Microstereo-Laryngoscopic Lipoinjection: Practical Considerations

The Laryngoscope Lippincott Williams & Wilkins, Inc. © 2004 The American Laryngological, Rhinological and Otological Society, Inc.

How I Do It

A Targeted Problem and Its Solution

Microstereo-Laryngoscopic Lipoinjection: Practical Considerations James A. Burns, MD; James B. Kobler, PhD; Steven M. Zeitels, MD, FACS

Key Words: Microlaryngoscopy, laryngoplasty, fat injection, lipoinjection, dysphonia, vocal cord, vocal fold, paralysis, dysphonia, glottic, glottis, hoarseness, laryngoscopy.

INTRODUCTION Bru¨nings1 introduced injection medialization by means of direct laryngoscopy in 1911. He described injection of paraffin into the paraglottic space to augment the atrophic soft tissues associated with vocal fold paralysis and thereby medialized the excavated musculomembranous region. In 1991, Mikaelian et al.2 described autologous fat injection for the treatment of vocal fold paralysis. Since then, injection of autologous fat for vocal fold augmentation has become commonplace. Lipoinjection laryngoplasty has been demonstrated to be a safe, efficacious technique for vocal fold augmentation. It has been used for phonosurgical treatment of dysphonia resulting from aerodynamic incompetency associated with paralysis2– 4 and cancer defects.5 Although the literature2,3,6 has been replete with articles describing techniques for harvesting and preparation of fat, methods for microlaryngoscopic injection with stereoscopic visualization have not been described in detail. It is a tribute to Bru¨nings that his injection device is still the most commonly used instrument for this purpose. However, the injector was designed approximately 50 years before the introduction of the surgical microscope to laryngoscopy. Therefore, it is not well suited for use given the limited working distance of approximately 20 cm between the microscope and the proximal lumen of the laryngoscope when a typical 400 mm lens is used (Fig. 1). In

From the Department of Otology and Laryngology, Harvard Medical School, Division of Laryngology, Massachusetts Eye and Ear Infirmary, Boston, MA, U.S.A. Editor’s Note: This Manuscript was accepted for publication March 10, 2004. Send Correspondence to Dr. Steven M. Zeitels, Department of Otolaryngology, MA Eye and Ear Infirmary, 243 Charles Street, Boston, MA 02114, U.S.A.

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addition, the narrow-lumen tubular speculae of most laryngoscopes preclude substantial angulation and range of motion of the needle shaft. The problem is exacerbated if there is a micromanipulator from a CO2 laser attached in front of the microscope objective. Previous solutions sacrifice stereoscopic vision or forego magnification altogether. It has even been proposed that the microscope should not be used for laryngeal injections because “it obstructs the instrumentation.”7 We believe that employing high-powered magnification and stereoscopic visualization of the surgical field during lipoinjection are laudable and achievable goals. This is based on the tenets espoused by the fathers of microlaryngoscopic surgery. The value of microlaryngoscopic lipoinjection with depth perception is further supported by the extensive body of literature describing complications of Teflon injection medialization resulting from technical mishaps of imprecise needle placement.8 In fact, many current Bru¨nings injection sets contain a needle with a rounded guard several millimeters before the beveled aperture to restrict penetration depth. Given the commonplace performance of lipoinjection, and the paucity of information regarding technical execution, practical considerations for magnified stereoscopic lipoinjection are detailed.

METHODS Surgical Technique Microstereo-laryngoscopic lipoinjection is performed with general anesthesia.9 A surgical microscope with a 400 mm front lens should be used to provide for the longest working distance between the microscope and the proximal lumen of the laryngoscope. If possible, the micromanipulator from an attached CO2 laser should be removed. The widest-lumen tubular or bivalve laryngoscope that can be admitted from the lips to the glottis is placed to optimize exposure. This is facilitated by a true suspension gallows (Endocraft LLC, Boston, MA; Pilling Co., Horsham, PA) if it is available. In this series, the universal modular glottiscope (Endocraft LLC) was used in all cases because its lancet– arch-shaped distal lumen (Fig. 2) is designed to optimally expose the deep paraglottic region. Recently, others (Storz Co., Tuttlin-

Burns et al.: Microstereo-Laryngoscopic Lipoinjection

Fig. 1. Intraoperative view showing the limited working space between microscope and laryngoscope. The needle of the Bru¨ning’s syringe has been positioned at the glottis, simulating a tubular speculum without using the lateral proximal slots. The handle is seen overlapping the microscope and the laser’s micromanipulator.

