Principles of Phonosurgery

Preoperative Examination

Critical to appropriate preoperative surgical planning is an accurate diagnosis, which hinges on the preoperative voice history, physical examination, voice recording, and videostroboscopy. A voice history should include a temporal description of the voice impairment, a carefully detailed description of how the voice has changed, social and occupational voice demands, prior voice therapy or laryngeal procedures, and relevant past medical history (e.g., connective tissue disorders, cervical spine abnormalities, use of anticoagulants). Physical examination should include a focused assessment of factors that will predict ease of direct laryngoscopic exposure, including a degree of neck extension, mouth opening, temporomandibular joint discomfort, mandibular tori, dental condition, thyromental distance, neck circumference, and body habitus. A voice recording, in general, can include the reading of a standardized passage, sustained vowels, upward glissando, and a brief sample of increased vocal projection. The recording should be tailored to the individual patient and include any task with which the patient has noted difficulty. The videostroboscopic exam is critical. A rigid exam is typically preferable if possible, due to superior optics. Images should be obtained at rest, during modal phonation, and during high-frequency phonation.

Informed Consent Process

A thorough description of potential risks of surgery is important. This includes the general risks associated with a direct microlaryngoscopy, including injury to the lips, gingiva, tongue, or teeth, as well as temporomandibular joint pain, and dysgeusia. If these symptoms occur, they are typically temporary on the order of weeks. Most relevant to phonomicrosurgical operations is the risk of no improvement in voice quality (1-2%) or decreased voice quality (1-2%). The plan for postoperative voice rest should be discussed along with the timing of the first follow-up visit for the patient to return to voice use. This is best done in conjunction with the speech-language pathologist, who can manage the patient in the transition back to voice use. We typically recommend a 5-7 day period of absolute voice rest after a microflap procedure, though voice rest recommendations vary widely and are primarily based on anecdotal evidence rather than evidence-based research. The patient's anticipated voice demands for the 2-3 months following surgery should be noted. This is important, for example, in a teacher with a phonotraumatic lesion in whom the timing of surgery should be based around extended scheduled breaks (summer).

Laryngoscope

Typically, the largest laryngoscope that can still provide a complete view of the glottis is recommended. A variety is available and the use of a particular one depends largely on personal preference. Examples include the Dedo laryngoscope (Pilling), Zeitels universal modular glottiscope (Endocraft), Sataloff laryngoscope (Integra), Lindholm laryngoscope (Karl Storz), Ossoff-Pilling laryngoscope (Pilling), and posterior commissure laryngoscope (Pilling). The Lindholm is particularly useful for any supraglottic procedures, the Ossoff-Pilling is a smaller bore laryngoscope that is helpful for patients where exposure cannot be obtained with a larger laryngoscope, and the posterior commissure laryngoscope is helpful for difficult posterior glottic exposure.

Microscope and Telescopes

A high-quality operating microscope is required for phonomicrosurgery. A working distance between 370 and 415 mm is used which is optimal for the long instruments used during the procedure. A fixed 400-mm focal length lens can be used, or a variable focal length design set between 370 and 415 mm. Articulated eyepieces allow for maximal surgeon comfort and optimal ergonomics. Compatibility with the CO₂ laser micromanipulator and KTP laser filters are useful. Though most procedures are done with cold steel instruments, lasers may be useful in the removal of recurrent respiratory papillomatosis or photocoagulation of vascular lesions.

Hopkins rod telescopes with 0-, 30-, and 70-degree angulation are required for intraoperative visualization. The telescope should be 4-5 mm in diameter and 30 cm long to provide adequate resolution and working length. Angled telescopes are particularly helpful for viewing the infraglottic surface of the vocal fold. The procedure itself is performed with microscopic visualization, but telescopic examination both at the beginning of the procedure and intermittently during it as needed helps provide a complete three-dimensional view of the pathology. Photodocumentation before, during, and after addressing the pathology is also best accomplished with the telescope.

