Injection Laryngoplasty
Trans cervical Injection laryngoplasty:
This is a treatment for glottal incompetence. Depending on the injectable used, the vocal fold can be medialized for weeks to years.
Glottal incompetence is seen in some of the following conditions:
1. Vocal fold paralysis
2. Vocal fold paresis
3. Vocal fold scar
4. Presbylaryngitis
5. Parkinson's disease
Before performing medialization procedure the physician should closely examine the vibratory vocal fold membrane on the affected side. In cases with vocal fold scar, the vocal fold may not vibrate well. Medialization in this condition may not improve patients voice at all.
Contraindications:
There are no absolute contraindications prevent a patient from being a candidate for vocal fold injection.
Individuals could have an allergic reaction to a specific injection product
If the etiology of patient's glottic incompetence is an irreversible cause like severed recurrent laryngeal nerve the patient is better served by a permanent procedure like thyroplasty.
Relative contraindications include patients who are anxious, unable to cooperate or on multiple anticoagulants.
Anesthesia:
Local anesthesia is used. Three sites are anesthetized for transcutaneous injection laryngoplasty. The nasal passae, the larynx, and the skin overlying the injection site.
Nasal cavity can be anesthetized by packing with 4% xylocaine mixed with 1 in 100000 adrenaline.
Larynx is anesthetized with topical 4% xylocaine spray. A syringe fixed with Abraham canula is used for this purpose. While the patient phonates, 4% xylocaine drops is dripped on to the tongue base, epiglottis, arytenoids and vocal folds.
For skin anesthesia, less than 1 ml of 1% xylocaine is infiltrated on the skin and subcutaneous tissue overlying the injection site.
Patient positioning:
The patient is positioned seated upright in a chair during this procedure and is asked to lean forward slightly with the chin held up.
Technique:
Three approaches can be used.
1. The needle can be placed through the thyrohyoid membrane
2. The needle can pass through thyroid cartilage
3. The needle can pass through cricothroid membrane.
The procedure:
Prior to performing the procedure, the hyoid bone, thyroid cartilage and cricoid cartilage are outlined in the midline with a skin marker. The three areas as stated above are anesthetized.
The surgeon pass the needle via any of the three approaches enumerated above. The needle is directed towards the posterior vocal fold. If the cord is immobile / hypomobile cord the injection is directed lateral to the vocal process. The goal of the injection is to rotate the arytenoid medially and medialize the true cord. A second injection, if necessary is placed more anterior at the midportion of the vocal fold.
Transthyrohyoid approach:
This approach ensures that the needle traverses the thyrohyoid membrane which is present between the hyoid bone superiorly and thyroid cartilage inferiorly. In this approach the needle is passed in an inferior direction through the midline thyrohyoid membrane and directed laterally into the vocal fold.
After infiltration anesthesia of the region of infiltration a syringe filled with augmentation material with a 25 gauge needle is passed superior to the thyroid notch through the skin, subcutaneous tissue and preepiglottic space, superior to the vocal folds into the airway. Once the needle enters the airway, it can be visualized with the nasopharyngoscope and is directed into the vocal fold. Augmentation material is placed within the paraglottic space under direct visualization.
Transthyroid cartilage approach:
This approach is best used in younger patients in whom thyroid cartilage is not ossified. In this approach the vocal fold is approached laterally and the needle is passed through the skin and thyroid cartilage into the vocal fold.
Thyroid prominence and lower border of thyroid cartilage are marked in the midline using skin marker. The level of vocal fold is midway between these two points and travels in a plane perpendicular to this line.
The skin overlying this area is anesthetized with 1% xylocaine. A 25 gauge needle attached to a syringe filled with augmentation material is passed through the lateral thyroid cartilage into the vocal fold. The position of the needle is visualized on the monitor via the nasopharyngoscope. Augemntation material is placed within the paraglottic space under direct vision.
Transcricothyroid membrane approach:
This approach allows for entry into the airway in the subglottic region in which the needle is passed into the vocal fold from below. This membrane is located inferior to the vocal folds between thyroid and cricoid cartilages.
