The Laryngoscope C 2015 The American Laryngological, V
Rhinological and Otological Society, Inc.
Transillumination for Needle Localization in the Larynx Henry T. Hoffman, MD; Seth H. Dailey, MD; Jonathan M. Bock, MD; Susan L. Thibeault, PhD; Timothy M. McCulloch, MD Objectives/Hypothesis: Transillumination through laryngeal soft tissue may be used to direct percutaneous transcricothyroid membrane subepithelial needle placement in the larynx. Study Design: Cadaver simulation (canine and human). Methods: Lighted devices, including sialendoscopes and fiberoptic cables, were tested as transilluminating obturators in trocars and needles through multiple studies to identify appropriate illumination, monitoring, and equipment for successful localization of needle/trocar tips placed within laryngeal tissue. Results: Lighted 250-micron fiberoptic cables within 23-gauge needles were successfully placed percutaneously through the cricothyroid membrane and maneuvered submucosally into Reinke’s space, the midlateral vocal fold, and through the thyroarytenoid gap with monitoring via flexible transnasal laryngoscopy. Technical adaptations in the course of study permitted successful simulation of clinical use in full cadaver study for accurate injection laryngoplasty, confirmed by laryngeal dissection following collagen injection. Conclusions: Small caliber fiberoptic cables are useful as transilluminating obturators to accurately direct needle position within laryngeal tissue. Clinical application of this new technique is anticipated to improve the accuracy of percutaneous needle localization in the larynx, as well as to assist in directed instrumentation of the larynx from an external approach. Key Words: Transillumination, larynx, laryngoplasty, laryngeal electromyography (EMG), injection, botulinum toxin, vocal fold, minithyrotomy. Level of Evidence: N/A. Laryngoscope, 125:2341–2348, 2015
INTRODUCTION Laryngoscopy enhanced with magnification and illumination directs precise vocal cord injection via needle insertion through the epithelium. Access can be obtained under general or local anesthesia employing either transnasal or transoral approaches.1,2 Injection laryngoplasty by these approaches creates a hole in the vocal fold epithelium that commonly results in extrusion of a portion of the injected material. Transgression of the vocal fold epithelium also introduces the potential for contamination, which is likely to become a more relevant concern as biologically active implants (e.g., stem cells) are placed to reconstitute specific regions within the larynx.3
From the Department of Otolaryngology University of Iowa (H.T.H.), Iowa City, Iowa; Division of Otolaryngology, Department of Surgery, University of Wisconsin (S.H.D., S.L.T., T.M.M.), Madison; and the Department of Otolaryngology Medical College of Wisconsin (J.M.B.), Milwaukee, Wisconsin, U.S.A Editor’s Note: This Manuscript was accepted for publication April 20, 2015. Presented at the Triological Society 2015 Combined Sections Meeting, San Diego, California, U.S.A., January 23, 2015. Dr. Hoffman is a consultant to Cook Medical Inc. The University of Iowa Research Foundation and Dr. Hoffman filed a provisional patent application on April 11, 2013, for Transilluminating Obturator (UIK04301). The authors have no other funding, financial relationships, or conflicts of interest to disclose. Send correspondence to Henry T. Hoffman, MD, Department of Otolaryngology, University of Iowa, Pomerantz Pavilion, 2nd Floor, 200 Hawkins Drive, Iowa City, IA 52242. E-mail: [email protected] DOI: 10.1002/lary.25372
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External approaches to vocal fold injection can be performed in a sterile fashion to avoid exposure to the bacterial-containing secretions and to enhance retention of the injected material. Percutaneous injection laryngoplasty, diagnostic electromyography (EMG) electrode placement, and laryngeal botulinum neurotoxin injection are all commonly done without visualizing the location of the needle tip within the larynx. Verification of the location of the blindly placed needle may be facilitated by EMG guidance; by the point-touch approach due to loss of resistance to needle placement through cartilage; and by endoscopic imaging of distortion of the vocal fold, either as the needle tip is moved or as the injection is delivered. These approaches are inhibited by poor localization due to blind needle tip placement, as well as possible cartilage plugging during needle insertion. Flexible laryngoscopy is often performed concurrently to assist in proper injection localization but does not guarantee proper injection due to uncertainty about needle tip location. The percutaneous approach to injection laryngoplasty was first reported in 1916 by Seifert, who described transoral mirror examination of the larynx to identify needle entry into the undersurface of the vocal fold via transcricothyroid membrane puncture for delivery of paraffin.4 Ward reported use of more advanced imaging with transnasal flexible fiberoptics to similarly direct placement of Teflon through a 16- or 18-gauge spinal needle maneuvered through the cricothyroid membrane into the subglottic airway and then back through mucosa into the vocal fold.5 A more contemporary report Hoffman et al.: Transillumination for Needle Localization
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Fig. 1. (A) Assembly of optical fiber, light source, and 23-gauge needle. (B) Laboratory setup with flexible transnasal laryngoscopy inspecting the cadaver larynx. (C) Preparation for placement of needle with transillumination to be placed through the cricothyroid membrane. [Color figure can be viewed in the online issue, which is available at www.laryngoscope.com.]