Instrumentation

A variety of phonomicrosurgical instrument sets are available. Important instruments to have available are the blunt probe, sickle knife, blunt microelevators, microscissors, microcup forceps, straight and curved alligator forceps, Bouchayer forceps, and microlaryngeal suctions (3, 5, and 7 French) (Fig. 2). The bunt probe helps in initial evaluation and palpation of pathology. Disposable single-use and reusable sickle knives are available; single-use blades are preferable to ensure adequate sharpness for microflap incisions. Blunt microelevators with different angulation of 30 and 60 degrees help develop dissection planes and separate pathology from surrounding normal epithelium and lamina propria. The 30-degree up-angled Woo laryngeal scissor (Integra) can be used both for sharp (with the tines apart) and blunt (with the tines together) dissection and is a very helpful and versatile instrument for phonomicrosurgery. Microcup forceps with up, left, and right angulation has a sharp cutting edge limited to the distal 180 degrees to allow for precise removal of pathology in certain situations (e.g., abnormal mucosa, papilloma). Curved alligator and Bouchayer forceps aid in flap retraction. Precise and delicate handling with these instruments is required to ensure appropriate flap preservation during the procedure.

Additional Equipment

Half-inch by half-inch cotton pledgets soaked in 1:10,000 epinephrine are used intraoperatively for hemostasis. A microdebrider can be used for bulky papilloma cases with the laryngeal skimmer blade. The more aggressive tri-cut or quad-cut blades used in endoscopic sinus surgery are not recommended for use in the endolarynx due to potential for inadvertent vocal fold injury. If subepithelial mucosal infusion of epinephrine or steroid is injected, an orotracheal injector (Integra) with disposable 27-gauge needle is used. A Lindholm vocal cord distractor is very useful for exposing anterior commissure disease.

Patient Positioning

The ideal position for the patient undergoing laryngoscopy is the sniffing, or Boyce-Jackson position, which requires flexion of the neck on the body and extension of the head on the neck (Fig. 3). A doughnut pillow is placed under the occiput. A shoulder roll prevents adequate neck flexion and should be avoided.

Dental Protection

The maxillary dentition should be protected. This is ideally done with a custom Aquaplast/Thermoplast sheet which is heated in near-boiling temperature. Once heated, the material becomes malleable. It is then placed over the maxillary dentition. As it cools, the material hardens. This process can be expedited by pouring about 5 cc of ice water once it is in place. For patients missing a single tooth, it is best to try and keep a straight contour to the mouthguard as if no teeth were missing. If Aquaplast is not available, a preformed plastic tooth guard commonly found in anesthesia carts can be used. This can be reinforced with three layers of 1” cloth tape placed on each side, overlapping in the middle, to provide additional protection for the central and lateral incisors which are at greatest risk for injury during laryngoscopy. For patients with an edentulous maxilla, the Aquaplast or preformed tooth guard can still be used, though additional attention must be paid to ensure it remains in appropriate position on the alveolus. Alternatively, foam padding commonly used in the operating room for elbow/wrist cushioning can be trimmed and used as well.

Laryngoscope Placement

Placement of the laryngoscope to allow for complete visualization of the glottis is of the utmost importance, and adequate time should be dedicated to this step. Without adequate visualization, the operation cannot be performed. The mouth is opened with the nondominant hand and the laryngoscope is passed along the right lingual gutter, displacing the tongue, and endotracheal tube to the left. The posterior pharyngeal wall is visualized, and the laryngoscope is then advanced inferiorly and anteriorly. Aside from the Lindholm laryngoscope which is positioned with the tip in the valleculae, laryngoscope positioning for phonosurgical procedures is typically with the tip of the laryngoscope in the endolarynx, positioned just superior to the true vocal folds, with the sides of the laryngoscope displacing the false vocal folds laterally to permit maximal visualization of the true vocal folds. Care is taken not to make contact with the superior surface of the vocal folds during this process, as this can induce edema and minor hemorrhage.

