The injection of a filling material into the vocal cords aims to increase the volume of one or both vocal cords in order to facilitate their closure. This allows the vocal cords to touch each other more easily when speaking, but also when swallowing and coughing.

The injection may be performed, among other indications, to treat vocal cord paralysis, vocal cord atrophy (thinning of the vocal cords), or vocal cord scarring.

There are different types of filling materials that can be injected into the vocal cords. The main ones include carboxymethylcellulose, hyaluronic acid, and calcium hydroxyapatite.

This procedure can be performed under local anesthesia or general anesthesia.

Local anesthesia

When the procedure is performed under local anesthesia alone, it may take place in the office or in the operating room. The patient remains awake for the entire procedure. The nose, mouth, and throat are numbed with xylocaine, which may be administered as a nebulized mist (inhaled), as a spray through the mouth, or by injection into the neck. Medication may also be given to help the patient relax during the procedure.

General anaesthesia

When general anesthesia is chosen, the injection is performed in the operating room. The patient is put to sleep, a breathing tube is placed in the throat to assist with breathing during the procedure, and is awakened at the end of the procedure.

Under Local Anesthesia

The patient is seated for the procedure. The procedure begins with the numbing of the throat.

A thin flexible camera is then inserted through one of the nostrils and advanced into the throat. If needed, an anesthetic gel can be applied to the camera and/or an anesthetic spray can be applied inside the nose. The flexible camera remains in place throughout the entire procedure. This camera allows visualization of the needle during the injection and ensures that the filling material is injected in the correct location.

Subsequently, the injection of the filling material can be performed either through the mouth (transoral injection) or through the neck (transcervical injection).

Transoral Injection

For transoral injection, the patient is then asked to stick out their tongue, which is gently held outside the mouth by an assistant. A tongue depressor is used to visualize the inside of the mouth, and a needle is passed through the mouth into the throat.

The injection is then performed into one or both vocal cords. A sensation of pressure may be felt in the neck and sometimes even in the ear during the injection. This sensation should resolve quickly after the injection.

Transcervical Injection

For transcervical injection, the needle is inserted through the skin of the neck, in the center, from the front toward the back of the neck. Once inserted, the needle become visible in the larynx with the flexible camera,

The injection is then performed into one or both vocal cords. A sensation of pressure may be felt in the neck and sometimes even in the ear during the injection. This sensation should resolve quickly after the injection.

Under General Anesthesia

The patient is in the operating room, lying on their back on the operating table. General anesthesia means that the patient will be asleep throughout the entire procedure and therefore unaware of what is happening. An endotracheal tube is inserted through the throat into the trachea to allow breathing throughout the procedure.

The injection is performed using a microlaryngeal surgery (MLS) technique. A rigid laryngoscope (a metal, tube-shaped instrument) is inserted through the mouth into the throat. The needle is then passed through this tube to reach the vocal cords and perform the injection. The patient is awakened at the end of the procedure in the recovery room.

Under Local Anesthesia

The injection itself takes less than 5 minutes. Preparation before and after the procedure means that the patient typically spends between 30 and 45 minutes in the office.

Under General Anesthesia

The surgery itself takes approximately 15 minutes. Preoperative preparation, general anesthesia, and the postoperative recovery period mean that the patient spends about half a day at the hospital. The patient may return home the same day.

Regardless of the technique used or the type of anesthesia used, the result should be the same.

After the injection, the voice quality should be better. There should be less vocal fatigue and less feeling like you have to force yourself to speak. It takes about two weeks for the voice to stabilize. Depending on the situation, swallowing (ability to swallow) as well as cough may be improved after the injection.

Different filling materials can be used. Depending on the product used, the duration of the effects may vary:

• Carboxymethyl cellulose: 4 to 6 months;
• Hyaluronic acid: 6 to 8 months;
• Calcium hydroxyapatite: 1 year.
  

To obtain an optimal voice result, speech therapy treatment may be suggested in addition to filler injection.

Le principal risque de cette procédure est que la voix reste la même ou qu’il n’y ait qu’une légère amélioration après la procédure. Ceci peut se produire si l’injection n’est pas faite au bon endroit, si le produit se déplace, ou s’il n’y a pas assez ou trop de produit injecté. Dans certains cas, il est possible de retourner injecter plus de produit ou le produit injecté au mauvais endroit peut être retiré. Il est rare que la voix soit pire après l’injection.

Dans certains cas rares, un saignement peut se produire durant l’injection ou immédiatement après l’injection. Il n’y a pas de risque plus élevé de saignement chez les patient⸱es prenant une médication anticoagulante. Même si un saignement se produit, il n’est pas attendu qu’un hématome se forme ou qu’il y ait un compromis respiratoire.

Dans moins de 0.02% des cas, l’injection d’acide hyaluronique peut entraîner une réaction allergique locale.

Il est extrêmement rare que la médialisation d’une ou des cordes vocales entraîne de l’enflure ou un saignement qui entraînera un compromis de la respiration, mais cela n’est pas impossible dans certaines situations bien spécifiques (voies respiratoires déjà réduites avant l’injection, fonction pulmonaire diminuée, mauvais état de santé général). Le risque spécifique de cette complication devrait être discuté avec l’ORL avant l’intervention si cela est applicable.

Il y a d’autres risques d’effets indésirables si la procédure est faite sous anesthésie générale. Pour les connaître, vous pouvez lire les risques reliés à la microchirurgie laryngée (MCL).

Après la procédure, il est demandé de ne pas parler pendant 24 h pour éviter que le produit injecté sorte des cordes vocales ou qu’il se déplace. Il ne serait toutefois pas dangereux de parler en cas d’urgence.

Selon le type d’anesthésie, il pourrait aussi être recommandé de ne pas manger ni boire pendant 2 h après la procédure. Passé ce délai, il est permis de manger et de boire normalement.