by Powel et al. (2014) identified 68 patients treated for laryngeal paralysis through a similar approach, with success reported using hyaluronic acid (Surgiderm 30 XP), calcium hydroxyapatite (Radiesse), or collagen (Zyplast) injected through a 21-gauge needle.6 Transcutaneous injection of the vocal fold through the cricothyroid space without entry into the subglottic lumen (extraluminal) was first reported in 1972 by Hurst, who monitored needle tip location with concurrent direct laryngoscopy.7 In 1985, Hirano et al. reported this extraluminal approach to be their preferred injection method, which they modified to employ transnasal fiberoptic laryngoscopy to monitor needle tip placement.8 In 1990, Hirano et al. amplified further on their initial experience, reporting on 51 patients injected with medical silicone rubber using this approach.9 They highlighted the importance of accurately estimating the vocal cord location through palpation of external landmarks to direct the initial blind needle placement. Once positioned through the cricothyroid membrane, concurrent transnasal laryngoscopy visualized the distortion of the vocal fold as “the needle is gently shaken medially back and forth as it proceeds” and “when small movements are observed in the region lateral and slightly anterior to the tip of the vocal process, the injection is started.” These investigators reported that it was important to avoid the transgression of the epithelium to avoid leakage of injected material. Laryngoscope 125: October 2015
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Diaphanoscopy (transillumination) is the practice of using the passage of light through an organ for diagnostic purposes. Its initial use to image the larynx has been credited by Feldmann to Czermak, who identified that the interior of the larynx could be inspected with a red glow using a mirror within the dark pharynx when the neck was illuminated externally by a strong light.10 Feldman additionally identified that development of brighter electric lamps directed Votonlini to use this transillumination technique to perform minor intralaryngeal operations. Diaphanoscopes were developed and marketed for use in laryngology but were not widely adopted. As recently as 1954, Pellnitz et al.11 reported the use of diaphanoscopy as an adjunct to the surgical treatment of small laryngeal cancers. Transillumination within the larynx was first used over a century ago with, to our knowledge, endoscopic transillumination through mucosa for needle localization in the larynx, as first reported in 2014 by Hoffman et al.12 These investigators used a light source (sialendoscope), which was placed through a needle (trocar) for transillumination through the pyriform sinus mucosa in cadaver dissection in order to confirm needle tip location, adjacent to the muscular process of the arytenoid, to direct the placement of an arytenoid repositioning device. We describe further work with laryngeal transillumination to introduce the technique and equipment applied to direct needle placement in other sites in the larynx. Hoffman et al.: Transillumination for Needle Localization
Fig. 2. The internal attachment of metal sheath to plastic hub of 23-gauge Becton-Dickenson needle (A, B) created ridge making placement of fiberoptic difficult. The tapered transition in 23-gauge Chiba needle (C, D) permitted ease in threading fiberoptic. [Color figure can be viewed in the online issue, which is available at www.laryngoscope.com.]
MATERIALS AND METHODS Cadaver experiments were performed during the laboratory session of the University of Wisconsin Phonosurgery Course (Madison, WI; July 12, 2014) and during the laboratory session at laboratories supported by Cook Medical Inc. at the Nicholson Center Cadaver/Model Laboratory (Celebration, FL; September 9, 2014) and the Medical Academic Center (Carmel, IN; April 4, 2014). Consultation with the University of Iowa Institutional Review Board provided assurance that U.S. federal guidelines exempt cadaver studies from specific protocol review. Initial efforts to test transillumination through injection needles included positioning of a light source at the proximal end of a 23-gauge needle in the clinical practice of percutaneous vocal fold injection. Subsequent cadaver study (human and canine) employed distal illumination, with the light source positioned at the sharp tip of the needle. Study focused on use of a microfiberoptic cable placed as an obturator through a 23-gauge needle to guide needle placement. This technique was first studied in excised larynges and was then followed by clinical simulation employing full cadavers, with concurrent transnasal flexible fiberoptic laryngoscopy with the Karl Storz 5.2-mm OD Broncho-Fiberoscope (Fig. 1). Video-recording (Karl Storz SCB image 1 hub 222010 20 with 22220130 NTSC Camera head and image 1 H3-Z camera system) was done of a vocal fold injection performed via percutaneous placement of an illuminated 23-gauge needle. Several optical fibers were employed, including a 250micron optical fiber used in the excised canine experiments that was provided by LEONI Fiber Optics Inc. These optical fibers were found to readily pass antegrade into the 23-gauge Chiba
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needle but only with difficulty into the similarly sized bore of the 23-gauge Becton-Dickenson (B-D) needle. The 23-gauge Chiba needle is made with resin fed into heated bond around preplaced metal to create an insert molding, which provides a gradual tapered conduit to the metal barrel that facilitates placement of the fiberoptic. Although the fiber could be passed retrograde (into the needle tip) of the 23-gauge B-D needle, antegrade placement was difficult due to the presence of a metal ridge at the interface between the plastic housing and the bore (Fig. 2). Fixation of the fiberoptic cable to the 23-gauge needle hub in the excised canine larynx study was accomplished with chewing gum. In all other cases the fiberoptic cable was secured to the needle with a clamp. In all experiments, the light source was the lithium-ion battery VueLite LED Light Source (Cook Medical Inc.). Anatomic comparisons were made to anatomic dissection of human cadaver larynges. Additionally, whole mount sections of human larynges were studied after they were formalin-fixed, decalcified, and embedded in celloidin, with representation made in 30-um to 35-um coronal sections, as per Bartlett et al.13 Injections initially were done with saline and in the final experiment with the collagen implant Zyderm 2 (purified bovine dermal collage; Allergan, Santa Barbara, CA).
RESULTS Initial efforts to transilluminate through the laryngeal tissue with a 11=2-inch 23-gauge needle and a light source (sialendoscope) applied externally at plastic cap Hoffman et al.: Transillumination for Needle Localization
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Fig. 3. Excised human larynx study identifies (A) light emitted from fiberoptic cable positioned through 23-gauge needle, (B) placement of illuminated needle through cricothyroid membrane in submucosal plane, (C) passage of needle through deep paraglottic space to region of posterior cricoarytenoid muscle, and (D) manipulation of needle tip into superficial submucosal site with needle bore traversing thyroarytenoid gap. [Color figure can be viewed in the online issue, which is available at www.laryngoscope.com.]