gen, Germany; Xomed Co., Jacksonville, FL) have adopted triangular-shaped laryngoscopes, which are an improvement over their prior designs. Angulated insertion of the long delivery system of the Bru¨ nings injector (Fig. 3) is necessary to avoid the front lens of the surgical microscope. This is ideally suited to the proximally slotted laryngoscopes (Endocraft LLC, Pilling, Storz Co.), but injections are still possible with other standard laryngoscopes available in most operating rooms. There are two further techniques to facilitate microlaryngoscopic lipoinjection. These simple, effective maneuvers substantially increase range of motion of the needle shaft for optimal positioning of the fat graft. First, the needle shaft can be bent (Fig. 4) to offset the long axis of the needle from the surgeon’s direct line of vision. When this maneuver is felt to be beneficial by the surgeon, a slight bend usually suffices. Care must be taken not to excessively bend the reusable Bru¨ nings needle to preserve it for future use. Second, the microscope can be angled slightly off perpendicular to widen the space into which the injection device can be introduced. Care must be taken not to reposition the microscope excessively until portions of the surgical field are only viewed through one ocular, which restricts a stereoscopic view and associated depth perception. The tolerance of microscope angulation is predicated on the diameter of the laryngoscope speculum. Persistence in applying various combinations of these manipulations allows for a binocular stereoscopic view of the glottis.

Fig. 2. Diagrammatic representation of the proximal and distal views through the universal modular glottiscope (courtesy of Endocraft).

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Fig. 3. Intraoperative view showing angulated insertion of the injection syringe. The micromanipulator has been displaced. Proximally slotted laryngoscopes allow for this angulation (see insert). Note the wide clearance of the injector handle with the associated availability of range of motion.

Once the glottal surgical field is adequately exposed and assessed, fat is harvested through a small incision in the crease of the axilla. Although we have used the axilla, other donor-site options exist, including the abdomen. After harvesting the fat, a rubber band drain is placed, the skin is closed in a single layer with 4 – 0 nylon suture, and a pressure dressing is placed. The fat is mechanically lysed with a scalpel to create small pieces and to remove fascia, which might plug the needle. The fat is then

Fig. 4. Bru¨ning’s syringe needle shaft being bent to offset the long axis of the needle.

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washed with lactated ringers solution before placement in a Bru¨ nings injector.5 After the syringe of the Bru¨ nings injector has been filled with fat, the plunger is attached, and fat is advanced to fill the large bore needle shaft. This also allows for compaction of fat within the syringe. The syringe with the needle is then detached from the handle so that more fat can be placed to refill the proximal portion of the syringe. The bevel of the needle is then adjusted to optimize its direction. The processed fat is then injected by means of magnified stereoscopic guidance until the desired clinical effect is achieved (Fig. 5). Fat is delivered through the 18 gauge Bru¨ nings needle and syringe. Care is taken to ensure that the beveled aperture of the needle is directed appropriately into the tissue so that the injected fat is placed accurately. To do this, the needle has to be adjusted at its attachment to the syringe. Injecting with the Bru¨ nings syringe should be done deliberately with individual clicks because the ratcheting mechanism of the handle does not provide precise control of injection volume. There is often a delay or an uncontrolled postclick extrusion, similar to the behavior of a caulking gun. Therefore, the surgical field should be observed patiently. Furthermore, slow, deliberate lipoinjection into a scarred postcancer-resection glottal defect leads to real-time tissue expansion of fibrous areas, which is desirable. Because fat is partially resorbed, patients are typically volumetrically over injected by 50%.5 The depth of needle placement is easily determined because the microscope provides a three-dimensional stereoscopic view of the target surface. This is critical in determining adequate injection volumes in defects that have a significant superior to inferior component.

RESULTS Lipoinjection under direct stereoscopic visualization has been performed on 40 patients since adopting the technique. These cases represent a consecutive series of

patients who needed paraglottic augmentation subsequent to tissue loss as a result of cancer resection (26), trauma (11), or failed thyroplasty at another institution for paralysis (3). The stereoscopic view optimized selection of the location for mucosal puncture, helped determine the depth of needle penetration, and provided a magnified view of the tissue to determine the final volume of injected fat. Initially, the drain was removed from the donor site on the first postoperative day; however, 3 of the first 26 patients developed a subcutaneous seroma in the axilla. In the latter part of the series, the drain was left in for 4 or more days, and there were no subsequent wound problems. There were no laryngeal complications.