Considerations for the Difficult Exposure

Some patients can be exposed easily and quickly, while others will be more challenging. In these situations, several adjuncts can assist with obtaining adequate visualization. First, it should be confirmed that the patient is in the Boyce-Jackson position. Second, additional neck flexion can be obtained by manually raising the angle of the head of the operating room table by one or two clicks. Third, anterior counter-pressure can be obtained using a folded 4x4 gauze placed over the cricoid cartilage and a roll of 1-inch cloth tape, which should be placed from one side of the operating room table, over the cricoid cartilage, and continued to the other side. This is placed by the surgeon as the glottis is visualized through the laryngoscope to optimize tape position and tension. The vector of force applied is posterior and slightly cephalad to bring the anterior commissure into view. Importantly, counter-tape could potentially injure the patient if they were to move or if the tape was not removed as the patient emerged from anesthesia. Thus, this tape should be released and the patient be taken out of suspension if the patient began to move during the procedure. In some cases, the main issue limiting visualization is passage of the laryngoscope underneath the epiglottis. This is more common in patients with a short or flaccid epiglottis. In these scenarios, several additional adjuncts are available to aid with laryngoscope placement. First, the laryngoscope can be passed between the endotracheal tube and the posterior pharyngeal wall and advanced into the infraglottic endolarynx, after which the endotracheal tube is allowed to slide posterior to the laryngoscope and the laryngoscope is withdrawn slowly until the vocal folds are visualized. Care must be taken during the infraglottic placement of the laryngoscope to angle posteriorly so as not to traumatize the vocal folds. Second, the epiglottis can be manipulated using a cup forceps and displaced anteriorly as the laryngoscope is passed posterior to it, and the epiglottis is released once visualization is obtained. Third, a temporary 4-0 silk suture can be passed through the epiglottis while visualizing it with the laryngoscope in a supra-epiglottic position. The laryngoscope is then withdrawn completely, and then reintroduced into the oral cavity with the silk suture external to it. The laryngoscope is then advanced while tension is placed on the suture to provide anterior and superior traction on the epiglottis so the laryngoscope tip can be advanced posterior to it into the endolarynx. If exposure is still limited after the above adjuncts have been employed, a smaller laryngoscope (e.g., Ossoff-Pilling laryngoscope) can be used which can provide visualization in almost any patient except for those with the most limited cervical spine mobility.

Suspension

Once the laryngoscope is in appropriate position, the patient is placed into suspension. Two main systems are available for this: a gallows suspension which provides upward and forward suspension, or a rotation/fulcrum suspension consisting of a Lewy arm onto a table-mounted Mayo stand. As the force on the fulcrum is increased, pressure on the maxillary dentition also increases, so care must be paid to recheck lips, teeth, and tongue with any change in laryngoscope or suspension position.

Surgeon Positioning

The surgeon should be seated comfortably with lower back support and the knees bent at 90 degrees. A hydraulic chair should be used to allow for easy subtle adjustments in positioning. Operating table height should be adjusted to maximize surgeon comfort, and the patient may need to be placed into slight Trendelenburg position depending on the position of the laryngoscope base. Elbows and wrists should both be supported (Fig. 4). This can be accomplished in a variety of ways, including specially designed chairs with adjustable arm supports, or a simple system comprised of an adjustable Mayo stand with stacked foam which is placed between the surgeon and the patient head and covered with a disposable Mayo stand cover.

Intraoperative Examination

Once the larynx is optimally exposed, careful examination should be performed. In cases of difficult exposure, this can be an opportunity for the surgeon to take a break and allow time for the transition between laryngoscopy (a gross motor task which can be physically taxing) and phonomicrosurgery (a fine motor task that requires significant dexterity). An initial examination is performed with 0-degree and angled (30- and/or 70-degree) telescopes. Complete characterization of the pathology is required with careful, systematic evaluation of the entire superior, medial, and infraglottic surface of each vocal fold. The operating microscope is then brought in and careful examination repeated, with palpation using blunt instruments also performed to palpate for pathology presence and extent. Palpation is performed in a systematic fashion, for example, anterior to posterior, and inferior to superior along each vocal fold to ensure primary pathology is characterized completely and secondary pathology is not missed. Notably, information obtained from the intraoperative exam can differ from the impressions on the office-based videostroboscopy, and the surgeon must be able to adapt accordingly.⁹