of the needle delivered light sufficiently intense to be detected at the distal tip of the needle but of inadequate intensity to transilluminate through laryngeal tissue. Further work with both human and canine cadaveric excised larynges employed illumination, which was made more intense by the placement of an optical fiber as an obturator through the needle lumen to abut its distal internal tip. This modification permitted view of the lighted tip through tissue to direct needle tip location into the deep to the medial apex of the pyriform sinus (adjacent the muscular process of the arytenoid), in Reinke’s space, and in the paraglottic space (Fig. 3). Success with transillumination in excised larynges led to two separate experiments using full upper body cadavers, with monitoring of needle tip location employing transnasal fiberoptic laryngoscopy. Percutaneous needle placement employed external landmarks to follow the technique described by Hirano et al.,9 with modification for the male larynx made by bending the needle superiorly to permit placement through the cricothyroid membrane into the paraglottic space, as depicted, into the left vocal fold (Fig. 4A, B, C). The intensity of the transillumination was sufficient to detect needle tip location without modifying the standard strength of the light produced by the flexible transnasal laryngoscope. Enhanced definition of the needle tip location occurred with dimming the light proLaryngoscope 125: October 2015
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duced by the flexible endoscope to identify needle tip location in Reinke’s space superficially, in the deep paraglottic space, and through the thyroarytenoid (TA) gap into the posterior cricoarytenoid muscle (PCA) (Fig. 5). Delivery of an injectate with transilluminated needle tip guidance required removal of the fiberoptic cable. Digital fixation to secure the needle to adjacent neck skin was followed by connecting a 1-cc needle containing collagen (Zyderm2) to the needle hub (Fig. 6A,B). Following injection of 0.4 cc of the collagen, dissection of the larynx demonstrated the location of the collagen in the paraglottic space (Fig. 6C, D). Additional manipulations (figures not shown) in both excised larynges and the full body cadavers permitted directed injection of saline into Reinke’s space without transgression of mucosa.
DISCUSSION In 2014, Chhetri and Jamal reported their approach to percutaneous vocal fold injection via the transcricothyroid membrane (TCM) and transthyroid cartilage approaches with concurrent flexible transnasal endoscopic monitoring.14 These investigators identified that it was necessary to develop expertise in correlating external landmarks with internal laryngeal anatomy for these blind approaches and that a “certain learning Hoffman et al.: Transillumination for Needle Localization
Fig. 4. (A) 23-gauge needle with flexible fiberoptic is bent to permit submucosal placement through cricothyroid membrane into paraglottic space. (B) Appearance of larynx before placement of needle. (C 1,2,3) Positioning of transilluminated needle tip permits repositioning to proper site for injection. [Color figure can be viewed in the online issue, which is available at www.laryngoscope.com.]
curve” is needed to master this technique.14 For transcricothyroid injection, Clary et al. similarly identified that “precise placement of the needle tip is more difficult to obtain and can require a significant level of experience.”15 Variability in laryngeal anatomy may compromise the reliability of determining needle tip placement directed by external palpation alone. Major anatomic differences are consistently identified between the male and female larynx that often warrant modification in the technique for TCM injection. A bend placed in the needle is commonly needed to curve the needle under the larger male thyroid cartilage to access the mid- and anterior vocal fold musculature (TA/lateral cricoarytenoid [LCA]) in a way that is not necessary for the female larynx. Additional subtle differences in laryngeal anatomy are commonly introduced by previous surgery such as thyroidectomy, neck dissection, and rhytidectomy. Our current practice limits the transcricothyroid injection laryngoplasty approach to collagen preparations such as Cymetra, which do not require the same precise location as is necessary for less forgiving injectables such as calcium hydroxylapatite.16 Through a comparative study, Woo et al. identified that percutaneous TCM injection laryngoplasty had less “visualization and precision” than did the thyrohyoid approach.17 Although we have used the transoral approach with curved 27gauge needle (Xomed Treace orotracheal injector) to Laryngoscope 125: October 2015
deliver Radiesse voice (calcium hydroxy apatite) in the clinic under local anesthesia due to the accuracy in needle localization when guided by concurrent rigid transoral videolaryngoscopy, we have abandoned this approach due to difficulties in reliably delivering the material through this small needle.18 Use of transillumination should permit greater confidence in the location of the larger bore needle tip to permit in-clinic injection of calcium hydroxyapatite preparations through the transcricothyroid membrane approach. The laryngeal transillumination technique may be expanded to applications beyond that of injection laryngoplasty for vocal fold augmentation. Gray et al.’s minithyrotomy approach requires accurate placement of dissecting instruments in a narrow and often scarred superficial layers of the vocal fold.19 Paniello et al. described their experience with this technique and identified that there is a high probability of graft extrusion if perforation of the epithelium occurs.20 Gunderson et al. acknowledged this concern with further modifications to the procedure, including use of a 27-gauge finder needle placed along the axial plane of the vocal fold to help guide dilation to develop a plane either within the lamina propria or superficial TA muscle.21 Transillumination to assist in placement of a finder needle would be expected to more reliably avoid mucosal transgression. The recording of EMG from laryngeal muscles is technically difficult and plagued by uncertainty of Hoffman et al.: Transillumination for Needle Localization
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Fig. 5. Anatomic correlates to needle tip location. (A11,A2,A3) Initial placement of needle shaft (solid arrow) with tip (X) superficial in left thyroarytenoid 5 X . (B1,B2,B3) Needle (solid arrow) is maneuvered in deep paraglottic space, with illuminate tip placed through thyroarytenoid gap 5 Y. (C1,2.) Needle tip transilluminated apex of pyriform sinus in posterior cricoarytenoid muscle below vocal process 5 Z. [Color figure can be viewed in the online issue, which is available at www.laryngoscope.com.]