DISCUSSION This evaluation and description of a method for microstereo-laryngoscopic lipoinjection was performed for a number of reasons. The phonosurgical value of autologous lipoinjection is well accepted in selected scenarios. In addition, there are substantial technical restrictions in performing the procedure with the available injecting devices and the surgical microscope. Finally, there is a paucity of literature detailing the methodology to overcome these restrictions. Because of these facts, it was our impression that prior investigators performed magnified lipoinjection without optimal stereoscopic visualization and depth perception. Laryngoscopic injection medialization of the vocal fold is a time-honored1 technique to correct dysphonia secondary to aerodynamic glottal incompetence. The primary design of injector instrumentation has not changed substantially in nearly a century despite the fact that the

Fig. 5. (A) Excavated vocal fold in the musculomembranous region in a patient who underwent phonomicrosurgical resection of a T1 carcinoma (magnification ⫻4). (B) (The point of Bru¨ ning’s injection needle is placed lateral to the concavity in the paraglottic space (magnification ⫻4). (C) (4⫻) The vocal fold has been augmented with fat as seen by the new convexity. A small amount of fat is seen extruding from the puncture site, which was removed (magnification ⫻4). (D) Higher magnification (magnification ⫻7). Reprinted with permission from Singular Publishing.

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microscope was introduced to enhance endolaryngeal surgery more than 40 years ago. Specifically, the injectors are not well suited for use with the limited working distance associated with the surgical microscope. It is ironic that the majority of the literature reporting injection medialization in the 20th century used synthetic substances.1,8 Despite the fact that there has been substantial regression of viscous laryngoscopic injection of permanent synthetic biomaterials (Teflon) for large-volume deficits and an increased use of autologous fat for a variety of indications, there are limited descriptions of microlaryngoscopic lipoinjection techniques. Previous studies reporting autologous fat grafts in vocal folds have focused on the long-term fate of fat grafts,10 enhanced voice quality,10,11 fat-harvesting techniques from the donor site,6 inflammatory effects of the injection on the vocal fold,12 and comparison of various injected substances with fat, such as collagen, fascia, and alloderm. None of the aforementioned studies primarily addressed the technical considerations of injecting fat in a precise manner. Current fat processing methods allow for delivery through larger caliber needles only. CampbellGraham and Newman13 showed that adipocyte morphology and viability were significantly affected when passed through needles that were 20 gauge or smaller. Therefore, lipoinjection requires a large-bore needle with an injector capable of infusing an extremely viscous substance. The Bru¨ nings injector has remained the primary device for this purpose. It is well known that the ratcheting system of this device delivers a variable amount of fat with each “click” and can often function in an irregularly irregular fashion, whereby very little volume is delivered on one “click,” whereas the very next “click” delivers a large volume. In addition, the nature of the Bru¨ ning’s injector precludes precise proprioceptive feedback for the surgeon. This imprecision is less critical in treatment of paralyzed vocal folds where the fat is injected in a pliable deep paraglottic region to provide diffuse bulk to medialize a denervated vocal fold. However, it is more problematic when the goal is to place fat in more superficial areas and in scarred soft tissue. Determining proper depth is difficult when the injector obscures visualization of the needle shaft and puncture site.8 These interdependent technical restrictions make the conceptually simple procedure of lipoinjection potentially arduous. It is advantageous to address these shortcomings in all microlaryngoscopic lipoinjection procedures, but it becomes even more critical when precision is more important (as with augmentation of complex glottal defects resulting from cancer resection or trauma). The depth perception that is provided by a stereomicro-laryngoscopic examination is invaluable not only for assessing these glottic defects in the planning stage of the procedure but also for augmenting these defects during the procedure. A variety of factors can potentially limit exposure in any given patient, so it is worthwhile to have a number of strategies to optimize conditions for magnified lipoinjection. These include ensuring that there is a stereoscopic view by bending the needle, angling the microscope, using slotted scopes, and detaching the micromanipulator, as well as precisely configuring the vector of the needle aperture. The improved endolaryngeal visualization allows for Laryngoscope 114: October 2004

more precise real-time three-dimensional procedural evaluation of the augmentation of the vocal fold soft tissues. Future directions to address the technical difficulties inherent in lipoinjection are focusing on developing fatprocessing methods that involve enzymatic removal of interstitial tissue. This may allow “pure” adipocyte aggregates with less viscosity to be delivered atraumatically through ergonomically favorable injectors and smaller caliber needles. When these processing techniques are perfected, fat may well prove to be a leading homologous substance suitable for injection into microscopic glottic defects. The precision associated with the aforementioned approach could make lipoinjection a useful tool for dealing with the ultimate glottal deficit: loss of superficial lamina propria.14,15 We believe that fat or other new biomaterials will be combined with inert substances to create variable “dial in” elasticity and viscosity. This will catalyze the design of new injection systems to accommodate this dissimilarity in rheology so that microstereo-laryngoscopic injection methods will become the platform technology for repairing a variety of vocal fold soft-tissue deficits, including mucosal pliability.

Acknowledgments. The authors thank James Heaton, PhD, for his assistance in preparing the graphics for this manuscript.

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