent stenosis and aspiration. Laryngoscope 85:978–984
Sataloff RT, Spiegel JR, Hawkshaw M, Rosen DC, Heuer RJ (1997) Autologous fat implantation for vocal fold scar: a preliminary report. J Voice 11:238–246
Woo P, Rahbar R, Wang Z (1999) Fat implantation into Reinke’s space: a histologic and stroboscopic study in the canine. Ann Otol Rhinol Laryngol 108:738–744
Pontes P, Behlau M (1993) Treatment of sulcus vocalis: auditory perceptual and acoustical analysis of the slicing mucosa surgical technique. J Voice 7:365–376
Neumann OG (1976) Oral mucosal grafts in laryngeal reconstruction (author’s transl). HNO 24:248–251
Isshiki N (1981) Phonosurgery, theory and practice, College Hill Press, Diego
Friedrich G (1996) Surgical treatment of glottic stenosis. Otorhinolaryngol Nova 10:218–220
Friedrich G, Bigenzahn W (2006) Phonochirurgie: einführung in die stimmverbessernde kehlkopfchirurgie. In: Gerhard Böhme (ed) Sprach-, Sprech-, Stimm- Und Schluckstörungen, vol 2. 4 edn. Elsevier GmbH, München, pp 177–189
Prufer N, Woo P, Altman KW (2010) Pulse dye and other laser treatments for vocal scar. Curr Opin Otolaryngol Head Neck Surg 18:492–497
Zeitels SM, Burns JA (2007) Office-based laryngeal laser surgery with the 532-nm pulsed-potassium-titanyl-phosphate laser. Curr Opin Otolaryngol Head Neck Surg 15:394–400
Mortensen MM, Woo P, Ivey C, Thompson C, Carroll L, Altman K (2008) The use of the pulse dye laser in the treatment of vocal fold scar: a preliminary study. Laryngoscope 118:1884–1888
Kishimoto Y, Hirano S, Kitani Y et al (2010) Chronic vocal fold scar restoration with hepatocyte growth factor hydrogel. Laryngoscope 120:108–113
Hirano S, Bless D, Heisey D, Ford C (2003) Roles of hepatocyte growth factor and transforming growth factor beta1 in production of extracellular matrix by canine vocal fold fibroblasts. Laryngoscope 113:144–148
Rousseau B, Tateya I, Lim X, Munoz-del-Rio A, Bless DM (2006) Investigation of anti-hyaluronidase treatment on vocal fold wound healing. J Voice 20:443–451
Hirano S, Bless DM, Heisey D, Ford CN (2003) Effect of growth factors on hyaluronan production by canine vocal fold fibroblasts. Ann Otol Rhinol Laryngol 112:617–624
Hirano S, Bless DM, Nagai H et al (2004) Growth factor therapy for vocal fold scarring in a canine model. Ann Otol Rhinol Laryngol 113:777–785
Hirano S, Thibeault S, Bless DM, Ford CN, Kanemaru S (2002) Hepatocyte growth factor and its receptor c-met in rat and rabbit vocal folds. Ann Otol Rhinol Laryngol 111:661–666
Hirano S, Kishimoto Y, Suehiro A, Kanemaru S, Ito J (2008) Regeneration of aged vocal fold: first human case treated with fibroblast growth factor. Laryngoscope 118:2254–2259
Derynck R, Feng XH (1997) TGF-beta receptor signaling. Biochim Biophys Acta 1333:F105–F150
Feng XH, Derynck R (2005) Specificity and versatility in tgf-beta signaling through Smads. Annu Rev Cell Dev Biol 21:659–693
Svensson B, Nagubothu RS, Cedervall J et al (2010) Injection of human mesenchymal stem cells improves healing of scarred vocal folds: analysis using a xenograft model. Laryngoscope 120:1370–1375
Kanemaru S, Nakamura T, Omori K et al (2003) Regeneration of the vocal fold using autologous mesenchymal stem cells. Ann Otol Rhinol Laryngol 112:915–920
Chhetri DK, Berke GS (2011) Injection of cultured autologous fibroblasts for human vocal fold scars. Laryngoscope 121:785–792
Carroll TL, Rosen CA (2010) Trial vocal fold injection. J Voice 24:494–498
Arens C (2010) Scarred larynx. In: Remacle M (eds) Surgery of Larynx and Trachea. Springer Verlag, Berlin, pp 171–181
Welham NV, Choi SH, Dailey SH, Ford CN, Jiang JJ, Bless DM (2011) Prospective multi-arm evaluation of surgical treatments for vocal fold scar and pathologic sulcus vocalis. Laryngoscope 121:1252–1260
Acknowledgments
The authors would like to acknowledge Claus Gerstenberger, PhD for his contribution in all graphic-design related works.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Friedrich, G., Dikkers, F.G., Arens, C. et al. Vocal fold scars: current concepts and future directions. Consensus report of the phonosurgery committee of the European laryngological society. Eur Arch Otorhinolaryngol 270, 2491–2507 (2013). https://doi.org/10.1007/s00405-013-2498-9
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00405-013-2498-9