electrode tip location. Closely applied muscles in the larynx, such as the TA and LCA, are discriminated by characteristics of the EMG signal that they produce. Uncharacteristic signals or the absence of a signal could reflect either an important finding or an error in electrode tip placement. Recommendations from the Neurolaryngology Study Group acknowledged this problem and conclude that “future studies should compare different techniques for electrode placement.”22 Transillumination is a new technique to guide electrode tip location within the larynx that should improve the accuracy of diagnostic laryngeal EMG. Difficulties in accessing the PCA muscle for botulinum toxin injection is widely acknowledged and considered an impediment to successful treatment of patients with abductor spasmodic dysphonia.23 We identified the capacity to place a needle into the PCA muscle via the paraglottic space in both canine and human excised larynges. To date, the sole clinical report of PCA injection via transcricothyroid needle placement through the paraglottic space comes from the inadvertent induction of bilateral abductor paralysis, which was reported by Venkatesan et al. as a complication of the effort to inject the TA muscle with EMG guidance.24 These investigators concluded that Laryngoscope 125: October 2015
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posterior location of the needle near the muscular processes of the arytenoids permitted diffusion of the botulinum toxin to the abductor muscles (PCA). This approach, guided by transillumination, may be exploited to purposefully introduce paresis of the PCA muscle in the treatment of abductor spasmodic dysphonia. Additional considerations regarding potential injury to the recurrent laryngeal nerve fibers to the LCA and TA muscles in the course of needle placement must also be considered in using this approach to target the PCA muscles. We identified that unmodified light from transnasal scopes permitted visualization of the white light transmitted by the fiberoptic cable through the soft tissue of the vocal cord. It is possible that improved visualization could result from modifications to the light source, as well as the fiberoptic scope monitoring that light source. Alternative sources of light such as currently exist for ultrathin laser fibers may be employed. Existing technology to modify imaging light within the larynx, such as narrow band imaging, may add further sophistication to this approach. Clinical application of the transilluminating obturator is anticipated to follow further testing and development. Adequate strength and flexibility to the fiberoptic Hoffman et al.: Transillumination for Needle Localization
Fig. 6. (A) The transilluminated needle tip is identified in left vocal cord to be optimally positioned for injection. (B) The fiberoptic light source is withdrawn and replaced to attach a collagen-containing syringe. (C) Injection of collagen results in filling left vocal cord. (D) The larynx is sectioned in coronal plane anterior to vocal process identifying location of collagen injection. L 5 left; R 5 right. [Color figure can be viewed in the online issue, which is available at www.laryngoscope. com.]
cable is desirable to permit bending of the needle housing the fiber, both to maintain illumination in this altered configuration and to avoid detaching a segment of fiber as a foreign body in the larynx.25 The potential for thermal injury to adjacent tissue warrants the study of heat dissipation at the tip of the fiberoptic in the course of adapting this technique to clinical use. Hirano et al. identified the orientation of the needle tip to be important and that the “bevel of the needle must be directed laterally so the silicone rubber does not enter the mucosa.”9 More sophisticated transilluminating needle obturators may be developed, with a formfitting beveled tip that would permit manipulation of the open end of the needle for directional placement of an injection and the visualized light intensity dependent on the direction the bevel is facing.
CONCLUSION We introduce a technique for needle localization in the larynx using transillumination. Clinical application of this technique is anticipated to improve the safety and accuracy of both laryngeal injections and diagnostic EMG, as well as to assist in directed instrumentation of the larynx from an external approach.
Acknowledgments Laboratory access, canine cadaver material, and instrumentation were provided by The University of Wisconsin Department of Surgery (Division of Otolaryngology) July 12, 2014. Laboratory access, human cadaver material, and instrumentation were provided by Cook Medical Inc. April Laryngoscope 125: October 2015
4, 2014 and September 9, 2014. Fiberoptic cable was provided by LEONI Fiber Optics Inc. Research was done at the University of Iowa (H.T.H.), Iowa City, Iowa; the University of Wisconsin (H.T.H., S.H.D., S.L.T., T.M.M.), Madison, Wisconsin; and the Cook Medical Inc.supported research laboratories (H.T.H.): Nicholson Center Cadaver/Model Laboratory in Celebration, Florida (September 9, 2014) and Medical Academic Center in Carmel, Indiana (April 4, 2014).
BIBLIOGRAPHY 1. Trask DK, Shellenberger DL, Hoffman HT. Transnasal, endoscopic vocal fold augmentation. Laryngoscope 2005;115: 2262–2265. 2. Ford CN, Bless DM. Selected problems treated by vocal fold injection of collagen. Am J Otolaryngol 1993;14:257–261. 3. Zapanta PE, Bielamowicz SA. Laryngeal abscess after injection laryngoplasty with micronized AlloDerm. Laryngoscope 2004;114:1522–1524. 4. Seifert A. [Percutaneous Paraffin Injection to Eliminate the Effects of Unilateral Laryngeal Paralysis] Perkutane Paraffininjektion zur Beseitigung der Folgen einseitiger Stimmbandlaehmung. Z Laryngol Rhinol Otol Ihre Grenzgeb 1916; 8:233–235. 5. Ward PH, Hanson DG, Abemayor E. Transcutaneous Teflon injection of the paralyzed vocal cord: a new technique. Laryngoscope 1985;95:644–649. 6. Powell J, Carding P, Birdi R Wilson JA. Injection laryngoplasty in the outpatient clinic under local anaesthetic: a case series of sixty-eight patients. Clin Otolaryngol 2014;39:224–227. 7. Hurst WB. Percutaneous injection of a vocal cord with Teflon. J Laryngol Otol 1972;86:633–635. 8. Hirano M, Ohkubo H, Yoshida T, Kurita S. Transcutaneous intrafold injection for vocal fold paralysis. Trans Am BronchoEsophagol Assoc 1985; 115–117. 9. Hirano M, Tanaka S, Tanaka Y, Hibi S. Transcutaneous intrafold injection for unilateral vocal fold paralysis: functional results. Ann Otol Rhinol Laryngol 1990;99:598–604. 10. Feldmann H. [History of diaphanoscopy. Pictures from the history of otorhinolaryngology, illustrated by instruments from the collection of the Ingolstadt German Medical History Museum]. [Article in German]. Laryngorhinootologie 1998;77:297–304. 11. Pellnitz D. [Special possibilities of larynx diagnosis by the use of diaphanoscopy]. [Article in German]. Pract Otorhinolaryngol (Basel) 1954;16:225– 232.