Microflap Approach to Submucosal Pathology

The microflap technique is the main approach in phonomicrosurgery. The key principles of the microflap technique are making an epithelial incision immediately adjacent to the pathology in order to preserve normal epithelium, remaining in as superficial a plane as possible to avoid disrupting normal lamina propria, and preserving epithelium and superficial lamina propria to ensure maintenance of the mucosal wave postoperatively.

Several variations of the microflap technique have been described. The lateral microflap describes placement of the epithelial incision at the lateral aspect of the superior surface near the junction with the ventricle.¹⁰ A subepithelial flap is then elevated, pathology excised, and the flap redraped at the end of the procedure. Though effective, it can be more technically challenging due to more than necessary flap elevation and thus more cumbersome flap retraction during the procedure. The mini-microflap was described by Sataloff et al. and consists of superior, anterior, and posterior incisions around the pathology, gentle separation of pathology from the lamina propria, and redraping of the small mucosal flap over the defect.¹¹ The medial microflap was described by Courey, Garrett, and Ossoff in 1997 and consists of a longitudinal incision overlying the lesion for pathology located on the medial surface of the vocal fold, followed by separation of pathology from the lamina propria, and trimming of any redundant epithelium.¹² Central to all techniques is excision of all pathology with preservation of maximal epithelium and superficial lamina propria without any violation of the vocal ligament.

The initial incision is made with a sharp sickle knife, immediately lateral to the pathology, typically in a posterior to anterior direction. The incision is extended about 2 mm anterior and posterior to the pathology to ensure there is not inadvertent tearing of the microflap edges during retraction. When making the incision, it is important to only incise through epithelium and not violate the lamina propria. This is best accomplished by inserting the tip of the knife and then elevating the mucosa superiorly while advancing the blade anteriorly (Fig. 5). Additionally, the incision should be made parallel to the free edge of the vocal fold. It is easy to inadvertently carry the incision laterally as it advances anteriorly; this should be avoided.

Subepithelial infusion of 1% lidocaine with 1:100,000 can be performed prior to the incision but is typically not necessary. It has the disadvantage of potentially obscuring the visual distinction between normal and abnormal tissue. The bleeding encountered during microflap surgery is usually minimal and responsive to epinephrine-soaked cotton pledgets.

Once the incision is made, a blunt elevator is used to develop the microflap between the pathology and the overlying epithelium (Fig. 6). This is a critical step and care should be taken to elevate this flap without violating the pathology or elevating the flap in too deep a plane. The flap should be sufficiently thin (comprised only of epithelium) so that the elevator can be visualized through it during the dissection. The epithelium may be adherent to the underlying pathology, and so beginning elevation either anterior or posterior to the pathology can be helpful. Flap elevation continues medially toward the infraglottic vocal fold, medial to the pathology. Small fibrous bands may intermittently need to be divided. Once the flap is elevated, the lateral-most edge is grasped with a curved alligator or Bouchayer forceps and retracted medially (Fig. 7). It is easy to inadvertently traumatize or tear the flap with the retracting hand if not paying attention to it. Thus, one should keep their eyes looking through the microscope at all times when retracting the flap. The surgical assistant can help by guiding any second instrument into the laryngoscope for the surgeon. The flap can also be draped laterally to protect it as well. Meticulous hemostasis should be maintained throughout, as even a minimal amount of blood can obscure visualization considerably when working in a small space at maximal magnification. Epinephrine-soaked cotton pledgets and a 3-French microlaryngeal suction without coverage of the thumb port are typically adequate for this purpose.