The position of the thyroid and cricoid cartilages are marked on the skin with a skin marker.
The skin overlying this area is infiltrated with 1% xylocaine.
The fibreoptic laryngoscope is passed through the nose and positioned just above the epiglottis by an assistant.
A syringe with 27 gauge needle is passed in the midline neck thorugh the cricothyroid membrane. The needle is visualized passing into the airway. The needle is passed underneath the true cord and inserted into the paraglottic space. Augmentation material is placed within the paraglottic space under direct visualization.
Precautions to be taken:
1. Always visualize the needle in the correct position before injecting. Blind injection should not be performed.
2. Patient should be in nil oral atleast one hour after the procedure to allow for local anesthetic effect to wear out
3. As the vocal fold is injected, it should be seen to bulk up rather immediately. If this does not occur needle may have to be repositioned
4. Approximately 0.6-0.8 ml of material is injected to medialize the cord. Only 0.4 ml is needed for females. The end point should be slightly overcorrected vocal fold because there could be some amount of resorption of material later
5. A slight bend placed in the neelde 2 cm away from the tip may assist in directing the needle to the vocal fold more easily in transcricoid membrane approach.
Complications:
1. Allergic reaction to injected material
2. Shortness of breath after injection
3. Extrusion of injected material into incorrect compartments
4. FB reactions
Intraoral injection method:
Injections for medialization of vocal folds can also be performed using transoral route. Kleinsausser suspension laryngoscope is used to kep the mouth open and larynx visualized. Ideally this procedure is performed under general anesthesia. Major drawback of this procedure is that voice cannot be tested on the table. A 19 gauge needle is used to inject fat. A Bruening syringe is used for this purpose.
Laryngeal framework surgery:
This surgery is generally reserved for treatment of glottic insufficiency from unilateral paralysis that is not expected to improve. Favourable factors of this procedure include: 1. Dysphagia 2. High degree of vocal disability / vocal demand 3. Poor functional prognosis 4. Large glottic gap (2mm - 3mm) 5. Posterior glottic gap
The simplest and most common form of this surgery includes medialization thyroplasty, the surgical insertion of an implant made of silicone, expanded polytetrafluoroethylene (Gortex) or some other biologically inert material into the paraglottic space to displace the paralysed vocal fold medially. This surgery is ideally performed under local anesthesia, with or without additional intravenous sedation. The surgeon guided by patient phonation and endoscopic visualization, may size and position the implant for optimal correction of patient's glottal insufficiency without functional restriction of the airway. The critial task is to identify the level of the vocal fold in relation to the thyroid lamina, so that the thyroid cartilage window through which the implant is inserted can be placed appropriately. This type of Medialization in contrast to injection is more predictable and durable than that of injection technqiues. Serious complications include airway obstruction and perforation into the laryngeal lumen. Necessarily, medialization narrows the airway and in combination with post op oedema and hematoma, can cause airway obstruction. It is precisely for this reason patient needs to be observed inside the hospital for a couple of days. Perforation of laryngeal mucosa increases the likelihood of infection and subsequent extrusion of the implanted material. Suboptimal voice outcome happens to be the most common complication following this procedure.
Arytenoid repositioning:
This is added to medialization thyroplasty when there is a poorly supported arytenoid or a posterior gap. This abnormality is difficult to remedy with thyroplasty alone. Arytenoid repositioning surgery is desinged to internally rotate / suspend the arytenoid in physiologic phonatory position. Commonly the muscular process of arytenoid cartilage is approached through the inferior constrictor muscle and around the back of the thyroid lamina. A nonabsorbable suture is passes through this structure and secured to the thyroid lamina to exert anterolateral traction on the muscular process and thus rotate the vocal process medially and slightly caudally. This is known as arytenoid adduction.
Adduction arytenoidopexy a less common approach involves opening the cricoarytenoid joint capsule and suturing the arytenoid in optimal position directly to the crest of the cricoid. These procedures are technically more demanding and time consuming than thyroplasty alone and have higher incidence of complications, because of oedema / bleeding into the paraglottic space can cause airway obstruction.