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12. Hoffman HT, Heaford AC, Dailey SH, et al. Arytenoid repositioning device. Ann Otol Rhinol Laryngol 2014;123:195–205. 13. Bartlett RS, Hoffman HT, Dailey SH, et al. Restructuring the vocal fold lamina propria with endoscopic microdissection. Laryngoscope 2013;1233:2780–2786. 14. Chhetri DK, Jamal N. Percutaneous injection laryngoplasty. Laryngoscope 2014;124:742–745. doi: 10.1002/lary.24417. Epub 2013. 15. Clary MS, Milam BM, Courey MS. Office-based vocal fold injection with the laryngeal introducer technique. Laryngoscope 2014;124:2114–2117. 16. Rosen CA, Gartner-Schmidt J, Casiano R, et al. Vocal fold augmentation with calcium hydroxyl apatite: twelve-month report. Laryngoscope 2009; 119:1033–1041. 17. Woo SH, Son Y, Lee SH, Park JJ, Kim J. Comparative analysis on the efficiency of the injection laryngoplasty technique using calcium hydroxyapatite (CaHA): The thyrohyoid approach versus the cricothyroid approach. J Voice 2013;27:236–241. 18. “Transoral injection laryngoplasty with videostroboscopy.” Hoffman HT, ed. Iowa Head and Neck Protocols. Available at: https://wiki.uiowa.edu/display/protocols/Transoral+injection+laryngoplasty+with+videostroboscopy Accessed January 2, 2015.
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19. Gray SD, Bielamowicz SA, Titze IR, Dove H, Ludlow C. Experimental approaches to vocal fold alteration: introduction to the minithyrotomy. Ann Otol Rhinol Laryngol 1999;108:1–9. 20. Paniello RC, Sulica L, Khosla SM Smith ME. Clinical experience with Gray’s minithyrotomy procedure. Ann Otol Rhinol Laryngol 2008;117: 437–442. 21. Gunderson M, Bauer B, Glab RC, Dailey SH. Technical refinements to the minithyrotomy procedure. J Voice 2014;28:501–507. 22. Blitzer A, Crumley RL, Dailey SH, et al. Recommendations of the Neurolaryngology Study Group on Laryngeal Electromyography. Otolaryngol Head Neck Surg 2009;140:782–793. 23. Woodson G, Hochstetler H, Murry T. Botulinum toxin therapy for abductor spasmodic dysphonia. J Voice 2006;20:137–143. 24. Venkatesan NN, Johns MM, Hapner ER DelGaudio JM. Abductor paralysis after botox injection for adductor spasmodic dysphonia. Laryngoscope 2010;120:1177–1180. 25. Ting JY, Musunuru S, Halum SL. Management of a laryngeal injection needle impacted in the paraglottic space. Otolaryngol Head Neck Sur 2011;145:876–877.
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Transillumination for Needle Localization in the Larynx Henry T. Hoffman, MD; Seth H. Dailey, MD; Jonathan M. Bock, MD; Susan L. Thibeault, PhD; Timothy M. McCulloch, MD Objectives/Hypothesis: Transillumination through laryngeal soft tissue may be used to direct percutaneous transcricothyroid membrane subepithelial needle placement in the larynx. Study Design: Cadaver simulation (canine and human). Methods: Lighted devices, including sialendoscopes and fiberoptic cables, were tested as transilluminating obturators in trocars and needles through multiple studies to identify appropriate illumination, monitoring, and equipment for successful localization of needle/trocar tips placed within laryngeal tissue. Results: Lighted 250-micron fiberoptic cables within 23-gauge needles were successfully placed percutaneously through the cricothyroid membrane and maneuvered submucosally into Reinke’s space, the midlateral vocal fold, and through the thyroarytenoid gap with monitoring via flexible transnasal laryngoscopy. Technical adaptations in the course of study permitted successful simulation of clinical use in full cadaver study for accurate injection laryngoplasty, confirmed by laryngeal dissection following collagen injection. Conclusions: Small caliber fiberoptic cables are useful as transilluminating obturators to accurately direct needle position within laryngeal tissue. Clinical application of this new technique is anticipated to improve the accuracy of percutaneous needle localization in the larynx, as well as to assist in directed instrumentation of the larynx from an external approach. Key Words: Transillumination, larynx, laryngoplasty, laryngeal electromyography (EMG), injection, botulinum toxin, vocal fold, minithyrotomy. Level of Evidence: N/A. Laryngoscope, 125:2341–2348, 2015
INTRODUCTION Laryngoscopy enhanced with magnification and illumination directs precise vocal cord injection via needle insertion through the epithelium. Access can be obtained under general or local anesthesia employing either transnasal or transoral approaches.1,2 Injection laryngoplasty by these approaches creates a hole in the vocal fold epithelium that commonly results in extrusion of a portion of the injected material. Transgression of the vocal fold epithelium also introduces the potential for contamination, which is likely to become a more relevant concern as biologically active implants (e.g., stem cells) are placed to reconstitute specific regions within the larynx.3
From the Department of Otolaryngology University of Iowa (H.T.H.), Iowa City, Iowa; Division of Otolaryngology, Department of Surgery, University of Wisconsin (S.H.D., S.L.T., T.M.M.), Madison; and the Department of Otolaryngology Medical College of Wisconsin (J.M.B.), Milwaukee, Wisconsin, U.S.A Editor’s Note: This Manuscript was accepted for publication April 20, 2015. Presented at the Triological Society 2015 Combined Sections Meeting, San Diego, California, U.S.A., January 23, 2015. Dr. Hoffman is a consultant to Cook Medical Inc. The University of Iowa Research Foundation and Dr. Hoffman filed a provisional patent application on April 11, 2013, for Transilluminating Obturator (UIK04301). The authors have no other funding, financial relationships, or conflicts of interest to disclose. Send correspondence to Henry T. Hoffman, MD, Department of Otolaryngology, University of Iowa, Pomerantz Pavilion, 2nd Floor, 200 Hawkins Drive, Iowa City, IA 52242. E-mail: [email protected] DOI: 10.1002/lary.25372
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External approaches to vocal fold injection can be performed in a sterile fashion to avoid exposure to the bacterial-containing secretions and to enhance retention of the injected material. Percutaneous injection laryngoplasty, diagnostic electromyography (EMG) electrode placement, and laryngeal botulinum neurotoxin injection are all commonly done without visualizing the location of the needle tip within the larynx. Verification of the location of the blindly placed needle may be facilitated by EMG guidance; by the point-touch approach due to loss of resistance to needle placement through cartilage; and by endoscopic imaging of distortion of the vocal fold, either as the needle tip is moved or as the injection is delivered. These approaches are inhibited by poor localization due to blind needle tip placement, as well as possible cartilage plugging during needle insertion. Flexible laryngoscopy is often performed concurrently to assist in proper injection localization but does not guarantee proper injection due to uncertainty about needle tip location. The percutaneous approach to injection laryngoplasty was first reported in 1916 by Seifert, who described transoral mirror examination of the larynx to identify needle entry into the undersurface of the vocal fold via transcricothyroid membrane puncture for delivery of paraffin.4 Ward reported use of more advanced imaging with transnasal flexible fiberoptics to similarly direct placement of Teflon through a 16- or 18-gauge spinal needle maneuvered through the cricothyroid membrane into the subglottic airway and then back through mucosa into the vocal fold.5 A more contemporary report Hoffman et al.: Transillumination for Needle Localization
2341
Fig. 1. (A) Assembly of optical fiber, light source, and 23-gauge needle. (B) Laboratory setup with flexible transnasal laryngoscopy inspecting the cadaver larynx. (C) Preparation for placement of needle with transillumination to be placed through the cricothyroid membrane. [Color figure can be viewed in the online issue, which is available at www.laryngoscope.com.]