Once the flap is elevated, the pathology is identified and the diagnosis confirmed. A second dissection plane is then created between the pathology and the underlying lamina propria. The majority of pathology will be adherent to the overlying epithelium, but some lesions (e.g., fibrous mass) will be deeper and adherent to the underlying vocal ligament. For superficial pathology, the development of the plane between the epithelium and the pathology is the most challenging aspect. For deeper pathology, elevation of this plane is easy but the separation of the pathology from the ligament is more challenging. Blunt dissection should be used whenever possible in both scenarios to avoid traversing planes and violating normal lamina propria or epithelium. Small cuts can be made when needed to divide fibrous bands with up-angled microscissors or Woo scissors.

Once the pathology is removed, the microflap is redraped laterally and any excess epithelium trimmed. Preservation of the inferior aspect of the flap helps in this regard, as it is usually more robust than the epithelium on the superior and medial edge overlying the lesion, and can be accomplished by dissecting the pathology toward the medial most edge of the microflap prior to excision, thus preserving maximal epithelium inferiorly for redraping (Fig. 8). Care should be taken to avoid any excessive trimming which would result in epithelial dehiscence. The vocal fold should now have a straight contour. If it does not, the flap should be retracted and the wound re-examined to ensure all pathology has been removed. If additional excision occurs at this step, particular care should be taken to avoid the removal of normal lamina propria.

Vocal Fold Polyp

Polyps can be removed via two approaches: microflap and truncation. With the microflap technique, the procedure begins as described above with an epithelial incision at the lateral aspect of the lesion. The flap is elevated. Gelatinous material is identified and removed with a micro-cup forceps or 3-French suction. Normal superficial lamina propria is preserved. The flap is redraped, redundant epithelium trimmed, and straight contour is confirmed (Fig. 9). If there is minimal healthy mucosa overlying the polyp, a truncation technique may be considered. With this approach, the medial edge of the polyp is grasped and retracted medially, and a microscissor is used to excise only the abnormal epithelium and gelatinous polyp to achieve a straight vocal fold contour (Fig. 10). It can be easy to inadvertently resect normal lamina propria with this approach, and so caution is advised not to over-retract medially and obscure perception of the location of the normal free edge of the vocal fold. Following polyp truncation, any potential abnormal residual mucosa at the anterior and posterior extents is trimmed conservatively using a curved scissor angled away from the free edge.

Vocal Fold Cyst

An epithelial incision is made just lateral to the cyst. The overlying epithelium is separated from the underlying cyst using the angled blunt microelevator. There may be adherence between the epithelium and the cyst wall, and patience should be exercised as the two are separated. It can be helpful to begin anterior or posterior to the cyst first, and then proceed to the more difficult portion of flap elevation. The superficial dissection should be performed first, when there is natural counter-traction provided by the adherence of the cyst to the underlying vocal ligament. Next, the cyst is separated from the vocal ligament using the blunt microelevator, with care taken not to violate the vocal ligament. Any small fibrous bands tethering the cyst can be divided with conservative sharp dissection, with the majority of dissection performed bluntly. Great effort should be made not to violate the cyst wall, which complicates removal and increases the risk of recurrence. If the cyst wall is violated, the defect should be grasped quickly and dissection performed expediently around the cyst before all cyst contents have been evacuated. Epithelial resection is typically not needed.

Fibrous Mass

The initial dissection for a fibrous mass may be similar to that for a cyst. Separation of the pathology from the vocal ligament may be more challenging, and there will often be anterior and posterior extensions of the mass along the vocal ligament (Fig. 7). It is often difficult to define the distinction between the fibrous mass and the vocal ligament. Care should be taken to ensure that a straight free edge is obtained at the conclusion of the procedure, and it is better to err on the side of leaving some minimal pathology present rather than excising a small amount of normal ligament.

Reactive Lesion

It is not uncommon for a reactive lesion to arise contralateral to the primary lesion of interest. Careful examination with the telescope and microscope at the beginning of the operation is crucial to identifying and characterizing these lesions. If the reactive lesion is small and soft, observation or steroid injection (dexamethasone, 10 mg/ml) is often adequate. If the lesion is firm or extends over 4 mm of the free edge of the vocal fold, excision should be considered.