Thyroplasty is a phonosurgical technique designed to improve the voice by altering the thyroid cartilage of the

larynx The larynx (), commonly called the voice box, is an organ (anatomy), organ in the top of the neck involved in breathing, producing sound and protecting the trachea against food aspiration. The opening of larynx into pharynx known as the laryngeal ...

(the voice box), which houses the

vocal cords In humans, the vocal cords, also known as vocal folds, are folds of throat tissues that are key in creating sounds through Speech, vocalization. The length of the vocal cords affects the pitch of voice, similar to a violin string. Open when brea ...

in order to change the position or the length of the vocal cords.

Types

There are four different types of thyroplasty procedures described by Isshiki: * Type 1 thyroplasty – Medialization of the vocal folds ''(most common surgery for unilateral vocal cord paralysis)''. * Type 2 thyroplasty – Lateralization of the vocal folds ''(in case of airway insufficiency after Laryngeal trauma)''. * Type 3 thyroplasty – Shortening of the vocal folds ''(done to lower the vocal pitch)''. * Type 4 thyroplasty – Lengthening of the vocal folds ''(done to raise the vocal pitch)''.

Type 1 thyroplasty ''(medialization thyroplasty)''

It is the most commonly used surgical procedure to correct unilateral vocal cord paralysis (a condition where the vocal cord of one side is paralysed).

Procedure

In this type of thyroplasty, a rectangular portion of the thyroid cartilage is mobilized and pushed towards the medial side using a piece of silastic block of proper shape under local anesthesia. Earlier, the piece of the thyroid cartilage was kept along with implant and the stitches were taken, but nowadays, the piece of the thyroid cartilage is cut and removed to avoid complications. Medialization Thyroplasty

Types of procedures

Currently, there are four types of implant procedures which are used to perform type 1 thyroplasty. ;Montgomery Thyroplasty Implant system: This system was discovered after years of research and the main advantage of this implant system is that it eliminates the process of customizing the implant at the time of surgery. This system consists of different sizes and shapes of shims made of silastic. It has the most proven success rate and the duration of the procedure is slow in comparison to other implant system. The other advantage is that it does not require suturing. It has reduced incidence of trauma. Montgomery Thyroplasty Implant System

;VoCoM system (vocal fold medialization): This system consists of different sizes and shapes of implants made from

hydroxyapatite Hydroxyapatite (International Mineralogical Association, IMA name: hydroxylapatite) (Hap, HAp, or HA) is a naturally occurring mineral form of calcium apatite with the Chemical formula, formula , often written to denote that the Crystal struc ...

(a naturally occurring mineral form of calcium

apatite Apatite is a group of phosphate minerals, usually hydroxyapatite, fluorapatite and chlorapatite, with high concentrations of Hydroxide, OH−, Fluoride, F− and Chloride, Cl− ion, respectively, in the crystal. The formula of the admixture of ...

). It helps in achieving accurate vocal fold medialization. This procedure is technically reversible. But it should be used in candidates of permanent implantation due to its biocompatible clinical use lasting for nearly a decade. ;TVFMI system: This system generally consists of two sizes of implants made out of pure titanium. It has a lot of advantages and the main one is that it reduces the operative time. Titanium is safer than other implants. It has great biocompatibility. The implants are available in only two variants and they are designed in such a way that they ensure optimal fixation. The implant can be easily made as the titanium sheet is easy to shape. The technique is relatively simple and does not require expensive instruments. ;

Gore-Tex Gore-Tex is W. L. Gore & Associates's trade name for waterproof, breathable fabric membrane. It was invented in 1969. Gore-Tex blocks liquid water while allowing water vapor to pass through and is designed to be a lightweight, waterproof fabri ...

Implant system: In this type of implant system, the implant is made of homopolymer of

polytetrafluoroethylene Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene, and has numerous applications because it is chemically inert. The commonly known brand name of PTFE-based composition is Teflon by Chemours, a corporate spin-of ...

in form of minute beads arranged in a fine fiber mesh. It is

malleable Ductility refers to the ability of a material to sustain significant plastic deformation before fracture. Plastic deformation is the permanent distortion of a material under applied stress, as opposed to elastic deformation, which is reversi ...

and can be inserted through a small window.

Indications

* Unilateral vocal cord paralysis where one vocal cord out of the two is paralysed. * Symptomatic

glottic The glottis (: glottises or glottides) is the opening between the vocal folds (the rima glottidis). The glottis is crucial in producing sound from the vocal folds. Etymology From Ancient Greek ''γλωττίς'' (glōttís), derived from ''� ...

insufficiency (

dysphonia A hoarse voice, also known as dysphonia or hoarseness, is when the voice involuntarily sounds breathy, raspy, or strained, or is softer in volume or lower in pitch. A hoarse voice can be associated with a feeling of unease or scratchiness in the ...

, aspiration) which leads to incomplete glottic closure which in turn results in failure to produce proper sound. * Age-related vocal fold atrophy leading to glottic insufficiency.

Contraindications

* Malignant diseases of the endolaryngeal mucosa. * Previous history of radiation therapy to the larynx for treatment of laryngeal and hypolaryngeal cancers. * Poor abduction of the contralateral vocal folds.

Complications

* Airway obstruction is the most common complication. * Implant migration or extrusion in cases where proper stitches are not taken. * Wound infection. * Penetration of the endolaryngeal mucosa. * Incomplete glottal closure in 10–15% of patients.

Advantages

* The most important advantage is that this procedure is reversible. * It is long-lasting. * It can be performed with minimal anesthesia. * No discomfort to the patient.

Disadvantages

* It is an open procedure. * It is technically more difficult. * There may be limited closure of the posterior glottis.

Limitations

* There is increase in average phonation time (from 4.6 seconds to 15 seconds). * It provides static change to the laryngeal framework but does not have any effect on the dynamic function.

Type 2 thyroplasty ''(lateralization thyroplasty)''

It is a surgical procedure used in conditions like adductor spasmodic dysphonia (a condition in which there is distortion of the voice due to excessively tight closure of the glottis on phonation). Generally, lateralization thyroplasty is intended to prevent this tight closure of the glottis at the terminal stage of phonation by lateralizing the position of the vocal cord. This is a completely mechanical process.

Procedure

An incision is made at midline of the thyroid cartilage. A silicon wedge is used to fix the incised thyroid cartilage in the newly abducted position.

Modified technique

In some specific conditions, different types of thyroplasties are combined for the desired results.

Medialization thyroplasty with arytenoid adduction ''(rotation technique)''

Purpose

The main purpose of this combination is the medialization of the entire vocal cord (anterior and posterior).

Indications

* Open posterior glottis. * In people with high vagal paralysis. * Recurrent laryngeal nerve paralysis with lateralized arytenoid. * Non-rotating arytenoid.

Medialization thyroplasty with arytenoid adduction ''(fixation technique)''

Purpose

* Medial vocal cord fixation.

{{Reflist Otorhinolaryngology