by Powel et al. (2014) identified 68 patients treated for laryngeal paralysis through a similar approach, with success reported using hyaluronic acid (Surgiderm 30 XP), calcium hydroxyapatite (Radiesse), or collagen (Zyplast) injected through a 21-gauge needle.6 Transcutaneous injection of the vocal fold through the cricothyroid space without entry into the subglottic lumen (extraluminal) was first reported in 1972 by Hurst, who monitored needle tip location with concurrent direct laryngoscopy.7 In 1985, Hirano et al. reported this extraluminal approach to be their preferred injection method, which they modified to employ transnasal fiberoptic laryngoscopy to monitor needle tip placement.8 In 1990, Hirano et al. amplified further on their initial experience, reporting on 51 patients injected with medical silicone rubber using this approach.9 They highlighted the importance of accurately estimating the vocal cord location through palpation of external landmarks to direct the initial blind needle placement. Once positioned through the cricothyroid membrane, concurrent transnasal laryngoscopy visualized the distortion of the vocal fold as “the needle is gently shaken medially back and forth as it proceeds” and “when small movements are observed in the region lateral and slightly anterior to the tip of the vocal process, the injection is started.” These investigators reported that it was important to avoid the transgression of the epithelium to avoid leakage of injected material. Laryngoscope 125: October 2015
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Diaphanoscopy (transillumination) is the practice of using the passage of light through an organ for diagnostic purposes. Its initial use to image the larynx has been credited by Feldmann to Czermak, who identified that the interior of the larynx could be inspected with a red glow using a mirror within the dark pharynx when the neck was illuminated externally by a strong light.10 Feldman additionally identified that development of brighter electric lamps directed Votonlini to use this transillumination technique to perform minor intralaryngeal operations. Diaphanoscopes were developed and marketed for use in laryngology but were not widely adopted. As recently as 1954, Pellnitz et al.11 reported the use of diaphanoscopy as an adjunct to the surgical treatment of small laryngeal cancers. Transillumination within the larynx was first used over a century ago with, to our knowledge, endoscopic transillumination through mucosa for needle localization in the larynx, as first reported in 2014 by Hoffman et al.12 These investigators used a light source (sialendoscope), which was placed through a needle (trocar) for transillumination through the pyriform sinus mucosa in cadaver dissection in order to confirm needle tip location, adjacent to the muscular process of the arytenoid, to direct the placement of an arytenoid repositioning device. We describe further work with laryngeal transillumination to introduce the technique and equipment applied to direct needle placement in other sites in the larynx. Hoffman et al.: Transillumination for Needle Localization
Fig. 2. The internal attachment of metal sheath to plastic hub of 23-gauge Becton-Dickenson needle (A, B) created ridge making placement of fiberoptic difficult. The tapered transition in 23-gauge Chiba needle (C, D) permitted ease in threading fiberoptic. [Color figure can be viewed in the online issue, which is available at www.laryngoscope.com.]
MATERIALS AND METHODS Cadaver experiments were performed during the laboratory session of the University of Wisconsin Phonosurgery Course (Madison, WI; July 12, 2014) and during the laboratory session at laboratories supported by Cook Medical Inc. at the Nicholson Center Cadaver/Model Laboratory (Celebration, FL; September 9, 2014) and the Medical Academic Center (Carmel, IN; April 4, 2014). Consultation with the University of Iowa Institutional Review Board provided assurance that U.S. federal guidelines exempt cadaver studies from specific protocol review. Initial efforts to test transillumination through injection needles included positioning of a light source at the proximal end of a 23-gauge needle in the clinical practice of percutaneous vocal fold injection. Subsequent cadaver study (human and canine) employed distal illumination, with the light source positioned at the sharp tip of the needle. Study focused on use of a microfiberoptic cable placed as an obturator through a 23-gauge needle to guide needle placement. This technique was first studied in excised larynges and was then followed by clinical simulation employing full cadavers, with concurrent transnasal flexible fiberoptic laryngoscopy with the Karl Storz 5.2-mm OD Broncho-Fiberoscope (Fig. 1). Video-recording (Karl Storz SCB image 1 hub 222010 20 with 22220130 NTSC Camera head and image 1 H3-Z camera system) was done of a vocal fold injection performed via percutaneous placement of an illuminated 23-gauge needle. Several optical fibers were employed, including a 250micron optical fiber used in the excised canine experiments that was provided by LEONI Fiber Optics Inc. These optical fibers were found to readily pass antegrade into the 23-gauge Chiba
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needle but only with difficulty into the similarly sized bore of the 23-gauge Becton-Dickenson (B-D) needle. The 23-gauge Chiba needle is made with resin fed into heated bond around preplaced metal to create an insert molding, which provides a gradual tapered conduit to the metal barrel that facilitates placement of the fiberoptic. Although the fiber could be passed retrograde (into the needle tip) of the 23-gauge B-D needle, antegrade placement was difficult due to the presence of a metal ridge at the interface between the plastic housing and the bore (Fig. 2). Fixation of the fiberoptic cable to the 23-gauge needle hub in the excised canine larynx study was accomplished with chewing gum. In all other cases the fiberoptic cable was secured to the needle with a clamp. In all experiments, the light source was the lithium-ion battery VueLite LED Light Source (Cook Medical Inc.). Anatomic comparisons were made to anatomic dissection of human cadaver larynges. Additionally, whole mount sections of human larynges were studied after they were formalin-fixed, decalcified, and embedded in celloidin, with representation made in 30-um to 35-um coronal sections, as per Bartlett et al.13 Injections initially were done with saline and in the final experiment with the collagen implant Zyderm 2 (purified bovine dermal collage; Allergan, Santa Barbara, CA).
