An injection laryngoplasty is an injection of a gel that changes the shape of the larynx. In more specific terms this involves pushing one or both vocal folds into the midline so that the vocal cords can then attain complete glottal closure. Complete glottal closure is one of the two requirements for normal phonation with the other being pliable vocal fold surfaces. The most common setting for injection of hyaluronic acid into the vocal fold is for a single sided vocal fold paralysis. In this setting one of the nerves to the vocal fold is not supplying adequate input and the never is not closing into the midline for phonation and coughing. As such, there can be substantial hoarseness or even severe breathiness and weakened cough. It can also impact the swallowing and lead to aspiration with or without pneumonia.
The other setting where this injection technique is employed is for the ageing or bowing vocal folds. As such, the vocal folds lose some of their bulk and there is muscle hyperfunction. In this setting plumping up the vocal folds so that they close efficiently can greatly improve the voice quality and reduce the vocal effort.
This injection is typically done as an awake procedure without sedation. Once the throat is adequately anaesthetised a small, curved injection cannula is brought into the mouth under direct view with an endoscopic camera. By viewing a large high definition monitor, Dr Broadhurst can direct the injection into the desired point of the larynx. This is an extremely well tolerated procedure and it is exceedingly rare that it cannot be performed adequately.
There are other materials on the market aside from hyaluronic acid but Dr Broadhurst discourages their use. There are some silicone-based pastes that have been injected into the larynx. As these are permanent and create a reasonable foreign body reaction, Dr Broadhurst has inherited a number of complications from outside institutions. In these settings the injection has thought to have been quite straightforward but the result has been the injected material in a suboptimal position. It then requires removal under general anaesthetic and a subsequent formal reconstruction. There is nothing that can dissolve or remove these other more permanent substances, unlike hyaluronic acid. Hyaluronic acid can be dissolved with Hyalase, making it extremely versatile to inject and then remove if need be.