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

thyroid cartilage The thyroid cartilage is the largest of the nine cartilages that make up the ''laryngeal skeleton'', the cartilage structure in and around the trachea that contains the larynx. It does not completely encircle the larynx (only the cricoid cartilage ...

of the

larynx The larynx (), commonly called the voice box, is an 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 inlet is about ...

(the voice box), which houses the

vocal cords In humans, vocal cords, also known as vocal folds or voice reeds, are folds of throat tissues that are key in creating sounds through vocalization. The size of vocal cords affects the pitch of voice. Open when breathing and vibrating for speech ...

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, also called hydroxylapatite (HA), is a naturally occurring mineral form of calcium apatite with the formula Ca5(PO4)3(OH), but it is usually written Ca10(PO4)6(OH)2 to denote that the crystal unit cell comprises two entities. ...

(a naturally occurring mineral form of calcium

apatite Apatite is a group of phosphate minerals, usually hydroxyapatite, fluorapatite and chlorapatite, with high concentrations of OH−, F− and Cl− ions, respectively, in the crystal. The formula of the admixture of the three most common e ...

). 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 a waterproof, breathable fabric membrane and registered trademark of W. L. Gore & Associates. Invented in 1969, Gore-Tex can repel liquid water while allowing water vapor to pass through and is designed to be a lightweight, waterpr ...

Implant system: In this type of implant system, the implant is made of homopolymer of polytetrafluoroethylene in form of minute beads arranged in a fine fiber mesh. It is

malleable Ductility is a mechanical property commonly described as a material's amenability to drawing (e.g. into wire). In materials science, ductility is defined by the degree to which a material can sustain plastic deformation under tensile stres ...

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 is the opening between the vocal folds (the rima glottidis). The glottis is crucial in producing vowels and voiced consonants. Etymology From Ancient Greek ''γλωττίς'' (glōttís), derived from ''γλῶττα'' (glôtta), va ...

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

A specially devised titanium bridge is used instead of silicon wedge. Nowadays, instead of one titanium bridge, two titanium bridges are used for permanent fixation of the thyroid cartilage.

Indications

* The only known indication for type 2 thyroplasty is adductor spasmodic dysphonia, a condition characterized by involuntary movements of muscles of the larynx during speech.

Contraindications

* It is contraindicated in irradiated larynx (when the larynx is exposed to

radiation In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. This includes: * ''electromagnetic radiation'', such as radio waves, microwaves, infrared, visi ...

Type 3 thyroplasty ''(relaxation thyroplasty)''

This procedure is generally done to lower the vocal pitch by shortening the thyroid ala.

Procedure

In this thyroplasty, the relaxation of the vocal cords is done by antero-posterior shortening of the thyroid ala.

Indications

* It is most commonly indicated in males with high-pitch voices (puberophonia) and those who are resistant to voice therapy. * In people with

spasmodic dysphonia Spasmodic dysphonia, also known as laryngeal dystonia, is a disorder in which the muscles that generate a person's voice go into periods of spasm. This results in breaks or interruptions in the voice, often every few sentences, which can make a pe ...

. * In people who have stiff vocal folds with high-pitched breathy voices.

Type 4 thyroplasty ''(stretching thyroplasty)''

Procedure

This procedure is done to elevate the vocal pitch. This procedure consists of lengthening of the thyroid cartilage. It includes

cricothyroid approximation "Voice therapy" or "voice training" refers to any non-surgical technique used to improve or modify the human voice. Because voice is a social cue to a person's sex and gender, transgender people may frequently undertake voice training or therapy ...

Indications

* It is done in people with bow-shaped vocal folds. * Androphonia (condition characterized by low vocal pitch). * Gender dysphonia, linked to

gender dysphoria Gender dysphoria (GD) is the distress a person experiences due to a mismatch between their gender identitytheir personal sense of their own genderand their sex assigned at birth. The diagnostic label gender identity disorder (GID) was used until ...

Combination

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.

Indications

* Arytenoid fracture where there is anterior dislocation of the arytenoid cartilage. * In

cricoarytenoid joint The cricoarytenoid joint is a joint connecting the cricoid cartilage and the arytenoid cartilage. It is a very shallow ball-and-socket joint. It allows for rotation and gliding motion. This controls the abduction and adduction of the vocal cords. ...

ankylosis Ankylosis is a stiffness of a joint due to abnormal adhesion and rigidity of the bones of the joint, which may be the result of injury or disease. The rigidity may be complete or partial and may be due to inflammation of the tendinous or muscular ...

where there is failed arytenoid adduction.

Medialization thyroplasty ''(type 1)'' with stretching thyroplasty ''(type 4)''

Purpose

* The main purpose of this combination is stretching of the vocal cord with medialization of the affected side.

Indications

* Unilateral superior laryngeal nerve weakness.

Medialization thyroplasty ''(type 1)'' with relaxation thyroplasty ''(type 3)''

Purpose

* The main aim of this combination is relaxation and increased mass of one vocal cord.

Indications

* In males with high-pitched, presbyphonic voice.

Bilateral medialization thyroplasty

Purpose

* Medialization of both the vocal cords.

Indications

* Open anterior glottis. * In presbyphonia where there is bilateral vocal cord weakness. * When there is bilateral loss of muscle mass. * Tremor-induced abductor spasmodic dysphonia (AbSD).

Bilateral relaxation thyroplasty

Purpose

* Relaxation of both the vocal cords.

Indications

* In males who have an overly high-pitched voice. * Stable abductor spasmodic dysphonia (AbSD)

References

{{Reflist Otorhinolaryngology