RESULTS Initial efforts to transilluminate through the laryngeal tissue with a 11=2-inch 23-gauge needle and a light source (sialendoscope) applied externally at plastic cap Hoffman et al.: Transillumination for Needle Localization
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Fig. 3. Excised human larynx study identifies (A) light emitted from fiberoptic cable positioned through 23-gauge needle, (B) placement of illuminated needle through cricothyroid membrane in submucosal plane, (C) passage of needle through deep paraglottic space to region of posterior cricoarytenoid muscle, and (D) manipulation of needle tip into superficial submucosal site with needle bore traversing thyroarytenoid gap. [Color figure can be viewed in the online issue, which is available at www.laryngoscope.com.]
of the needle delivered light sufficiently intense to be detected at the distal tip of the needle but of inadequate intensity to transilluminate through laryngeal tissue. Further work with both human and canine cadaveric excised larynges employed illumination, which was made more intense by the placement of an optical fiber as an obturator through the needle lumen to abut its distal internal tip. This modification permitted view of the lighted tip through tissue to direct needle tip location into the deep to the medial apex of the pyriform sinus (adjacent the muscular process of the arytenoid), in Reinke’s space, and in the paraglottic space (Fig. 3). Success with transillumination in excised larynges led to two separate experiments using full upper body cadavers, with monitoring of needle tip location employing transnasal fiberoptic laryngoscopy. Percutaneous needle placement employed external landmarks to follow the technique described by Hirano et al.,9 with modification for the male larynx made by bending the needle superiorly to permit placement through the cricothyroid membrane into the paraglottic space, as depicted, into the left vocal fold (Fig. 4A, B, C). The intensity of the transillumination was sufficient to detect needle tip location without modifying the standard strength of the light produced by the flexible transnasal laryngoscope. Enhanced definition of the needle tip location occurred with dimming the light proLaryngoscope 125: October 2015
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duced by the flexible endoscope to identify needle tip location in Reinke’s space superficially, in the deep paraglottic space, and through the thyroarytenoid (TA) gap into the posterior cricoarytenoid muscle (PCA) (Fig. 5). Delivery of an injectate with transilluminated needle tip guidance required removal of the fiberoptic cable. Digital fixation to secure the needle to adjacent neck skin was followed by connecting a 1-cc needle containing collagen (Zyderm2) to the needle hub (Fig. 6A,B). Following injection of 0.4 cc of the collagen, dissection of the larynx demonstrated the location of the collagen in the paraglottic space (Fig. 6C, D). Additional manipulations (figures not shown) in both excised larynges and the full body cadavers permitted directed injection of saline into Reinke’s space without transgression of mucosa.
DISCUSSION In 2014, Chhetri and Jamal reported their approach to percutaneous vocal fold injection via the transcricothyroid membrane (TCM) and transthyroid cartilage approaches with concurrent flexible transnasal endoscopic monitoring.14 These investigators identified that it was necessary to develop expertise in correlating external landmarks with internal laryngeal anatomy for these blind approaches and that a “certain learning Hoffman et al.: Transillumination for Needle Localization
Fig. 4. (A) 23-gauge needle with flexible fiberoptic is bent to permit submucosal placement through cricothyroid membrane into paraglottic space. (B) Appearance of larynx before placement of needle. (C 1,2,3) Positioning of transilluminated needle tip permits repositioning to proper site for injection. [Color figure can be viewed in the online issue, which is available at www.laryngoscope.com.]
curve” is needed to master this technique.14 For transcricothyroid injection, Clary et al. similarly identified that “precise placement of the needle tip is more difficult to obtain and can require a significant level of experience.”15 Variability in laryngeal anatomy may compromise the reliability of determining needle tip placement directed by external palpation alone. Major anatomic differences are consistently identified between the male and female larynx that often warrant modification in the technique for TCM injection. A bend placed in the needle is commonly needed to curve the needle under the larger male thyroid cartilage to access the mid- and anterior vocal fold musculature (TA/lateral cricoarytenoid [LCA]) in a way that is not necessary for the female larynx. Additional subtle differences in laryngeal anatomy are commonly introduced by previous surgery such as thyroidectomy, neck dissection, and rhytidectomy. Our current practice limits the transcricothyroid injection laryngoplasty approach to collagen preparations such as Cymetra, which do not require the same precise location as is necessary for less forgiving injectables such as calcium hydroxylapatite.16 Through a comparative study, Woo et al. identified that percutaneous TCM injection laryngoplasty had less “visualization and precision” than did the thyrohyoid approach.17 Although we have used the transoral approach with curved 27gauge needle (Xomed Treace orotracheal injector) to Laryngoscope 125: October 2015
deliver Radiesse voice (calcium hydroxy apatite) in the clinic under local anesthesia due to the accuracy in needle localization when guided by concurrent rigid transoral videolaryngoscopy, we have abandoned this approach due to difficulties in reliably delivering the material through this small needle.18 Use of transillumination should permit greater confidence in the location of the larger bore needle tip to permit in-clinic injection of calcium hydroxyapatite preparations through the transcricothyroid membrane approach. The laryngeal transillumination technique may be expanded to applications beyond that of injection laryngoplasty for vocal fold augmentation. Gray et al.’s minithyrotomy approach requires accurate placement of dissecting instruments in a narrow and often scarred superficial layers of the vocal fold.19 Paniello et al. described their experience with this technique and identified that there is a high probability of graft extrusion if perforation of the epithelium occurs.20 Gunderson et al. acknowledged this concern with further modifications to the procedure, including use of a 27-gauge finder needle placed along the axial plane of the vocal fold to help guide dilation to develop a plane either within the lamina propria or superficial TA muscle.21 Transillumination to assist in placement of a finder needle would be expected to more reliably avoid mucosal transgression. The recording of EMG from laryngeal muscles is technically difficult and plagued by uncertainty of Hoffman et al.: Transillumination for Needle Localization
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Fig. 5. Anatomic correlates to needle tip location. (A11,A2,A3) Initial placement of needle shaft (solid arrow) with tip (X) superficial in left thyroarytenoid 5 X . (B1,B2,B3) Needle (solid arrow) is maneuvered in deep paraglottic space, with illuminate tip placed through thyroarytenoid gap 5 Y. (C1,2.) Needle tip transilluminated apex of pyriform sinus in posterior cricoarytenoid muscle below vocal process 5 Z. [Color figure can be viewed in the online issue, which is available at www.laryngoscope.com.]
electrode tip location. Closely applied muscles in the larynx, such as the TA and LCA, are discriminated by characteristics of the EMG signal that they produce. Uncharacteristic signals or the absence of a signal could reflect either an important finding or an error in electrode tip placement. Recommendations from the Neurolaryngology Study Group acknowledged this problem and conclude that “future studies should compare different techniques for electrode placement.”22 Transillumination is a new technique to guide electrode tip location within the larynx that should improve the accuracy of diagnostic laryngeal EMG. Difficulties in accessing the PCA muscle for botulinum toxin injection is widely acknowledged and considered an impediment to successful treatment of patients with abductor spasmodic dysphonia.23 We identified the capacity to place a needle into the PCA muscle via the paraglottic space in both canine and human excised larynges. To date, the sole clinical report of PCA injection via transcricothyroid needle placement through the paraglottic space comes from the inadvertent induction of bilateral abductor paralysis, which was reported by Venkatesan et al. as a complication of the effort to inject the TA muscle with EMG guidance.24 These investigators concluded that Laryngoscope 125: October 2015
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posterior location of the needle near the muscular processes of the arytenoids permitted diffusion of the botulinum toxin to the abductor muscles (PCA). This approach, guided by transillumination, may be exploited to purposefully introduce paresis of the PCA muscle in the treatment of abductor spasmodic dysphonia. Additional considerations regarding potential injury to the recurrent laryngeal nerve fibers to the LCA and TA muscles in the course of needle placement must also be considered in using this approach to target the PCA muscles. We identified that unmodified light from transnasal scopes permitted visualization of the white light transmitted by the fiberoptic cable through the soft tissue of the vocal cord. It is possible that improved visualization could result from modifications to the light source, as well as the fiberoptic scope monitoring that light source. Alternative sources of light such as currently exist for ultrathin laser fibers may be employed. Existing technology to modify imaging light within the larynx, such as narrow band imaging, may add further sophistication to this approach. Clinical application of the transilluminating obturator is anticipated to follow further testing and development. Adequate strength and flexibility to the fiberoptic Hoffman et al.: Transillumination for Needle Localization
Fig. 6. (A) The transilluminated needle tip is identified in left vocal cord to be optimally positioned for injection. (B) The fiberoptic light source is withdrawn and replaced to attach a collagen-containing syringe. (C) Injection of collagen results in filling left vocal cord. (D) The larynx is sectioned in coronal plane anterior to vocal process identifying location of collagen injection. L 5 left; R 5 right. [Color figure can be viewed in the online issue, which is available at www.laryngoscope. com.]
cable is desirable to permit bending of the needle housing the fiber, both to maintain illumination in this altered configuration and to avoid detaching a segment of fiber as a foreign body in the larynx.25 The potential for thermal injury to adjacent tissue warrants the study of heat dissipation at the tip of the fiberoptic in the course of adapting this technique to clinical use. Hirano et al. identified the orientation of the needle tip to be important and that the “bevel of the needle must be directed laterally so the silicone rubber does not enter the mucosa.”9 More sophisticated transilluminating needle obturators may be developed, with a formfitting beveled tip that would permit manipulation of the open end of the needle for directional placement of an injection and the visualized light intensity dependent on the direction the bevel is facing.
CONCLUSION We introduce a technique for needle localization in the larynx using transillumination. Clinical application of this technique is anticipated to improve the safety and accuracy of both laryngeal injections and diagnostic EMG, as well as to assist in directed instrumentation of the larynx from an external approach.
Acknowledgments Laboratory access, canine cadaver material, and instrumentation were provided by The University of Wisconsin Department of Surgery (Division of Otolaryngology) July 12, 2014. Laboratory access, human cadaver material, and instrumentation were provided by Cook Medical Inc. April Laryngoscope 125: October 2015
4, 2014 and September 9, 2014. Fiberoptic cable was provided by LEONI Fiber Optics Inc. Research was done at the University of Iowa (H.T.H.), Iowa City, Iowa; the University of Wisconsin (H.T.H., S.H.D., S.L.T., T.M.M.), Madison, Wisconsin; and the Cook Medical Inc.supported research laboratories (H.T.H.): Nicholson Center Cadaver/Model Laboratory in Celebration, Florida (September 9, 2014) and Medical Academic Center in Carmel, Indiana (April 4, 2014).
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